Abstract

In compliance with up-to-date concrete technology requirements combining technological and ecological aspects, this chapter describes the effect of the type and maximum aggregate size and cement content on some properties of high-strength concrete (HSC). The following kinds of coarse aggregate were used to produce concrete: natural mineral (gravel) and crushed (granite and basalt) aggregates and pozzolana cement, an ingredient classified as an ecological binder. The concretes contained a highly effective superplasticizer and microsilica, in some cases also an air-entraining agent. Air content in concrete mixes, water absorption, and concrete compressive strength after various periods of hardening were examined. Certain calculations (based on compressive strength, in some cases lost as the result of frost aggression) on values of intensity indexes of cement used and carbon dioxide, treating them as a key for evaluation of eco-efficiency of concrete, were performed. Using pozzolana cement with simultaneous use of a highly effective superplasticizer and microsilica made it possible to obtain HSC made of mineral natural and crushed aggregates. More encouraging strength-test results were achieved for concrete of crushed aggregates, particularly granite. It was discovered that using aggregate with a maximum particle size less than 8mm instead of aggregate with particles measuring up to 16mm with a simultaneous increase in the cement content led to a greater rise in concrete strength. The smallest indexes of binder and carbon dioxide intensity were obtained as a result of use of granite and basalt aggregate, with a maximum particle size up to 16mm. The coefficients bi and ci should be estimated at the concrete design stage, especially for concrete durability connected with freeze–thaw action. The latter has been presented in the second part of these investigations, for ordinary concretes with granite aggregate.

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