Pull-out and push-off behavior of self-compacting concrete for precast structures after elevated temperature

Abstract

The present study aims to develop and evaluate a sustainable, cement-free self-compacting geopolymer concrete (SCGC) using recycled aggregates and to assess its performance under elevated temperature conditions. The main objective is to compare the bond and shear behavior of SCGC with conventional cement concrete (reference concrete) and cement-based self-compacting concrete (SCC) before and after fire exposure. Three concrete types were prepared namely, reference concrete, SCC, and SCGC. The SCC and SCGC mixes met EFNARC guidelines for self-compacting behavior. Specimens were subjected to elevated temperatures for 1 and 2 h. Post-heating performance was evaluated based on mass loss, compressive strength, bond stress (BS), and interfacial shear stress (ISS). Results showed that after 1 h of heating, SCGC exhibited the highest bond stress, followed by SCC and reference concrete. Mass loss for SCGC was lower (4.5 % after 1 h; 5.6 % after 2 h) than others. Strength losses after 2 h were severe (65 % for reference, 69 % for SCC, and 67 % for SCGC). Bond stress and ISS losses exceeded 90 % after 2 h, representing severe degradation. Increased heating also resulted in higher slip, reducing bond integrity. SCGC demonstrated better thermal resistance initially, but all concrete types experienced substantial performance loss after prolonged high-temperature exposure.