Freeze-Thaw Behavior of Pervious Rubberized Concrete

摘要

Pervious concrete has been gaining wide acceptance due to its favorable environmental characteristics. The high percolation and filtration rate of the concrete makes it an ideal material for sidewalks, parking lots, alleys, and parks. Its use reduces the heat island effect, replenishes underground water aquifers, and helps break the long-chain oil compounds by the microorganisms residing within the pores of the material. In addition, the need for drainage accessories to discharge storm water decreases. Pervious concrete can be made even more environmentally friendly by adding rubber crumb derived from waste tires. Waste tires constitute a challenging environmental problem because they are not biodegradable, occupy significant landfill space, represent a source of fire hazard, and if ignited, their fumes are air-polluting and their residue is ground-contaminating. In this study, an attempt is made to replace a portion of the fine aggregate in the concrete with ground rubber. This has the advantage of reducing the volume of tire that requires disposal, producing concrete with better durability, and reducing the potential of concrete's brittle failure.rnAlthough pervious rubberized concrete is designed to allow easier transmission of water to the soil layers beneath, this study was undertaken to examine the performance of pervious rubberized concrete should water become stagnant and freeze within the pores. Although this scenario may be a remote possibility, the focus of this study is to report on the performance of such concrete under cycles of freeze and thaw conditions to learn how this can affect its mechanical properties. The standard specifications of testing documented by ASTM were used to test samples in both fresh and salted waters. Concrete cubes were placed in water baths that were frozen and thawed for 10 cycles, 24-hours each. Freezing was done at 18 degrees Celsius below zero. Because of the high porosity of the pervious rubberized concrete samples, when the water in the pores froze and expanded, it subjected the samples to extensive internal damage, which negatively impacted the residual strength. The damage was even greater to samples frozen in the salted water bath. The study concludes that pervious rubberized concrete should not be used in an environment where water may saturate the concrete and become stationary within the pores of the material, then freeze; however, this situation is a rare occurrence. The intensity of internal forces due to frozen ice could have a destructive effect on the waffle-like structure of the material