Study of the key technologies of application of tuff powder concrete at the Daigo hydropower station in Tibet

High-mix fly ash (FA) is often used in roller compacted concrete (RCC) to ensure construction quality and reduce project cost. However, cost and difficulty of schedule control will increase if FA is transferred from other areas because the resource is relatively scarce in Tibet of China. Based on the richness of tuff resources at the Daigo hydropower station in Tibet, studying the feasibility of concrete application with tuff powder as the admixture is necessary because of the low cost and small impact on schedule. Research compared the performance indicators of RCC of tuff concrete (concrete mixed with only tuff powder), FA concrete (concrete mixed with only FA) and concrete mixed with FA and tuff. The results showed the tuff concrete increased the earlier compressive strength, earlier tensile strength and the drying shrinkage ratio and reduced the impermeability and frost resistance in freeze-thaw cycles. The tuff concrete performed well against cracks and deformation in comparison with the FA concrete and can meet the design requirements of the Daigo hydropower station. The results provide data for the selection of concrete mixtures for the Daigo hydropower stations.