Monitoring the long-term durability and microstructure of polymer concrete patching materials with high content of secondary raw materials using advanced methods

For commercially produced polymer systems, only primary raw materials are used as fillers. These fillers are predominantly pure silica sand of various grading. The substitution of primary materials with secondary raw materials, and their efficient use in the manufacture of polymeric repairing substances, is an indisputable advantage of the use of secondary raw materials. There is currently no general methodology for monitoring the long-term durability and microstructure of repairing substances on a polymeric basis. In this article, long-term durability was assessed by subjecting developed substances with a high content of secondary raw materials (60% fly ash, 75% glass recyclate) to freezing cycles and subsequent cohesion testing. Additionally, through exposure of a concrete element reprofiled by the developed substance, the weather effects for approximately one year. The microstructure of polymeric repairing substances cannot be observed by the same methods used for silicate substances. With regard to the type of tested substance and the filler used, advanced CT tomography and high resolution optical microscopy were chosen for monitoring the microstructure. Based on the results of the tested substances cohesion with the underlying concrete following the freezing cycles, and the evaluation of the taken images, it can be stated that the test repairing substances have excellent long-term durability and can be used in different applications. Furthermore, it was confirmed that replacing the primary filler with the secondary raw material does not reduce the long-term durability of the polymeric repairing substances on an epoxy basis. It was confirmed that only slight degradation occurs due to the photooxidation of epoxy resin by UV radiation, but this does not have a significant effect on physical and mechanical properties.