Utilization of new perlite aggregate strengthened by cold-bonding process in lightweight self-compacting concrete production

The development of lightweight self-compacting concrete, which integrates the advantageous characteristics of self-compacting concrete and lightweight aggregate concrete, is crucial for civil engineering applications. Expanded perlite aggregates typically pose challenges in the manufacture of lightweight concrete due to their significant loss of the concrete's mechanical characteristics. The utilization of expanded perlite aggregate in the manufacture of lightweight concrete is considerably limited for this reason. A multi-layered strengthened expanded perlite aggregate was created to solve this issue, allowing for modification of its strength. This aggregate is employed in the manufacture of lightweight self-compacting concrete. The multilayer strengthened expanded perlite aggregates were created by sequentially covering the surface of expanded perlite aggregates with cement-silica fume at three different thicknesses using this procedure. The multilayer strengthened expanded perlite aggregates were utilized to replace 33%, 66%, and 100% of the uncoated expanded perlite aggregates in the manufacture of lightweight concrete. To assess the hardened properties of self-compacting concrete, tests for oven-dry density, water absorption, porosity, compressive strength, flexural strength, sorptivity, and thermal conductivity were performed, while slump-flow diameter, T_50, V-funnel, and L-box tests were conducted to evaluate the fresh properties. This study achieved the workability criteria for self-compacting concrete by producing lightweight self-compacting concrete without segregation, utilizing multilayer strengthened expanded perlite aggregate. The compressive and flexural strength of self-compacting concrete made using multilayer strengthened expanded perlite aggregate increased by approximately 350% and 76%, respectively, compared to 100% uncoated expanded perlite aggregate. Moreover, the values for water absorption and apparent porosity diminished by approximately 57% and 44%, respectively. The findings demonstrated that it is possible to produce lightweight self-compacting concrete with a high strength level using multilayer strengthened expanded perlite aggregates developed in this study. This study presents a feasible design framework for ascertaining the ideal coating thickness and replacement ratio of the multilayer strengthened expanded perlite aggregate concerning density and strength parameters.