Influence of type and composition of aggregate on mechanical parameters of concrete

Abstract

The paper deals with a thorough analysis of the influence of the type of aggregate and its resulting grain size curve on the basic strength parameters of concrete. From the point of view of the type, natural crushed aggregate of amphibolitic type, natural crushed aggregate of granodioritic type and natural mined sedimentary aggregate of the psammitic type were monitored. The same concrete strength class was proposed for the analysis of the impact of individual types of aggregates. In one case it was a concrete mixture with a maximum aggregate grain size Dmax 16 mm with a continuous grain size curve and in the second case a concrete mixture with a maximum grain size Dmax of 22 mm with a discontinuous grain size curve, in the absence of a 4-8 mm fiction. In both cases, the mixture of individual aggregate fractions was determined so that the resulting grain size curve of the mixture was the same for all aggregate types. Thanks to this approach it was possible to directly monitor the influence of the type of aggregate and the grain size curves on the resulting concrete parameters. The results of the experiment show that a significant impact while maintaining the same grain size curves of the resulting aggregate mixture can be seen mainly in the type of aggregate. The absence of a 4-8 mm fraction when designing a concrete mixture with a Dmax of 22 mm proves to be completely problem-free from the point of view of concrete parameters in both fresh and hardened condition. A part of the research was also verification of the possibility of using natural crushed sand of fraction 0-4 mm for production of high-strength situ ready-mixed concretes.