| Strain-hardening cementitious composites(SHCCs)are featured by high ductility and excellent impact resistance.Synthetic fibers in SHCCs have poor stability at elevated temperatures,resulting in SHCCs’ loss of high tensile ductility.As a result,SHCC’s performance under thermo-mechanical loading is not satisfactory.This paper plan to produce the basalt fiber reinforced strain-hardening cementitious composites(BF-SHCC)which exhibits strain-hardening behavior and excellent resistance to elevated temperatures.And to study the mechanical properties of BF-SHCC at room temperture and the elevated temperatures at the same time.Fathermore,to study the mechanism of strain-hardening feature and the mechanism of the changing of mechanical properties at the elevated temperatures to resolve the lossing of ductility of SHCC at elevated temperatures.The specific content is as follws:(1)The development of the BF-SHCC and the study of mechanical properties of BFSHCC at normal temperatureUsing the Ordinary Portland Cement(OPC),Calcium Sulfoaluminate Cement(CSA),Calcium Aluminate Cement(CAC)and High-flexural strength Low-heat slag calcium sulfaoaluminate cement(HFLH-CSA)as the binding material to study the feasibility of producing the BF-SHCC by using different mixtures of raw material and fiber contents.Besides,discussing the mechanical properties all types BF-SHCC produced by different proportions,optimized the proportion at the same time.The study of mechanical properties include: the uniaxial tension test to study the tensile strength,tensile strain capacity and the information about cracks,the four-point bending test to study the flexural strength and flexural deflection,the compressive test to study the compressive strength,the notched(single cracking)tension test to study the relationship between the bridging stress crack width.Testing the mechanical properties of BF-SHCC at different ages(28 days and 100 days)to study mechanical properties of BF-SHCC at long term.The mechanical performance of the BF-SHCC of CSA at the age of 100 days has the best results.(2)The study of mechanical properties of BF-SHCC at elevated temperaturesUsing the optimized proportion from the all proportions of each cement to produce the BF-SHCC,and study the changing of mechanical properties suffered 100℃,200℃,400℃,600℃ and 800℃.The mechanical properties same as the mechanical properties at the normal temperature.The mechanical performance of the BF-SHCC of CSA has the best results at the elevated temperatures.(3)The characterization of BF-SHCC from micro view at room and elevated temperaturesThe TGA and XRD as the auxilliary way to study the trend of water loss and the composition and content changing of hydration products of BF-SHCC.To study the microscopic morphology by using the SEM,include: the surface changing of BF at normal temperature and at different elevated temperatues,the changing of interface between BF and matrix and the corrode degree of BF of long term BF-SHCC.The CT is used to study the influence of the inherent flaw to cracking trend and law of cracks. |
