Investigation of the effect of recycled fine aggregate substitution in raw perlite aggregate concrete on mechanical, capillarity and high temperature resistance properties of concretes

Lightweight concretes are used in applications requiring acoustic and heat insulation due to their low unit weight and can also be used as a load-bearing element in the structure when the necessary properties are provided. Considering that our country is an earthquake zone, it can be said that the widespread use of lightweight concretes in structures is important in terms of reducing earthquake loads affecting the structure. On the other hand, crushing and grinding construction concrete wastes and using them as aggregates in concrete contributes to both the reduction of environmental waste and the reduction of consumption of natural resources. In this study, the changes in the mechanical, capillarity and high temperature resistance of lightweight concretes using different proportions of recycled fine aggregate (RFA) in lightweight concretes produced using raw perlite aggregate supplied from Erzincan province were investigated. For this purpose, lightweight concretes were produced by replacing RFA with fine raw perlite aggregate at 0%, 20%, 40%, 60%, 80% and 100% by volume. In order to investigate the effect of high temperature, weight losses, compressive strength losses, ultrasonic pulse velocity on lightweight concretes exposed to temperatures of 0℃, 200℃, 400℃, 600℃ and 800℃ were measured by experiments and the results obtained by examining both visually and with SEM (scanning electron microscope) were examined and discussed according to the change of RFA substitution rate and temperature parameters. It was determined that losses in mechanical and durability properties of concretes occurred with iii the increase in RFA usage rate in lightweight concretes produced using natural perlite aggregate. It was observed that high temperature caused serious losses in concrete properties. These losses increased even more depending on the RFA substitution rate. It was observed that increasing the curing period from 28 days to 90 days had a positive effect on concretes. 20% RFA content is the recommended rate for RFA usage in this study. A more environmentally friendly and sustainable lightweight concrete production can be made possible with the production of lightweight concrete with 20% RFA content.