Effect Of Glass Powder On Mechanical Properties Of Rubber Concrete And Its Prediction Model

At present,a large amount of solid waste not only causes serious pollution to the environment,but also causes huge waste of resources,such as construction waste,waste glass,and waste rubber tires.China has the largest number of concrete projects in the world.Reduce the use of natural resources(such as cement,sand,stone,etc.)and use more mineral admixtures and regeneration of waste to replace the part of cement or natural aggregate in concrete,under the premise of meeting the concrete quality requirement,can reduce production cost,lower energy consumption,save resources and reduce pollution to the environment,is the inevitable development trend of green concrete.In this paper,the influence of glass powder on rubber concrete and its influence mechanism was studied.On the basis of testing and analyzing by used pressure testing machine,elastic modulus meter,scanning electron microscope,energy spectrometer,mercury injection meter,nano indentation meter and other instruments.The effects of different glass powder substitution of rubber concrete on mechanical properties,microstructure,porosity,hydration products and nano-mechanical properties were analyzed from macroscopic,microscopic and nano-mechanical perspectives.The prediction models of compressive strength and elastic modulus for rubber concrete mixed with glass powder was proposed.Main work contents and conclusions are as follows:(1)The rubber concrete was prepared by replacing some fine aggregates with the volume of rubber powder.At the same time,in order to carry out three basic mechanical properties tests of cubic compressive strength,axial compressive strength and elastic modulus.The substitution amount of glass powder and the water-to-binder ratio were used as variables to design the mix ratio,and the concrete specimen was molded.The macroscopic mechanical properties of rubber concrete mixed with glass powder were discussed.The results show that with the increase of glass powder substitution,the early mechanical properties of rubber concrete decrease,and the mechanical properties show a tendency to increase first and then decrease.It can be said that the glass powder contributes more to the late strength of the rubber concrete.When the glass powder substitution amount is 10%,the mechanical properties of the rubber concrete are superior to the reference group after 28 days.From the results of the macroscopic test,when 10% of the cement is replaced by glass powder with equal weight,the macroscopic mechanical properties of the rubber concrete would be improved.(2)The influence mechanism of glass powder on rubber concrete is relatively complex,and its macroscopic influence is the result of the combined effect of volcanic ash effect and micro-aggregate filling effect.The microcosmic test results show that there is a wide gap between rubber and slurry,but a narrow gap between sand and slurry.At the same age,the total porosity of rubber concrete decreases first and then increases with the increase of the replacement amount of glass powder.When the replacement amount of glass powder is 10%,the porosity is the smallest and the micromorphology is the most compact.When the replacement amount of glass powder is 20% and 30%,the total porosity is greater than that of the reference group without glass powder.Compared with the reference group,the content of hydration product C-S-H in rubber concrete with 10% replacement of glass powder was relatively increased,while the content of CH was relatively decreased,and the nano-mechanical properties of cement matrix and interfacial transition zone were enhanced.(3)The measured compressive strength of rubber concrete cube is compared with the predicted values of China standard model,sp-24 model and zhu bofang model.It was found that the relationship between strength and age of rubber concrete in the reference group was close to that of sp-24 model.With the increase of glass powder substitution,the relationship between strength and age was closer to that of zhu bofang model.This result also existed under different water-binder ratios.Therefore,on the basis of sp-24 model,the influence factor of glass powder substitution was introduced to establish the prediction model of rubber concrete compressive strength,which has certain accuracy and reliability.The elastic modulus of rubber concrete is also compared with other prediction models,and its compressive strength is used as the basic parameter to establish the elastic modulus prediction model of rubber concrete.