Study in Properties of Cement Composites with use of Internal Curing Agent

Rapid growth of the construction sector, particularly in India, has intensified the demand for concrete and cement mortar, resulting in significant freshwater consumption for hydration and curing. Conventional external curing practices are often inefficient, labour-intensive, and highly dependent on environmental conditions, leading to water wastage and inconsistent performance. Internal curing offers a sustainable alternative by supplying moisture from within the cementitious matrix; however, its application in cement mortar remains insufficiently explored. In this study, mortar mixes were prepared using Ordinary Portland Cement (OPC 53 grade), standard graded sand, potable water, and a polycarboxylate-based superplasticizer. Three internal curing agents—Drumstick Resin (DSR), Superabsorbent Polymer (SAP), and Polyethylene Glycol-400 (PEG-400)—representing natural, polymeric, and chemical moisture-retention mechanisms, were investigated under air-curing conditions. A control mix and experimental mixes with varying dosages were evaluated through tests on fresh properties, mechanical strength, durability, and microstructure. The results indicate that internal curing efficiency is strongly dependent on agent type and dosage. DSR showed limited improvement, while SAP at an optimum dosage of 0.5% enhanced long-term strength and reduced water absorption. PEG-400 demonstrated the most consistent improvement in workability, strength, stiffness, and durability, with 1.0% identified as the optimum dosage. Overall, SAP and PEG-400 proved effective for improving mortar performance under limited curing conditions, emphasizing the importance of dosage optimization for sustainable cementitious composites.