Potential for Reduced Greenhouse Gas Emissions in Texas Through the Use of High Volume Fly Ash Concrete

The objective of this study was to determine the potential for reductions in carbon dioxide emissions in Texas by substituting high volumes of fly ash in concrete production and to identify the resulting benefits and challenges. Researchers reviewed the literature and determined that high volume fly ash (HVFA) can improve the properties of both the fresh and hardened concrete. It can improve workability, heat of hydration, strength, permeability, and resistance to chemical attack. A laboratory investigation was performed to investigate the potential of HVFA concrete in mitigating the effects of alkali-silica reactivity, which was recently a serious concern in Texas. The laboratory study showed high volumes of Class F ash are very effective in reducing the alkali-silica reaction from a potentially reactive state to an innocuous state. Researchers compiled data for 18 power plants located throughout Texas and determined that a total of 6.6 million tons of fly ash are produced annually in Texas and about 2.7 million tons (or 40%) are generally sold for use in concrete or other end products. Researchers estimated production of concrete in Texas and determined that if 60 percent of the portland cement used in Texas concrete production were replaced with fly ash, carbon dioxide emissions could potentially be reduced by 6.6 million tons annually by the year 2015. More education is needed for design engineers and for the concrete industry regarding the performance and environmental benefits which can be realized through increased use of fly ash in concrete.