Study On Fracture Test And Numerical Simulation Of Composite Ceramsite Concrete

Compared with ordinary concrete under the same conditions,lightweight aggregate concrete has a series of excellent characteristics,such as light weight,good thermal insulation effect,strong fire resistance due to high seismic performance.In order to improve the mechanical properties of lightweight aggregate concrete,the mechanical properties of lightweight aggregate concrete were improved by replacing lightweight aggregate with ordinary crushed stone and adding fiber at the same time.In order to further analyze the working performance and fracture mechanism of lightweight aggregate fiber reinforced concrete,the damage and fracture mechanism of light aggregate fiber reinforced concrete is studied simultaneously from macroscopic and microscopic perspectives.On the basis of the proportion of LC30 all-lightweight concrete(ALWC),where all of the aggregates are lightweight material and Lightweight concrete substituted by part of fine aggregate(LWCSCA)studied by the research group,steel fiber(SF),chopped basalt fiber(CBF)and polypropylene fiber(PPT)are added in the experiment.The main contents are as follows:(1)Based on LC30 ALWC and LWCSCA,the compressive strength,axial compressive strength,splitting tensile strength and fiber hybrid effect of the FRALWC and FRLWCSCA are studied by single and double mixed steel fiber,basalt fiber and polypropylene fiber;(2)Fracture study on fiber reinforced all-lightweight concrete(FRALWC)and fiber reinforced LWCSCA(FRLWCSCA)is carried out through the type Ⅰ tensile test on a three-point bending notched beam to analyze the load-deflection curves,initial and unstable fracture toughness,fracture energy and brittleness index of beams under different working conditions;(3)Fracture study on FRALWC and LWCSCA is carried out through type Ⅱ shear test on unilateral double-cut cube specimen to analysis of mode Ⅱ fracture toughness,load-deflection curve of concrete with different fibers and the change of failure pattern of shear specimens;(4)The comparative analysis of type Ⅰ tensile test and type Ⅱ shear test includes: the advantages and disadvantages of the two fracture tests,load-displacement curve,fracture toughness,and the fracture mechanism of the two modes;(5)A method based on ANSYS fine mesh aggregate construction is proposed by finite element software.This method can construct any shape aggregate,realize the quick generation and release of lightweight aggregate concrete particles,and simulate the concrete failure process under compression.The internal damage evolution process of lightweight aggregate concrete is revealed from the microscopic point of view.