How to Effectively Sell Concrete Countertops to Homeowners

Selling concrete countertops to a homeowner is a very different experience than working with a general contractor or architect or designer. For one thing, the homeowner will often not know exactly what to expect, or will have biased ideas of what the process is going to entail, so it’s very important to communicate well and effectively. Even if you’ve been selling countertops for years, you still might have some kinks in your processes to work out.

The sales process for each client will generally go through the same steps:

  • Initial inquiry/info seeking
  • Meeting for sample viewing or measuring
  • Estimate
  • Buying decision/closing
  • Project execution
  • Follow-up

Navigating the initial inquiry

“Show interest in and be excited about their project. Engage them in conversation.”

The potential client may have found your website via a web search or heard about you from a friend. They may call or email to get more information. Always respond to inquiries the same business day if at all humanly possible.

Spend most of your time asking and answering questions, not spewing information. Answer the client’s questions succinctly and in a way that is consistent with your messaging, and then encourage them to tell you more about what they’re looking for or to ask you more questions. Engage them in conversation.

Show interest in and be excited about their project. You don’t want to come across like you’re grilling them, but your goal is to learn as much about them as possible so that what you teach them about your company and your product fits what they are looking for.

As you talk to more and more people, you will develop your own style and wording for your answers. And you should always tailor your answers to that particular client’s concerns or needs. However, you will hear the same questions about concrete countertops over and over again.

Some Common Questions You Should Know How to Answer

“The more confident you can answer these common questions, the more your customer will trust you.”

Question: How does concrete compare to granite?

Answer: Concrete is very similar to granite in terms of physical properties. It’s a hard, durable countertop surface, and it weighs about the same as granite. It is templated and installed just like granite. It’s very practical in the kitchen. The main difference is the look. Concrete has a more natural, matte look, and it is completely customizable. It really fills a void in countertop looks.

Question: I’ve heard that concrete countertops stain and require a lot of maintenance. Is this true?

Answer: Concrete countertops actually behave similarly to granite in this regard. Granite countertops are also porous and have to be sealed and maintained. Most people don’t realize this because granite is usually too dark and patterned to show stains. Food, acids, and oil will not stain your concrete countertop because we use a high performance sealer.

Question: How much do your countertops cost?

Answer: The cost depends on the square footage, what type of sink you have, backsplashes, edging. Do you have a sketch of your kitchen yet? I’d be happy to give you an estimate on the whole project.

Question: Why are concrete countertops so expensive? It’s just concrete.

Answer: The materials are cheap – just sand and cement. It’s the craftsmanship and work that go into it. It’s like the reason a violin costs more than a wooden pallet – they use the same material, but different levels of craftsmanship. Concrete countertops are really the highest-end possible countertops because they’re made completely from scratch custom and personalized for you.

The Bottom Line

If you’re going to have a successful business relationship with a client, you need to be absolutely crystal clear on what their desires are, and how you plan to meet those desires. You need to be honest: if they have unrealistic expectations, do NOT assure them that you can make it work, but rather educate them as to what exactly you will be able to do and what you CAN’T do.

A Quick Guide to Preventing Efflorescence in Your Concrete Countertops


Severe efflorescence in concrete

Efflorescence. It’s the whitish powdery material that forms on the surfaces of masonry or concrete construction, and also it’s the white blush that can form on sealed concrete floors or concrete countertops. While it poses no threat structurally, efflorescence is an aesthetic nuisance that affects both interior and exterior concrete. This article discusses why efflorescence occurs, how it can be prevented and how to deal with it if it does happen.

There are two kinds of efflorescence: primary and secondary. Primary efflorescence occurs when concrete bleedwater dries on the surface. Secondary efflorescence occurs when soluble mineral salts are leached out of cured concrete.

Efflorescence “growing” on the inside of a concrete block wall.

Primary Efflorescence

Eliminating primary efflorescence begins before the concrete is cast, simply by using basic good concreting practices: Start with a concrete mix that uses well-graded aggregates, a low water-to-cement (w/c) ratio, and fly ash or other pozzolan as a partial cement replacement; use a water reducer to increase workability without adding extra water to the mix.

Extra water in the concrete makes it more porous, weaker, and more susceptible to shrinkage cracking. The extra water is an unwanted internal reservoir that can leach the salts out of the concrete. Concrete made with a w/c of 0.45 or less will produce a relatively strong, dense mix that’s unlikely to have excessive bleedwater.

Making good concrete is just the first step. It does no good to have a well-designed, low w/c ratio concrete if it’s not cured properly. Wet curing under burlap, plastic sheeting or curing blankets allows the concrete to gain strength and density during the critical early days after casting. Well-cured concrete inhibits water movement, and this is one important step to controlling primary and secondary efflorescence. If the concrete doesn’t allow moisture movement, the salts deep within the concrete can’t be leached out.

efflorescence on a polished concrete big-box store floor.

Secondary Efflorescence

All masonry and concrete materials are susceptible to secondary efflorescence, including concrete countertops. Secondary efflorescence is most often caused by moisture or water vapor migrating through a concrete slab, bringing soluble salts to the surface of the concrete. The amount and character of the deposits vary according to the nature of the soluble materials and the atmospheric conditions.

Concrete contains a variety of soluble mineral salts, both from the cement and from admixtures like calcium chloride, and even from chemicals applied to the concrete after it has hardened. It’s those salts that are the “seeds” of efflorescence.

While all concrete has some soluble salts in it, not all concrete will effloresce. Efflorescence will occur only if all of the following conditions exist within the concrete:

  • The concrete must have soluble mineral salts within it.
  • There must be moisture to dissolve the soluble salts.
  • Evaporation or hydrostatic pressure must cause the mineral salt solution to move towards the concrete surface.

If any one of these conditions is eliminated, efflorescence will not occur.

Controlling secondary efflorescence is a more common problem for contractors who have “inherited” pre-existing concrete. The mix itself can’t be changed, so factors that affect water movement into and out of the concrete are where steps can be taken. Identifying and minimizing the sources of moisture are the first step. Reducing the porosity of the concrete to prevent the soluble salts from being leached out is the second step.

This second step to controlling efflorescence is to apply chemical hardeners, also known as densifiers, to existing concrete. These make the matrix less porous by generating calcium silicate hydrates that plug the pores and clog the capillaries.

Curious how repairing efflorescence plays out in a real-world scenario? Read this blog from our backlog that details an example of how to repair a concrete floor with efflorescence that was progressively worsening.

6 Problems with Concrete Countertop Mix Designs and How to Prevent Them

Murphy’s Law states, “Anything that can go wrong will go wrong.” This doesn’t have to be the case with concrete countertops. With some basic knowledge, you can prevent these basic problems with concrete countertop mix designs.

1. Air Bubbles (Pinholes)

Underside of a wet cast ramp sink. The large holes are where air bubbles got trapped under the top cap of the mold.

All concrete will have air trapped in the mix due to the mixing process. Fine aggregates and sand tend to trap air bubbles, and a stiff cement paste won’t allow the air to rise and escape.

The only way to cast traditional concrete so there are no air bubbles (large or small) on the surface is to design the mix so that the fresh concrete is very fluid or can be made very fluid by vibration. Air cannot be made to disappear, dissolve or not get entrapped by adding an admixture. Only a very fluid concrete will allow the air bubbles to push their way through the concrete and rise to the surface.

Often the cast surface will be hole-free but any significant grinding will reveal tiny pinholes just below the surface. Large air bubbles have enough buoyant force to push aside the aggregate and escape, while the smallest bubbles get left behind because they are too small and not buoyant enough to push their way through the concrete.

Defoamers work by preventing stable air bubbles from forming during mixing. Defoamers don’t make air disappear, rather they reduce the cement paste’s surface tension characteristics so bubbles are harder to form. The concrete still needs to be fluid enough to allow the bubbles to escape.

It is often nearly impossible to completely eliminate pinholes. In this case, you can fill them in with a fine cement paste called grout. (This is sometimes called slurry, incorrectly. Slurry is the dirty water produced by wet grinding concrete.)

For a detailed grouting procedure, see this article.

Pinholes in GFRC

When working with GFRC, the energy of spraying the mist coat lays down a thin veneer with no air bubbles. It is still important to use defoamer with liquid GFRC polymers because denser GFRC is stronger GFRC.

It is also possible to direct cast GFRC. This is essentially casting a fluid backer without mist coat. With this technique, it’s possible for fibers to show and for trapped air to cause pinholes to show. The shape of the piece dictates whether you can get a good casting – air rises, so horizontal surfaces may be fine, but vertical surfaces probably will have some exposed air voids. This is also true for traditional wet cast concrete.

2. Curling

Thin concrete beams that have curled (the middle is higher than the ends)

“Concrete mixes that are shrinkage prone will curl more than mixes that are shrinkage resistant.”

Curling is caused by poor curing and storage conditions. When one side of a concrete slab is allowed to dry out while the other side remains moist (or is moister), the concrete will tend to shrink towards the dry side. Prolonged moist curing, and storing the slabs so both sides get even airflow, can control curling.

As a general rule, traditional concrete should moist cure for a minimum of 5-7 days before being allowed to slowly and evenly dry out. However, most concrete countertop artisans use high-performance mixes that allow for a cure time of 1-2 days before proceeding with processing and sealing.

GFRC does not need to be moist cured. GFRC uses a polymer that acts as an internal barrier to keep moisture inside, and that is what achieves “moist curing” over 5-7 days. GFRC should still be kept evenly moist/dry on both sides.

Concrete mixes that are shrinkage prone will curl more than mixes that are shrinkage resistant. Good aggregate gradation, lower cement contents, and low water-cement ratios are the key to making shrinkage resistant concrete. In addition, shrinkage reducing admixtures (SRA) can manage or reduce shrinkage and curling. Some shrinkage reducing admixtures increase the mix water demand and may reduce the strength of the concrete.

For GFRC, the base mix design is extremely shrinkage prone because it is so cement rich. Furthermore, GFRC tends to be used for large, thin slabs which exacerbates the tendency to curl. Make sure that GFRC slabs are well supported so they don’t sag, and ensure there is good airflow under the slab so that moisture doesn’t build up and create differential shrinkage.

