The alteration in microstructure or phase composition of concrete subjected to aggressive surroundings results in the reduced working life of concrete structure. The diffusion of ions in concrete subjected to aggressive surrounding mainly chloride and sulfate are not uniform and depends on various parameters that make complex variations in the microstructure or phase composition along the depth of concrete, which may affect the further ingress behavior of ions and reaction mechanism. This study reported the change in microstructure or phase composition along the depth of concrete subjected to aggressive solutions containing chloride and sulfate. For this purpose, chloride diffusion and microstructure analyses were performed on various concrete mixes along the depth and exposed to chloride (3 % NaCl: 3NC) and chloride with sulfate (3 % NaCl with 4 % Na₂SO₄: 3NC with 4NS) solutions. From the result of chloride ingress test, the existence of NS in surrounding solution retards ingress/diffusion of chloride ions into the concrete. The microstructure analysis revealed non-uniform distributions of key phases, including calcium hydroxide (CH), ettringite (E), and calcium chloroaluminate (CCA), within the concrete matrix. The distribution patterns, which varied with the depth of concrete and type of exposure solutions and binder used, are described comprehensively. CH content decreased closer to the exposure surface and increased with greater depth intervals, while E was more prominent at intermediate depths compared to lower and higher levels. CCA content was slightly higher at lower depth intervals. Notably, CCA was more prevalent in ordinary portland cement with 20 % fly ash concrete (O20FAC) at lower depths, while E content exhibited differences between binder types and exposure solutions, with implications for concrete performance.