Study on the influence of nanosilicon penetrant on the self-healing properties and mechanical properties of cement mortar

As a new type of crystal additive, nano-silicon penetrant can interact with the hydration products in the mortar to form Hydrated calcium silicate(C-S-H) gel and other repair products. The effects of nano-silicon penetrant on the mechanical properties and self-healing properties of mortar at different ages and under different exposure conditions were systematically evaluated by using flexural and compressive strength, surface crack observation, water permeability coefficient and load damage recovery rate. The experimental results show that the optimal dosage of nano-silicon penetrant is 2 wt%. After 28 days of curing, the flexural strength and compressive strength of the mortar increased by 12.3 % and 6.66 %, respectively.Cracks up to 0.335 mm wide can be repaired effectively. The nano-silicon solution's water penetration experiment demonstrates its capacity to effectively fill mortar's internal fractures and markedly decrease the relative permeability index. With 28 days of standard curing completed, After 28 days of curing, the relative permeability coefficient of the mortar was reduced to zero. The compressive strength recovery test shows that the nano-silicon penetrant significantly enhances the self-healing phenomenon of the mortar, and the compressive strength recovery rate of the pre-cracked specimen reaches 100 %.Specimens in a 30°C immersion environment have a near-perfect healing capacity, which is better than that of a specimen in a 20°C immersion environment, while specimens in wet-dry cycles and air-exposed environments have relatively weak healing capacity. SEM-EDS and FTIR analyses showed that the product was mainly composed of C-S-H, calcium carbonate and aluminate.