Yükleniyor…
Yükleniyor…
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.
Due to the very dry consistency of roller compacted concrete (RCC) pavements the curing of RCC compared to conventional concretes, requires much more attention and important. In this thesis, the most suitable type of curing and application time for RCC pavements were researched and strenght properties of RCC were investigated. Within the scope of the study, a mixture with standards of 350 kg cement dosage was prepared according to optimum moisture contents as a result of the modified proctor test. It was applied to this mixture 15, 30, 60 min. and immediately after casting in four different time periods four different cures consisting of chemical curing, burlap, membrane and water were applied for 7 days. On the cured samples, experiments like uniaxial compression test, flexural strength test, ultrasonic pulse velocity test and schmidt rebound hammer test were carried out Based on the results obtained, water cure technique has been determined as the most suitable curing method for RCC. This method followed the membrane cure. For water cure technique the best application time was 60 min. after casting has been determined. The time period for which compressive strength for opening to public traffic was found to be seven hours. Key Words: Roller Compacted Concrete, Curing, Strenght Properties.