Study on the deterioration behavior of freeze-thaw cycle on PP-ECC
Aiming at the influence of freeze-thaw cycle on the performance of polypropylene fiber engineering cement based composites(PP-ECC),the freeze-thaw deterioration was characterized by indicators such as mass loss,relative dynamic elastic modulus,compressive resistance and tensile strength.Then used the test data to establish the deterioration rules of the properties of PP-ECC materials under freez-ing,and analyzed the freeze-thaw destruction mechanism of PP-ECC specimens from a microscopic point of view in combination with scanning electron microscope(SEM)and mercury intrusion porosimetry(MIP).The results show that freeze-thaw damage is a gradual pro-cess.The axial compressive strength and ultimate compressive strain of PP-ECC materials are linear relevant with the times of freeze-thaw cycles,but in this cycle,the degradation law of relative dynamic elastic modulus,splitting tensile strength,cracking tensile performance and ultimate tensile performance are the quadratic curve decrease.It observed the phenomenon in the SEM and MIP tests that with the in-crease of freeze-thaw cycles,a large number of holes and microcracks appear inside of the sample,the cracks continue to develop and ex-tend and eventually show a network distribution,the average aperture continue to increase,harmful pores and more harmful pores begin to increase,and the structure become more loose.
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