compatibility of ultra high performance concrete as repair material

mismatch and load eccentricity. Though the specifications given by ASTM C1583 were followed, the small thickness of the overlay attached with theproperties mismatch between overlay and substrate might have been a factor inthe low failure stress observed in the concrete substrate. Further research is needto prove if the current specifications given by ASTM C 1583 are still valid foroverlays with a shallow thickness and significant mechanical properties mismatchwith the concrete substrate.g. The modulus mismatch might cause local stress concentrations in the pull-off andslant-shear tests. Austin et al. (1999) stated that an eccentricity of the loading canoccur due to a modulus mismatch between the overlay and substrate materialsresulting in a lower failure load in the slant-shear test. It is convenient to developFinite Element Models (FEM) of the different loading configurations used in thisexperimental program to help to understand better the stress distribution along thecomposite specimens.5.3 Further researchThis report focuses on the characterization of the bond UHPC and conventional concreteunder different loading configurations, age, roughness degree of the concrete substrateand freeze-thaw cycles exposure. The outstanding bond performance has beendemonstrated throughout this report. However, further research is needed to complete theunderstanding of the bond between these materials and to evaluate the potential use ofUHPC as repair material.a. Microstructure observations of the bond interface by using a scanning electronmicroscope (SEM) could provide a better understanding of the reason wherebyUHPC seems to have a high adhesion to the normal concrete.b. To repeat the bonding tests with different UHPC formulations to have a widerscenario that represent the variations in the mix designs that can exist betweendifferent UHPC’s.c. The development of new UHPC formulations that utilize local materials and canbe placed in the field with a certain inclination would help to promote its use.100