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Magnesium phosphate cement (MPC) foam concrete was manufactured using MPC as cementitious material and hydrogen peroxide (H2O2) as foaming agent and investigated the properties of this material. The 28 d compressive strength, thermal conductivity and strength retention coefficient of the MPC foam concrete prepared with dry densities varying from 300 to 1000 kg/m3 are 1.8–21.6 MPa, 0.136–0.347 W/(m·K) and 0.51–0.72, respectively. It is interesting to note that the MPC foam concrete prepared has a characteristic of early strength and the strength- porosity relationship concurs with Balshin’s model. And the probability density function and normal distribution can well analyze the pore size distribution of the MPC foam concrete prepared, and the results show that the MPC foam concrete with a higher dry density has a narrower pore size distribution and a smaller average pore size. In addition, the MPC foam concrete, for a given dry density or a given thermal conductivity, has a higher compressive strength compared with the foam concrete from OPC, implying the MPC foam concrete prepared has potential to be used as structural concrete and thermal insulation material.

The purpose of this paper is to prepare a foamed concrete with low thermal conductivity from the perspective of raw material selection. According to the results of literature survey, sulphoaluminate cement (SAC) is selected as the cementing material, and the mixture of aluminum nitrate and sodium bicarbonate is selected as the foaming agent. Subsequently, the related properties of the sulphoaluminate cement foamed concrete (SAC-FC) were evaluated. The results show that the SAC-FC not only possesses good thermal insulation performance, but also exhibits excellent mechanical and water-resistant properties. The compressive strength, thermal conductivity, water absorption and softening coefficient of the SAC-FC with 0.3 ~ 1.0 g/cm3 bulk density are 1.2 MPa ~ 15.2 MPa, 0.052 ~ 0.129 W/(m • K), 38.2% ~ 7.6% and 0.764 ~ 0.952, respectively. And the fluctuation ranges of the ratio of flexural strength to compressive strength and the ratio of tensile strength to compressive strength are 20% ~ 30% and 17.5% ~ 22.5%, respectively. In addition, the SAC-FC also presents the early strength characteristic and its 7-day strength is approximately 83% of the 28-day strength.

This study has been carried out to investigate the effect of the thermal conductivity of foaming gas and cement type on that of foamed concrete. The results show that the foamed concrete employed a gas having lower thermal conductivity as foaming gas or prepared from a type of cement with lower thermal conductivity takes on lower thermal conductivity. And the thermal conductivity of foamed concrete is directly proportional to the thermal conductivity of foaming gas. In addition, with the length of age, the thermal conductivity of the foamed concrete whose foaming gas is not air gradually approaches to those using air as foaming gas at the initial stage. Using the foaming gas or cement with lower thermal conductivity to prepare foamed concrete may be a feasible as well as effective way to improve the thermal insulation of foamed concrete.