Abstract
Surface coatings are mainly applied to protect concrete structures against various environmental conditions. However, the interface between the concrete and coating is a weak link, and interfacial delamination is the primary mode of failure. Fracture resistance is the main design criteria for these materials, and therefore, it is necessary to investigate possible causes of interfacial failure for preventive measures. To this end, we have investigated the potential failure mechanisms and measured interfacial strength by performing a pull-off adhesion test on epoxy coated cement paste. From the pull-off adhesion test, adhesive (interface) failure between cement paste and epoxy is predominantly observed. It is observed that the adhesive (interfacial) strength for the sample tested on 50th day is more than the 28 days hydrated sample. This is due to additional curing of cement paste samples after coating epoxy which leads to higher interfacial strength. We also present the phase-field model (PFM) to predict the adhesive failure for this system. The results obtained from the PFM, i.e., load at failure and crack path are validated against experimental results. Finally, the influence of various material parameters such as elastic modulus and fracture energy of the interface on interfacial fracture behaviour is studied.
Highlights
Concrete is the world's most commonly used construction material and is the second most‐consumed material after water [1]
The differences in the results of peak load obtained from phase‐field model (PFM) and pull‐off adhesion test experiments may be attributed to the assumption of elastic materials and brittle fracture for both epoxy and cement paste
We have investigated the role of elastic modulus and fracture energy of the interface on the crack path and load‐ displacement response of the cement paste‐epoxy coating system
Summary
Concrete is the world's most commonly used construction material and is the second most‐consumed material after water [1]. Surface coatings are used to protect against these different environmental conditions and be the most effective form of protection. The durability of different concrete coatings has been widely studied [2,3,4,5]. Almusallam et al [2] evaluated the durability performance of various types of coatings on concrete exposed to different environmental conditions. Berndt et al [3] investigated the effect of different supplementary cementitious materials, protective coatings, and mortars in improving the resistance to microbiologically influenced corrosion in concrete cooling tower structures at geothermal power plants. For concrete‐coating systems, the interface between concrete and coating is a weak link and interfacial delamination is the primary mode of failure observed with this material class. Experimental investigation of performance between various coating materials and cementitious materials needs to be done to investigate the possible causes and the mechanism of failure associated with preventive measures
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