Evaluation Of Bond Strength In Roller Compacted Concrete Under Various Normal Pressures
Free (open access)
M. Madhkhan & A. Arasteh
The construction of dams using Roller Compacted Concrete (RCC) is a relatively new technology, which has rapidly developed in recent years. To increase the safety factor in designing the various horizontal construction joints in RCC dams, an experimental research using interlayer cement grout has been carried out to improve the bond strength. A device with the ability of exerting the normal pressure in the direct shear method has been designed and used. 144 tests were carried out to assess the effect of interlayer cement grout along with exerting the normal pressure. The tests include different proportions of water to cement of the interlayer grout (0.5, 0.75, 1) and different values of normal pressure (0, 5, 10, 15 kg/cm 2 ) in the ages of 7, 28 and 90 days. The results indicate that the use of interlayer cement grout in the range of the normal pressure exerted gives higher bond strength compared to the state of no grout. By reducing the ratio of water to cement of the grout, the bond strength increases. Keywords: Roller Compacted Concrete, horizontal construction joint, interlayer cement grout, bond strength, normal pressure. 1 Introduction The RCC dams are built in relatively thin layers, with a thickness of approximately 30 centimeters placed, spread and compacted over each other; therefore a large number of horizontal joints are formed in the dam. The quality of the concrete at the joint surface is of great importance to ensure the integration of layers. But in practice, this surface has a lower quality compared to the concrete mass; and a lower tensile and shear strength and a higher permeability is expected .
Roller Compacted Concrete, horizontal construction joint, interlayer cement grout, bond strength, normal pressure.