Important Raw Material—Coarse Aggregate

Abstract

Aggregate is a very crucial raw material for preparing concrete, especially coarse aggregate, which greatly affects the concrete performance. Concrete performances, such as frost resistance, permeability resistance, drying shrinkage, and durability, are closely related with aggregate. This chapter focuses on a summary and research on this question by utilizing different kinds of rock distributed in most parts of China. Rock, employed in concrete as coarse aggregate, is a kind of material which distributes widely. Rock can be divided into three types—sedimentary rock, igneous rock, and metamorphic rock. Different kinds of rocks have different impacts on concrete. 2.1 Aggregate Varieties and Causes Overview Different aggregates have different formation mechanism. In order to make it clear about the question, we ought to explain from engineering geology. Figure 2.1 has described briefly the formation process of sedimentary rock, igneous rock, metamorphic rock, various rock names commonly used in concrete engineering, and probable formation zone. Figure 2.1 is simplified from the engineering geology textbooks according to practical demands of concrete project by the author. Some parts may not be very consistent with the principles of geology, mainly for the purpose of making con-crete workers to understand the formation and evolution process of rock concisely and clearly. This is of great meaning for us to finish qualified concrete works.