Experimental Study On Sand Erosion Of Rubber Mortar Before And After Compound Action Of Salt And Freeze-thaw Cycle

Inner Mongolia Midwest Badain Jaran Desert,Tengger Desert and Reservoir desert is the main source of sand dust storms in China.A lot of salty soil and severe temperature changes have a significant impact on the service life and quality of concrete structures and pavement.Because of concrete structures and pavements in the construction of the vibration effect can cause the surface material with mortar,in this paper rubber mortar is used to replace rubber concrete to study the damage of three factors: saline environment,freeze-thaw alternation,wind sand environment.The compound salt solution was prepared according to the analysis results of the salted soil,and the freezing thawing cyclic corrosion test of rubber mortar was carried out.The erosion simulation system of wind-blow sand environment was utilized to study the rubber mortar before and after freeze-thaw,and analysis of damage under erosion mechanical parameters and mass loss under the times of freeze-thaw.The effect degree of the influence factors are analyzed by Taguchi method.The morphology of the damaged surface of the specimen was observed by FESEM and LSCM.The changes of surface chemical composition after freeze-thaw were analyzed by X-ray diffractometer,which explore the failure mechanism from microcosmic angle.The results are significant to improve the salt frost resistance and wind erosion resistance of concrete structures and pavement.This project is supported by the National Natural Science Foundation of China(Study of erosion mechanical behavior and evaluation on surface coating of steel structure in sandstorm)(Project approval number: 11162011),(Damage mechanism of sandstorm erosion to pavement concrete had been corroded by cold and saline environment in the western region)(Project approval number: 51468049),The specific research contents are as follows:1.The characteristics of saline soil with large species and the drastic change in temperature in Inner Mongolia are analyzed,and the characteristics of wind sand environment caused by rich sand dust source,strong wind and thermal condition.2.According to the characteristics of sand dust weather in Inner Mongolia,10 mesh,40 mesh and 80 mesh rubber mortar and cement mortar were tested.To wind(wind speed)rank table as the basis,from 7 to 11 scale select five speed,six values from 15 to 90 degrees are selected as the erosion angle.The relationship between the concentration of outdoor sand dust and the sand flow rate under test is obtained by using the principle of dimensional homogeneous,after considering equipment and the test effect,the five groups of 15g/min to 55g/min are selected.3.Erosion speed,erosion angle and sand flow rate are studied by using erosion simulation system of wind-blow sand environment,and use FESEM and LSCM observation after erosion morphology.The results show that,the erosion rate of the specimen increases with the increase of the erosion speed and erosion angle.With the increase of sand flow rate,the erosion rate of the specimen decreases first and then increases,meeting its minimum at 45g/min.Under the same erosion condition,the size of the erosion rate is as follows: 10 mesh rubber mortar<Cement mortar<80 mesh rubber mortar<40 mesh rubber mortar.Through the analysis of micromorphology,it is concluded that the 10 rubber particles are closely associated with the cement paste,and have a strong absorption effect on the impact of sand,40 rubber particles are easy to fall off.4.In order to obtain the degree of erosion damage caused by various factors to rubber mortar,Taguchi method was used to design the test.The results show that,the minimum erosion rate at 17m/s,10 rubber particles,5% of the rubber content,45°and 45g/min.The impact of various factors: sand flow rate>erosion rate>rubber mesh>erosion angle>rubber content.5.According to the collected results of saline soil,the composite salt solution of 3.6% was used for freeze-thaw cycle test,and the surface after freeze-thaw was observed by FESEM and XRD.The results show that,with the increase of the number of freeze-thaw cycles,the quality loss is first reduced and then increased,which minimum at 10 times.The quality loss of cement mortar is small before 15 times,and the rubber mortar is better after 15 times,40 mesh rubber mortar shows smaller quality loss.6.Wind sand erosion test on the specimens after the freeze-thaw cycle of the compound salt.The results show that,after the same cycle times,the resistance to sand erosion of the material is: 80 mesh rubber mortar<40 mesh rubber mortar<cement mortar<10 mesh rubber mortar.In the erosion of sand,columnar gypsum and Ettringite detached from rubber mortar,and the surface becomes smooth,with rubber particles.