چكيده به لاتين
In order to find solutions about the problems attributed to scrap tires in the environment and make them as a useful material; new ways for their innovative usage in different applications, should be considered. Annually tons of scrap tires due to the increase in vehicles quantity are being dumped in the environment and usually in uncontrolled way. The water being accumulated in tire has an appropriate environment for the livings like insect to propagate; on the other hand, appropriate environment in scrap tires can lead to a fire to happen and can damage the atmosphere and also human health as a consequence. According to these problems, the engineers have designed and investigated series of methods (e.g. recycling) to avoid this volume of scrap tire production in the environment.
In the first part of this study an investigation about the use of scrap tire crumbs as reinforcement for sandy soil in a physical large scale model with a 1.2m length, 0.8m width and 0.9m height is made. The tire contents of the test samples are 15, 20,25,30,35 and 45 by volume of the mixture. The tires crumbs sizes are about 1 to 3 millimeter. Moreover 2 types of footing, square and strip, for exerting the load to soil mixture are being used. The results show that tire crumbs addition makes the mixture of soil-tire (up to the failure point) more ductile than the soil alone; This quantity for the strip footing in the mixture of 45% tire content is about 2 times more than the sand alone. Furthermore, the bearing capacity of the mixture for both footing was not much affected with rubber addition; at high rubber content this matter is much more considerable that the bearing capacity is even lower than the sand alone. Therefore, it seems that a minimum size for the rubbery reinforcements of the soil must be considered.
In the second part a series of direct shear test accomplished to study aboust the physical model results. The results show that the effects of rubber addition to the internal friction angle of the soil mixture is negligible; but since the sand have no or little sign of cohesion the rubber content of the mixture can improve this quantity. Moreover, the shear resistance of the soil-rubber mixtures decreases with the rubber content increase. On the other hand, like the first part results, the increase in ductility is observed for the mixture comparing to the sand alone.
Keyword:sand-rubber-bearing capacity-direct shear test
