Cantilever demonstrates the power of proper reinforcing.
December 15, 2005
Students produced a cantilevered countertop that supported up to 
960 pounds.
The countertop used Jeff Girard's mix design, steel reinforcing near the bottom to counteract the typical flexural forces at the bottom of the countertop, and TechFab's CT-300 carbon grid near the top to counteract the flexural forces produced when a cantilever section is loaded from the top.
Jeff placed 16 60-pound bags of sand on the 12" long
cantilever, and no cracking occurred. "I stopped adding bags because
they got too high, and I felt it was dangerous for me to continue
lifting bags above my head.", Girard said. "Based on my calculations, I
know I was close to the failure point of the countertop, but I didn't
reach it."
This countertop had cured for several days before loading. The bags remained on the countertop for 3 weeks, with no cracking.
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