Mix proportion optimization and early strength development in modified foam concrete: an experimental study

The influence of the single polycarboxylate superplasticizer (PCE) and blending it mixed hydroxypropyl methylcellulose (HPMC) on hardening moulding quality and surface pulverisation of foam concrete was investigated. An orthogonal experimental design was employed to determine the optimum combination of parameters for four property indexes (PIs) in this paper. A multi-index matrix analysis method was used to evaluate the parameter combinations and obtain the overall optimal performance for the PIs. The effect of calcium formate (CaF) on the early compressive strength of modified foam concrete with the most optimal combination in different density grades was also studied. The results indicate that the incomplete cement hydration reaction is the essential cause of pulverisation, which can be alleviated by adding a suitable PCE. Defoaming and precipitation occur when the PCE incorporated exceeds 0.1%, which can be mitigated by the addition of 0.02 to 0.06% HPMC. The orthogonal analysis indicates that the anti-cracking agent has a more substantial effect on the strength of the foam concrete than the thickening agent. The most significant factor of mechanical properties is PP fiber followed by dispersible latex powder (DLP). The optimal combination of foam concrete is 0.06% HPMC, 0.3% DLP, and 0.5% PP fiber. The early compressive strength of foam concrete can be significantly enhanced by increasing the CaF content. However, increasing the density level results in a decrease in the 28-day compressive strength of the foam concrete.