Thermal and mechanical properties of lightweight foamed concrete at elevated temperatures

Abstract

This paper reports the main findings from a comprehensive study undertaken to evaluate the thermal and mechanical properties of lightweight foamed concrete (LFC) exposed to high temperatures. Experimental and analytical studies were carried out to develop quantification models to obtain thermal and mechanical properties of LFC at ambient and elevated temperatures. LFC of densities of 650 and 1000 kg/m3 was comprehensively tested; supplementary tests on LFC densities of 800, 1200 and 1400 kg/m3 were carried out for additional data. To quantify thermal conductivity, LFC is treated as a porous material and the effects of radiant heat transfer within the pores are included. This thermal conductivity model produced results in very good agreement with the experimental results obtained from guarded hot plate tests. The elevated mechanical property models consist of two parts: the prediction of compressive modulus of elasticity and peak stress as functions of porosity and the prediction of strength and stiffness retention factors as functions of temperature. The reduction in strength and stiffness of LFC at high temperatures can be predicted using the mechanical property models for normal-strength concrete, provided that the LFC is based on Portland cement CEM1. This paper describes the models in full and presents comparisons with test results.