Effect of microwave pre-curing technology on carbide slag-fly ash autoclaved aerated concrete (CS-FA AAC): Porosity rough body formation, pore characteristics and hydration products

Abstract In objective to clarify the effect mechanism of microwave pre-curing method on carbide slag-fly ash autoclaved aerated concrete (CS-FA AAC), porosity rough body formation process, physic-mechanical properties, pore characteristics and hydration products were investigated. Slurry foaming course and rough body strength development were characterized to illuminate the porosity rough body formation process. Furthermore, bulk density and compressive strength were measured to expound physic-mechanical properties. Areometry, X-ray 3D imaging and MIP method were introduced to represent the total porosity, macroscopic pores and microscopic void, respectively. The hydration products of CS-FA AAC were comprehensively analyzed by detecting of morphology (FESEM), mineralogical (XRD), and thermal behavior (DSC-TG). As results demonstrated, the innovative microwave pre-curing technology accelerated slurry foaming and thickening rate, thus shorten the pre-curing duration and improve the stability of CS-FA AAC rough body. Furthermore, the total porosity of CS-FA AAC products was obviously enlarged which attributed to the magnification of foaming pores. However, in pore partition zone, the total porosity was decreased under microwave pre-curing, but the volume of pores between 0.01 and 1 μm were improved significantly. The microwave pre-curing technology significantly promoted the generation of intermediate hydration products and improved the crystallinity of strength contributing minerals in final products. Therefore, due to the divergence effect of microwave pre-curing technology on pore characteristics and hydration products, the subsequent effect on strength is nonlinear.