Abstract
The use of scrap tires in various engineering applications has been extensively explored. The present study has the following aim: to evaluate the suitability of tire-sand mixtures as backfill material based on its shear strength. To achieve this objective, modified Proctor compaction tests were performed on tire shred-sand mixture with mixing proportions by weight of tire shreds and sand (0/100, 20/80, 30/70, and 40/60) using different sizes of tire shreds (50 mm, 75 mm, and 100 mm). Based on the results of the modified Proctor compaction test, the two mixing proportions, i.e., tire shred/sand, 20/80 and 30/70, respectively, were selected. Large-scale direct shear test indicated higher internal friction angle and cohesion values for tire shred-sand mixtures (30/70) with 100 mm tire size (38.5° and 19 kPa) as compared with sand-only backfill material (30.9° and 0 kPa). Based on stress-strain behavior plots, it was indicated that the inclusion of tire shreds imparts ductility to backfill mixtures. To achieve the second objective, the pull-out tests were performed with deformed steel bars of two different diameters (12.7 mm and 15.8 mm) embedded in various backfill mixtures prepared with tire shreds of three different sizes (50, 75, and 100 mm). The pull-out test result indicated that the deformed steel bars exhibit higher pull-out resistance in tire shred-sand mixtures (9.9 kN/m) compared with sand-only backfill material (4.1 kN/m).
Highlights
For the past many decades, scrap tires are produced in huge quantities worldwide. e nonbiodegradable nature of vulcanized rubber in tires has a serious environmental impact
In this research, deformed bars with diameters of 12.7 mm and 15.8 mm were used. e length of the bar was kept at 214 mm (i.e., 0.7 times the height of the mechanically stabilized earth (MSE) wall) as specified by the Federal Highway Administration Manual (FHWA) on the MSE wall construction [47]. e pull-out capacity primarily depends on two major factors, that is, the frictional resistance between reinforcement and fill particles and the passive resistance due to the contact area and with the projections of the bar [43]
An increase in percentage and size of tire shred increases the angle of internal friction and cohesion values. e largest values for the angle of friction and cohesion were obtained for 30/70 backfill mixture with 100 mm tires shred size, that is, 38.56° and 19 kPa, respectively. e angle of internal friction increases because of the angularity of the tire shreds and their adequate interlocking with sand grains
Summary
For the past many decades, scrap tires are produced in huge quantities worldwide. e nonbiodegradable nature of vulcanized rubber in tires has a serious environmental impact. One of the most important applications of tire shred-sand mixture is its use as backfill material in mechanically stabilized earth (MSE) walls. Erefore, in this work, the effectiveness of deformed bars embedded in tire shred-sand mixtures in terms of pull-out resistance has been comprehensively investigated. To achieve this goal, two bars with diameters of 12.7 mm and 15.8 mm were used as reinforcement. The shear strength parameters of tire shred-sand backfill mixtures were evaluated using a large-scale direct shear apparatus. Erefore, the use of deformed bars as major reinforcement as well as tire shred-sand mixtures as backfill material in MSE walls proved to be an effective technique in improving their overall performance The shear strength parameters of tire shred-sand backfill mixtures were evaluated using a large-scale direct shear apparatus. erefore, the use of deformed bars as major reinforcement as well as tire shred-sand mixtures as backfill material in MSE walls proved to be an effective technique in improving their overall performance
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