Constitutive Relationship Of Steel Fiber-And-Nanosilica-Reinforced Crumb Rubber Concrete Under Axial Compression

The waste tires can be crushed and sieved to act as admixture,partly or totally replace the natural aggregate to produce the crumb rubber concrete(CRC).CRC can reduce serious "black pollution" caused by waste tires,turn waste into wealth,and it is also an effective way to realize the sustainable development of building materials.In order to make up for the low strength and elastic modulus deficiencies of CRC,in this paper,steel fiber and nanosilica are added into CRC to make the steel fiber-and-nanosilica-reinforced crumb rubber concrete(SFNS-CRC).The axial compression constitutive relation of SFNS-CRC was studied.The main content as follows:(1)The cubic and prism compressive test were performed,the influence of the steel fiber volume ratio 、 nanosilica content and crumb rubber volume ratio on compressive strength,failure mechanism,elastic modulus,peak strain,the stress-strain curves and compressive toughness were studied.The calculated relationship formulas between prism compressive strength,elastic modulus,peak strain and cubic compressive strength were put forward.(2)Based on the stress-strain curves of SFNS-CRC,a function expression with a parameter constitutive model was chosen.In this paper,considering the effect of steel fiber and nanosilica,the stress-strain constitutive equation of SFNS-CRC were obtained by modifying the coefficient.The mathematical expressions between constitutive parameter values and steel fiber、nanosilica test parameters were given,which lays a theoretical foundation for the study on the constitutive relationship of SFNS-CRC.(3)Based on the two-parameters Weibull statistical distribution theory and strain equivalent hypothesis,one damage threshold parameter was introduced,and the damage constitutive models of SFNS-CRC with the damage threshold parameter were established.And the relationships between constitutive parameters and steel fiber volume ratio as well as the nanosilica content were given.At the same time,the influence of the damage threshold value on the damage constitutive equation was discussed.