The effect of elongated and flaky aggregate on local concrete

Abstract

Since at least three-fourths of the volume of concrete is occupied by aggregate, it is not surprising that its quality is of considerable importance. Not only may the aggregate limit the strength of concrete, as weak aggregate cannot produce strong concrete, but the properties of aggregate greatly affect the durability and structural performance of concrete. Aggregate was originally viewed as an inert material dispersed through the cement paste for largely economic reasons. It is possible, however, to take an opposite view and to look on aggregate as a building material connected into a cohesive whole by means of the cement paste, in a manner similar to masonry construction. In fact, aggregate is not truly inert, and its physical, thermal and sometimes also chemical properties influence the performance of concrete. Many properties of the aggregate depend entirely on the properties of the parent rock, for instance specific gravity, hardness, pore structure and mineral composition, to mention but a few. On the other hand, there are some properties possessed by the aggregate but absent in the parent rock, like particle shape and size, surface texture and absorption. These properties may have a considerable influence on the quality of the concrete, either fresh or in the hardened state.