The Portland cement concrete pavement(PCCP)often suffers from different environmental distresses and vehicle load failure,resulting in slab corner fractures,potholes,and other diseases.Rapid repair has become one of t...The Portland cement concrete pavement(PCCP)often suffers from different environmental distresses and vehicle load failure,resulting in slab corner fractures,potholes,and other diseases.Rapid repair has become one of the effective ways to open traffic rapidly.In this study,a novel type of rapid repair material,basalt fiber reinforced polymer modified magnesium phosphate cement(BFPMPC),is used to rapidly repair PCCP.Notably,the mechanical properties and characteristics of the repair interfaces which are named interfacial transition zones(ITZs)formed by BFPMPC and cement concrete are focused on as a decisive factor for the performance of the rapid repair.The changing trend of the elastic moduli was studied by nanoindentation experiments in the ITZs with the deconvolution analysis that the elastic moduli of certain kinds of substances can be determined.The experimental results show that the elastic modulus of ITZ-1 with a width of about20μm can be regarded as 0.098 times of the aggregate,and 0.51 times of the ordinary Portland cement(OPC)mortar.The BFPMPC-OPC mortar ITZ has roughly the same mechanical properties as the ITZ between aggregate and BFPMPC.A multi-scale representative two-dimensional model was established by random aggregate and a two-dimensional extended finite element method(XFEM)to study the mechanical properties of the repair interface.The simulation results show that the ITZ formed by the interface of BFPMPC and OPC mortar and basalt aggregate is the most vulnerable to failure,which is consistent with the nano-indentation experimental results.展开更多
Magnesium phosphate cement(MPC)received increased attention in recent years,but MPC-based concrete is rarely reported.The micro-steel fibers(MSF)were added to MPC-based concrete to enhance its ductility due to the hig...Magnesium phosphate cement(MPC)received increased attention in recent years,but MPC-based concrete is rarely reported.The micro-steel fibers(MSF)were added to MPC-based concrete to enhance its ductility due to the high brittleness in tensile and flexural strength properties of MPC.This paper investigates the effect of MSF volume fraction on the mechanical properties of a new pattern of MPC-based concrete.The temperature development curve,fluidity,cubic compressive strength,modulus of elastic,axial compressive strength,and four-point flexural strength were experimentally studied with 192 specimens,and a scanning electron microscopy(SEM)test was carried out after the specimens were failed.Based on the test results,the correlations between the cubic compressive strength and curing age,the axial and cubic compressive strength of MPC-based concrete were proposed.The results showed that with the increase of MSF volume fraction,the fluidity of fresh MPC-based concrete decreased gradually.MSF had no apparent influence on the compressive strength,while it enhanced the four-point flexural strength of MPC-based concrete.The four-point flexural strength of specimens with MSF volume fraction from 0.25%to 0.75%were 12.3%,21.1%,24.6%higher than that of the specimens without MSF,respectively.展开更多
基金financially supported by the Fundamental Research Funds for the Central Universities(DUT20JC50,DUT17RC(3)006)the National Natural Science Foundation of China(51508137)the Research Center of Civil Aviation Airport Safety and Operation Engineering Technology(KFKT2021-01)。
文摘The Portland cement concrete pavement(PCCP)often suffers from different environmental distresses and vehicle load failure,resulting in slab corner fractures,potholes,and other diseases.Rapid repair has become one of the effective ways to open traffic rapidly.In this study,a novel type of rapid repair material,basalt fiber reinforced polymer modified magnesium phosphate cement(BFPMPC),is used to rapidly repair PCCP.Notably,the mechanical properties and characteristics of the repair interfaces which are named interfacial transition zones(ITZs)formed by BFPMPC and cement concrete are focused on as a decisive factor for the performance of the rapid repair.The changing trend of the elastic moduli was studied by nanoindentation experiments in the ITZs with the deconvolution analysis that the elastic moduli of certain kinds of substances can be determined.The experimental results show that the elastic modulus of ITZ-1 with a width of about20μm can be regarded as 0.098 times of the aggregate,and 0.51 times of the ordinary Portland cement(OPC)mortar.The BFPMPC-OPC mortar ITZ has roughly the same mechanical properties as the ITZ between aggregate and BFPMPC.A multi-scale representative two-dimensional model was established by random aggregate and a two-dimensional extended finite element method(XFEM)to study the mechanical properties of the repair interface.The simulation results show that the ITZ formed by the interface of BFPMPC and OPC mortar and basalt aggregate is the most vulnerable to failure,which is consistent with the nano-indentation experimental results.
基金This research was supported by the National Key Research and Development Program of China(No.2017YFC0703405)the Cultivation Program for The Excellent Doctoral Dissertation of Nanjing Tech University(2020-08)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX20_1008).
文摘Magnesium phosphate cement(MPC)received increased attention in recent years,but MPC-based concrete is rarely reported.The micro-steel fibers(MSF)were added to MPC-based concrete to enhance its ductility due to the high brittleness in tensile and flexural strength properties of MPC.This paper investigates the effect of MSF volume fraction on the mechanical properties of a new pattern of MPC-based concrete.The temperature development curve,fluidity,cubic compressive strength,modulus of elastic,axial compressive strength,and four-point flexural strength were experimentally studied with 192 specimens,and a scanning electron microscopy(SEM)test was carried out after the specimens were failed.Based on the test results,the correlations between the cubic compressive strength and curing age,the axial and cubic compressive strength of MPC-based concrete were proposed.The results showed that with the increase of MSF volume fraction,the fluidity of fresh MPC-based concrete decreased gradually.MSF had no apparent influence on the compressive strength,while it enhanced the four-point flexural strength of MPC-based concrete.The four-point flexural strength of specimens with MSF volume fraction from 0.25%to 0.75%were 12.3%,21.1%,24.6%higher than that of the specimens without MSF,respectively.
