Properties of a foamed concrete with soil as filler

• Soil-based foam concrete exhibits unusual physical properties, such as strength, thermal insulation and water resistance.
• Silica fume added into soil-based foamed concrete can greatly increase the physical properties.
• The fit of mathematical expressions based on hygroscopic test results was investigated.

Ordinary Portland cement, soil and foaming agent are the raw materials used to make soil-based foamed concrete. The effects of foam content and silica fume on the physical properties of soil-based foamed concrete, such as the dry density, 28-day compressive strength, thermal conductivity, water resistance and pore structure, were studied. The experimental results indicate that the foam and silica fume contents have a large impact on the physical properties of soil-based foamed concrete. The thermal conductivity, density, water resistance and compressive strength decrease with increasing volume fractions of foam. The compressive strength, the thermal insulation and water resistance are all improved by increasing the content of silica fume. Soil-based foamed concrete consisting of 20% silica fume with a density of 800 kg/m3, compressive strength of 7.5 MPa and thermal conductivity of 0.16 W/m K can be used as water-resistant lightweight concrete. The hygroscopic tests were performed and the results indicate that the addition of silica fume has some effect on the hygroscopic property of soil-based foamed concrete. Several fitting curves have been obtained, the fitted functions developed by the Kumaran model and Cubic function have better fitting parameters.