Investigation of The Performance of Roller Compacted Concrete (RCC) Pavements Containing Waste Rubber

Purpose: In this study, in order to produce sustainable roller compacted concrete (RCC) pavements, waste rubber tyres of different sizes, which pollute the environment and cannot be disposed of sufficiently every year, were used as coarse and fine aggregate substitutes to investigate the effects of waste rubber on the mechanical, durability and thermal properties of RCC pavements. Method: Waste rubber in three different sizes (shredded, crumb and powder) was replaced by aggregate at six levels (2.5%, 5%, 7.5%, 10%, 20% and 30%) with a maximum of 30% in SSB mixtures. The compressive, flexural and splitting tensile strengths as well as UPV, unit weight and modulus of elasticity were determined and compared with each other in order to investigate the mechanical properties of the SSB pavement mixtures with waste rubber composition. In order to determine the durability properties of SSB pavement mixtures containing waste rubber, the specimens were subjected to elevated temperature, freeze thaw, acid and sulphate effects. In addition, microstructural analysis was performed using scanning electron microscopy (SEM) to investigate the physical structure of SSB with waste rubber and its effect on concrete properties. In addition, using outdoor temperature data, modeling was performed by finite element analysis using the 3D software package ANSYS. With these models, the effects of waste rubber tires on the stresses caused by temperature changes in SSB pavements were investigated. Findings: In SSB specimens with 30% waste rubber content, 81%, 60% and 74% strength loss occurred in compressive, flexural and splitting tensile strengths, respectively, when compared to control specimens without waste rubber. Although it caused a decrease in strength, a mixture with a flexural strength of 4,96 MPa was obtained with the use of 20% waste rubber, making it possible to use them in pavements. In mixtures with 30% waste rubber content, 62%, 71% and 97% loss occurred in compressive, splitting tensile and flexural strengths after elevated temperature. In mixtures containing 30% waste rubber, a 21% loss in compressive strength occurred after 300 cycles of freeze thawing. After 180 days of acid effect, compressive strength loss was 55% in 30% waste tire-containing specimens, while compressive strength loss was 18% in 30% waste tire-containing specimens after 180 days of sulfate effect. With the partial replacement of coarse and fine aggregate with waste tires, a significant decrease of approximately 90% in the modulus of elasticity was determined. Results: The use of waste rubber in SSB instead of aggregate had a negative effect on the mechanical and durability properties of the mixtures. The increase in the amount of waste rubber resulted in the need for more water for the mixture and resulted in a 15% lighter mixture due to its low specific gravity and hollow structure. From a thermal point of view, the finite element analysis results show that the stresses in the pavement layer due to temperature differences decrease with increasing waste rubber content. Keywords: Roller compacted concrete, waste rubber, mechanical properties, durability properties, thermal analysis, finite element method.