Durability performance of nano-silica modified fly ash concrete under accelerated CO2 carbonation conditions

ABSTRACT Greenhouse gases, namely carbon dioxide emissions, cause variations in global temperature and relative humidity (RH), which some projections show that there will be a reduction in RH in certain areas as CO2 level increases. These fluctuations in CO2, temperature and RH significantly impact on carbonation depth in current systems. However, models for forecasting carbonation depth as a function of time in concrete components are limited to the extent of implementing important factors associated with the effects of climate change. Various concrete mixes containing 10 to 30% fly ash (FA), 3% nano silica particles (NSP) with a constant water to cement (w/c) ratio of 0.34 were used to test the durability and mechanical characteristics of nano fly ash concrete (NFC). After exposing these specimens for up to 28 days, the depth of carbonation (2% (vol.) CO2, 20°C, 65% RH) were investigated. Carbonation results show that NSP incorporated concrete mixes reduce carbonation depth by approximately 73% when compared to the control specimens.