3. Hairline Cracks

Hairline cracks (and all cracks for that matter) form when tension forces in the concrete exceed the tensile strength of the concrete. Tension forces in the concrete can be generated from shrinkage, heat or deflection.

Generally, hairline cracks are very narrow and represent a stress-relief response to the excessive tension force. Larger cracks tend to be caused by bending forces that generate large deflections that open up the cracks.

Most hairline cracks form over time as the concrete dries out and shrinkage stresses build up. Keys to managing shrinkage involve good curing, good mix design and possibly the use of SRA’s; see Curling, above.

Heat can cause micro-cracking where the concrete develops micro-hairline spider web or map cracks. Often these can only be seen if water or other liquid is applied to the affected concrete. The use of PVA or AR glass fibers, good curing, and good aggregate gradations can minimize the effects of intense heat. Limiting the temperature and/or duration of heating will greatly reduce the likelihood of thermal cracking.

Bending, due to uneven supports or excessive loading, can cause hairline cracks. If the concrete just cracks but does not open up, and if the load that caused the crack is removed, then the resulting crack is often called a hairline crack. If the load is high enough or sustained, and movement is allowed, then the crack can open up. This is what is called a structural crack.

4. Harsh or Stiff Mix

A very harsh and dry concrete mix

Harsh mixes usually have too much large aggregate or very rough, angular aggregate. This is an issue only with traditional aggregate-based concrete mixes.

Simply adding more cement to the concrete mix can help, but too much cement can cause excessive shrinkage. The better solution is to regrade the aggregates to allow for more fine aggregate. Often blending coarse and rounded aggregate will help with a harsh mix.

Sometimes concrete has low workability or is very stiff because it has a very low water/cement ratio. The common solution to stiff concrete is to add extra water to make it more flowable. This is a very poor solution to a common problem. Cracking, shrinkage, low strength and high porosity often result. This describes common sidewalk concrete.

The better solution is to add water reducer. Concrete countertop mixes typically use high range water reducers that are polycarboxylate based, called “superplasticizers”. Here is a video of how well superplasticizers work:


The equivalent superplasticizer to the one used in the video is WR310. I generally prefer working with a liquid superplasticizer such as WR420.

5. Segregation

“Sometimes a good concrete mix can segregate when too much superplasticizer is used.”

Ideally, all ingredients in your mix are evenly distributed. Segregation is when gravity causes the heavy ingredients such as aggregate/sand to settle, and fluid cement paste and water rise to the top.

Highly fluid concrete mixes tend to segregate if the cement paste viscosity is not stabilized. Segregation occurs when the cement paste is too fluid and not viscous enough to support and suspend the larger aggregate. What happens is that the large aggregate sinks to the bottom of the forms and the pure cement paste forms a runny, scummy layer on top of the concrete. The fluid is not water; rather it is the highly fluid cement paste that has separated from the aggregates due to gravity.

Two common solutions can solve segregation. One is to use a viscosity-modifying admixture (VMA). It’s a stabilizer and thickener.

Another solution is to increase the very fine aggregate content of the concrete. Typically fly ash, microspheres or powdered stone is added, or during the mix design, some of the coarse aggregates are replaced with equal amounts of very fine material. Typically the fine material accounts for about 5% by volume of concrete.

Sometimes a good concrete mix can segregate when too much superplasticizer is used, or, the wrong superplasticizer is used in the attempt to create a highly fluid mix. Polycarboxylate superplasticizers have paste stabilization characteristics that other superplasticizers don’t, and the use of either VMA’s or extra fines can augment the stabilization.

6. Long Set Time/Low Early Strength

Several factors influence the set time for concrete. These include temperature, admixtures, and water content.

Temperature: Colder temperatures slow the hydration rate, increasing set time and strength development. In contrast, high temperatures sometimes speed the set time so much that you can’t work with the concrete fast enough. In this case I use ice as a substitute for some of the mix water. Both are measured by weight.

Admixtures: Chemical retarders, some synthetic pigments, some liquid pigments, low reactivity pozzolans used as cement replacements, and some water reducers can all slow or retard the setting rate of concrete.

Water content: High w/c ratios also slow the setting time somewhat.

These are a few of the issues that could occur with concrete countertop mixes. To understand more about precast concrete countertop mix design, please see the article “The best mix design for concrete countertops”. There is also a huge amount of information about GFRC and its mix design available here.

Crafting Unique and Custom Concrete Projects | Curtis and Jamie McCharles of Timmins, Ontario

Concrete Bar crafted by CMGC

Getting into the Concrete Business

“It’s not just about learning concrete. You have to get good at everything that goes along with being a business owner if you want to make this work.”

Curtis and Jamie McCharles, of CMGC in Timmins, Ontario, got into the custom concrete business in a rather unexpected way. After taking in a football game while traveling around Ontario, they stopped off at a bar. That bar had a counter that was made of concrete, and it caught their attention.

Both Curtis and Jamie had plenty of experience working in the construction business and had launched CMGC in 2013. The business name stands for “Curtis McCharles General Carpenter,” and the couple handles all manner of home renovations. Nonetheless, Jamie describes being captivated by the beauty and versatility of concrete and its potential applications.

“We drove around looking for artisans who did it, and we couldn’t really find anyone,” Jamie McCharles said.

While they eventually found a weekend course in concrete, and plenty of information online, that didn’t provide the sort of in-depth education the pair were in search of. They decided to explore CCI as an option. A conversation with Jeff and Lane of CCI persuaded Jamie and Curtis that CCI’s program was what they were looking for.

“Speaking to Jeff and Lane: from their interview process, it was clear they didn’t want people in the class who weren’t ready to take that step. Just the professionalism that we saw in their website, in their content, that’s what spoke to us. We’ve always felt that way about the standard of work in our carpentry business.”

A unique fireplace concrete project by CMGC

The CCI intake interview convinced Jamie and Curtis that CCI could give them the level of training they sought. “I’ll always remember that interview. Curtis and I were sitting in a pickup truck and, when we got off the phone, we said ‘Yeah, this is going to be worth it.’”

Curtis and Jamie flew down to Raleigh to attend CCI, along with their son, who was less than a year old at the time. “We’re a team,” Jamie explains. “So he couldn’t leave me behind.”

Jamie said the class lived up to the expectations they’d developed from speaking with Lane and from CCI’s marketing. “There were no distractions or time wasting,” she said. “They want people who are serious about this and who want to learn. When we told Lane what our background was, she felt that it would really be an asset for us.”

Jamie and Curtis work as a team in every aspect of their business, which has proven an asset, as well. As involved as working in custom concrete can be, there’s a lot more to being successful in the business than being knowledgeable about GFRC.

“We didn’t just have to learn this industry,” Jamie says. “We had to become entrepreneurs, marketing experts, smart business people. We had to build a network. It’s not just about learning concrete. You have to get good at everything that goes along with being a business owner if you want to make this work.

The artisans behind CMGC

How CMGC Approaches Their Work and Clients

“That’s what special about concrete: good concrete is made by people who care.”

While CMGC sets high standards for their work, they also put a strong emphasis on building connections with their clients.

“We’ve been very lucky,” Jamie says. “After each of our projects, we walk away with a new set of friends. Our close group of friends are our past clients.”

According to Jamie, building those relationships isn’t just about skill. Authenticity also plays a big part in establishing a reputation. “People can tell if you’re only in this for a buck or if you’re in it because you love what you do,” she says.

The quality and creativity of CMGC’s work reflects that artisanal love of their craft, with great attention being given to the details of each piece they produce. They strive to create concrete pieces that are truly made to suit the client.

“That’s our edge, our marketing tool,” Jamie explains. “We’ve committed ourselves to never making the same piece twice. Every piece is made to fit the space that we’ve seen, for the people that we’ve met. I have a harvester that sources timber and trees that we’ve described to him. We have steel suppliers that bring in the pieces we need. Everything’s thought out it in a way that makes each piece special to the client.”

In the end, Jamie says, it’s the attention to craft and creativity that prevents a piece from being generic. “You need a person who cares to do that,” she says. “That’s what special about concrete: good concrete is made by people who care.”

There was plenty of practice required for Curtis and Jamie to achieve their current level of skill. As many new concrete artisans have likely experienced themselves, the first piece CMGC produced, a laundry top for their own house, wasn’t their best work, but they found nostalgic value in it.

A beautiful sink made by CMGC

”We made every mistake we could have made,” Jamie laughs. “We installed it anyway. It’s a reminder of how far we’ve come.”

Reaching Out to a New Market and a Community of Professionals

“For the money a client spends to work with an artisan, they need to be one-hundred-percent confident.”

While CMGC has established a good reputation in their market and plans on expanding their reach through further marketing and their growing reputation, there have been challenges.

“No one really knew about concrete here,” Jamie says. “We’re eight hours north of large urban centers like Toronto which tend to set the trends and have the largest variety of products. Being so far away leaves places like Timmins a little behind when it comes to innovative or trending design. It was a challenge to bring this new product that no one had experienced before and develop our own skills and style with it and make that appealing to our market.”

The environment itself and the business’s location sometimes pose challenges, as well. “We’re dealing with different humidity, temperatures, finding products that can be delivered to Canada,” Jamie said. “There’s a huge learning curve.”

While CMGC has embraced those local challenges, they also feel that what they do reflects on the entire industry and they take that quite seriously.

“You have to go into it willing to make this product the best it can be,” she says. “If you don’t, then you’re hurting the entire industry. For the money a client spends to work with an artisan, they need to be one-hundred-percent confident.”

Gorgeous concrete countertop from CMGC

McCharles says that, in addition to feeling like they can reach out to other professionals for help when they need it, they also try to help other people in the industry, and Jamie stresses that such a spirit is beneficial across trades.

“When you’re a successful tradesperson and your priorities are based on doing a good job and being honest and providing people with the best that you can do, when you care about what you do and what you put out there, it doesn’t matter what industry you’re in,” she says. “There are carpenters and associated tradespeople we get along with wonderfully. It all depends upon what standards you put yourself on. When you’re communicating with people working to that same standard, it’s very easy to let information come and go.”

