Mechanical reinforcement of cement-based materials using slow-release polythiotactic acid-grafted Nano-SiO2 hybrid

Inorganic nanomaterials are widely used in improving the mechanical strength of cement-based materials. However, when used in cement-based materials, inorganic nanomaterials are not only easy to agglomerate, but also often leads to the problem of significant decrease in flexural strength. In this paper, a novel organic-inorganic hybrid strategy is adopted by grafting α-lipoic acid, polyether amine, and nano-SiO 2 to synthesize a new type of polymeric nanohybrid material PTNS. The new PNTS exhibits multiple structural characteristics, including dynamic chemical S-S bonds, polycarboxylate frameworks, and steric hindrance effects derived from polyether amines. By adding PTNS to the cement paste, the agglomeration of nano-SiO 2 in cement-based materials can be effectively avoided. The mechanical strength test results show that polymeric nanohybrid material PTNS with dynamic chemical bond can achieve the synergistic improvement of the compressive strength and flexural strength of cement paste. The flexural strength of cement paste mixed with 2.0 wt‰ PTNS-2 increased by 5.3 %, 13.0 % and 9.3 % compared with the control sample after curing for 1, 7 and 28 days, respectively; The compressive strength increased by 18.6 %, 1.5 % and 6.2 % respectively. Furthermore, X-ray diffraction, scanning electron microscopy and cement hydration tests, which revealed the mechanism of mechanical properties enhancement of the slow-release polythioctic acid grafted nano-SiO 2 hybrid material PNTS.