Evaluation of the Mechanical Properties of Lightweight Foamed Concrete at Varying Elevated Temperatures

Lightweight foamed concrete (LFC) made from cementitious materials with air pores entrapped in the matrix by mechanically entrained foam in the mortar slurry has several economic and environmental benefits. Most recently, LFC has been heralded as the next generation of lightweight construction industry concrete because of its versatility and technological advancements. Owing to its many desirable qualities, including low density, low cost, low thermal conductivity, low dimensional change, amazing load-bearing capacity, great workability, and low weight, it is considered an adaptable and flexible construction material. Given that LFC is a brittle building material and since fire is among the most frequent catastrophes to affect structures, it is crucial to consider the structural performance of LFC subjected to high temperatures. Hence, this experiment attempts to ascertain the effect of varying elevated temperatures on the LFC’s strength properties. Three LFC densities of 500, 1000 and 1500 kg/m3 were prepared. The LFC specimens were exposed to predetermined ambient and elevated temperatures of 20, 100, 200, 300, 400, 500, 600, 700 and 800 °C, and the LFC samples were assessed for porosity, compressive and flexural strengths. The outcomes of this investigation showed that, regardless of density, the loss of LFC stiffness exposed to elevated temperatures happened primarily after 90 °C. This shows that the underlying process triggering stiffness loss is internal cracking, that transpires when water grows and dissolves from a porous medium. Lowering the LFC dry density diminishes its strength and rigidity. The LFC-normalized strength and stiffness–temperature relationships of various dry densities, on the other hand, are very comparable. From ambient temperature up until 400 °C, all densities exhibit a moderate and constant loss in strength and stiffness. Nevertheless, the decline is faster up to 600 °C or 800 °C, at which point it loses its ability to support any given weight. This study emphasized the necessity for more study and codes’ provisions that take into consideration various LFC constituent types and cutting-edge construction material technologies.