Bond Strength of Normal-to-Lightweight Concrete Interfaces

Structural lightweight aggregate concrete (LWAC) can be used with advantage in new structures, especially in pre-cast components, as well as in the rehabilitation of existing structures. In both situations, the result is a composite structural element, with parts in LWAC and others in normal weight concrete (NWC). Besides material properties, it is also important to characterize the behaviour of LWAC-to-NWC interfaces. With this aim, an experimental study was conducted to characterize the shear strength and the tensile strength of NWC-to-NWC, LWAC-to-NWC and LWAC-to-LWAC interfaces and to compare results with codes’ predictions. A NWC and three different LWAC were considered. Six different types of surface roughness were produced on the concrete substrate and characterized with roughness parameters assessed using the 2D-LRA method, developed by the authors. Slant shear and splitting tests were adopted to quantify the bond strength of the interface in shear and in tension, respectively.