Abstract: In consequence of froth breaking, there is a caved problem about air-foam treated lightweight soil after casting indoor and in-site. To analyze and solve the problem, a series of samples preparation experiments on sand were conducted on air-foam treated lightweight soil with three specific densities under different conditions, i.e., temperature, humidity and sand mixing or not. Meanwhile, the height and strength of samples were measured. Based on the thermodynamics theory, the effects of three factors on the preparation and strength of the samples were analyzed using experimental data. The results show that temperature difference is the decisive factor affecting the shrinkage and expansion of air-foam treated lightweight soil. The temperature difference impact greatly in sample of high bubble content. Humidity and sand mixing barely affect sample preparation while the mold unloading time of samples will be extended and the integrity of samples will be affected when ambient humidity becomes higher. Early strength of samples is influenced by temperature and temperature difference. temperature difference mainly affects the density of samples, and the temperature mainly affects the rate of hydration reaction of cement. The results of this study provide reference for the preparation and construction time of air-foam treated lightweight soil.

Key words: air-foam treated lightweight soil, temperature difference, humidity, strength