Features of physical and mechanical properties of modified concrete based on portland-composite cement

Abstract

Joining the European Green Deal implies a change in the course of construction to energy-efficient and resource-saving. Therefore, in the manufacture of concrete, as the most common building material, it is advisable to use such types of cement as Portland-composite cement. However, it should be borne in mind that such cements have reduced strength formation kinetics in the early stages of curing. The use of a limestone component, in particular calcium carbonate, in Portland-composite cement helps to increase their activity and improve their properties. However, this does not solve the problem in full. At the same time, it is known that the use of surfactants in ultra-low concentrations to change the structure of water for the manufacture of fine-grained concrete can significantly increase strength at an early age. However, no studies of physical properties have been presented for such nanomodified fine-grained concretes. Therefore, in this study, the physical and mechanical properties of nanomodified fine-grained concrete made on Portland-composite cement were investigated. To change the structure of water, a superplasticizer was used in ultra-low concentrations. To evaluate the porosity of concrete as an indicator that directly affects the durability of concrete, studies of the water absorption of fine-grained concrete on Portland-composite cement were conducted. As a result, it was found that the degree of volumetric water absorption of fine-grained concrete depends on the content of calcium carbonate in the composition of Portland-composite cement. It was determined that the water absorption by volume of fine-grained concrete, which was modified by the use of ultra-low concentrations of superplasticizer to change the water structure, depends on the content of the modifier. The analysis of the relationship between the physical and mechanical properties of modified fine-grained concrete on Portland-composite cement showed that there is a certain optimal content of the water structure modifier, at which the greatest increase in early concrete strength is observed with the lowest water absorption by volume.