Influence of Curing Method on Strength Development of Concrete Using Fly Ash

点击翻译按钮获取中文摘要

With the recent progress of the social environment promoting recycling, it is required that the use for fly ash be increased in building construction. However, there is few data on fly ash concrete accumulated in except those be moist cured at early age. To elucidate the effects of early curing conditions on the mid-and long-term strength development of concrete containing fly ash for reinforced concrete building structures, this study investigated the effects of various moisture conditions during early curing of concrete containing fly ash on its mid-and long-term strength development by experiments, and examined the relationship between the contributions of fly ash to strength, k, and fly ash qualities, concrete mixture proportions, and curing conditions by analyses. The following results are made :(1)The strength contributions of fly ash, k, under various conditions in high-strength and normal-strength concrete were experimented, and the relationships between k and initial curing condition type and curing period were examined. As a result, the influence of curing condition on k was clarified.(2)The past experiment data on strength of fly ash concrete were collected. Based on the organized data, the relationships between k and Blaine specific surface area of fly ash, portiand cement content, content ratio of portland cement and fly ash (C/Fa) and curing condition were examined. The following observations were made : the bigger Blaine specific surface area of fly ash is, the higher k is. k at long-term ages tends to increase as C/Fa increases. k at long-term ages by sealed curing are about 80% times as large as those by standard curing, and k by air curing are about 40-50% times as large as those by standard curing.(3)The strength expression of mortar containing fly ash could be expressed by the summation of the strength of mortar without fly ash and the strength increase due to pozzoknic reaction of fly ash and the powder effect of fly ash.