In this study, the effects of styrene–acrylic ester (SAE), nanocalcined clay (NCC), and irradiation dose on the thermal, mineralogical, and microstructural characterizations of irradiated polymer‐blended cement mortar composites have been investigated. The composites were prepared by partial replacement of cement with 5 and 10% NCC and mixed with sand, SAE latex was added with different ratios (2, 4, 6, 8, 10, and 15%); the composites were subjected to various doses of γ‐irradiation ranged from 10 to 50 kGy. Physicomechanical properties, thermogravimetric analysis, X‐ray diffractometry, and scanning electron microscopy techniques were carried out. Mechanical investigation manifested that composites loaded with SAE up to 8% showed the best mechanical performance as compared with composites contains 10 and 15% SAE. POLYM. COMPOS., 36:1849–1858, 2015. © 2014 Society of Plastics Engineers