Still, for CMGC, it’s the end product, and all the work and creativity invested in it, that forges a connection between the client and the final product that CMGC delivers. According to Jamie, that’s not something that can be mass-produced, and there’s a genuine artistic spirit to how the couple approaches their work.

“If you go buy a print of a painting off of eBay,” she says, “yeah, it’ll look good, but it’s not going to speak to you in the same way as seeing the original painting in a gallery.”

CMGC’s web presence can be found on Facebook and at

Fibers in Precast, GFRC, and ECC Concrete Countertops

In the last article, I discussed how PVA fibers are used in engineered cementitious composite concrete (ECC). Today I’d like to review some of the many types of fibers that you can use when making concrete countertops and some of their purposes, as well as explain which types of fibers are appropriate for which method/mix:

  • Traditional precast
  • GFRC
  • ECC

3D Fibers

What Fibers Can Help With

Fibers are used in concrete for a variety of reasons, but not all fibers do the same thing or have the same effect. They can be used for reinforcing or can be used to prevent shrinkage and cracking.

  • When fibers are used for improving the flexural/tensile properties of the concrete, this is known as primary reinforcing.
  • When fibers are used for plastic shrinkage control, and to prevent crack creation and propagation in the cement matrix by bridging the microcracks, it is known as secondary reinforcing.

The choice of what fiber to use depends upon a variety of factors. In commercial construction, cost is often the primary factor, as most fibers are used for secondary reinforcement reasons. For concrete countertops and other creative concrete applications, the cost of the fiber is often less important than the effect of the fiber on the concrete’s performance and on its appearance.

Additionally, different mixes are best suited for different fibers. GFRC fibers must be used in high volumes, so the mix is built around a specific fiber used in a specific dose. ECC is the same way, but with different mix proportions and very different fibers.

The takeaway here is that fibers are not generic ingredients that can be plugged into any mix without considering the benefits those fibers can bring and their effect on the concrete’s workability.

Fibers as Primary Reinforcing

Most fibers used in most types of concrete don’t provide any benefit to boosting the tensile strength of the concrete. These tend to include cellulose, polypropylene, nylon, and other common types of “stealthy” fibers. Only certain types of fibers can, and these must be carefully matched with a tailored mix design built around the type and amount of fiber used in the mix. GFRC and ECC are two examples of specialized mixes that use specialized fibers.

Fibers as Secondary Reinforcing

As the concrete sets and transforms from a workable paste into a hard solid, plastic shrinkage can occur. This is especially true in concrete slabs exposed to heat or wind. The matrix of fibers helps to stabilize the wet concrete and distribute the shrinkage stresses so that large cracks are minimized or eliminated.

Fibers can help reduce shrinkage and cracking.

Fibers can also help combat shrinkage by spreading the tensile loads across the concrete. The fibers act as a net, in this case holding small cracks together and transferring stresses across cracks into adjacent concrete. This helps keep any cracks that appear small, often too small to even see. Rather than having one or two large, highly visible cracks, you’re left with a series of small, hard to see cracks spread across the slab.

The Different Types of Fibers used for Traditional Precast

Fibers in precast concrete countertops can play a valuable role in both boosting primary reinforcing and providing secondary reinforcing. However, the type of fibers and the methods used will vary depending on which type of reinforcing you’re after.

Most commonly used fibers are synthetic, either polypropylene or nylon, but some are natural, like cellulose fibers. Let’s dive into a few of your fiber options. Remember, this is not an exhaustive list!

PVA Fiber for Concrete Countertops

Polypropylene or Nylon Fibers – Polypropylene and nylon fibers are used for shrinkage control; they add no structural tensile strength to the concrete. These fibers play a valuable role during the curing process but provide no benefit after. They simply stretch too much to provide any resistance to tensile stresses.

Polyvinyl Alcohol (PVA) Fibers – PVA fibers have some structural strength and can also be used for shrinkage control. While they cannot replace reinforcing steel, they improve the mechanical properties of cured concrete, boosting its strength. These are the best choice when the fibers cannot show at all. However, caution must be used because these fibers are so fine, very small volumes can choke the mix. They are an important component of ECC (see below).

Alkali Resistant Glass Fibers – AR glass fibers are the type of fiber primarily used with GFRC (see below). They can also be used to provide primary and secondary reinforcing in traditional steel reinforced concrete countertops. These fibers are special glass fibers that won’t break down, even when in contact with alkaline concrete. They will show in traditional precast, however, and are not commonly used.

Other Fiber Choices for Precast

Some fibers are strong and can provide adequate structural strength, but the material they’re made of doesn’t make them a good choice for concrete countertops. They are primarily in large industrial concrete projects.

hooked steel fibers

Hooked Steel Fibers

Hooked Steel Fibers – Hooked steel fibers possess structural strength. They can help to distribute tensile stresses across the countertop. However, they are large, ugly and will show.

Chopped Carbon Fibers – Chopped carbon fibers have stiffness and strengths equal to or greater than steel. Reinforcing is still needed, but the fibers provide a helpful boost of strength and minimize shrinkage during the curing process. But because they are black, carbon fibers will show definitely show in most concrete that’s not black or very dark.

Fibers used for GFRC

Properly Aligned Fibers in GFRC, Resulting from Thin Layer and Rolling

GFRC utilizes both specialized concrete and strong AR glass fibers. Both possess benefits on their own, but when combined they become something amazing. The tensile strength helps GFRC to resist pulling apart forces while the flexural strength helps it to resist bending. The glass fibers and the high polymer content of GFRC provide these unique properties that are essential to a long lasting concrete countertop.

Rather than using steel for reinforcement, GFRC relies on these glass fibers to prevent cracking and breakage. Making GFRC isn’t as simple as just adding some fibers to your concrete mix design. The size, shape, material, and amount of fibers used has a significant effect on the concrete. Using the wrong type of fiber, or not using enough, can lead to disappointment and a failed concrete countertop.

Because AR glass fibers are used in such high volumes in GFRC in order to provide the necessary strength, they would be extremely visible if a veneer coat without fibers were not used. This fiber-free veneer coat is called a mist coat or face coat. It has no strength and is solely for aesthetic purposes.

For more information about GFRC, please see this index of GFRC articles and videos.

Fibers Used in ECC

As explained in the last article, PVA fibers are used in ECC to provide both structural strength and shrinkage control. The combination of well-dispersed, micro PVA fibers and the strong, fine-grained homogeneous matrix is what results in the amazing ability of ECC to bend and crack without losing strength. Because of the highly dispersed microfibers, cracks tend to be small, and sometimes even invisible.


There are many different types of fibers used for different reasons in the various methods of creating concrete countertops. My recommended usage is:

  • Precast: For the type of precast concrete we make, you may optionally use acrylic, nylon and PVA fibers, at a dose of 0% to 0.5% of total mix weight. This is only for secondary reinforcement and plastic shrinkage cracking. It does not replace primary steel reinforcing. Higher doses can choke the mix – essentially turning it into a big hairball!
  • GFRC: Use AR glass fibers, 3% of total mix weight, properly compacted. GFRC is not GFRC without AR glass fibers as a replacement for primary steel reinforcing. (See this article.) To purchase AR glass fibers, click here.
  • ECC: ECC is a complex composite of PVA fibers, 1% to 2% of total mix weight, in a properly engineered mix utilizing very fine aggregates. It is impractical to prescribe a DIY recipe for ECC due to the complexity of the mix design.

The Versatility of ECC Concrete

Conventional concrete versus bendable concrete made with ECC

ECC (Engineered Cementitious Composite) is a specialized form of concrete developed in the early 1990’s by Dr. Victor Li, a professor of Structural and Materials Engineering at the University of Michigan. Dr. Li wanted to produce a form of concrete that wasn’t brittle, and that retained its strength even after it cracked.

ECC has properties and characteristics not shared by other forms of fiber reinforced concrete (FRC). These include:

  1. Tensile properties greater than conventional FRC
  2. Easy mixing and casting
  3. Low fiber volume (compared to GFRC)
  4. No weak planes in the cast concrete

Not Your Average Concrete

ECC is a mix that provides flexibility and high bending (flexural) strength.

ECC is not just ordinary concrete with fibers in it. It is a carefully tailored marriage of:

  • cementitious binder
  • very fine aggregates
  • PVA fibers

The types and amount of fiber play an important role, but so too does the formulation of the concrete itself.

ECC depends upon the micromechanical interaction between a strong, fine-grained homogeneous matrix, and well-dispersed structural microfibers. This engineered composite is carefully tailored to create a form of concrete that can bend and crack without losing strength. And because of the highly dispersed microfibers, cracks tend to be small, and sometimes even invisible.

ECC bends without developing large cracks, but it can have visible cracks.

The basic ingredients, composition, and proportions of ECC are similar to, but not the same as, the base mix used for GFRC. ECC mixes have less sand than GFRC, and the sand gradation itself is more important in ECC. The greatest difference between the two is in the fibers.

ECC is a mix that provides flexibility and high bending (flexural) strength, similar to what GFRC provides. While GFRC uses high volumes of large AR glass fibers, ECC uses comparatively low volumes of small synthetic PVA (polyvinyl alcohol) fibers.

Like AR glass fibers, PVA fibers have excellent structural properties that are ideal for ECC and set them apart from the ordinary fibers used in flatwork.

Ordinary fibers like nylon, polypropylene, and cellulose are either too stretchy, weak, or both, and these ordinary fibers function as stabilizing agents and are there only to help control plastic shrinkage. None of these add any strength after the concrete hardens.

In contrast, PVA fibers have some structural strength and can also be used for shrinkage control. They improve the mechanical properties of cured concrete, boosting its strength.

Comparing ECC with GFRC

Casting is faster and more efficient.

GFRC uses bundled alkali-resistant (AR) glass fibers in high doses (typically 3% for premix GFRC, and 5% and higher for spray-up applications). AR glass fibers are typically 19mm long, and the large, 200 filament bundles can be very visible if the fibers become exposed. This aesthetic drawback is why GFRC usually has a face coat, which is a decorative veneer layer that often is fiber-free.

GFRC is a material originally designed and optimized for the efficient casting of single-sided pieces, where one face of the casting is decorative, and the opposite side remains unseen.

