Performance of rubberized concrete under moderate freeze-thaw conditions

摘要

The problem of the disposal of waste tires constitutes a serious environmental challenge. Tight landfill space, coupled with the fact that waste tires do not decompose made the problem of recycling waste tires more appealing than ever before. Waste tires can be shredded into small pieces or chips that can be used in useful applications. Rubber chips in this experimental investigation were mixed with concrete to produce rubberized concrete. The goal was to produce durable concrete that can benefit from the durability of rubber. Durable concrete is desirable in environments where freeze and thaw cycles are expected. A total of 144 concrete cubes were made with varying percentages of water-cement ratio, rubber content, and testing conditions. Three water-cement ratios were used, 0.47, 0.54, and 0.61. In addition to non-rubberized concrete cubes, three rubber contents were used, 5, 10, and 15% by volume of fine aggregate used in the concrete mix. To simulate a variety of exposure conditions, the cubes were tested under the following conditions: normal no-freeze, freeze once in air for 12 hours, freeze once in water for 12 hours, and six freeze-thaw cycles in water, 12 hours each. Concrete specimens were frozen to -5 degrees centigrade. It was concluded that the addition of rubber in concrete reduces the workability of the fresh mix and its 2 8-day strength. Freezing the specimens once in air results in little or no effect on the strength of the concrete as compared with that of the specimens tested without freezing. Freezing the specimens once in water results in a very slight, insignificant reduction in the strength of concrete. Subjecting the concrete specimens six freeze-thaw cycles in water results in a small loss of strength. In all cases, rubberized concrete demonstrated greater ability to deform under the application of compressive forces. Failure of rubberized concrete can be described as appreciably less brittle than that of non-rubberized concrete. This ductile behavior allowed the concrete to absorb the applied load without extensive cracking.