Until now the so-called knead bag test has been used to determine concrete hardening or solidification time, tE. It entails filling a plastic bag with a small amount of mix, testing at different time intervals to measure when the concrete can no longer be pressed by thumb. European practitioners find the method subjective and uncertain, which is why the time determined in accordance with the German DIN 18218 standard must be extended by 25 percent.
Manufacturers offer a range ofperformance options as producers gear for improved market conditions.
Ready mixed concrete plants are recycling process water to attain more sustainable operation and save on discharge costs or the amount of fresh water consumed. As cement fines accumulate in settling vessels, process water becomes less usable in fresh concrete mixes due to limits on the amount of solids that can be present in the makeup water. The solids also present scaling problems in pumps, valves and other fittings in the piping systems that carry recycled water.
A leader in bringing building information modeling (BIM) software and online tools to the architectural, engineering and construction markets, Tekla Inc. has included in its latest version of 3D modeling software, Tekla Structures 19, a new graphic feature to help contractors and ready mixed producers plan concrete orders in optimal delivery sequences.
To meet demand for precast concrete with smooth surface, uniform matrix and high performance characteristics, Active Minerals Intl. has developed Acti-Gel 208, a mineral based additive suited to self-consolidating and zero slump mixes. As a low-dose rheology modifier and anti-settling agent, it provides aggregate suspension, stabilizes mixtures, and improves workability, flowability, and pumpability throughout fabrication of wet cast and dry cast products.