Use of waste tire as aggregate in lightweight geopolymer concrete production

The construction industry is developing day by day and material usage rates are increasing day by day with the increasing population. Portland cement is preferred as the binder in concrete, which is a composite material. Portland cement emits high amounts of CO2 into nature during its production. This situation has accelerated the search for alternative materials instead of Portland cement. Nowadays, the use of natural or artificial pozzolans is being investigated as alternative materials. One of the most preferred ones among the pozzolans is fly ash. On the other hand, with the increasing vehicle usage, the use of vehicle tires has also increased. However, the excess waste tires creates a pollution problem that must be prevented. The aim of the thesis study is to test the usability of waste tires instead of pumice in lightweight geopolymer concrete. For this reason, waste tires (0-5 mm) and pumice (0-5 mm) were replaced with sand (0-5 mm) at the rates of 10%, 40%, 70% and 100%. Mini-spreading, unit volume weight, compressive strength, bending strength, water absorption and thermal conductivity coefficient tests were carried out on the obtained geopolymer mortar samples. In the experiments carried out within the scope of the study, as the rate of waste tire and pumice usage increased, bending and compressive strength decreased, and the reference sample gave better results than other samples. It was observed that as the volume of light aggregate (waste tire and pumice) in the composite increased, water absorption values increased, while unit volume weight and general workability values decreased. In thermal conductivity experiments, as the volume of lightweight aggregate increased, the thermal conductivity coefficient values of the composite were lower than the reference sample, meaning that it affected the insulation property positively. In general, it has been concluded that the use of waste tires instead of pumice in different proportions gives good results in terms of insulation and can be evaluated as aggregate in lightweight geopolymer concrete from a sustainability perspective.