soil improvement using shredded rubber tires

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Ezedin Hamad
Wael Alaqma
Ahmad Bdair
Bahaa Hamdan
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Usually selected fill is used as a backfill material for retaining wall. It has a high unit weight, therefore, the lateral pressure will be high and the retaining wall will be larger and need a high quantity of reinforcement. Modern application has been appeared in backfill subject which is to use lighter material in the fill, such as, Polystyrene, straw, shredded tires and etc…. Scrap tires have become a growing disposal problem worldwide, caused by the increasing number of vehicles on the roads. Scrape tires are non-degradable and Because of their shape, quantity and compaction resistance, require a large amount of space for stockpiling and land filling. To overcome this problem, we can use these scrap tires in backfill application which will not affect the health or the environment if we use it in this effective economical way. One of the objective of this project to use shredded rubber tires mixed with suitable quantity of selected fill as a backfill material behind retaining walls. Rubber tires have many benefits such as:  Available every where  Environment friendly (if used correctly)  Light weight  Less lateral pressure compare with backfill material The main work of this project to design different retaining walls with normal backfill material and then with backfill mixed with appropriate percentages of shredded tires and then comparing the outcomes between the two cases in the design and the cost of retaining wall. In chapter two we obtained by experiment (modified proctor compaction test) that the best percent is 10% which gives the lower dry unit weight equal 1.72 gm/cm3 and with optimum moisture content equal 3.6 %,and this value of dry unit weigh can be decreased more if we use a crushed pieces of tires which make the mix homogeneous more than before but this need a special machines which is not available widely in Palestine (limited) and this is an obstacle if we want to apply this in reality . Then in the next chapters we design retaining walls with different heights(2-7)m using PROKON software in two cases, the first case is before we add the shredded tires on the backfill material (backfill only) with the original unit weigh equal 2.28 gm/cm3 and the second case is after we mix shredded tires with backfill material with the new dry unit weight which equal 1.72 gm/cm3 and based on the obtained results from the program we conclude that the second case can give us less dimensions for the retaining wall than the first case at same heights for both cases and this is logical because when the density of the backfill decreased this means the lateral loads apply on the wall will decrease . After that, in the last chapter we made comparison of cost per meter run for retaining walls between the two cases and the cost conclude the two main and most expensive parameters concrete and steel and then we compute the percent save for each type of soil bearing (clay, marl, rock) and we obtained that the highest percent saved is for retaining wall number 1 (2m height) which is 23% from the old cost.