Novel in-situ controllably grown CSH: Synthesis, characterization and the effect on cement hydration

CSH nanoparticles are distinctly different from other nano-additives because they are supposed to be ideal nucleation substrates for hydration products. One of the biggest obstacles is the difficulty in achieving a good dispersion of CSH nanoparticles in the matrix. We utilize a novel method to prepare composites by in-situ grown CSH nanoparticles (ICSH) on the surface of iron tailings powder (ITP) particles, and the growth amount and Ca/Si ratio of CSH can be precisely controlled. The results show that the agglomeration of CSH nanoparticles can be reduced by using the inert ITP admixture which is easy to disperse uniformly in cement-based materials. Studies on the properties of modified cement show that ICSH is significantly better than pure CSH powder in improving early hydration, pore structure and long-term compressive strength. These improvements are mainly attributed to the good dispersion of ICSH and the rigid system of the ITP matrix. This study provides theoretical guidance for improving the dispersion of nanoparticles in cement matrices.