Title: Accelerated, Early, and Immediate Evaluation of Concrete Quality
Author(s): Edward A. Abdun-Nur
Publication: Symposium Paper
Appears on pages(s): 1-14
Keywords: accelerated tests; age-strength relation; batching; com-pressive
strength; concretes; evaluation; history; quality control;
Accelerated curing and testing of concrete cylinders came into being because of the need for faster evaluation of the quality control of the concrete, as a result of accelerated construction sched-ules and increased volumes of concrete required in structures, so that it was not practical to await the standard 28-day strength results. This same speed-up of construction and increase in concrete vol-umes involved in structures, brought about faster or early evaluation needs, and the maturity concept of concrete (degree-hours) is supple-menting and displacing the accelerated tests. The continuation of this faster trend and increasing volumes has brought about immediate evaluation while the materials are still in the weighing hopper or mixer, so that if a batch is out of tolerance it can be dumped out, instead of sent out to the job. To further meet today's needs, continuous mixing plants are appear-ing on the scene. Their virtues are lower capital costs, reduced variability of the process, and thus possibility of reduced cement content, lower operation and maintenance, and more satisfied operators. And just below the horizon, as the next improvement, is a process that forcibly mixes the water and cement, so that every grain of the latter is hydrated, as against only partially hydrated in existing mixing processes, thus permitting still further reduction in cement content. This particular process is also the cheapest way to eliminate cement dust around concrete plants.