| With the development of the construction industry,the requirements for cement-based materials have increased.However,when cement paste exposes to environmental for a long time calcium ions will constantly leach out and mechanical properties of cement paste will deteriorate.Therefore,to ensure the expected service life of cement paste in hydaulic engineering and nuclear industry engineering,it is necessary to study leached cement paste.The constitutive model is the key to analyzing the mechanical properties of leached cement paste.The study in this paper aims to the constitutive model and mechanical analysis of leached cement paste.The elasto-plastic damage model based on the damage energy release rate is introduced and theoretically extended in combination with the characteristics of leached cement past.Two methods: holistic modeling and hierarchic modeling are proposed.The software ABAQUS is incorpotated by coding a user subroutine.The validity of the constitutive relationship and the applicability to the mechanical analysis of leached cement paste are verified.The results show that the elasto-plastic damage constitutive model can better characterize the degradation in the mechanical properties of concrete under uniaxial and biaxial stresses.The simulation results on three-point bending beams are in good agreement with experimental results.The influential factors of three-point bending concrete beams are analyzed.It is found that the ultimate loading-bearing capacity is related linearly to the elastic modulus,ultimate tensile strength,beam width,and beam height.The ultimate load-bearing capacity decreases significantly as the concentrated load percentage increases.The holistic modeling and the hierarchic modeling agree well with the experimental results.The stress and strain between the leached zone and the sound zone change suddenly.With the increase of leaching time,the stress and strain have a strong regularity,which is consistent with theoretical analyses.By simulating cement paste beams subjected to different leaching styles,it is found that when beams are leached on all surfaces,the flexural strength decreases the most significantly.The effect of leaching on the side or bottom surface on the flexural strength is almost the same.When beams are leached on the top surface,the flexural strength reduces most slowly. |
