by tom kuennen
From Rice University, Houston … Bringing order to disorder is key to making stronger and greener cement and concrete. In National Science Foundation and U.S. Department of Energy-backed research, Rice University scientists have decoded the kinetic properties of cement and developed a way to “program” the microscopic, semicrystalline particles within. The process turns particles from disordered clumps into regimented cubes, or spheres that combine to make the material less porous and more durable.
One of the largest problems ready mixed producers face every day on the job is the quality and consistency of concrete field testing. Ask if they have experienced poor quality testing then brace yourself for stories of uncalibrated machines, uncovered cylinders, incorrect curing temperatures and uncertified technicians.
“Crushable” concrete for better protection against terrorists ... improved designs for precast rockfall barriers ... corrosion of precast concrete barrier connections ... lightweight, high-performance, self-consolidating concrete for bulb-T beams. They’re all part of new research presented earlier this year during the 94th annual Transportation Research Board annual meeting, which drew 12,000-plus design, engineering and allied professionals to Washington, D.C.
Replacement of recycled concrete aggregate (RCA) for natural coarse aggregate by up to 45 percent by volume had no significant effects on any of the concrete properties studied, indicating high-quality RCA can be used as a replacement for a portion of the coarse natural aggregates in new portland cement concrete pavements. That’s what Haifang Wen, Ph.D., P.E., Washington State University; David I. McLean, Ph.D., P.E., Colorado State University; and, Kim Willoughby, Washington State DOT, report in their 2015 TRB paper, Evaluation of Recycled Concrete as Aggregates in New Concrete Pavements.