PARTICLE-SIZE DISTRIBUTION ASSESSMENT OF THE RECYCLED AGGREGATES FROM CONCRETE REMAINS

Abstract

The reuse of the remainders of destroyed concrete structures is becoming more and more urgent problem not only in Ukraine, but also in the whole world. According to the current strategy of secondary use of resources, concrete waste is either crushed into recycled aggregate as a substitute for natural aggregate or crushed into recycled powder as a substitute for cement in mortar and concrete. The reuse of construction waste as secondary construction materials can reduce the need for natural resources for construction and free areas from accumulated construction debris. The purpose of the work is to evaluate the particle size composition of aggregates obtained from recycled concrete of waste reinforced concrete railway sleepers. To achieve the goal, the following tasks were set: to grind of sleeper waste in various ways; to determine the granulometric composition of coarse and fine aggregates; compare the obtained data with the standard requirements for concrete aggregates. Destroyed reinforced concrete railway sleepers were used as material for research. After removing the reinforcement, the sleeper parts were first loaded into a jaw crusher with a fixed distance between the working plates at 20 mm. The obtained material was reloaded into a drum mill and grinded for 30 minutes. After that, the mixture was unloaded on a standard set of sieves to determine the particle size distribution. As a result of an experimental study of crushed waste of reinforced concrete sleepers, the following was established. The granulometric composition of particles larger than 5 mm meet the requirements for coarse aggregates to produce concrete mixtures. Fractions with particle sizes less than 5 mm are very fine with a fineness modulus at 0.9 which does not meet the requirements for fine aggregates to produce concrete mixtures. Further research will be aimed at studying other properties that determine the possibility of using aggregates for reuse in concrete mixes, namely moisture content, average density, compressive strength, etc. Also, the ways for usage of fine fractions as fillers will be search for other building materials in order to dispose of crushed concrete waste.