Investigation of the mechanical properties of the mortar developed for the repair and strengthening of historical buildings on building elements

In this thesis study, the mechanical properties of geopolymer historical building mortars produced by using blast furnace slag (YFC), brick dust and hydrated lime as binder material were investigated. Since the standard historical building mortar is lime-based, it was ensured that the geopolymer mortars developed were also lime-based, the amount of slaked lime used in the mixtures was kept constant and 48% of the binder material by weight was used. In order to find the optimum mixture, GGBFS was used at the rates of 29%, 33%, 38% and 43% by weight of the binder material, while brick dust was used at the rates of 10%, 14%, 19% and 24% by weight of the binder material. In addition, potassium hydroxide (KOH) and sodium hydroxide (NaOH) solutions at different concentrations were used as activators, and the productions using sodium hydroxide (NaOH) solution were repeated with the addition of sodium silicate liquid. The amount of activator was adjusted according to the standart consistency. The aggregate/binder ratio was kept constant as 2 and stream aggregate with a grain diameter of 0-2 mm was used. In addition, the production of the standard historical building mortar was carried out, and thus its mechanical properties could be compared with the developed geopolymer historical building mortar. According to the results of the compressive strength tests performed on the samples, the mortar producing the highest final strength is the mixture numbered K56 (400 g lime, 80 g brick powder, 360 g GGBFS, SS/SH (12 m) 820 g). Model wall units and arch systems were produced in order to examine the mechanical properties on the building elements. In the compressive strength tests performed on the samples, it was determined that the geopolymer historical building mortar gave much more effective results than the standard historical building mortar. In the compressive and shear strength tests performed on the wall units, significant improvements were observed in the geopolymer historical building mortar compared to the standard historical building mortar. In arch systems, although the flexural strength of the arch element produced with the standard historical building mortar is higher than the geopolymer historical building mortar, the arch system produced with the geopolymer historical building mortar exhibits a more ductile behavior when the displacement results are taken into account. Keywords: Geopolymer, historical building, mortar, strenght, wall units, arch systems