Study On The Damage Of Load Bearing Reinforcement Concrete Under Axial Compression Capacity Coupled Effects Of Salt Corrosion And Freeze-thaw Cycles

Concrete is one of the most widely used building materials in the field of industrial and civil construction in China.With the increase of the service life of concrete buildings,the durability of structure and materials has attracted more and more attention of many scholars at home and abroad.As an important index to measure the durability of concrete,many theories and experiments have been put forward by scholars at home and abroad,including the research on the performance of concrete specimens under the environmental coupling effects of dry wet cycle,salt corrosion and freeze-thaw damage.However,the research on the damage of compressive bearing capacity of steel reinforced concrete members under the effects of load,composite salt and freeze-thaw cycle has been carried out Less.Freeze-thaw damage has become one of the main problems of the aging disease of concrete buildings in the Northeast,Northwest and North China.At the same time,the west of Jilin Province is one of the largest alkaline soil regions in China,and the degree of soil salinization is increasing year by year.In this practical engineering environment,the study on the damage of load bearing reinforcement concrete under axial compression capacity coupled effects of salt corrosion and freeze-thaw cycles can be carried out.These results will provide reference under the west of Jilin Province and such environment.In this paper,the concrete structure in Da an of Western Jilin Province is taken as the research object.The sustained load,composite salt corrosion and freeze-thaw cycle tests are carried out on the reinforced concrete component columns(size 120mm× 120mm×600mm).The sustained load value is 70% of the design value of axial compression bearing capacity.The composite salt corrosion includes two stages: electrified accelerated migration corrosion and full immersion corrosion.The freezing and thawing cycle adopts the quick freezing method,and the working principle is water freezing and water thawing.The main study work and conclusion of this paper are as follows.1.Through the axial compression bearing capacity test of load-bearing members after being subjected to the freeze-thaw cycle,it can be concluded that the mass fluctuation of load-bearing members is greater in the process of freeze-thaw cycle.From the damage of bearing capacity,it can be seen that the load-bearing of members in the early stage of freeze-thaw cycle is conducive to improving the frost resistance,but in the later stage of freeze-thaw cycle,the performance deterioration of concrete members will be aggravated.2.Through the composite salt erosion treatment and the axial compression bearing capacity test after the salt freeze-thaw cycle,it can be concluded that the composite salt solution with a mass fraction of 3.4% is conducive to improving the frost resistance and delaying the damage of the concrete components in the early stage of the freeze-thaw cycle.With the increase of the number of freeze-thaw cycles,the deterioration of the components in the late stage of the freeze-thaw cycle is intensified,but from the perspective of the bearing capacity damage under the condition of loading,the deterioration rate of the component is faster than that under this concentration.3.Through the axial compression bearing capacity test of load-bearing members after the composite salt erosion treatment and salt freeze-thaw cycle,it can be concluded that the composite salt erosion of this concentration can significantly delay the damage of members in the early stage of freeze-thaw cycle.Although after 150 cycles,the loss of bearing capacity is smaller than that of members without load,but from the trend of bearing capacity damage coefficient curve from the perspective of potential,its loss of bearing capacity decreases faster.