Lakhasly

Using different sizes of rubber particles in concrete as part of the fine aggregates affects the workability and water permeability considerably more than the fresh density and concrete strengths.?Concrete prepared with the larger rubber particles showsa better workability than those with finer ones.Conversely, concrete with the finer rubber particles has a better performance in strengths and water permeability than those with the larger rubber particles.?Varying sized rubber aggregates with continuous grading offer better workability and resistance to water permeability compared to the singly-sized rubber particles.In terms of the strength of concrete, the varying sized rubber performed similar to the finer rubber particles in the tests when added to the concrete mix.It decreases gradually with the simultaneous increase of recycled aggregate and rubber replacement ratio Different substitution has a different effect on the reduction level of this concrete material.

Using different sizes of rubber particles in concrete as part of the fine aggregates affects the workability and water permeability considerably more than the fresh density and concrete strengths.Concrete prepared with the larger rubber particles showsa better workability than those with finer ones.Conversely, concrete with the finer rubber particles has a better performance in strengths and water permeability than those with the larger rubber particles.Varying sized rubber aggregates with continuous grading offer better workability and resistance to water permeability compared to the singly-sized rubber particles.In terms of the strength of concrete, the varying sized rubber performed similar to the finer rubber particles in the tests when added to the concrete mix.
Regarding the analysis and prediction of cube compressive strength for concrete with both recycled aggregate and scrap tyre rubber aggregate Concrete strength is affected by both the content of recycled aggregate and rubber particles. It decreases gradually with the simultaneous increase of recycled aggregate and rubber replacement ratio Different substitution has a different effect on the reduction level of this concrete material. From the statistical analyses of experiment results and failure mechanism investigations of tested specimens, it can be concluded that rubber has a much more significant impact than recycled aggregate.When natural coarse aggregate was fully substituted by recycled aggregate by weight, the concrete still reached the target mean strength. However, rubber replacement ratio over 20% for fine aggregate by volume caused the strength of this concrete material lower than the designed compressive strength. Therefore, rubber aggregate for replacing over 20% of sand by volume is not recommended, especially for structural application. Polynomial fitting surfaces were proposed from the experiment testing results. Equations
re valid to predict the compressive strength of this concrete material at different ages if the replacement ratio of rubber used is within the tested range of 0-40%.
1867.1.3 Regarding the effect of surface modified rubber aggregate on the performance of rubber concreteSurface modified rubber pre-treated with silane coupling agent has a more positive effect on the concrete properties than that treated with saturated Sodium hydroxidesolution.Pre-treatment with saturated sodium hydroxidesolution for less than 24 hours does not produce significant changes in the properties of concrete compared to concrete containing as-received rubber.However, compared to the control mix, the pre-treatment withsilane coupling agentthat acts as an adhesion promoter enhances the adhesion of tyre rubber particles tothe matrix, resulting in a reduction in the slump values of fresh concrete by 13.6% an improvement in the compressive strength of hardened concrete by 19.3% at 1 day, 9.3% at 7 days, and 6.8% at 28 days an increase in the Young’s modulus of hardened concrete by 7.7% at 28 days an improvement in flexural strength of hardened concrete by 2.2% at 28 daysand a decrease of the water permeability index of hardened concrete by 13.1%. Deformability of rubber concrete is better than normal concrete, irrespectiveof rubber surface modification. Peak strain of concrete with silane coupling agent-treated rubber aggregate at mid-span is higher than those of concrete with as-received or sodium hydroxide-treated, all of which have a similar result.
187Fatigue life of normal concrete and rubber concrete follows a two-parameter Weibull distribution with a high statistical correlation coefficient.Fatigue fracture process of both normal concrete and rubber concrete subjected to flexural loading canbe divided into three distinct stages.Wastetyrerubberparticles as part substitution of fine aggregateresults in an improvementin fatigue life. Concrete with silane coupling agent-treated rubber aggregate exhibits longer fatigue life than concrete with as-received or sodium hydroxide rubber aggregate at each stress level of 0.95, 0.90, 0.85 and 0.80.The addition of rubber particles increases the maximum deflection, residual deformation and stored strain energy of normal concrete subjected to cyclicloading.Surface modification on rubber particles indicates a positive effect on improving ductility and damping capacity of concrete with as-received rubber.The scanning optical microscopic inspection of test specimens showed that the rubber-matrix adhesion was enhanced with the use of silane coupling agent.The X-ray diffraction data of different mixes shows similar diffraction patterns, which means that pre-treatment by saturated sodium hydroxidesolution or by silane coupling agent does not change the crystalline phase ofrubber concrete significantly.The mercury intrusion porosimetry test showed that concrete with silane coupling agent-treated rubber has a similar pore size distribution to the control mix and to the concrete with sodium hydroxide-treated rubber, but it achieved the lowest porosity and the highest tortuosity, which results in the best water permeability resistance.
188In addition, it is experimentally shown that silane coupling agenthas a positive effect on improving strength of cement-based rubber concrete containing recycled aggregate, especially when concrete is weak. This effect becomes more significant with the increase of mass fraction of silane coupling agentsolution.The nature of cohesion of silane coupling agentplaysan important role in improving the adhesion in interfacial transition zone, leading to an enhancement of bond strength of interface between rubber and cement paste. It offers an approach to reduce the loss of strength for cement-based rubber concrete, which is potential for practical application.A brief cost analysis was also carried out, demonstrating the economical viability of this type of rubber concrete that uses waste tyres. This feature, together with the well accepted sustainable attractiveness and technical benefits, reinforce the potential prospects of this concrete material. Basing on the provided fatigue load spectrum and fatigue failure mechanism, the method of surface modification on rubber particles to improve the fatigue performance of concrete is potentially for high-cycle fatigue application such as airport pavement and bridges.