الفهرس 
CHAPTER 1: INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Scrap tires are being generated and accumulated in large volumes causing an increasing threat to the environment. There is a great interest in the recycling of these non-hazardous solid wastes in applications where tires can be used and where the addition of tire rubber has proven to be effective in protecting the environment. One of the possible solutions for the use of waste tire rubber is to incorporate into cement concrete to replace some of the natural aggregates. This attempt could be environmental friendly as it helps to dispose the waste tires and prevent environmental pollution. It also helps to reduce the carbon dioxide emission (CO2) by the prevention of tire fires.
This thesis evaluates the mechanical properties of rubberized concrete mixes containing rubber treated in sodium hydroxide solution and similar mixes containing untreated rubber and the test results are compared to those control mixes without rubber. The aim of the present work is treating rubber to increase the bond between the rubber particles and concrete. Crumb rubber was utilized as partial replacement of sand in concrete. The replacement ratios were (5, 10 and 15%) by volume of sand. Silica fume was used as an addition to increase the compressive strength. The water to cement ratio used in all concrete mixes was 0.42. The concentrations of the NaOH solution were (15%, 20% and 30%). It was found that using 20% concentration of NaOH for crumb rubber treatment was the most effective resulting in favorable hardened concrete characteristics. Experimental results showed higher compressive and flexural strengths, modulus of elasticity and tensile strength of rubberized concrete containing treated rubber compared to untreated rubber mixes. The 28-day compressive strength was reduced due to sand replacement with rubber. The reduction ratio was 24% at 5% replacement and increased to 38 percent when the replacement ratio increased to 15% in case of untreated rubber. The 28-day splitting tensile strength was reduced due to sand replacement with rubber. The reduction ratio was 28.5% at 5% replacement and increased to 38 percent when the replacement ratio increased to 15% in case of untreated rubber. The 28-day flexural strength was reduced due to sand replacement with rubber. The reduction ratio was 31.9% at 5% replacement and increased to 40.7 percent when the replacement ratio increased to 15% in case of untreated rubber. The flexural rigidity of beam containing treated rubber was increased compared to beam containing untreated rubber. Although, there was a remarkable reduction in the strength and modulus of elasticity values with the increase in rubber content, using of fine rubber in building construction could help save energy, reduce costs and solve the solid waste disposal problem posed by this type of waste instead of negative effects on society and environment. Recommendations for practical applications were summarized and suggestions for future research works in the field of rubberized concrete were presented.