Mechanical Properties of Sustainable Foam Lightweight Soil at Varying Curing Temperatures and Its Early-Stage Quality Control

Sustainable foam lightweight soil (FLS) with the introduction of solid waste-based binders and dredged mud has shown high engineering and environmental value in expressway reconstruction and extension projects. Accelerated testing through high-temperature curing is considered a crucial method for early-stage assessment of sustainable FLS construction quality. This study aims to explore the curing temperature effect on the strength development of the FLS with different mix proportions and the applicability of accelerated curing method. Strength tests were first conducted on kaolin clay-based FLS with three wet densities and three water contents under different curing temperatures (T), and the strength of the dredged mud-based FLS was also tested to broaden the applicability. Results indicate that higher T and increased wet density significantly enhance the strength of clay-based FLS at any curing age, while higher water content reduces it. The wet density and water content of the proposed FLS recommended in this study considering the strength and lightweight requirements are 800 kg/m3 and 100%, respectively. Moreover, the effectiveness of the accelerated aging method for clay-based FLS is demonstrated by the fact that no dramatic strength loss occurs due to foam expansion and collapse at elevated T of up to 50 °C. On this basis, a strength prediction model based on the concept of activation energy is proposed for both kaolin clay-based and dredged mud-based FLS considering the temperature effect. Changes in wet density have a minimal impact on model parameters, but variations in soil type and water content require updating these parameters to ensure prediction accuracy. Finally, an early quality control method is introduced for applying the sustainable FLS in field projects.