Effects of Polymers on Cement Hydration and Properties of Concrete: A Review

Polymer compounds have become a popular choice for the synthesis of novel products and are being used in cementitious mixtures principally for altering the properties in the fresh state and as repair materials. These polymers are used in various combinations. Their interaction with cement is worth studying because its hydration, followed by setting and hardening, is the primary phenomenon contributing to the strength gain and performance of concrete. This paper summarizes the effects of different polymers on the hydration of cement and the properties of concrete/mortar. Studies have established that the incorporation of polymers as a workability enhancing admixture or for improving strength, durability, and other properties severely affects the early hydration of cement and reduces the overall strength gain in most cases. The hydration retarding effect depends on the charge, architecture, and the amount (wt %) of polymer added. However, owing to the densification of the interfacial transition zone and formation of polymer films/bridges between stacks of calcium hydroxide surfaces and air, the later age properties show beneficial effects such as higher flexural strength, enhanced compressive strength, and modulus of elasticity, better resistance against frost, and corrosion of steel reinforcement. Further, it is seen that the hydration retardation may be mitigated to some extent by the addition of silica fume or zeolite; using a defoaming agent; curing at high temperatures; and following a combination of wet, moist, and dry curing regimes. This review is expected to be helpful to all practicing civil engineers who are the immediate users of these chemicals and are working to achieve quality concrete construction.