Research On Acoustic Emission Characteristics Of Basalt Fiber Reinforced Concrete Under Compression/Bending

Faced with the ever-expanding demand for fiber-reinforced concrete in the ever-expanding construction market both at home and abroad,the research on the properties and applications of this new type of materials has also been carried out extensively by scholars at home and abroad.At present,the research and application of using fiber to improve concrete are mainly aimed at industrial fibers such as steel fiber and polyester fiber.Such fiber production and post-processing will cause environmental pollution.Therefore,there is an urgent need for environment-friendly type with excellent physical and mechanical properties.Fiber in the field of concrete research,application and promotion.Basalt fiber has the advantages of extensive raw materials,no pollution in production,high tensile strength and good durability,and has broad application prospects in the field of concrete modification.However,there are not many studies on basalt fiber modified concrete.In this paper,the author carried out the related research.As a new non-destructive testing technology,acoustic emission technology has many advantages such as high sensitivity and full-cycle monitoring.Compared with other non-destructive testing technologies,acoustic emission technology comes from the material itself,which is more credible.Therefore,acoustic emission monitoring technology has broad application prospects.At present,some foreign scholars have applied acoustic emission technology in the field of concrete,but the report about the application of acoustic emission technology in the field of basalt fiber concrete is still limited.Based on the excellent testing environment and equipment in Jilin University laboratory,the author applies acoustic emission as a technical measure to evaluate the reinforcement effect and mechanism analysis of basalt fiber modified concrete.The main contents of this paper include:(1)Three sets of short-cut basalt fiber reinforced concrete with different dosages were made.Ordinary concrete was used as the contrasting group to carry out cubic compression test and four-point bending test in order to investigate the basic mechanical properties of basalt fiber reinforced concrete.The basalt fiber reinforced concrete with fiber content of 4kg / m3 has the highest flexural capacity with the improvement rate of 7.1%(compared with ordinary concrete).When the dosage is 6kg / m3,the compressive strength is the largest,increased by 4.6%.(2)During the compression and bending failure of concrete,the acoustic emission rate can be roughly divided into three stages according to the acoustic emission rate: in the first stage,the acoustic emission rate is larger and the concrete is in the initiation stage of micro-crack;in the second stage,the acoustic emission The rate becomes smaller and the concrete is in a stable stage of fracture.Concrete is in a safe condition.In the third stage,the acoustic emission rate is slow and the concrete is in an unstable expansion stage of the crack.Concrete is in danger.(3)With the increase of fiber content,the total number of acoustic emission impacts caused by compression and bending failure of concrete specimens increases continuously.Under the same stress state,the number of AE events increased with the increase of fiber content.(4)During the test of all four-point bending test specimens and specimens,the statistical value of acoustic emission Ib can be suddenly decreased from 70% to 80% of the ultimate bearing capacity,indicating that the acoustic emission statistics Ib can be used as basalt Prediction Index of Fiber Reinforced Concrete Fracture.(5)In the cubic compression test,due to the incorporation of fiber,different content of basalt fiber reinforced concrete in different strain stage changes in the occurrence of cracks,the fracture types also have corresponding changes.