Influence of Different Curing Conditions on Strength Development of High-Strength Concrete Using Fly Ash

摘要

In this study, the influence of moist curing on strength development of high-strength concrete containing fly ash was investigated. The fly-ash concrete was prepared with a w/c and w/cm of 0.40 and 0.30, respectively. To evaluate the relative contribution of fly ash to strength development, two reference concretes (w/c=0.40 and w/c=0.30) without fly ash were also tested. The specimens were kept in three basic curing conditions: underwater-, sealed-, and exposed to atmosphere. At ages of 7 or 28 days, specimens were subjected to various curing conditions. Fifteen types of curing sequences were adopted in all. The changes in the density and compressive strength were measured at ages of 7,28,91,182,273, and 358 days. It was concluded that, when the fly-ash concrete was kept in moist conditions, the contribution of fly ash to the long-term strength exceeds 0.8. However, when specimens were allowed to air dry, the contribution of fly ash to the long-term strength was around 0.4, as low as its contribution to the early-age strength.