Potential of Pyrogenic Nanosilica to Enhance the Service Life of Concrete

Abstract

The continuous advancement in construction materials and technology demands novel admixtures to make concrete more sustainable and durable. Several supplementary cementitious materials are already being used to replace cement partially for alleviating the destructive environmental aspects. The common durability issues faced by concrete are drying shrinkage, sulfate attacks, alkali-silica reaction, and chloride attacks. This experimental study presents a solution by analysing the effect of fumed silica nanoparticles on durability, most of which are related to permeability. The fumed silica nanoparticles were incorporated in concrete as cement substitution at 0.5%, 1.0%, 1.5%, and 2.0%. Durability performance was examined by conducting the rapid chloride permeability test (RCPT), sulfate attack resistivity test, drying shrinkage test, and water absorption test. The additional tests were conducted to determine the density, void content, and compressive strength of concrete and cement mortar samples. Also, field emission scanning electron microscopy (FESEM) and energy dispersive X-ray analysis (EDAX) were performed to understand the microstructure. The test results indicated that 2% fumed silica provided optimum results in terms of workability and mechanical performance. Compressive strength was increased by 20% and 27% in mortar and concrete, respectively. In addition, drying shrinkage was reduced by 72%, and expansion due to sulfate attack and alkali-silica were reduced by 79%, and 71% respectively. Furthermore, the rapid chloride permeability test showed that addition of 2% fumed silica resulted in overall reduction in permeability by 47%. This study corroborates that fumed silica nanoparticles-incorporated concrete is more durable than ordinary concrete. Fumed nanosilica can be effectively used in the production of performance-based cement composites. These nanoparticles have shown excellent potential in controlling drying shrinkage and permeability-related issues, including sulfate attacks and corrosion.