Investigation of mechanical properties of waste tire added geopolimer concrete

The construction industry is increasingly turning to the use of environmentally friendly materials to meet the sustainability required by modern infrastructures. This is a result of concerns about the widespread use of Portland cement (OPC), which has been caused by increased global warming and is known to emit a high amount of CaO2 gas in its production over the past two decades. The development of geopolymer concrete, which is considered as an alternative to OPC, which aims to eliminate these concerns, is increasing its importance in the construction sector as a promising material for producing environmentally friendly concrete. However, considering geopolymer binders as an alternative to ordinary Portland cement is a 'new' material that has become a potential alternative binder to OPC in some applications due to lower greenhouse gas emissions and low energy consumption. On the other hand, waste tires remain important as another waste problem caused by increased road transport and the use of vehicles, which requires immediate action for the environment. These waste tires, which are discarded, often cause 'black pollution' because they do not break down easily and biologically, they pose a potential threat to the environment. This thesis it investigates the effect of using waste rubber in both fresh and hardened properties in geopolymer concrete that can be produced with blast furnace slag (GBFS), which is an industrial waste product. For this purpose, four types of waste rubber were used and these types included, A (0-1 mm), B (1-2 mm), C (2-4 mm) and D (0-4 mm), which define different sizes, are 5%, 10% and 15%. waste rubber was used as aggregate and totaly13 mixes were prepared with the control group. GBFS content has been used as a constant of 800 kg / m3 for all mixtures. Fresh and hardened state concrete tests have been carried out, the coducted tests included; flow diameter, density, water absorption rate, flexural strength and compressive strength. In addition, the effects of 3 different elevated temperatures in the geopolymer concrete, as 300 oC, 600 oC and 900 oC, were investigated. The obtained results within the scope of this study have indicated that flow diameter decreased due to the change of waste tire, the lowest value was 21 cm in D type and 15% mixture, and the increase in the tire content decreased the workability of the mixture. In addition, it was observed that the compressive strength decreased as expected due to the increasing rate of tyre rubber. Despite this, the highest value of compressive strength was 50.16 MPa in 3 days and 52.87 MPa in 7-day strength, while in 28 days, by using group B and 5% waste tires; 56,18 MPa compressive strengths was achieved. In water absorption results, a value of 15.35% was achieved in the use of C type waste tires and 15.03% in the use of type D waste tires. In addition, when the high temperature effects were examined, flexural strength and compressive strength could not be determined due to the damage in the samples at 900 ºC. However, at lower temperatures, as expected, it was determined that the compressive strength decreases as the temperature increases. The best compressive strength in high temperature strengths was obtained by using type A and 5% waste tires with 39.56 MPa at 300 ºC. On the other hand, increased grain size (2-4 mm), caused a decrease in strength at the end of high temperature and a value of 8.76 MPa was obtained. These results revealed that waste tires can be used up to a certain rate, provided that precautions are taken in geopolymer concretes.