Experimental Study On Bond Behavior Of Glazed Hollow Beads Thermal Insulation Concrete After Freeze-thaw Cycles

Glazed hollow beads thermal insulation concrete(TIC)has solved the problems of building energy conservation,which conforms to the measures for energy saving and emission reduction in Chinese.TIC behaves well in both mechanical and thermal insulation performances,which can meet the requirements for load-bearing.Meanwhile,it can reduce energy consumption in the whole building life-cycle.In this paper,based on previous results of TIC,experimental study was conducted on the bond behavior between TIC and steel bars after freeze-thaw(FT)cycles based on national and international standards to analyze the change of bond behavior of TIC with different bar diameters and shapes.At the same time,the bond behavior of normal concrete(NC)was also studied as a reference to research the similarities and differences between TIC and NC subjected to FT cycles.The results of this paper can provide references for durability design of TIC.The main works and conclusions of this paper are as follows:1.The frost resistance of TIC and NC under 0,30,50,100,200 and 300 FT cycles are stuied based on the fast FT test and the relative dynamic elastic modulus,cylinder compressive strength and splitting tensile strength are measured.?he experimental results show that loss rate of relative dynamic elastic modulus,compressive strength and splitting tensile strength of TIC is much smaller than that of NC after the same FT cycles.The relative dynamic elastic modulus of TIC still meets the required in ASTM C666M-15.However,the relative dynamic elastic modulus of NC reduces to 58.94% after 200 FT cycles.TIC shows a better frost resistance than NC taking relative dynamic elastic modulus as evaluation index.2.The pull-out test has been conducted on TIC with different FT cycles as well as different diameters and shapes of steel bars.The effects of FT cycles on bond-slip curves?relative bond strength and peak slip of TIC are investigated.Test results show that no significant effect of FT cycles on the ascending branches is observed.However,as an increment of the FT cycles,the descending branches become flatter.Relative bond strength decreases and peak slip increases with increasing FT cycles and the FT cycles have a great effect on TIC when the diameters of steel bars are small.With the same diameter,TIC with plain round bars show a larger loss of relative bond strength and increment of peak slip than that with HRB when subjected to the same FT cycles.The relative bond strength and peak slip decline with the increase of bar diameters.Based on regression analysis,the calculation formulas of the relative bond strength and peak slip of TIC after FT cycles are established.3.The bond behavior of TIC and NC with the same steel bar diameters and concrete strength subjected to FT cycles are experimented and the effect of thermal insulation aggregates on the bond performance of the concrete after FT cycles was also analyzed.?he results show that the frost resistance property of TIC is better than that of NC.With HRB?12,the failure modes of NC change with increasing FT cycles,while the shearing failure mode was observed in both the undamaged specimens and frost-damaged ones for TIC.When subejected to the same FT cycles,loss of relative bond strength and increment of peak slip is samaller for TIC(except splitting failure).4.The bond-slip constitutive model for TIC is established by test data analysis.