Effect of Mineral Admixture and Fibers on Shrinkage Crack of Sacrificial Concrete

The ferro-siliceous sacrificial concrete is an important protection material to Nuclear power plant, high density aggregate and high fluidity can lead to occurrence of shrinkage crack. In this paper, the early-age crack and restrained shrinkage crack of sixteen types of sacrificial concrete containing different content of cementitious materials and two kinds of fibers were researched. Results showed that the workability of sacrificial concrete decreased with increasing addition of fiber, and the slump loss resulted from polypropylene (PP) fiber was much higher than that of basalt fiber. The fibers had less influence on the compressive strength, while had greater impact on the flexural strength, which was improved by 10-20%. The reduction of total cementitious materials and replacement ratio increment of mineral admixtures including fly ash and Ground Granulated Blastfurnace Slag (GGBS) in sacrificial concrete could decrease its early-age crack obviously. The utilization of 1.0-1.5kg/m(3) PP fiber could extend the cracking time and reduce the crack width of sacrificial concrete and total cracking area. The improving crack resistance capacity of sacrificial concrete resulted by basalt fiber was weaker than PP fiber. The optimized mix proportion of sacrificial concrete mixture was 450kg/m(3) total cementitious materials, 50% replacement ration of mineral admixtures and 1.0kg/m(3) PP fiber.