The California Department of Transportation (Caltrans) needed a concrete pavement that would deliver a surface ready for traffic in 4 hours. Different admixture manufacturers experimented with various combinations to try to achieve this. Finally, Master Builders came up with what they call "4x4 Concrete," an innovative mixture that develops 400-psi flexural strength in just 4 hours after placement. This material costs about half as much as current fast-setting hydraulic cement concrete and can be produced with standard locally available materials. Chumo Construction recently placed over 500 cubic yards of this new mix on a remove-and-replace job for the California Department of Transportation with great success. We asked Tom Pyle, chief, Office of Rigid Pavements & Structural Concrete with Caltrans, and James Anderson, engineering service western manager for Master Builders, to discuss this new development in high-early-strength concrete for paving repair.
Although we don't actually want concrete to crack, we certainly expect it to, and all good designs plan for it. Indeed, the reinforcement in concrete doesn't even begin to work until it cracks. We even put in lines of weakness and beg the cracks to follow, which of course they sometimes don't.
Failing to cap a crack properly before injecting epoxy resin can cause a leak that wastes costly resin. Why do setups leak? Usually it's because of incorrect capping methods. Using the right method prevents leaks.