Effect of granulated rubber on shear strength of fine-grained sand

Review of the literature related to the mixture of shredded tire and sand shows that,despite of the increase in shear strength due to addition of tire chips,granulated rubber causes reduction in shear strength of sand.In this study,the shear behavior of mixtures of fine-grained sand and 1-5 mm granulated rubber is investigated.Sixty direct shear tests were conducted on sandegranulated rubber mixtures with various rubber contents(0%,5%,10%,20% and 30%) at different relative densities(50%,70% and 90%) and different normal stresses(34.5 kPa,54.5 kPa,74.5 kPa and 104.5 kPa).The obtained results show that the granulated rubber improves the shear strength of fine-grained sand at medium relative density and low normal stress.The degree of improvement in shear strength is a function of rubber content,relative density and normal stress.The results show that at relative density of 50%,by adding 5% granulated rubber,the internal friction angle of sand increases from 35.1° to 39.2°.However,at relative densities of 70% and 90%,addition of granulated rubber to sand decreases its internal friction angle.The results also indicate that the behavior of sand becomes more ductile with increasing granulated rubber content.Adding granulated rubber leads to greater yielding strain and less tangent stiffness of sand.The maximum dilation angle decreases with the decrease in granulated rubber content.The stress ratio of sample at critical state(ψ= 0°) decreases with increasing granulated rubber content.

FLEXURAL PERFORMANCE OF RUBBERIZED CONCRETE PANELS REINFORCED WITH POLYMER GRID

The disposal of discarded tires is a problem of significant proportion.In the present experimental study,rubber produced from the granulation of discarded tires was used as an additive to replace certain portions of mineral aggregates in concrete.This rubberized concrete was used in making thin panels.A layer of polymer grid was used to reinforce the rubberized concrete panels.These panels were developed to study their performance in applications where the concrete could be subjected to flexure.Buildings constructed in areas with extreme wind pressures resulting from hurricanes or tornadoes are examples of structures that require concrete that can handle considerable deformation without failing catastrophically.Three different panel thicknesses,three different water-cement ratios,and three different rubber contents were the parameters evaluated in this study.All panels were loaded in bending with two equal loads applied at two equal distances from the supports.Test results showed that the flexural resistance of the panel increases with an increase in the thickness of the section,and with a reduction in the water-cement ratio of the concrete.The panels behaved in a ductile manner and there were no signs of brittle failure.Considerable deformation was measured during load application where loaded panels fractured but remained intact relying on the elongating polymer reinforcement.In addition to the lightweight properties,it was concluded that rubber concrete and polymer grid could be used as effective tools to impart ductility to the concrete and to control the mode and nature of the brittle failure of conventional concrete.