Regulation of pore structure of Brick-concrete recycled sand powder autoclaved aerated concrete and its relationship with key properties

•Brick-concrete recycled sand powder (RBCSP) was utilized as siliceous material to produce autoclaved aerated concrete (AAC).•The pore structure parameters such as porosity, number of holes, average pore size and pore shape factor of RBCSP-AAC were extracted.•The interaction between fluidity and gas forming agent content-pore structure parameters-dry density and compressive strength was established.•The grey system theory is used to analyze the factors affecting the dry density and compressive strength of RBCSP-AAC.