High-Volume Fly Ash Concrete with High Strength and Low Drying Shrinkage

In this work, a laboratory investigation was carried out to evaluate the strength and particularly the shrinkage properties of concrete containing high volumes of fly ash. The concrete mixtures made with 50 and 70% replacement (by mass) of ordinary portland cement (OPC) with fly ash were prepared. Water-cementitious material ratios ranged from 0.28 to 0.34. Some concrete mixtures were also made with superplasticizer. The strength and shrinkage properties of the concrete mixtures cured at 20°C temperature with 65% relative humidity are reported. The laboratory test results show that high-volume fly ash (HVFA) concrete attained satisfactory compressive and tensile strength at 1 day of age. It also showed that 50% replacement HVFA concrete developed higher strength than OPC concrete at 28 days and beyond. The inclusion of high volumes of fly ash in concrete with a low water-cementitious material ratio resulted in a reduction in the shrinkage values of up to 30% when compared to OPC concrete. The concrete mixtures made with superplasticizer showed higher shrinkage values of up to 50% when compared to the concrete made with no superplasticizer.