While wet casting GFRC with only a flowable backer is possible (it’s called direct casting, and foregoes a face coat), the large AR glass fibers just below the surface are sometimes noticeable, and, the presence of the highly visible fibers in the concrete preclude grinding and polishing. Thus, direct casting is limited to pieces where an as-cast surface is desired, and the visible presence of large fibers is acceptable.

PVA Fiber for Concrete Countertops

PVA Fiber for Concrete Countertops

What makes ECC different from GFRC is that the PVA fibers are mixed into the whole mass of the concrete, instead of just in the backer layer. PVA fibers are nearly invisible when properly dispersed during mixing, unlike GFRC fibers which need to stay in large, very visible bundles.

Since PVA fibers are transparent, short (only 6-8mm long), and their diameter is a fraction of the diameter of a human hair, they disappear in the mix. This greatly simplifies mixing and casting, as there is no need for a separate face coat.

ECC can be made stiff and hand-packable, or, it can be made fluid and vibrated. Casting is faster and more efficient, as molds can be filled in one continuous pour, rather than in individual layers. This versatility makes ECC a smart choice for both precast and cast-in-place applications.

However, the complexity of ECC makes it impractical to prescribe a from-scratch mix formula. (In contrast, GFRC is a very simple mix easily made from scratch.) For this reason, The Concrete Countertop Institute does not have a from-scratch mix calculator for ECC and recommends that you buy a preblended ECC mix such as the Buddy Rhodes ECC Blended Mix product.

Sponge for Knowledge: How to ensure that training benefits your business

Getting Equipped in Class

“If I had known how to do it [CCI’s] way, it would have been a lot easier.”

Like many of the students who come to The Concrete Countertop Institute, Matt Shields of Owasso, OK already had experience working with concrete. He ran his own business, Ramcrete Concrete Designs, for more than ten years. CCI’s classes, as Shields hoped, helped him develop very advanced skills in GFRC. In addition to those GFRC skills, Shields learned a great deal about business, and has applied those lessons in ways that have helped his to business grow.

Right before attending CCI’s Ultimate class in 2016, Shields had taken on a precasting job that motivated him to update his skills.

“I went there [to CCI] because of the process that they were teaching,” Shields says. “I wanted to know how to do the GFRC style and to get better at precasting. I had precasted a job before that and we made solid, and heavy, multiple pieces. If I had known how to do it [CCI’s] way, it would have been a lot easier. We were carrying pieces that were basically twice as heavy as we were making in class. I said, ‘There has to be a better way to do this.’”

A self-described sponge for knowledge, Shields said he went into class with the right attitude, determined to get as much as he could out of the GFRC training. The benefits of the training turned out to be multifaceted. Since the training, Shields has gotten more attention for his work, has been able to handle customer questions in a way that gives them confidence in his abilities and, importantly, he has been able to charge a fair price for the intricate, knowledge-intensive work that GFRC involves. Those benefits did not take long to manifest after Shields finished his training.

“My Facebook has gone from twenty people liking it to almost three hundred within a couple of months, just because we’re promoting concrete countertops,” Shields says. “People are searching for that and finding it. Last week, I had forty new views on my website from Facebook.”

Shields is able to handle quite a bit of his advertising himself. While a website company handles his web page, Shields takes portfolio pictures himself, posts them on Facebook and sends them off to the website designers to be included in his site.

The increased interest in his work is not solely due to the venues he uses for publicity. Shields credits his improved outreach largely to the quality of the work he’s been able to produce since attending CCI.

The Business Side

‘”This is a high end product, you should not give your training away.”

Quality work, however, requires time and money. In addition to teaching state-of-the-art GFRC skills, Shields noted that Lane Mangum of CCI emphasized the need to run a business in a legitimate way, which means charging appropriate prices for one’s work.

“Lane’s very nice about it,” Shields explains, “but she says, ‘This is a high end product, you should not give your training away.’ Lane’s been out there and has done it and can explain it in a real way,” Shields says. “I liked that part of it. I didn’t expect the business side of it as much as I got.”

Shields said the knowledge and skills he acquired also translated to him being able to outdo his competition in terms of customer service.

“You get the skills to explain things to the client without giving away your secrets,” he says. “When customers call you, they want you to know what you’re talking about. If you don’t, the customer will know that. With the education, you can transfer that to working with the client and that’s why people will pay more.”

Shields has only had one client who turned him down over price. Shields didn’t offer a discount and the customer was not receptive to the idea of paying a bit more for a quality product. “He wanted something cheap and that’s probably what he got. He was just interested in one thing: price.”

Shields has stuck to his guns about prices and, because of that, he was able to pay the entire cost of his CCI training with the income from his first job after he graduated, a strong argument for not lowballing work.

Simply because Shields has acquired a range of updated skills and has been able to demand a better price for his work doesn’t mean that Ramcrete now only takes on the priciest jobs. Shields wants to work with customers at all price ranges and is also coming up with new ways to translate his skills into more business. He’s currently in the process of launching a new product that makes outdoor kitchens, a big seller in Shields’s market, more flexible and customizable. The old process Shields used to create outdoor kitchens required hiring a mason and was overly complex. His new product will incorporate all the flexibility and quality of GFRC, along with multiple purchasing options, to make outdoor kitchens more accessible, no matter what the customer might want. Shields is ambitious when it comes to getting his idea to market.

“I want to sell two hundred of these next year,” he says. “That’s less than one per day. I can make that work.”

Advice for New Graduates

Shields has some simple advice for newly-graduated alumni of CCI, and his advice speaks to having skill and integrity as a business person.

“Start making samples,” Shields says when asked what graduates should do first. “Get your hands dirty making this stuff and tell everyone about it. You need to get your mistakes out of the way.”

Shields is not offering armchair advice. Making samples is exactly what he started doing as soon as he returned home from class. Shields compares it to writing out one’s homework after getting home from school. The process of using the knowledge fosters memorization of what was learned and allows the development of better skills. Shields has even gotten sales from pictures of samples he worked on while at CCI.

Shields says there’s another real advantage that comes with being able to show customers samples of your own work. “I do not believe in showing someone else’s work if you didn’t do it,” Shields says. “You’ll set yourself up for failure really fast.” By creating samples and only showing customers projects he’s worked on, Shields can assure customers that he can deliver on what he promises.

In fact, Shields has already gone through several pallets of material since graduating CCI. He strongly advises new graduates to do the same; to not just think about how they want to apply their skills, but to actively do so, right away.

“If you go to class and don’t buy any product and don’t make anything right away, you’ll never do it,” he says.

Why You Should Be Using GFRC For Your Concrete Projects

What is GFRC?

“GFRC is a great option for concrete countertops, three-dimensional elements and more.”

If you aren’t yet familiar with glass fiber reinforced concrete (GFRC) you should be. It’s made by combining a mixture of fine sand, cement, polymer (usually an acrylic polymer), water, other admixtures and alkali-resistant (AR) glass fibers. Many mix designs are available online, but you’ll find that all share similarities in the ingredients and proportions used.

Just like regular concrete, GFRC can accommodate a variety of artistic embellishments including acid staining, dying, integral pigmentation, decorative aggregates, veining and more. It can also be etched, polished, sandblasted and stenciled. If you can imagine it, you can do it, making GFRC a great option for creating concrete countertops and especially three-dimensional concrete elements.

Some Reasons to Love GFRC

1. It’s lighter than precast.

This beautiful outdoor table by DecoBton in Haiti is made from foam cored GFRC.

Because GFRC can be made 1/2 the thickness of traditional precast, it is automatically 1/2 the weight. And, because GFRC does not use stone or as much sand, which are denser and heavier than cement, the weight savings is even greater.

Precast is typically made 1.5″ thick and weighs 18 pounds. 3/4″ thick GFRC weighs 8 pounds per square foot.

2. It’s really thin.

The effective minimum thickness for precast is 1.5″ because of the strength and the steel reinforcing required. GFRC’s practical limit is only about 1/4″.

3. You can work fast with it.

Because GFRC has high early strength, in part provided by the fibers, it can be demolded quickly. Most GFRC projects can be demolded in 24 hours. In general, traditional precast projects should stay in the molds at least a couple of days. Faster turnaround means you can do more projects and bring in more revenue.

4. There’s less likelihood of cracking compared to precast.

Because of GFRC’s strength and toughness, it can take a lot more abuse before it cracks. GFRC can even bend!

5. Complex 3-dimensional shapes are easy.

If you can build the mold for it, you can make it out of GFRC. Even shapes that seem difficult because of the spraying angle can be created by clever assembly of the mold.

GFRC In Action

“GFRC provides many advantages to creative concrete professionals.”

Here’s a student project from CCI alumnus Jake Creighton of Countryside Concrete in Belle Plaine, Minnesota.


GFRC makes one great concrete countertop, but that isn’t all it can do. Unique concrete projects like this one are usually born from some kind of need. The homeowner had a preexisting cast iron tub with tiled walls. They were tired of cleaning grout and dealing with broken tiles and cracked grout. They wanted an easy, low maintenance solution. Jake suggested using concrete panels as a surround. The homeowner loved the idea and Jake got to work.

GFRC was a great choice for this project, because it can be made lighter than conventional concrete, and therefore allows for larger panels.

GFRC provides many advantages to creative concrete professionals, allowing them to be more creative and ultimately be more successful in their businesses.

Take the Next Step

You can learn GFRC! We offer a variety of video GFRC training as well as GFRC Equipment and GFRC Materials, also available in convenient kits. For the ultimate in hands-on training that includes GFRC techniques, check out our Ultimate Concrete Countertop Training class.

Advice for New Concrete Countertop Professionals

By Jason Gillis of OASIS Custom Concrete Designs

Get started on your creative concrete journey by hearing from three alumni of the Concrete Countertop Institute. Hear advice directly from concrete professionals on how to start, improve and thrive in this industry.

Drew Teaman

“High standards pay off.”

In only three years, Concrete Countertop Institute graduate Drew Teaman has built a successful custom concrete business——in Jacksonville, Florida, with 6 employees and a company-owned building.

