Study On Fracture Behavior Of Waste Glass Concrete In Complex Environment

Nowadays,the society is in a high-speed development stage,and the development is bound to be accompanied by many solid wastes,among which waste glass accounts for a large proportion.There are many recycling methods for waste glass,one of which is to use waste glass in concrete,which can not only save costs,but also conform to the concept of green sustainable development advocated by the state.In the research process of glass concrete performance,basic performance is the basis of research,and fracture performance is a very important research direction.In this paper,the basic properties of glass concrete specimens in normal environment,freeze-thaw environment and erosion environment are studied firstly,and then the fracture properties of specimens are studied by three-point bending beam test.The fracture properties include fracture energy and fracture toughness,and the specific research contents and results are as follows:(1)Through the experimental study of cube blocks in complex environment,the compressive strength and splitting tensile strength of each group of blocks can be obtained.By comparison,we can get: The change rule of compressive strength is basically consistent with that of splitting tensile strength.Freeze-thaw environment can weaken compressive strength and splitting tensile strength,while 15 times sulfate erosion environment can improve compressive strength and splitting tensile strength.The replacement rate of fine glass aggregate is 50%,which has a good replacement effect,but the replacement effect of coarse aggregate is poor.(2)Three-point bending beam test is selected as the research method of fracture performance.Through the test,the P-δ(load-mid-span deflection)curve of the specimen can be obtained,and then the fracture energy value can be calculated according to the fracture energy formula.In order to study the change trend of fracture energy,the following conclusions can be obtained by linear fitting of fracture energy data: Glass coarse aggregate can improve fracture energy,while glass fine aggregate can weaken fracture energy.Erosion environment can improve fracture energy of specimens replaced by coarse and fine aggregate.Freeze-thaw environment can also improve fracture energy of specimens replaced by fine aggregate.However,the effect of freeze-thaw environment on fracture energy of specimens replaced by fine aggregate should be analyzed with specific substitution rate.(3)According to the P-ε(load-strain)curve and P-CMOD(load-crack opening displacement)curve measured by three-point bending beam test,the linear fitting results of crack initiation toughness and instability toughness can be obtained by using double K fracture criterion.The test results show that: When the replacement situation is fine aggregate replacement,the crack initiation toughness and instability toughness of specimens in normal environment and freeze-thaw environment show a decreasing trend,while those in erosion environment show an increasing trend.When the replacement situation is coarse aggregate replacement,the crack initiation toughness of specimens decreases in all environments,while the instability toughness of specimens increases.When the environment is freeze-thaw environment,the crack initiation toughness of all specimens decreases,and the instability toughness of specimens should be analyzed according to the different environment and substitution rate.When the environment is erosive,the erosive environment can weaken the cracking toughness of the specimen to some extent.By analyzing the instability toughness,it can be seen that the erosive environment can improve the instability toughness of the specimen with larger glass fine aggregate replacement rate,but has little effect on the instability toughness of the specimen replaced by glass coarse aggregate.