Production parameters of novel geopolymer masonry mortar in heritage buildings: Application in masonry building elements

The aim of this study is to develop an innovative high-strength restoration mortar using recycled materials as an alternative to the mortars used in historical buildings. Compressive strength tests were carried out on the samples and, according to the results, the mortar giving the highest strength was determined as the optimum mixture. The compressive strength, shear strength, displacement and load-carrying capacity values of the masonry units were tested by using the geopolymer mortar with the highest strength among the mortar samples produced. The novelty of this research is that geopolymer repair mortars were produced as an alternative to standard mortars and applied in masonry building units. The results showed that blast furnace slag and brick powder can effectively improve the compressive and bond strength of the geopolymer. In the compressive strength tests performed on the samples, much higher strength results were obtained with geopolymer historical building mortar than standard historical building mortar. In the compressive and shear strength performed on the masonry units, the geopolymer historical building mortar showed higher mechanical properties compared to the standard historical building mortars. When the compressive strength test results are compared, a strength of 1.8 times was observed in the masonry unit (GHB1) produced using geopolymer historical building mortar, compared to the masonry unit (HB1) produced with standard historical building mortar. As a result of the shear strength test, the masonry unit (GHK1) produced with geopolymer mortar demonstrated seven times more load carrying capacity than the masonry unit (HK1) elements produced with standard historical building mortar. Moreover, the masonry arch systems produced with standard historical building mortar showed close load bearing capacity with the geopolymer historical building mortar, but the masonry arch element produced with geopolymer mortar exhibited a more ductile behavior. It has been determined that the use of geopolymer mortars with recycled materials with increasing molarity in masonry arch elements improves the compressive strength and accelerates the geopolymerization mechanism. Innovative highstrength geopolymer mortars used in masonry walls provided good adhesion with the hollow brick, creating a compact structure.