LAUSR

The interface behavior of rock and concrete and between layers of concrete highly affects the performance of concrete dam structures. In this investigation, a modified direct shear test was implemented in the laboratory to evaluate the interface behavior between (1) rock and conventional vibrated concrete (CVC), (2) rock and roller compacted concrete (RCC), (3) CVC and RCC and (4) two layers of RCC. Series of in situ shear tests were also performed between rock and concrete. The friction angle and cohesion for all tested interface were determined and analyzed. The effect of uniaxial compressive strength (UCS) of concrete on the interface behavior was determined. Additionally, the effect of surface roughness on the interface behavior was studied by determining the joint roughness coefficient values. The rock-CVC interface had a higher shear strength than the rock-RCC interface and the RCC–RCC interface had a significantly higher cohesion than the CVC–RCC interface. The peak friction angle equation for the rock joints was verified for rock-concrete interfaces. The high shear stress at the interface increases the dissipated energy. Based on the investigation, the rock-CVC interface with the highest concrete UCS had the highest cohesion, shear strength, and dissipated energy among the laboratory rock-concrete interfaces.