Estimate of Dosage of Superplasiticizer in Self-Compacting Concrete Using High-Volume Fly Ash
Yoshitaka MITSUIWA, Junji NAKAMOTO and Kazuo TOGAWA
Abstract:Authors have been studying for several years on the effective utilization of fly ash, which is a by-product of the combustion of pulverized coal fired thermal power plants. The purpose of this study is to obtain the fundamental data on mixture proportioning of self-compacting concrete incorporating high-volume fly ash, especially how to determine the dosage requirement of superplasiticizer in order to get the self-compacting concrete. The results obtained in this study can be summarized as follows; (1) When fly ash is substituted for not only a part of cementitious materials but also a part of fine aggregate, it can be said that the relative flow area ratio(ƒ¡c) is in proportional to the relative funnel speed ratio(Rc). And the gradients of the lines, which means the value of the relative flow area ratio divided by the relative funnel speed ratio, increases continuously with increasing in the percent by volume of portland cement replaced by fly ash. (2) There is a linear relation between the ratio of ƒ¡c to Rc and the dosage of superplasiticizer for dosage of powder. Therefore, the dosage of superplasiticizer can be predicted by supposing the aimed slump flow and the aimed efflux time of concrete. Key Words:High-Volume fly ash, Self-Compacting concrete, Superplasiticizer, Relative flow area ratioCRelative funnel speed ratio