Influence of additives on flexural strength of concrete

In earlier studies, the effect of chemical and mineral additives on the compressive strength of concretes was considered, but little attention was paid to the flexural strength of concrete. However, monolithic concretes of transport purpose, including road concretes, operate under conditions of tensile loads, which lead to their destruction. Therefore, it is actual to analyze the effect of superplasticizers, especially carboxylate type, as well as mineral additives and their complexes on the flexural strength of concrete. The article shows the results of studies for determining the influence of a superplasticizer of a carboxylate type, microfiller and fiber on the flexural strength of concrete. The influence of the time for maintaining a concrete mixture on the physical and mechanical properties of concrete is shown. The article shown that the addition of the mineral additive into the concrete mixture leads to an increase of flexural strength to 13 %. The use of an organomineral complex leads to an increase the early flexural strength of concrete to 37 %, and at the age of 28 days - to 20 %. The use of the complex of additives and polypropylene fibers results in an insignificant increase of the flexural strength in comparison with concretes containing only a complex of additives