Self-Compacting Concrete On The Basis Of Concrete Scrap Of Demolished Residential Buildings

Abstract

When dismantling dilapidated buildings, a huge amount of concrete and reinforced concrete scrap is formed. The possibility of effective use of crushed concrete rubble and screening of its crushing as raw materials for self-compacting concrete is shown. The physical and mechanical properties of crushed concrete rubble are investigated. The use of a crushing dropout activated together with a polycarboxylate-based superplasticizer as a micro-filler in self-compacting concrete mixtures is also considered. The optimal content of the micro-filler in self-compacting concrete mixture is determined. The optimal grinding mode of the crushing dropout is set, due to the working conditions of the grinding equipment, to obtain the micro-filler of a given specific surface. The grain-size composition of mixture consisting of quartz sand and crushed concrete aggregate based on the maximum approximation condition to the reference Fuller's curve is designed. The mathematical-statistical method was used for the selection of the composition of self-compacting concrete with application of common structural argumentative characteristics determined by the end of the structure formation period. As these characteristics of self-compacting concrete, the volume concentration of the binder, which determines the macrostructure of concrete, and the true water-binder ratio, which has a decisive influence on the volume and nature of the pores in the cement stone, on the quality of the contact zone between the cement stone and the filler were adopted. Adequate polynomial mathematical models are obtained. They describe the properties of self-compacting concrete mix and concrete, and can also be used when designing their composition.