Sandy soil based foam concrete with ultra-small pore structure through in-situ mechanical frothing

During the manufacturing of foam concrete, conventional chemical and physical foaming methods are still inadequate for regulating and stabilizing the bubble properties. In this work, an one-pot method, denoted as in-situ mechanical frothing, was proposed preparing foam concrete by vigorously stirring the mixture of water, cement, sandy soil, and foaming agent. Sandy soil (SS) was used in the content range of 25-75% as cement replacement to decrease the binder consumption and reduce costs. The influence of in-situ mechanical frothing technology and SS dosage on the properties of paste rheology, pore structure, compressive strength, and thermal properties was investigated. The results showed that the average pore size of foam concrete prepared by this method is between 45.73 and 74.58 μm. The compressive strength of the formed foam concrete at dry density of 600-1000 kg/cm3 was 2.78-16.37 MPa, which was 85%-231% higher than that the standard values. The incorporation of SS resulted in smaller and homogeneous pore structure in foam concrete. Moreover, foam concrete with 25-75% SS dosage showed 7-40% decrease in thermal conductivity. The overall analysis showed that the 25-50% SS-incorporated foam concrete enabled achieving higher standard properties through in-situ mechanical frothing.