Experimental Study On Impermeability And Frost Resistance Of Crumb Rubber Concrete

Crumb rubber concrete as a new type of concrete material has the prominent characteristicsof light weight, high toughness, large deformation, high damping, strong impact resistance, smallshrinkage, low thermal conductivity and good sound absorption. Not only make up for manyshortcomings of traditional cement concrete, but also eliminate a large number of unfavorabledegradation industrial solid waste-Automobile tire. Crumb rubber concrete research only has ahistory of twenty years, and its durability research has just started. Therefore crumb rubberconcrete durability Experimental study and analysis for the expansion of crumb rubber concreteapplications, to solve the practical engineering problems, to extend the service life of concretestructures is crucial. In addition, also for the waste rubber recycling provides scientific basis.In this paper, the crumb rubber concrete water-resistant impermeability, chloridepermeability and freeze-thaw properties were studied; At the same time, aiming at rubberparticles lighter, during molding and vibrating process occur the phenomenon such as floatingparticles has been systematically studied. The research methods, main results are summarized asfollows:(1) In the concrete workability test，focus on the mixture vibration time on concrete strengthand heterogeneity of the effect. As long as the crumb rubber concrete mix design is reasonable,crumb rubber concrete working performance is good, can achieve the pumping concrete onslump requirements, However, too thick or too small rubber particles will result in reducedliquidity. When the mechanical vibration time less than30S, compressive and splitting tensilestrength is less than manual vibrating fashioned concrete, and the shorter the vibration time, thelower the strength. When the vibration time is30S, splitting tensile strength reached themaximum value. The vibration time in the range of30~60S, compressive strength improvinggradually with the prolong of vibration time, and the range of strength growing rate increase, butthe splitting tensile strength decrease little by little; with the vibration time prolonging, thevolume density increases gradually, the floating phenomenon of rubber particles graduallyobvious. Therefore the suitable vibration time for rubber concrete is30~40S.(2) In the concrete strength test, focus on the dosage and particle size of rubber aggregateson concrete strength of the effect. The result shows that: Adding rubber particles in the concrete,the compressive and splitting tensile strength decreases significantly, when the rubber particle size1~2mm dosage is150Kg/m~3, the compressive strength decreases47.7%, splitting tensilestrength decreases46.6%. The dosage and particle size of rubber aggregates on7d,28d strengthinfluence is particularly significant, the interaction between the two had no effect on the7dstrength, but on28d were particularly significant. The dosage and particle size of rubberaggregates have a linear correlation relationship with compressive strength of concrete.(3) In crumb rubber concrete water-resistant impermeability test, using seepage height testmethods, crumb rubber concrete water-resistant penetration is determined.The results show that:in the same dosage conditions, the greater the particle size of rubber, the better of it’simpermeability. In the same size conditions, the higher the dosage of rubber, the better of it’simpermeability. Crumb rubber concrete permeability and strength does not have an inevitablelink, it is determined by varieties of coupling factors. Through the analysis of aperture, crumbrubber concrete most probable pore size are higher than that of ordinary concrete, rubberparticles can significantly improve the connectivity of the pore structure of concrete and improvethe permeability of concrete. Crumb rubber concrete binary analysis shows that, the rubberaggregate replace quantity and fineness modulus have remarkable linear relationship withpermeation height.(4) In crumb rubber concrete chloride permeability test, using NEL test methods, with thesame strength grade and water-cement ratio of crumb rubber concrete chloride diffusioncoefficient is determined. The results show that：the same strength grade of crumb rubberconcrete as water-cement ratio is relatively small, its chloride permeability is better than theordinary concrete.The same water-cement ratio of different rubber dosage concrete, the chloridepermeability with crumb rubber increases is obviously improved. Using the existing concreteservice life prediction model and Matlab software to forecaste the crumb rubber concrete andordinary concrete’s service life. The result shows that：crumb rubber concrete is more suitablefor harsh environments in concrete engineering.(5) In crumb rubber concrete freeze-thaw test, using slow-freezing method, the frostresistance of the same strength grade and the same water-cement ratio of crumb rubber concreteare studied. The study shows that: rubber aggregate in a reasonable dosage range (≤100kg/m~3),which could evidently improve frost resistance of concrete. After100times freeze-thaw cycles,the strength of concrete specimens loss rate is less than25%, the mass loss rate is less than5%.