Effect of recycled asphalt waste on mechanical properties of alkali-activated mortars

Abstract

In the next century, negative effects, such as an increase in temperature level, rise in sea level and decrease in forests and agricultural areas, are expected as a result of the harmful effects of global warming. The construction industry is among the main actors of global warming. Cement, the most used building material of the construction industry, is responsible for approximately 8% of CO2 emissions worldwide. Reducing the amount of cement production and using alternative materials and wastes can contribute to reducing CO2 emissions in the production of building materials. In this study, Alkali-Activated Mortar (AAM) mixtures which contain Ground Granulated Blast Furnace Slag (GGBFS) and Fly Ash (FA) were prepared. Recycled Asphalt Waste (RAW) is reduced to 0–4 mm size in order to use as fine aggregate in AAM mixes. Three different activation temperatures (40 °C, 80 °C and 120 °C) were applied for 18 h in order to examine the effect of activation temperature on the prepared AAM samples. After the application of activation temperature, the samples were kept in the standard curing pool for 7 and 28 days. After curing, physical and mechanical experiments were carried out on AAM samples. Water absorption and porosity, compressive strength and electrical resistivity tests were performed on the hardened samples. In addition, the acid effect on the samples was investigated comparatively with the changes in mechanical and physical properties. As a result, the study, in which high-strength mortar mixtures were obtained, shows promising results in terms of sustainable environmentalism. The compressive strength value of 45.74 MPa was found in the mortar mixtures produced using RAW. In addition, it was concluded that the optimum activation temperature is an important parameter of compressive strength and acid resistance.