The important of bond strength of a multilayer concrete system is increased with
the increase of the use of the advanced composite materials in the field of repair or
strengthening. Experimental and analytical models based on different testing
methods are developed in attempt to evaluate the actual bond strength of the
system. The most common techniques used to prepare the interfacial bonding
surface can be classified into physical, chemical, and mechanical techniques.
Analytical and experimental study was conducted to find out the dominant factors
that control the tensile bond strength at the interface. The variables were the surface
roughness, the chemical coating, and the steel connectors. The experimental study
was conducted on 48 specimens which were prepared for the splitting test. The
analytical modeling was carried out using ANSYS12.0.1, where 8 different cases of
surface conditions were considered. Interface of smooth surface (SS) was used as a
reference while the physical bond was expressed in terms of horizontal roughening
(HR), vertical roughening (VR) and grid roughening (GR). The mechanical
bonding was induced by using mild steel bar (SC1) and high grade steel bar (SC2).
The results of the presented research work show the role of the relative rigidity of
the mixes on the tensile bond strength. Simplified and reliable formulas were
presented to relate the experimental and theoretical tensile bond strength based on
the interface condition. The results also show that using the grid roughening (GR)
gave the highest value of the tensile bond strength. The case of using the epoxy
(EP) gave competitive tensile bond strength values.
Good agreement between the experimental and theoretical results and similar
trends were observed for the cases (SS), (HR), (VR), (GR) and (AB). Slight
differences were found for the cases (EP), (SC1) and (SC2).