Influence of Crushed Stone Powder with Different Specific Surface Area on Fluidity of Crushed Sand Mortar

Abstract

Production of crushed stone and crushed sand used as aggregate for concrete is classified into two types, dry process type and wet process type. In the dry process type, a large amount of crushed stone powder is produced as a by-product. In 2009, crushed stone powder was standardized by JIS A 5041. However, there is no discussion on the utilization method and the specific surface area of the crushed powder satisfactory. In this study, we made many types of mortar with different mix proportion. The mortar was made from two types of crushed sands which were produced from dry process and wet process, and three types of crushed stone powders with different specific surface areas. The table flow tests were conducted to clarify the fluidity of these mortar. As a result, it was revealed that the difference in the specific surface area of the crushed powder influences the fluidity of the mortar, and in particular, the crushed stone powder having a large specific surface area deteriorated the fluidity of the mortal remarkably. Therefore, it was suggested that the upper limit which is 9%, of fine particles quantity in crushed sand (JIS A 5005) could be moderated.