Feasibility assessment of microwave-cured lightweight aggregate concrete by mineral encapsulated self-healing

A novel lightweight foam aggregate (FLWA) has been developed in this study through geopolymerization and microwave curing. Sodium silicate (Na2SiO3) is used as both an alkaline activator and a foaming agent. Afterwards, Na2SiO3 is impregnated into FLWA as a healing agent. The feasibility of FLWA for autonomous self-healing is evaluated using three scales: micro (optical microscopy, SEM-EDX, and sorptivity), molecular (FTIR), and macro (compression and flexural tests). To quantify the efficiency of healing at both autonomous and autogenous levels, two types of concrete specimens are cast: one using encapsulated self-healing FLWA and the other without any healing agent. The efficiency of crack healing is visualized using optical microscopy and SEM techniques. Then, the healing products are confirmed through EDX and FTIR analysis. As a result, the efficiency of autonomous crack healing is 100% after 90 d, compared to autogenous healing which is only 20.4%. Significant strength recovery is observed in compression and flexure. Therefore, developed FLWA with healing agent can be applicable for both autonomous and autogenous self-healing performance.