“[At first] I did a lot of DIY stuff, helping people out, and then I got into concrete very, very slowly,” he says. “One day, I decided I was going to go for it and started this thing on my own.”

Where the aspects of customer service are concerned, Drew sets high standards and it pays off in boosting the company’s reputation and customer relations.

Good salespeople know that managing expectations is a significant part of customer service, something that, from his many years in sales, Teaman brought to his business. Sometimes, that means educating customers about what custom concrete work really entails.

Teaman makes an effort to reach out to the customers so that they understand the work involved with GFRC. “We just walk them through. They’re like ‘Okay, I get it,” he explains. “For most people, they understand that it’s an expensive product because it’s hand-made.”

He credits Jeff and Lane of CCI with offering a lot of insight into customer relationships. “Jeff and Lane did a good job of making sure you know how to set those expectations with customers, “he says. “There’s room for variation. This is a custom, hand-made product. As long as the customer understands that, it’s good.”

He credits some of his success to tenacity but, in the end, he still comes back to the people he works with, and that doesn’t mean hiring “yes” men. “You need a support network of people to check you; checks and balances,” he says.

Brent Indenbosch

“Make sure you’re prepared to invest in the right tools.”


Brent Indenbosch, an alumnus of The Concrete Countertop Institute, has a creative streak. Ability is one thing, but one must have the means to manifest their best ideas into something real, and something salable, of course. To that end, Indenbosch offers some excellent advice to those who might be considering starting up their own businesses, or even applying the skills they’ve learned just for themselves.

Fiber optic bathroom concrete countertop by Brent Indenbosch

“Make sure you’re prepared to invest in the right tools,” Indenbosch replied when asked about what he’d advise people before starting out. “You need a decently sized shop,” he added, emphasizing that space is an important consideration when creating pieces. Indenbosch also recommended being aware of the time involved in creating a given project, as they can sometimes be surprisingly demanding in that regard.

“I’m really looking forward to going back [to CCI] again,” he said. Indenbosch believes that the real world experience he’s acquired since attending The Concrete Countertop Institute will help him to get more out of further education. He noted that having experience certainly gives one an edge in knowing which questions to ask.


Jason Gillis

“CCI is the basic institution for learning this trade.”

Jason Gillis of OASIS Custom Concrete Designs in Leominster, MA has a business that’s been steadily building steam since he attended The Concrete Countertop Institute. Formerly a flatwork concrete contractor, Gillis has been working on artisan concrete projects for major designers in the area he services.

Gillis has put a lot of effort, and creativity, into building OASIS Custom Concrete Designs. He went to work right away after getting his education at CCI. Asked what advice he’d give people just starting out as concrete countertop artisans, Gillis said “You’ve got to be confident, because it works. All these other businesses prove it works.”

By Jason Gillis of OASIS Custom Concrete Designs

By Jason Gillis of OASIS Custom Concrete Designs

“Getting paid education is key,” he said. “Like going to CCI with Jeff and Lane. I don’t think I could have learned it any better than what they taught. The technique you learn at CCI; that’s where the highest end of this trade comes from,” Gillis said. “Jeff’s amazing,” he added, “as is Lane.”

Gillis noted that the skills he learned at The Concrete Countertop Institute were foundational. “CCI is the basic institution for learning this trade,” he said.

Caleb Lawson: Alumnus Success Story

Outdoor Grill Countertops

Caleb Lawson of Price Concrete Studio in Orlando, FL spends a lot of time educating people about what concrete can bring to their building plans, whether he’s talking to homeowners, architects or designers. Aside from spreading understanding about the versatility of the material, the time he spends educating people is also good for his business. Even the architects and designers he regularly reaches out to often have no idea what types of creative challenges can be addressed with concrete.

“A lot of these architects are looking for what we do, but they’re unaware that concrete can do it,” he says. “They’re left with trying to make workarounds with other materials when, really, concrete could do it.”

Lawson met one designer he works with by chance. The designer had an office near Price Concrete Studio and took it upon himself to see what Lawson’s company had to offer. It just so happened that Lawson’s company was the ideal provider for the kind of creative work the designer prefers.

Price Concrete Studio

“He just stopped by one day and, through that conversation, we got two jobs,” Lawson says. “He likes to push the envelope. I love it.”

Price Concrete Studio has created some truly innovative pieces for that designer’s firm, including a green concrete table with brass inlays, a pink console table and more. Lawson continues to work with the designer, and several others, today.

Starting With An Advantage

For many people starting out with their own concrete countertop business, such luck might be harder to come by. Landing their first clients is a significant and, sometimes, very intimidating challenge. Lawson had something of an advantage in that regard. Price Concrete Studio had been in business for ten years before he purchased it, so the firm already had a client base.

Initially, Lawson, who says he “loves working with his hands,” approached the owner of Price Concrete Studio and proposed purchasing the company. The owner wasn’t ready to sell, but Lawson started working with the firm.

“Getting projects was a bit easier for me than it would be for someone starting from scratch,” Lawson says, “but I had to learn the trade. My challenge was to maintain the reputation that my predecessor had built over the last 10 years. After about eight months [with Price], I realized I was in over my head and needed to be trained better, so I went to CCI,” he says.

Color Treated Concrete

Six months after finishing CCI concrete countertop training in 2013, Lawson took over Price Concrete Studio as the full owner.

Maintaining the company’s reputation turned out to be no small endeavor. Price Concrete Studio routinely partners with builders who work on multi-million-dollar construction; a clientele that demands the highest-quality. “Because of CCI, I was able to provide that,” Lawson says.

Building on Existing Business

“It’s all about relationships and education”

To keep the business growing, Lawson used an educational outreach effort to architects and designers. He hosts what he calls “lunch and learn” events. At those events, Price Concrete Studio provides lunch for a group of architects and designers. In exchange, Lawson gets the hour to tell the attendees about what custom concrete work can add to their projects.

“To me, it’s all about relationships and education,” he says. “They don’t know [concrete] is there. You have to explain to people that concrete can pretty much do anything you want.”


Outdoor Concrete

Lawson says that his educational outreach to clients often extends to homeowners, as well. Many of them have no idea about the flexibility that concrete offers, assuming that it’s only suitable for the traditional roles concrete occupies in construction.

“A lot of my job with homeowners is telling them, ‘Don’t be limited, it doesn’t have to be just gray. It can be purple; it can be pink: you can have whatever you want. If you want grey, fine. If you want a particular shade of blue, we can do that, too.’”

Even after having learned about what concrete can do for their projects, it sometimes takes time for customers to decide to go with what Lawson has to offer.

“It’s kind of a long game. Sometimes you tell people what you can do and have to wait for six months or a year for them to tell you to go ahead,” Lawson says.

Education > Appreciation

“Get the education and then use your resources.”

Waiting for clients to come around takes patience, of course, and Lawson particularly advises against low-balling jobs just to get the work. For Lawson, part of educating clients about the work involved in creating custom concrete countertops and other features is explaining to them the long and complicated process from concept to completion.

Barstools and Countertop

Lawson also recommends using available resources as much as possible. He still calls Jeff and Lane from The Concrete Countertop Institute when he needs advice and, beyond that, he relies on the community of skilled craftspeople who work in the industry for assistance, as well. Lawson sees more potential in fostering a helpful, cooperative community than he does in undercutting prices and other forms of aggressive competition between concrete countertop companies.

“If you help the community develop a better product, then ultimately, it’s going to help you because people will see the high bar that’s been set,” Lawson says.

Lawson advises two strategies, in particular, for those just getting started out in GFRC.
“My advice to everybody is to get the education, and then use your resources,” he says.

How Concrete Commander Built a Successful Creative Concrete Business


Creative concrete and wood furniture and fire bowl

In only three years, Concrete Countertop Institute graduate Drew Teaman has managed to build a successful custom concrete business——in Jacksonville, Florida. Though easy-going and laid-back in conversation, the story of how he built his business demonstrates a level of flexibility, tenacity and creativity that oftentimes separates successful business owners from those who struggle to get off the ground.

Teaman, with a degree in exercise science, experience as a personal trainer and fifteen years of experience in pharmaceutical sales, doesn’t, at least on the surface, sound like someone who’d be interested in going into GFRC. Before he took up pharmaceutical sales, however, he worked as a salesperson for a company that sold concrete repair products to the military. Eventually, Teaman graduated from both the Ultimate and Advanced Molding technique programs at The Concrete Countertop Institute and launched his own business.

“[At first] I did a lot of DIY stuff, helping people out, and then I got into concrete very, very slowly,” he says. “One day, I decided I was going to go for it and started this thing on my own. Three years later, we own a building and we have six employees.”

Teaman credits a great deal of’s success to “we,” as opposed to only himself.

“What we’ve done is we’ve really developed some good people,” he says. “We’ve changed some lives in our shop.” With the support of friends and family, and Jeff Girard from CCI when required, Teaman and his team have managed to build not only a sustainable business, but one that continues to grow and evolve.

That successful business didn’t come without an investment of time, effort and some serious financial planning on the part of Teaman. Eventually, he even relocated for the sake of the business. He started out in Indiana, but the climate made the business environment particularly challenging.
“When I was up there, we hit a lull in the winters,” he says. “It was like five months of nothingness.”

Teaman’s long-time friend, Brett, lived in Jacksonville. The two coordinated and Brett visited some home shows to see if the market would be friendly for Teaman. There wasn’t any competition for Teaman in Jacksonville, so the two jumped on the opportunity.

“We made some sales calls, got some jobs and I drove down and brought my equipment,” Teaman says. “I was working back and forth, back and forth, just to keep things going.”

Eventually, the investment paid off and Teaman permanently relocated to Florida. In addition to assembling a great team, Teaman credits some of’s success to applying the lessons he’d learned in the pharmaceutical business; customer service, in particular.


Custom concrete fireplace surround by Concrete Commander

Concrete Customer Service

Good sales people know that managing expectations is a significant part of customer service, something that, from his many years in sales, Teaman brought to his new business.

“I was in pharmaceuticals for fifteen years,” he says. “We brought in the customer service at that level.”

Sometimes, that means educating customers about what custom concrete work really entails.

