Preparation of epoxy resin-geopolymer (ERG) for repairing and the microstructures of the new-to-old interface

Abstract

Geopolymer with great durability and bonding properties, as a kind of low-carbon cementitious material, has become a potential repairing material for concrete repair. In this work, epoxy resin-geopolymer (ERG) were prepared, and the new-to-old interface was characterized. Results show the incorporation of epoxy resin (ER) would increase the mechanical properties and bonding performance, while it would also increase the porosity of ERG. Geopolymer with 4% ER (mass ratio) exhibited both great compressive strength and flexural strength. The interaction between ER and geopolymer was clarified by X-Ray Diffraction (XRD), Thermogravimetric-Differential Thermal Analysis (TG/DTA) and Fourier Transform infrared spectroscopy (FTIR), indicating that there might be formed hydrogen bonds between ER and geopolymer while ER would not affect the main types of geopolymerization products. For repaired composites using geopolymers, the results of the newly defined interfacial water absorption coefficient were consistent with the interfacial flexural-tensile strength results, probably providing an easy and non-destructive method for evaluating the bonding performance of repairing materials. From the interfacial water absorption results, the incorporation of ER would reduce the porosity of the new-to-old interface, which was also verified through Back Scattered Electron (BSE) images analysis, explaining the improved bonding performance of geopolymer with ER.