Study On Energy Dissipation Characteristics And Damage Of Basalt Fiber Concrete

Basalt,as a green mineral in the 21 st century,is now widely used in the preparation of basalt fiber.Basalt fiber has good fire resistance,acid and alkali resistance,good crack resistance,and no pollution in production,so it can be mixed into concrete to play Its high quality performance.A triaxial compression test was carried out on basalt fiber concrete,the loading and unloading points of the cyclic loading and unloading test were analyzed on the basis of the conventional triaxial test,and the cyclic loading and unloading test was carried out to analyze the characteristics of energy dissipation and damage changes under different confining pressures.The main research contents are as follows:(1)In order to select the favorite basalt fiber,the mechanical properties of the basalt were experimentally studied,and the energy drop coefficient was used to numerically analyze the brittle-ductile transition under different confining pressures.(2)First,pre-analytical tests were carried out on some existing fiber-reinforced concrete proportioning methods.Combined with the existing equipment in the laboratory,the tests were compared,and the fiber addition method was selected to calculate the basalt fiber content.The fiber diameter is 15μm and the length is 12 mm and 18 mm,respectively,and the fiber addition method is selected for comparative analysis to calculate the basalt fiber concrete with the fiber content of 0%,0.2% and 0.4%respectively.(3)In order to study the mechanical properties of basalt fiber concrete,five conventional triaxial tests under confining pressure were carried out.The analysis of the experimental results is obtained: under the same confining pressure and fiber content,it is found that with the increase of fiber length,the mechanical properties of the specimen increase,and under the condition of increasing confining pressure,the increase rate decreases;Under the same pressure and fiber length,the basic mechanical properties will decrease as the fiber content increases when the fiber content is changed.In the conventional triaxial test,the energy drop coefficient can be well observed to reduce the brittleness after adding the fiber,which proves that the addition of the fiber can improve the ductility of the concrete.(4)The cyclic loading and unloading test is similar to the conventional triaxial test.Under the same confining pressure,the peak stress and strain of the specimen increase with the increase of the fiber length,but the peak stress is increased when its content increases.And strain has declined.Compared with the conventional triaxial test,the peak stress and residual strength after cyclic loading and unloading are improved.(5)The change of the elastic modulus during each cycle of the cyclic loading and unloading test is calculated by the elastic modulus method,because the elastic modulus method has an applicable interval,and the dissipated energy method can well define each cycle period Calculate the damage to the energy change amount of,and get the maximum damage factor near its peak stress.With the increase of the confining pressure,the energy of the samples under different confining pressures firstly increases and then decreases to a stable level.The elastic energy and dissipation energy have reached the maximum near the stress peak,while the input energy and plasticity peaks reach Maximum value.