Research On Dynamic Mechanical Properties Of Basalt Fiber Strain Hardening Cementitious Composites

Basalt Fiber Strain-Hardening Cementitious Composites(BF-SHCC)show multi-slit cracking and strain hardening under static axial tensile conditions.BF-SHCC have the advantages of high ductility,good toughness,high tensile strength and high temperature resistance.BF-SHCC is a potential impact resistant material.The dynamic mechanical properties of the material are closely related to its impact resistance.This paper mainly conducts experimental research on the dynamic mechanical properties of basalt fiber reinforced high ductility cement-based composites.(1)The static and dynamic compressive properties of BF-SHCC with 0%,2%,and 3%volume content of basalt fiber are studied by static compression test and Split Hopkinson Pressure Bar(SHPB)impact compression test.Under the test conditions,with the increase of the basalt fiber content,the static compressive strength of BF-SHCC increase,and the damage degree of the test piece weaken.Under the condition of dynamic compression test,with the increase of strain rate,the dynamic compressive strength and toughness of BF-SHCC are significantly improve,showing strain rate sensitivity,the dynamic compressive strength and the toughness of BF-SHCC with 2% and 3% fiber volume content are close,both of which are greater than the dynamic compressive strength and toughness of BF-SHCC with a fiber content of 0%.With the increase of basalt fiber content and the increase of strain rate,the dynamic peak strain of BF-SHCC does not change significantly.As the strain rate increases,the strengthening and toughening effects of the fiber are weakened.(2)The static and dynamic splitting tensile properties of BF-SHCC with 0%,2%,and3% BF-SHCC volume content are studied by a static splitting test and an impact splitting test,respectively.Under the static splitting tensile condition,with the increase of the basalt fiber content,the static splitting tensile strength of BF-SHCC increase,and the damage degree of the specimen weaken.Under the condition of dynamic splitting tensile,with the increase of strain rate,both the dynamic splitting tensile strength of BF-SHCC and the energy absorbed by the test piece increase,showing strain rate sensitivity.With the increase of fiber content,both the dynamic splitting tensile strength of BF-SHCC and the energy absorbed by the test piece increase,the fiber exhibite enhanced toughening effects.(3)Drawing on the high-speed tensile test methods of metals and polymers,the test piece size,test die and connection method suitable for BF-SHCC high-speed axial tensile test are designed;study high-speed and low-speed axial tensile tests respectively to study the BFSHCC high-speed and low-speed axial tensile properties,the study find that with the increase of the tensile speed(that is,the increase of the material strain rate),the initial tensile strength and ultimate tensile strength of BF-SHCC increase.Under the low-speed tensile test conditions,as the strain rate increases,the ultimate elongation and toughness of the material decrease.Under the condition of high-speed tensile test,the ultimate elongation and toughness of the material are improved;the test specimen continues to show multi-slit cracking under the condition of low-speed axial tensile test.Under the high-speed axial tensile test condition,the test specimen show a single slit crack damage;under low and high axial tensile test conditions,the material exhibite strain hardening.