Study On The Impacts Of Artificial Aggregates On The Properties Of Concrete

As an important component, aggregates account for more than 70% in concrete, and its' geometrical property, physical property, chemical constitution have assignable effect on the workability, mechanical property and lasting quality of concrete. However, for a long period of time, the researchers have been focusing their studies on the hydration of cement, chemistry admixtures and mineral admixtures, etc. But there are few systematic research productions about the effect of aggregates on concrete. Recently, the research about aggregates has been one of hot point with development of high strength concrete, high performance concrete and large-scale construction of express highway.As a part of the project of Shandong province traffic science and technology named"Study and control on manufacturing technique index of cement concrete aggregate in Shandong province", experimental researches on the effect of needle and ragstone particle content, gradation, max-diameter and artificial sand substitute for river sand on the workability and durability of concrete are carried out, with considering of representative production technology of aggregates, technical criterion for production of aggregates in Shandong province is present to guide the selection of aggregates in concrete and offer standard and scientific reference in design of concrete mix proportion.The results of experimental investigation indicate that, the ratio between needle and ragstone particle in coarse aggregate has relation with production facility and technology, small size aggregates have high ragstone content but the large size have high needle content; when the content of needle and ragstone in coarse aggregate varies from 10% to 15%, the workability and mechanical property of concrete begin to descend; with increase of needle and ragstone content, the flexural modulus of concrete reduce gradually but the compressive modulus has small change just a little increase; there exist maximum effect in coarse aggregate, with increase of coarse aggregate size, the workability, mechanical property and durability of concrete all reduce gradually, and the elastic modulus reduces at the beginning and increase latter, so it's considered that the optimum size of coarse aggregate exists between 10% and 25%;concrete has good workability, mechanical property and durability when large, medium and small size particle have proper ratio; proper gradation of artificial sand in concrete are confirmed, it has fine difference with the reference gradation of river sand, artificial sand concrete may has the same workability, mechanical property and durability as...