Chemically functionalized manufactured sand as the novel additive for enhancing the properties of cement-based composites

The extensive applications of manufactured sand (AS) in cement-based composites were restricted because of its coarse surface texture, poor gradation and inevitable agglomeration. In this paper, a specifically designed polycarboxylate superplasticizer (PCE) decorated manufactured sand (AS-PCE) composite was synthesized via radical polymerization. The AS-PCE composite was characterized by FTIR, TGA, XPS and SEM. The load of PCE on the surface of AS was ∼12 wt%. Our results show that AS-PCE can promote cement hydration reaction and refine the microstructure of a cement-based material, thus, reinforcing its mechanical strength. Meanwhile, the fluidity of cement mortar with 1 wt% AS-PCE particles was increased by 35% after 1 h hydration, due to the steric hindrance effect provided by polycarboxylate superplasticizer affiliated with AS-PCE. The AS-PCE can also significantly enhance the mechanical strength (especially, the flexural strength was about 25% increased after curing for 28 days) of mortar. The excellent improvements result from the synergistic effects of AS-PCE including superb dispersibility, promotion of cement hydration reaction and the repair of interfacial defects between AS particles and the cementitious material. The research provides a promising method for the AS application in cement-based materials.