“When they [customers] see the website, eighty-percent of the people are going to think that they’re getting a cheap product because it’s concrete,” he says. “They’re tire kicking. They don’t realize that the cost is higher than it is for cheap granite. Sometimes they’re blown away.”

Teaman makes an effort to reach out to the customers so that they understand the work involved with GFRC. “We just walk them through. They’re like ‘Okay, I get it,” he explains. “For most people, they understand that it’s an expensive product because it’s hand made.”

He credits Jeff and Lane of CCI with offering a lot of insight into customer relationships. “Jeff and Lane did a good job of making sure you know how to set those expectations with customers, “he says. “There’s room for variation. This is a custom, hand-made product. As long as the customer understands that, it’s good.”

In addition to helping customers to understand the skill and work involved in creating custom concrete products, Teaman has developed his business so that it’s flexible and sustainable when custom work goes through its predictable spikes and lulls.

“Our goal is to have our custom side, but then we want to have a production line,” he says.

That production line includes products that are of equally high quality to custom work, but come at a more affordable—but not cheap—price. “Our production looks like custom,” he says. “If you want to soup it up, though, we can really make it a piece of art.”

The production line has a great deal of value to the business. Putting a fire bowl on a palate and shipping it to the customer’s door is not difficult for the business and, for the customer, the production line combines high quality with a great deal of convenience.

Where the other aspects of customer service are concerned, also sets high standards and it pays off in boosting the company’s reputation and customer relations.

“The way we work, we’re really punctual. If we’re going to be late, we’re texting. People are so appreciative of that,” he says. That also extends to website contacts, “When you can follow up within a half an hour, you’ll blow people away.”


Production concrete fire bowl by Concrete Commander

Flexibility and Return on Investment’s success did not just drop into Teaman’s lap. Before he launched the business, he had a plan.

“So many businesses fail in twelve to eighteen months,” he says. “I was able to save money to make this work. We prepared for it. That old adage that you have to spend money to make money is true. If you think you need fifty, you might as well have a hundred and then work hard so you don’t even have to spend the fifty.”

Like most of what Teaman has done with his business, the inclusion of production work is part of a broader plan. “That insulates us a bit,” he says. “If custom slows down, we have production.”

Though he graduated from CCI years ago, Teaman still relies on Jeff Girard when he runs into a particularly difficult challenge and, as is the case with his other connections, he attributes some of his success to that relationship. “You surround yourself with greatness,” he says, “and Jeff is one of those people. He’s always there if I have ‘Jeff questions.’ He is of huge value to what we do.”

Planning aside, Teaman still enjoys quite a bit of spontaneity in his business style. Many of the ideas that have helped to grow were written on napkins and were the results of not only coming up with good plans, but also the results of maintaining good working relationships. In fact, Teaman’s work history is based on fostering productive relationships and being flexible enough to let one opportunity become another.

“If you think about the progression,” he says, “I was a personal trainer for two years out of college. I met the owner of a [concrete] company and helped him rehab his knee. I used a PowerPoint presentation to help with the rehab and he asked if I could come and train his sales reps to use PowerPoint.”

Teaman took the time he spent travelling and training the salesforce to learn the products they sold and came into the concrete company as a salesperson. His eventual move to pharmaceuticals only required sales experience, which he had in abundance by the time he made the move, and he turned pharmaceuticals into a fifteen-year career that, eventually and through a lot of hard work and investment, led to
He credits some of his success to tenacity but, in the end, he still comes back to the people he works with, and that doesn’t mean hiring “yes” men. “You need a support network of people to check you; checks and balances,” he says.

He also advises that people going into the custom concrete business anticipate that it will take time to make money. “You have to save money for it to work,” he says.

Nonetheless, he also advises sticking with what works. “We work hard and play hard,” he says. “This started with an idea written on a napkin, and we still work on napkins.”

Learn more about Concrete Commander at

More work by Concrete Commander in Jacksonville, Florida and beyond:




Building a Concrete Countertop Business by Building Relationships

Getting training, building a clientele and a portfolio; anyone starting out in concrete countertops certainly has a lot to think about. For Judive and François Jean-Gilles, personal networking has been particularly significant in building their business. Growing their enterprise, Cygne Beton of Quebec, also required the father/daughter team to make connections that crossed both distance and languages, but the effort has certainly paid off in the end.

Judive got interested in the concrete countertop business in 2009. With a degree in business and fifteen years of experience in the banking world, she was well-equipped to launch a new enterprise, but needed to know more about GFRC. Her journey started with a book, but quickly came to incorporate formal training. She found The Concrete Countertop Institute on the web, but distance was an issue.

“I was looking at the 5-day Ultimate class, but it was a lot of money because I’m Canadian and would have had travel expenses,” she said. “So, I tried the online courses (Level 3).” Judive had extensive experience in online training before she started taking classes at CCI, so she took to the online option quickly.

Once the distance barrier was taken care of, there was still a language barrier to deal with. “I used the books Lane and Jeff sent me,” Judive explained. “My father speaks French, so I had to translate. All the information about working with concrete I had to translate. There were other books I didn’t have to translate because they were about marketing, and that’s what I do.”

The effort Judive put into translating the CCI books helped François to take his vast experience working with concrete in a new direction. François had built foundations and houses out of concrete in Haiti, but hadn’t studied concrete in detail before. “We built upon his knowledge,” Judive said. “He had the experience, but now we had the theory.”

Growing a Business Through Partnerships

Between François and Judive’s extensive experience and their training from CCI, they were ready to launch Cygne Beton. As is the case for any fledgling business, however, finding clients was a concern. Fortunately, Judive is a member of several business networking organizations and she leveraged her relationships with other entrepreneurs, fostering partnerships that helped Cygne Beton, and the businesses it partners with, to succeed.

“I’m in an organization for women in business and we have a lot of meetings,” Judive said. “We have conferences and other activities. I’ve met a lot of clients and I meet contractors there. I can form partnerships with them and join my knowledge with theirs so that we can work as a team.”

Judive’s partnerships with other businesses have allowed her to offer clients package deals. When a client has a need that she cannot meet, Judive has people to rely upon who can fill in the gap, allowing both businesses to capitalize on opportunities that might otherwise be lost. She detailed one such situation in which her networking managed to turn a meeting with a client that didn’t go so well initially into a sale.

“I felt that the client didn’t really trust me,” she said. “I understand why. He wanted measurements; to know how I was going to do the job. I gave him some measurements, but I saw that he wasn’t happy. So, the next time I went, I took my designer and he was amazed.” Despite the client spending most of that second meeting talking to Judive’s designer, he was elated when Judive came back to discuss the project further. “Everything changed because trust was built,” she said. “He saw that I was well supported, that I have a team with me.”

Judive recommends in-person networking for those launching their own business. “The web is good, but you don’t really build relationships online,” she said. “Before I had a portfolio, how could I advertise on the web? When I have more pictures, however, then I can advertise on the web.”

Also thanks to Judive’s networking, Cygne Beton will soon have a website. One of Judive’s business associates is a web designer and will be putting together a site for Cygne Beton in the near future.

In the meantime, Judive does make use of technology on a person-to-person level. She brings her iPad along with her to meetings with clients, which allows them to see the work she and her father have already completed. Nonetheless, Cygne Beton’s cooperative relationships with complimentary businesses are what helped the enterprise to really take off. “I’m building by giving and receiving,” she said. “Building really healthy relationships with other people who do something complimentary to what you do is really the best thing.”

Launching a business is always a significant undertaking, and the risk can be intimidating, but Judive and François have seen it pay off already and Cygne Beton is poised to grow even more. “It was a big decision,” Judive said, “but I’m so happy I did it.”

If you have any questions please contact us.

How to Be Successful with Dry Polymers in GFRC Mixes

As shown in the study The Concrete Countertop Institute published in April 2015, dry polymers perform as well as liquid polymers in terms of flexural strength in GFRC. However, the behavior of the mix can differ in important ways that can make working with the mix challenging if you are not familiar with it.

For example, when I first used the Buddy Rhodes GFRC Blended Mix, (which is an all-in-one mix containing sand, cement, dry polymer, pozzolan, and other ingredients) quite honestly, I didn’t like it because it seemed too thick and difficult to work with. The consistency is very different from a Forton liquid polymer mix, and I had trouble adjusting. What I’ve found is that a couple of things are critical to success with this particular mix:

  • Pre-dosing a superplasticizer
  • Waiting for false set to occur

You may find that mixes using other dry (or liquid) polymers exhibit different behavior. By being aware of the 2 factors above, you can adjust your procedures to work best with your mix.

Recommended Mixing Procedure for Buddy Rhodes GFRC Blended Mix (or Admix)

The order the ingredients are mixed in can have a profound effect on the ease and speed of blending, and quality of the mix. Follow the mixing order outlined below to ensure the mix is blended as thoroughly, quickly and completely as possible. Altering the mix order, or skipping steps may result in a sub-optimal mix that is difficult to blend, may be too stiff (or too runny), and may have poorly mixed ingredients that show up after demolding.

By carefully reading and following the instructions regarding pre-dosing superplasticizer and managing false set, you will be much more successful with this mix.

Note that these instructions also apply if you are using the Buddy Rhodes GFRC Admix and adding your own sand and cement.

Pre-Mix Preparation

  • Mix liquid ingredients together (water, ice, liquid superplasticizer)
  • Blend all of dry ingredients together (Blended GFRC Mix, pigments, dry superplasticizer)
  • Do not blend fibers with the dry ingredients

Either a liquid (e.g Buddy Rhodes WR 420) or a dry (e.g. Buddy Rhodes WR 310) superplasticizer may be added to the pre-mixed ingredients. Choose one or the other based on experience and personal preference.

Superplasticizer Dosing Rates

The following recommended dosing rates are for making a sprayable GFRC mist coat. Use half the recommended dose if a stiffer, hand-packable mix is desired. Adjust dose according to desired consistency.

WR 420 is a powerful liquid superplasticizer optimized and ideal for use in Buddy Rhodes Products. It adds significant workability and fluidity, acts quickly and doesn’t make the mix thick or sticky.

  • Recommended dosing rate: 1 mL per 1 lb of GFRC Blended Mix.

