Performance Evaluation of Portland Slag Cement Concrete under Harsh Environmental Curing with and without Chemical Admixtures

This paper presents the assessment of the mechanical and durability performance of Conventional Concrete and Portland Slag Cement concrete exposed to normal, hydrochloric acid, and sulphuric acid curing, with and without admixtures. Nine mixes were investigated for workability, compressive, split tensile, and flexural strength, effective porosity, and chloride permeability. The best performance was recorded by the admixture-based concrete under normal curing, showing a 28-day compressive strength of 28.89 MPa, split tensile strength of 2.53 MPa, and flexural strength of 3.76 MPa. PSC showed better acid resistance compared to conventional concretes. Under hydrochloric acid curing, the PSC mix with admixture recorded 28.24 MPa, but sulphuric acid curing, it recorded 27.26 MPa, reflecting better durability. Sulphuric acid caused greater strength reduction and higher porosity due to the formation of gypsum. The lowest porosity of 4.25% and minimum chloride permeability of 1764 Coulombs were recorded in the admixture mix under normal curing, confirming improved. Compact Calcium–Silicate–Hydrate gel was observed in the admixture mixes, while pronounced observed in the sulphuric acid–cured samples. The results point out that in acidic/chemically aggressive environments, PSC concrete with admixtures is the most effective and durable option.