EFFICIENT APPLICATION OF MINERAL ADDITIVES TO REDUCE BINDER CONSUMPTION

The paper addresses the issues of Portland cement saving in concretes by replacing part of the binder and fine aggregate with a mineral additive. The studies were carried out on concrete mixtures of various compositions, simulating different binder contents (≈250, 350 and 450 kg/m3) and fine aggregate amounts. A regular influence of the mineral additive amount on the compressive strength of concrete was established, depending on the binder content and the resulting saving of the latter. It was found that in concretes with low binder consumption (190–230 kg/m3), the highest strength and specific Portland cement saving (Ec = 58.8%) are achieved at the maximum dosage of the mineral additive (70%), whereas in concretes with high cement content (430–390 kg/m³), the maximum strength and specific cement saving (Ec = 42.8%) were observed at the minimum additive dosage (40%). The excess compressive strength of the modified concrete specimens compared to the reference mixtures indicates a reserve for cement saving. It is shown that the combination of the fine aggregate particle size and the fine additive has a significant effect on concrete strength. The research results may be useful in designing concrete mixes for different strength classes, which is of fundamental importance under conditions of resource saving and reduction of the environmental load of the construction industry