WR 310 is a potent dry powder superplasticizer that adds significant amounts of workability and fluidity, but it can make a mix sticky. WR 310 should be first blended into the dry ingredients to ensure good dispersion and to prevent clumping.

  • Recommended dosing rate: 0.5 grams per 1 lb of GFRC Blended Mix, or 0.11% dose.

Be sure to have a viscosity modifying admixture, such as Fritz-Pak’s Super Slump Buster, on hand to adjust consistency if your mix becomes too runny. This is especially important with WR 310 because it is so powerful.

See this page for more information on superplasticizers and viscosity modifiers.

Mixing Order

  1. In the empty mixing bucket, add:
    1. All liquid ingredients
    2. Half of the pre-blended dry ingredients
  2. Mix until no dry ingredients remain.
  3. If PVA or acrylic fibers are to be added to your mist or face coat, add them to the mix  now and blend until fully dispersed.
  4. Add half of remaining dry ingredients and mix until no dry ingredients remain.
  5. Add remaining dry ingredients and mix until no dry ingredients remain.
  6. Scrape the sides and bottom of the mixing bucket.
  7. Mix until all dry ingredients are fully incorporated.

False Set

8. Let the mix rest for 10 minutes to allow false set to occur.
9. Re-mix to break false set stiffness before adjusting consistency.

Adjust Consistency

10. Add WR 420 liquid superplasticizer to adjust mix consistency if necessary. Add it 5 mL at a time and mix well before checking.

Add AR Glass Fibers (Only for backer coats)

11. Add AR glass fibers after the mix has been fully blended and adjusted for consistency. Gently mix to just incorporate the fibers into the mix.

Where to Buy Dry Polymers for GFRC

CCI sells the Buddy Rhodes GFRC Blended Mix, GFRC Admix, and the superplasticizers mentioned in this article – Click here for our online store.

Other brands of dry polymer blends and plasticizers are available from other vendors. Search for “GFRC polymer” or “GFRC dry polymer”. Note that the consistency and false set behavior of these products may be different from the Buddy Rhodes products.


How to know when your GFRC mist coat is ready for backer

After you’ve sprayed your GFRC mist coat, the general guideline, under typical shop conditions, is to wait about 10-15 minutes before applying your first coat of backer mix. This allows the mist coat to set up a bit and get firm enough that the fibers won’t push through but still wet enough that the mist coat will bond to the backer coat.

The following video shows you exactly what you’re looking for:

  • The mist coat should be soft, moist and pliable, but not sticky. Touch the mist coat gently with gloved fingers to test it.
  • Mist coat that has been left too long may look the same but be stiff, dry and crumbly. It risks crazing, cracking and delamination.

Note that shop conditions have a huge effect on timing of when the mist coat is ready. Very dry or hot shop conditions will cause the mist coat to dry out or cure very quickly. You must be ready with your backer mix, monitor the mist coat closely, and not leave it unattended.

How to Attach Legs to a Concrete Table

Q: I am about to start building indoor/outdoor concrete tables with square tubular welded frames.  Can you recommend how best to fix the concrete top to the steel frame?  I’m not sure if it’s best to cast some type of flanged nut into the concrete and bolt the frame to it, or try something else.  If there is some hardware that would provide a simple solution, I’d love to know about it.

A: I like to use stainless steel tee nuts embedded in the concrete.


There are a lot of considerations when it comes to attaching legs to a concrete top. Connecting legs to a table is a classic challenge, and solutions to it are seen in all forms of table construction. Different materials require different solutions:

  • Wood legs often require an apron and a stretcher or trestle to keep the legs from wobbling or breaking off if the table is dragged across a floor.
  • Steel legs tend to be simpler, since steel can be bolted or welded to create a much more compact, strong and rigid connection.
  • Concrete is a relatively poor material to make legs out of, since the legs need to be fairly massive to provide the necessary bending stiffness that table legs require, and in order to make a strong and rigid connection to the top.

Designing a table and legs involves a number of choices and decisions; those decisions and choices are both structural and aesthetic and are interdependent. Factors that affect both include top and leg material (steel, wood, GFRC, etc.) are:

  • aesthetics
  • top thickness
  • leg location
  • leg shape
  • weight limits
  • handling characteristics (will this be moved once or many times)
  • seating location
  • etc.

Aesthetics usually drive a design, so I suggest you start there.

The table’s top thickness depends upon the span and what is providing the strength. This decision influences the structural design of the GFRC top itself, especially if the GFRC is expected to be self-supporting (meaning it’s not sitting on a structural frame). It also affects how the top and legs are connected. Thin tops can’t span long open spaces and don’t provide much strength for an embedded anchor, while thicker tops can (and do). A good compromise between strong legs and a thin top would be to weld the legs to horizontal steel beams that connect the legs together and keep them rigid and strong. The horizontal steel beams form a frame that also fully supports a thin GFRC slab. The slab can simply sit on top of the frame unbonded, or it could be glued to it using construction adhesive.

Alternatively, if the legs of the table are separate and bolted to the GFRC top, then the top must be made to be fully self-supporting. This forces the table top to be thicker, which in turn affects aesthetics. In addition, the top must have stout anchors cast into it where the legs bolt to the top (and the leg design must accommodate such a connection method). Stainless steel tee nuts can be used for this connection.

Tee nuts are usually used in furniture made of plywood or particle board. The tee nut forms a solid anchor within the concrete top where a machine bolt can thread into. Each tee nut should be buried at least 1″ into the concrete.

When embedding the tee nut, grease the nut and the bolt threads (I use Vaseline), then run the greased machine bolt into the nut to keep concrete out of the threads. A good tip is to run the bolt through the nut so about 1/4″ of bare thread extends beyond the base of the tee nut. This will create a pocket inside the concrete and will keep the bolt from bottoming out (and possibly creating a blowout). Use a jig, as shown, to keep the nut and the bolt hole perfectly vertical in the concrete.


Q: Can I use monofilament fibers in GFRC?

A: No.

First, let’s understand what “monofilament” means. Fibers can be configured in single strands (monofilament) or bundles (fibrillated). Many types of fibers that are sold in fibrillated configuration have fiber bundles that are designed to disperse in the mix – break up into single fiber strands.

GFRC fibers are different. The fiber bundles are meant to stay bundled (about 200 filaments per bundle with 19mm “fibers”). Each bundle is bonded together so that the filaments remain grouped during mixing. Here’s why:

With monofilament fibers, each fiber is exposed to the concrete’s cement paste and is well bonded to the matrix. While this seems ideal, it creates a composite that results in stiffer, less elastic material.


Monofilament Fibers (image courtesy of

GFRC fibers, on the other hand, remain in a bundle. This results in a stiffer fiber grouping that maintains the fiber’s orientation even when the overall length gets very long compared to the diameter of the individual fiber filament. Long, stiff fibers (or fiber groupings) are far more effective than long, thin, floppy fibers that fold over and ball up.


Fibrillated Fibers (not GFRC fibers, image courtesy of

Fiber Bundle Properties

In addition, the fiber bundles themselves are engineered to create a strong, yet flexible concrete. The spacing between each filament is about 0.1 microns, or 1/10,000,000 of a meter. That’s 1000 times smaller than the average diameter of a human hair! The spacing between the filaments is too small to let cement particles penetrate, but it is large enough to let the polymer enter.

Capillary action draws water and polymer into the dry fibers as they’re mixed into the concrete. By filling the spaces between the filaments with polymer, two things are achieved:

  1. The polymer blocks any mineral growth from entering the fiber bundle.
  2. The stretchy polymer bonds the inner filaments to the filaments at the outside of the bundle.

Only the outside filaments are in contact with the concrete matrix, but the inner filaments are not. This is important because:

  • If the spaces between the filaments were to become filled with rigid crystalline mineral deposits (which occurs during concrete hydration over time), all of the filaments would be rigidly bonded together and the fiber would act as a single, thick fiber bar.
  • Rather, the stretchy polymer allows the inner filaments to move relative to the outer filaments, yet still bear some of the load.

In a way, the polymer and glass fiber filaments create mini bungee cords within the concrete, giving GFRC great flexibility.

The Importance of Surface Area

As explained above, the surface area of fiber which is exposed to the cement paste is important. This is true for a number of concrete ingredients. For example, the surface area of pigment and how well it disperses in the mix are important factors in creating the final color. Surface area is an important concept that plays a role in mix design and adjustments.

Other Considerations about Fibers

Please note, this article discusses only the difference between monofilament and fibrillated fibers. There are many other important characteristics relevant to fibers. For example, depending on the material the fiber is made of, the fiber may be hydrophobic (repel water and therefore have no effect on mix water requirements) or hydrophilic (attract water and therefore affect mix water requirements).

Here are some good articles by Concrete Construction magazine about the broader topic of various fiber chemistries and configurations. While they don’t cover GFRC, they give a good overview of other types of fibers.


How to Polish Inside Concrete Sinks

Polishing flat surfaces is challenging enough. You must take care to keep the polisher flat and not gouge the concrete. What happens when you try to polish inside curves such as a sink?

Actually, polishing inside a sink is easy – if you have the right equipment. You can use the same polisher and the same 5″ diamond pads you usually use (assuming the diamond pads are flexible). The difference is in the backer.

The backer pads that come with a polisher when you purchase it are usually a hard rubber. They are supposedly flexible, but they are designed for granite, not concrete. They are too hard, and instead of flexing will just scallop the concrete.

In order to polish curved surfaces, such as inside sinks, you need a very flexible backer. By using a very flexible 4″ backer with 5″ diamond pads, you are able to polish tighter curves without risking gouging the concrete.

Ultra Flexible backer pad

A thick foam 3″ backer does not flex uniformly. Where the larger pad meets the edge of the backer, there is a pressure point that gouges the concrete. A small, 3″ backer also tends to lose grip on 5″ pads.

