Residual durability, mechanical, and microstructural properties of foamed concrete subjected to various elevated temperatures

Abstract

Three different densities (500 kg/m3, 1000 kg/m3, and 1500 kg/m3) of foamed concrete (FC) were tested alongside mortar with a density of 1980 kg/m3 to investigate how high temperatures affect the qualities of FC. A flow table test was used to examine the fresh qualities of the mixtures. The modulus of elasticity, ultrasonic pulse velocity (UPV), bending strength, split tensile strength, compressive strength, thermal conductivity, porosity, and appearance and colour changes at ambient temperature and after exposure to various high temperatures (100 °C, 150 °C, 200 °C, 400 °C, 600 °C, and 800 °C) were evaluated. To study the effects of varying densities, microstructure analysis was performed utilizing scanning electron microscopy and mercury intrusion porosimetry. According to the findings, the four varied densities appeared dissimilar. FC with lower densities (500 kg/m3 and 1000 kg/m3) showed signs of cracking, while FC with a higher density (1500 kg/m3) enabled for precise detection of the pore connectivity and surface spalling occurrences. High temperatures had less effect on the mortar than FC mixtures. As the temperature increased, the modulus of elasticity, split tensile strength, bending strength, compressive strength, thermal conductivity, and mass loss decreased for all the mortar and FC samples. The UPV values increased marginally up to 100 °C before decreasing. This investigation highlighted the need for additional research and code provisions that consider different innovative construction materials and FC constituent classes.

Keywords

• Foamed concrete
• Elevated temperatures
• Durability and hardened characteristics
• Pore size distribution
• Thermal conductivity
• Scanning electron microscopy analysis