Research On Damage Characteristics Of Rubber-Basalt Fiber Composite Modified Concrete Under Uniaxial Compression

In recent years,with the rapid development of the transportation industry,the number of cars has increased sharply.While this has brought convenience to the people’s lives,some problems have also arisen.For example,the production of a large number of waste tires not only pollutes the natural environment,but also wastes natural resources due to improper treatment methods.The waste rubber tires are prepared into rubber aggregates by physical grinding.The use of rubber aggregates to modify concrete not only solves the above problems,realizes the recycling of waste,but also improves the economics of concrete.The prepared rubber concrete is expected to become a green building material.Basalt is a characteristic mineral resource in Jilin Province.Basalt fiber produced with basalt as a raw material is a green material that meets the requirements of the ecological environment in the 21st century.Incorporating basalt fiber into concrete can form a spatial network structure in concrete and improve the mechanical properties of concrete.Acoustic emission technology is a high-sensitivity,full-period monitoring non-destructive testing technology,which has broad application prospects in concrete damage monitoring and damage assessment.Using acoustic emission technology,the damage process of rubber-basalt fiber composite modified concrete has been clarified.It can not only realize the early warning of damage and destruction of modified concrete,but also judge the fracture mode of concrete,and provide scientific basis for the maintenance and maintenance of concrete structure.This article relies on the Jilin Province Science and Technology Development Program Project"Research and Engineering Application of Key Technology of Rubber Particle-Basalt Fiber Composite Modified Concrete in Seasonal Frozen Zone".A multi-objective optimization design method was used to explore the influence of the preparation parameters of rubber-basalt fiber composite modified concrete on its working performance and mechanical properties.At the same time,the mechanical properties and acoustic characteristics of rubber-basalt fiber composite modified concrete under uniaxial compression were studied,and the damage process was evaluated.The specific work is as follows:(1)Based on the multi-objective optimization method,the Box-Behnken Design(BBD)in the response surface method is used for experimental design.The influence of water-cement ratio,rubber content,and basalt fiber content on the slump,compressive strength and flexural strength of rubber-basalt fiber composite modified concrete was studied.The best regression model of independent variables(preparation parameters)was established,and the significance of the model was judged by analysis of variance.Finally,an optimization plan for the mix ratio was proposed:the water-to-binder ratio is 0.39,the basalt fiber content is 4.56 kg/m~3,and the rubber content is 10%.(2)Based on the mix ratio parameters,the uniaxial compressive strength test of plain concrete,rubber powder concrete,rubber particle concrete,rubber powder-basalt fiber concrete and rubber particle-basalt fiber concrete was carried out.The stress-strain curve relationship of five different concretes was explored,and the mechanical properties of the five concretes under uniaxial compression were studied.Through comparative analysis,it can be found that the incorporation of rubber aggregate can improve the brittleness of concrete materials,and the incorporation of basalt fiber can significantly improve the mechanical properties of concrete.(3)The acoustic emission acquisition and analysis system was used to record the acoustic emission signals of the above five types of unused concrete during uniaxial compression damage.The acoustic characteristic parameters of different concretes under compression were analyzed.And by comparing the RA-AF value,the fracture mode in the concrete damage process was distinguished.(4)The acoustic emission b value calculated by the Gutenberg-Richter theory was used to evaluate the concrete damage process.It is found that the change of b value can reflect the development of cracks in rubber-basalt fiber composite modified concrete.The change of b value can be used to monitor the damage process of concrete.