Control brick specimens showed homogenous and dense structure under microscopic observations. However, RHA and SBA brick specimens showed comparatively less binding and densification along with open pores, which were irregular shaped and interconnected. Presence of micro pores in all the specimens might be related to the crystallization process [62]. SEM images are also consistent with porosity and water absorption results. Increase in porosity after incorporation of SBA and RHA reduced the compressive strength of clay bricks.