The Properties Of Cement-Based Materials Containing Rubber

With the development of the automobile industries, the growing amount of waste rubber produced from scrap tires has resulted in an environmental problem. The utilization of scrapped rubber tyre in concrete has attracted attention with both energy crisis and the rise of environmental consciousness. Most properties of the concrete can be improved by incorporating different kinds of waste rubber. In general, the inclusion of rubber powder into concrete can retard micro-crack initiation and growth, absorb vibration and impact energy. In this thesis, influences of both size and amount of the rubber chips on the properties for the rubberized concretes were investigated in terms of workability, mechanical properties and durability. Fabrication pressures on mechanical properties and freezing-thawing resistance were also investigated. Micro-scale analysis based on S.E.M. and XRD were conducted to verify effects of rubber powder in concrete.The research shows: workability,mechanical properties and modulus of elasticity of the rubber concrete are decreased. The properties decreased with the increasing of the incorporating percentage of the rubber powder. The pre-stress forming technology enhance the mechanical properties of rubber concrete while the differences between two stresses (1.4MPa and 0.7MPa) are not evident.Durability: by changing the size of the rubber, the durability of the rubber concrete is changed. The durability of rubber concrete with low percentage rubber powder is improved, however, the effect of the one with granulated rubber is not evident. According incorporating small amount 100 sieves rubber powder, the positive effects are presented as follows: the properties of permeability and freeze thaw resistance are improved evidently; the freeze thaw resistance is decreased when utilizing pre-stress forming technology; the ability of resist chloride attack is enhanced, in the contrary , in the environment of circulation of dry-wet and in the solution of sulfate the ability is not improved evidently; in the circumstance of high temperature and dry-wet circulation, the ability of sulfate resistance decrease sharply. The study shows that the incorporating of rubber powder decreases the carbonation resistance of C30 rubber concrete while improves the ability of C50 rubber concrete.Micro-analysis: Scanning electron microscopy (SEM) and XRD experiments show consistent results with macro-tests. Micro-analysis verified from micro-mechanism that the rubber powders restrict the development of micro-cracks in the process of freeze-thaw cycles, ettringite promote the development of micro-cracks in sulfate attack conditions and fractures are observed between the interface of the rubber and the cement matrix in the common action of dry-wet circulation and sulfate attack.