Influence of fine inclusions on the morphology and mechanical performance of lightweight foam concrete

Lightweight foam concrete is a cementitious cellular solid with a series of functional properties. Its non-structural applications potentially permit a high-volume inclusion of particles (e.g., recycled fines). However, the particle inclusion tends to alter the foam morphology and diminish the mechanical performance of foam concrete. To promote the acceptance of particle inclusion while minimizing the performance loss, this work studies the impact of sand inclusions on the mechanical properties of a group of lightweight foam concrete mixtures at 0.4 and 0.6 g/cm³, with various particle sizes and inclusion ratios. The morphology of lightweight foam concrete that is closely related to its mechanical performance is characterized using optical and scanning electron microscope (SEM) imaging. Several tests characterizing the fundamental resonant frequency, elastic modulus, crushing strength, and compressive strength, are also implemented as direct mechanical measurements of the foam concrete samples. Based on the experimental results, a model is derived for predicting the strength of lightweight foam concrete with different particle inclusions. Our study suggests that the degradation of foam structure is the major cause of the loss on mechanical performance, but a high-volume particle inclusion can be achieved with proper implementation.