Our very thin, very flexible 4″ backer securely grips the polishing pad and allows it to flex more uniformly and produce a better quality surface. The backer is available for purchase here:

Ultra Flexible backer and 5-inch diamond pad

Keep in mind that not all diamond pad are flexible enough to handle this. Make sure that your diamond pad will flex and not crack.

flexible diamond pad for concrete

Here is a video that shows me using the backer to polish inside a concrete sink:

In this video, I explain how to position the backer as you move along curves, to avoid gouging:

This backer makes it very easy to get a high quality finish and/or expose aggregate inside a sink. It is available for purchase here:

Here’s the finished mother of pearl sink:


Pixie inspected and approved the sink:

Pixie Minidoxie inspects integral concrete sink vanity

Here is another integral sink vanity we made in class (shown wet):


Keep in mind, only sinks with smooth curves can be polished mechanically – not hard angles. It is possible to hand sand inside an angular sink with wet/dry sandpaper, but it’s nearly impossible to grind and polish to expose aggregate inside an angular sink.

The Quest for a Pinhole-Free Concrete Countertop Surface

Pinholes are aggravating. These tiny holes in the concrete surface are formed by air bubbles trapped in the concrete. Bubbles become pinholes when they form on the surface of the concrete during casting and when the concrete is ground or honed. When creating something like a kitchen countertop, pinholes are especially undesirable because they can allow food residue to collect inside and develop bacteria.

In a traditional wet cast concrete mix, vibrating the mix might get rid of them. In a sprayed GFRC mist coat, the energy of spraying might eliminate all air and prevent pinholes. In a pourable GFRC mix, it might be dense enough to be pinhole-free.

The key word in all these sentences is might. Sometimes, you are left with that one pinhole, staring you in the face. Recasting is an extreme measure. What if there were an easy way to fill in that pinhole?

There is. It’s called grout. (I call it grout, many people call it slurry, and Buddy Rhodes calls it paste and is a master of manipulating it into works of art. But more on that later.)

Grout Recipe

Grout at its most basic is concrete taken to the extreme – just cement and water, hold the sand and aggregate, please. In reality, you need to use another important ingredient to make grout practical – bonding agent. Here’s a tried-and-true from scratch grout recipe:

  • Blend together:
    • The same ratio of cement and pozzolan you used in your concrete
    • The same % of pigment to cementitious materials you used in your concrete
  • Add bonding agent diluted with water, until the mixture is the consistency of peanut butter
  • Spread on with your (gloved) hands or a plastic spatula
  • Adjust the consistency by adding more bonding agent or more dry mix as needed

Bonding agent is essentially glue. Without it, the very thin layer of grout you spread onto the concrete is prone to drying out and therefore not curing properly, and worse, likely to flake off the concrete. Bonding agent will make that thin layer of grout stick to the concrete and stay there.

Various types of bonding agents will work. Acrylic additives such as Acryl 60 or are excellent bonding agents. GFRC polymer can also be used. It is mainly a curing agent, but it also functions as a bonding agent.

The amount you should dilute liquid bonding agents with water depends on the bonding agent. Some off-the-shelf acrylic admixtures are already dilute enough to use straight, others will need even more dilution.

The end consistency of the diluted bonding agent should be similar to whole milk. For example, before I started using GFRC, I used Acryl 60 in my grout, and I found that diluting it 1:1 with water yielded excellent results. After I started making GFRC, I used my GFRC curing polymer in my grout. Since it has a higher solids content (51% in my case), I needed to dilute it more. A 2-parts-water to 1-part-GFRC curing polymer worked very well. Precision isn’t critical, but using too much water can cause the grout to flake off.

You may be thinking that I usually advocate extreme precision in mixes, keeping your water-cement ratio low, and never adding water to make a mix more fluid but using superplasticizer instead. I do. And in fact, you could use superplasticizer to make your grout more fluid, instead of adding more bonding agent diluted with water. You could also use accelerator to accelerate the curing rate. Grout is a kind of concrete, after all.

But grout is filling only small holes that do not affect the structural performance of the concrete. As long as it sticks and you are able to hone it off in a reasonable amount of time, it’s fine.

There is a grout premix that I find very convenient, and it actually offers slightly better adherence to the concrete than the from-scratch grout made with liquid GFRC polymer. The product is Buddy Rhodes Concrete Products’ “Bone Paste Plus”. Click here to view details about that product.

Grouting Procedure

The grouting procedure differs depending upon whether the concrete has a cement-cream finish or if it has been honed or ground to expose the sand-grains or larger aggregate.

  • Use a food processor to premix all of the dry grout you will need to the entire project using the grout formula above. Store the dry grout in a labeled, air tight and moisture-proof container.
  • Dilute your bonding agent with water until it is the consistency of whole milk.
  • Wet-mix a small amount (about 1 cup) of grout at a time. Add just enough diluted bonding agent to make a paste that has the consistency of peanut butter. Stiffer is better, since it’s easier to work a stiff grout mix into the small holes.
  • Mist or spray water onto the concrete with a spray bottle. Remember that wet or very moist concrete will cause the grout to turn to a liquid, possibly diluting the grout and causing shrinkage. Do not let water collect in the air voids.
  • Spread the grout paste onto the entire surface of the slightly damp concrete. Do not apply grout to individual pinholes. It’s important not to spot-grout but to grout the entire surface of the slab. If spot grouting is done, dark grout “shadows” or spots will be visible after sealing.
  • Work the grout with your fingers (wear rubber gloves), plastic putty knife or rubber float. Force the grout into the holes, but make sure you scrape away any excess from the concrete; this way you can check to be sure all the holes are filled.
  • Deep or large holes might require mounding excess grout over them to counteract shrinkage. You can mix sand into the grout when filling larger voids. This helps make the filled-in void look more like the surrounding concrete. More on this later.

For ground or honed surfaces: You can leave a thick film of grout on the surface, because you will later use a diamond polisher to hone it off.

For cream finishes: Do not leave any buildup or residue on the surface. There should only be a light haze remaining. Physical buildup or residue that hardens will be difficult to sand off, and aggressive sanding will likely cut through the fragile cement cream layer, ruining the finish.

  • Let the grout air dry 4-6 hours or overnight (if using Portland cement). The hardened grout should be well bonded to the concrete and not be soft or crumbly.
  • Hone off the hardened grout.

For ground or honed surfaces: Using a 200 to 400 grit resin bond disc, hone the excess grout off the concrete. The goal is to remove all the excess grout and to smooth the surface, not to remove any more concrete. Removing more concrete will open up new pinholes and voids.

For cream finishes: Use 400 grit wet/dry sandpaper and lightly hand sand to remove the grout haze, being very careful not to cut into the cream layer. Do not use diamonds, either a hand pad or a diamond polisher.

  • If there are any holes remaining, repeat the grouting process. 

applying grout

Grouting Considerations

One issue I find with Portland cement based grouts is that they take too long to achieve enough strength and hardness to allow me to hone them off quickly without tearing out or eroding. Grout that is too soft will not mill flat. Depending on temperature, you may have to leave Portland grout on for 4-6 hours or even overnight.

The solution is to use rapid setting CSA cement in your grout. This allows you to hone off the grout within 1 to 2 hours. (Remember, no pozzolan is necessary when you use CSA cement.)

Be aware that if you’ve used Portland cement in your concrete, the color of your grout may differ because the color of CSA cement differs. Regardless of your cement, the color of your grout will be at least slightly different from the color of your concrete because there is no sand in it. The visual difference will be even greater if you’ve exposed sand grains or aggregate in your concrete surface.

An important rule of grouting is that it is best to grout the entire surface, not to spot grout. If you smear a large circle of grout around a pinhole, let it cure, then hone it off, the appearance of the entire circle, not just the pinhole, may be changed. In the case of a single pinhole, try to apply the grout to as small an area as possible.

The appearance change happens for the same reason that leaving a can of soda or any object on top of a slab overnight causes a dark mark: You’ve changed the moisture level in that area, which causes the concrete to cure differently in that area. That mark is permanent.

Filling Larger Holes

Sometimes you may need to fill larger holes with grout, and if your concrete surface has exposed sand grains, the appearance of the grout will be too different from the appearance of the concrete. The solution is simple: Add sand to your grout. You wouldn’t use sand for smaller pinholes because it would make it too difficult to get the grout into the small holes, but for larger holes, sand will make them easier to fill and closer to the appearance of the surrounding concrete.

However, if you find that you are having issues with large holes in your concrete when you were trying to achieve a uniform look, you need to evaluate your mix and casting methods to determine the root cause of the problem.

In some cases, large voids are not a problem, but a deliberate design choice, such as in the Buddy Rhodes pressed technique. In this technique, you are not trying to match the surface appearance of the concrete in order to hide the voids, you are accenting them on purpose.

This is Buddy Rhodes’ signature technique, which he taught in CCI’s Creative Concrete Finishing Techniques class in Spring 2016.

Buddy Rhodes pressed techniqueBuddy Rhodes pressed look

Partnership between CCI and Buddy Rhodes Concrete Products

I usually write about either a technical topic or an alumnus. This is a news article, because I have exciting news!

I’m pleased to announce that CCI has partnered with Buddy Rhodes Concrete Products (BRCP). CCI will develop new online and hands-on training, as well as expanded documentation, instructions and technical data sheets for BRCP. BRCP will handle CCI’s material and equipment orders, giving CCI customers a more streamlined ordering and fulfillment process.

BRCP is the only products company that recognizes that excellent, engineering-based training and documentation provide a firm foundation for creativity, and that’s what I’m going to help provide. They also have the widest range of choices for creative concrete professionals, from a just add water mix to the raw materials to make your own mixes.

I have used Blue Concrete pigments (now part of Buddy Rhodes Concrete Products) since 1999. An article about Buddy is what originally inspired me to make that very first concrete countertop in 1999. More recently, through the rigorous testing I’ve performed, I am impressed with the quality and performance of the new products such as the GFRC Admix and the new Reactive Polyurethane Sealer. I am confident in standing behind the BRCP products as an additional choice for creative concrete professionals, and in working with the passionate and upstanding folks over there such as Jeremy French and Buddy himself.

CCI’s training and membership programs remain the same, with some future additions. I remain dedicated to all of my alumni and members, regardless of which products anyone chooses to use, and will continue to provide sound, engineering-based advice. I look forward to continuing with all of you on the journey to success with creative concrete, as both BRCP and CCI continue our commitment to the growth and success of creative concrete artisans.