| To meet the market demand,the assembly building market urgently needs a lightweight,high-strength,modular-producible high-performance concrete.Lightweight aggregate concrete has been widely used because of its lightweight and thermal insulation,but the problem of its high brittleness needs to be solved.It has been demonstrated that the textile as toughening material can significantly improve the bending performance of lightweight aggregate concrete,but the composition of its matrix needs to be determined,the bonding mechanism and effect of the interface needs to be elaborated,and the relationship between microstructure and macroscopic mechanical properties needs to be clarified.To address these issues,this paper develops a new composite Textile Reinforced Light aggregate Concrete(TRLC)from matrix,interface,and mechanical properties as follows:(1)The properties of TRLC components were measured by material tests.The measured properties were good gradation of ceramic sand,the apparent density of 1740 kg/m~3,water absorption of 20%,and the need to be infiltrated for 1h before mixing;the tensile strength of basalt fiber bundles impregnated with epoxy resin was determined to be 524 MPa by tensile test.based on the measured properties,the initial mix ratio of the matrix was designed based on relevant specifications and literature.(2)The TRLC matrix ratio was determined by an orthogonal test.On the basis of the initial mix ratio,fly ash,silica fume,and slag admixture were selected as the test factors,and orthogonal tests were conducted with flexural and compressive strength,flow rate,and specific strength as the test indexes,and the microscopic mechanism was analyzed by SEM.The study found thatthe influencing factors were ranked as follows:fly ash dosage>slag dosage>silica fume dosage;the optimized ratio was:20%-25%fly ash,5%silica fume,no slag;the density was:between 1710 and 1810 kg/m~3,which was 30%-40%lower than the density of traditional TRC matrix;the mechanical properties were:28d flexural strength reached 8.8MPa,28d compressive strength reached 55MPa,specific strength reached 0.030.(3)The effects of fiber treatment and matrix type on the interfacial adhesion performance of TRLC were derived from the pull-out test,and the fiber damage pattern and load-slip curve were analyzed.The conclusions are as follows:the adhesion between the textile and lightweight aggregate concrete is not strong,and treatment of the matrix or fiber bundles is required;epoxy resin impregnation or sticky sand effectively improvesthe interfacial adhesion of TRLC,and after treatment,the pullout ultimate load increases by 28%to 45%and the ultimate strain increases by 67%to 88%;the pullout ultimate load of TRLC with external hydroxypropyl methylcellulose(HPMC)decreases by 27%-34%,but the ultimate strain increased by 36%-52%.The tensile damage model of TRLC was established based on the test results,and the reliability of the model was demonstrated by analyzing the interface mechanism of TRLC through SEM.(4)The effects of fiber treatment,substrate type,and distribution rate on the bending performance of the TRLC thin plate were derived from the bending tests,and the load-deflection curve,the relationship between the number of cracks and ultimate load,and the bending toughness index were analyzed.The conclusions are as follows:increasing the mating rate can effectively improve the ultimate stress of the TRLC thin plate,which is 29%-47%for the common matrix and 117%-213%for the externally doped HPMC matrix.Epoxy resin impregnated and sand-bonded can improve the toughness of the TRLC thin plate,and the bending toughness index is improved by up to 12.27 times.The matrix external doping HPMC has a greater effect on the bending toughness of the TRLC thin plate.Although the initial cracking load is reduced by 14%～58%,the matrix consistency is enhanced,the ultimate load is increased by up to 69%and the bending toughness index is increased by up to 11.61 times. |
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