Strength and durability of marine cement-based mortar modified by colloidal nano-silica with epoxy silane for low CO2 emission

The heavy use of marine concrete consumes a large amount of cement increasing CO2 emission. Improving the strength and durability of marine concrete is an effective strategy to reduce CO2 emission. This study aimed to introduce colloidal nano-silica (CNS) and epoxy silane modified colloidal nano-silica (M-CNS) to improve the mechanical performance and durability of High Sulfate Resistance Portland cement. Meanwhile, the CNS and MCNS were incorporated to marine cement mortar, and the aggregation of CNS, and the hydration mechanism and micro-mechanism of the mortar were investigated. The results indicated that the workability, mechanical properties and durability of marine cement samples were enhanced with M-CNS addition. When adding 1 wt% M-CNS with grafting rate of 15% (M-CNS1), the chloride diffusion coefficient was reduced by 9.49% and the porosity was reduced by 18.84%. In addition, the compressive strength of cement mortar with M-CNS1 increased by 10.42%, 28.71% and 10.49% compared with blank specimens after curing for 3-, 7- and 28-days. The improvements in strength and durability indicate that M-CNS has a promising application for reducing CO2 emissions by marine concrete industry.

Automated summary

The heavy use of marine concrete consumes a large amount of cement, leading to increased CO2 emission. This study aimed to improve the mechanical performance and durability of marine concrete by introducing colloidal nano-silica (CNS) and epoxy silane modified colloidal nano-silica (M-CNS) to High Sulfate Resistance Portland cement. The results showed that the addition of M-CNS enhanced the workability, mechanical properties, and durability of marine cement samples, reducing the chloride diffusion coefficient and porosity, and increasing compressive strength.