Durability of High Performance Concrete Containing Nano Silica Using Rapid Chloride Permeability Test

Abstract

Till the end of 20th century, scientists and engineers emphasized in developing high strength materials without considering the performance of the structures in different environmental conditions. Corrosion of reinforced steal in marine structures, bridges, water retaining structures, etc. is due to ingress of chloride ion which is present in water. This is one of the major environmental problems, which affects the overall performance of the structure. Rapid chloride permeability test (RCPT) was suggested by ASTM C 1202-1997, which is the most accepted durability test on concrete. Development of High Performance Concrete is the solution to overcome this environmental problem.

This study deals with the durability of M60 Grade High Performance Concrete with and without Nano Silica using RCPT, test results are validated using Scanning Electron Microscopy (SEM) and Energy Dispersion Spectroscopy(EDS). Results of RCPT show that charges passed in the HPC with Nano Silica is less compared to HPC without Nano Silica for all dosages of superplasticizer (0.5% to 2%). At 1% superplasticizer, passing of charges is lowest for both HPC’s. Hence, 1% superplasticizer is the optimum dosage to achieve durability. Results of EDS and SEM show that, better packing of  HPC can be achieved using Nano Silica.