Experimental Study On Mechanical Behavior Of Sintered Brick Materials Under Freeze-thawing Cycles

At present,in the northern and western regions of China,there are still a large number of masonry structures in service,among which civil buildings and ancient buildings are mostly present.Because of the severe winter weather conditions in this area,the relatively large temperature difference between day and night,the number of freeze-thaw cycles that the structure is subjected to,and the relatively poor frost resistance of masonry structures,freezing damage has become a major factor affecting its working performance and durability.one.Among the masonry structures,especially in low-rise buildings and rural buildings,brick materials are still used in large quantities as important constituent materials.In order to better evaluate the performance of brick structures under frost damage,this paper uses clay-clay bricks as an example.A series of experimental studies on performance degradation were conducted.This article mainly adopts the quick freeze-thaw test method for sintered clay bricks,and uses strength as the main control index to conduct serial water freezing test on the baked brick test blocks.By performing different cycles of freeze-thaw cycles on clay fired bricks,the appearance change,mass loss,compressive strength loss,relative dynamic elastic modulus change,and damage amount of the test block are compared and analyzed,and based on macroscopic damage mechanics theory.The damage evolution equation of the fired brick in water under freezing and thawing cycles was established,and the rule of damage evolution of the fired brick was discussed with the change of the freeze-thaw cycles.By observing and testing the relevant parameters of clay bricks subjected to freezing-thawing cycles,it was found that the pores on the surface of the sintered bricks showed a change in pores,and with the increase in the number of freeze-thaw cycles,the pore distribution was more dispersed;the quality of the test blocks was weighed.It is important to know that the quality of the sintered brick test block is negative;with the increase in the number of freeze-thaw cycles,the freezing and thawing in water is a deterrent to the destruction of the fired brick.Through the quick freeze-thaw cycles in the water of the sintered brick test blocks,the uniaxial compression test was conducted,the compressive strength was measured,and the relevant stress-strain curve parameters of the fired bricks under water freezing were collected.Based on this,the stress-strain curves of uniaxial compression under different freezing and thawing cycles in water are simulated and analyzed,and the stress-strain curve equation is established.With the increase of the number of freeze-thaw cycles,the peak stress and elastic modulus of the sintered bricks decrease,the peak strain increases,and the stress-strain curve of the sintered bricks gradually flattens.The initial freeze-thaw effect and the later freeze-thaw cycle exhibit different degradation rates compared to the properties of the sintered brick,and the peak stress,peak strain and elastic modulus of the sintered bricks change rapidly in the initial stage.