Fracture and Tension Properties of Roller Compacted Concrete Cores in Uniaxial Tension

This paper deals with the behavior of roller compacted concrete (RCC) cores in uniaxial tension cored from a practical RCC dam. Properties included are tensile strength, peak strain, modulus of elasticity, fracture energy, brittleness, complete stress-deformation curve, and stress-crack width curve both for the RCC matrix and the interface. Two categories of compressive strengths of RCC, 15 and 20 MPa, respectively, were tested in order to investigate the effect of RCC compressive strength on their behaviors. Two categories of specimen sizes of RCC, $150\times 300$ mm and $250\times 500$ mm cylindrical specimens, were also tested in order to investigate the effect of specimen size on their behaviors. The complete stress-deformation curves for RCC specimens were achieved by using a servohydraulic closed-loop testing system and four extensometers, of which the extensometer indicating maximum deformation is employed as feedback signal. Based on the stress-deformation curves, their stress-crack width curves were also obtained and theoretically modeled. The present results support the following conclusions. The uniaxial tensile strength of the RCC matrix is related to both the square root of its nominal compressive strength and the ratio of the maximum size of aggregate to the characteristic dimension of the specimen, but the uniaxial tensile strength of the interface is related only to the later. The modulus of elasticity both for the RCC matrix and for the interface are related to the square root of their nominal compressive strength and the ratio of the maximum size of the aggregate to the characteristic dimension of the specimen. The ultimate crack width of the RCC matrix is governed by the maximum size of the aggregate, but the ultimate crack width of the RCC interface is governed by the ratio of the maximum size of aggregate to the characteristic dimension of the specimen. The fracture energy of the RCC matrix is related to the square root of its nominal compressive strength and the ratio of the maximum size of the aggregate to the characteristic dimension of the specimen, whereas the fracture energy of the RCC interface is related to the square root of its nominal compressive strength and the maximum size of aggregate. The characteristic length of the RCC matrix and interface is related to both the square root of their nominal compressive strength and the ratio of the maximum size of the aggregate to the characteristic dimension of the specimen.