Investigation of the effect of silica fume and synthetic foam additive on cell structure in ultra-low density foam concrete

In this study, the properties of ultra-low density foam concrete with silica fume substitute and synthetic foam additive were investigated. Two different references and silica fume substituted foam concretes with densities of 220 and 200 kg/m3 were produced. Silica fume was used as the replacement material and its ratio in the mixtures was kept constant at 5% by weight. According to the results of the study, the compressive strengths and the thermal conductivity coefficients of the references and silica fume substituted foam concretes with densities of 220 and 200 kg/m3 were found to be 0.26, 0.21 and 0.32, 0.26 Mpa at 28 days and 0.073, 0.069 and 0.068, 0.060 W/mK, respectively. In addition, the behavior of foam concrete at high temperatures was investigated using a flame source, which can reach up to 1200 °C, since temperatures usually exceed 1000 °C during a fire. At the end of ten minutes, the heat permeability of silica fume substituted foam concrete exposed to a 1200 °C temperature was 6.5% and 5.3%, which was better than reference foam concretes, respectively. As a result, silica fume has positively affected the compressive strength at later ages and thermal conductivity properties of foam concrete.