Three different composition ratios of chitosan-g- acrylic acid, P[Ch-g-AA] were prepared in the presence of potassium persulphate as an initiator using free radical technique. The grafted copolymers were characterized through FT-IR, TGA, DSC, and SEM. The results showed that these grafted copolymers have a single glass transition indicating that these copolymers can form a miscible phase. The P[Ch-g-AA] exhibit thermal stability. SEM of the grafted copolymers showed no phase separation, when compared with the pure Ch. The effect of grafted copolymers on the physico-mechanical properties of cement pastes was investigated. The addition of water mixed with grafted copolymer to the cement, improves properties of cement pastes. As the ratios of AA in the grafted copolymer increases, the water-to-cement (WC) ratio, setting time as well as water absorption decreases. While The compressive strength was sharply increased at nearly all hydration ages.