Experimental Study On Sulfate Attack Of Pervious Eco-concrete In Different Environments

Since the 20 th century,with the rapid expansion of human engineering practice,environmental problems have become more and more serious.At the beginning of the 21 st century,countries around the world pay more attention to the eco-environment.At present,China has made remarkable achievements in the development of urbanization.At the same time,in order to solve the problem of urban waterlogging and water pollution,the construction of "sponge city" was proposed in 2015.In order to break through the limitation of traditional concrete materials,pervious eco-concrete is selected to replace ordinary concrete in slope protection and small roads.At present,pervious eco-concrete is more and more widely used.In order to further study and improve the durability of pervious eco-concrete,theoretical basis is provided for practical engineering.The subject of this paper comes from the project of National Natural Science Foundation of China: dynamic water erosion test and damage mechanism research of porous eco-concrete based on freeze-thaw and sulfate attack environment(Project No.: 51608235),the durability of sulfate attack of pervious eco-concrete was studied,and based on the existing research basis of the research group,the durability of sulfate attack of pervious eco-concrete in different environments was explored.The main research contents are as follows:1.The raw material information and preparation process of pervious eco-concrete are briefly described,and two kinds of mix proportion are designed for comparative analysis of sulfate attack.2.In this paper,the sulfate attack test of pervious eco-concrete in three external environments,namely,wet and dry environment,immersion environment and freeze-thaw environment,is studied.The basic mechanical properties of pervious eco-oncrete are analyzed and compared,and the changing trend of strength,quality and dynamic modulus is analyzed.The results show that with the increase of sulfate attack cycle,the mass,compressive strength,corrosion resistance coefficient and transverse relative dynamic modulus of the specimens will be slightly strengthened,and then decreased.At the same time,the influence of different water binder ratio on sulfate attack is also obvious.As a whole,the durability of pervious ecoconcrete is better with low water binder ratio.3.The results show that the main body of the corrosion crystallization is different in different environments.The main types of the corrosion crystallization are sodium sulfate crystallization,gypsum crystallization and ettringite crystallization.In the dry and wet environment,almost all erosion crystallization will occur.At the same time,it is found that the high temperature will accelerate the carbonation of the test piece to generate calcium carbonate,which will also cause the carbonation of ettringite crystal,and convert it into the crystal of carbon sulfur calcium silicate;in the freeze-thaw environment,the main erosion crystallization of the test piece is mainly ettringite,and gypsum crystallization will also occur;in the longterm immersion environment,the main erosion crystallization of the test piece is gypsum.4.In this paper,the durability of water permeable eco concrete under sulfate attack is studied.The gray correlation method is adopted,which mainly considers the compressive strength,corrosion resistance coefficient and relative dynamic modulus as the main body.The average weight of pervious ecological concrete is 0.665,0.302 and 0.033 respectively.Through calculation and analysis,the durability of pervious eco concrete is classified into three grades: excellent,good,bad and bad.At the same time,the evaluation interval of sulfate corrosion durability of pervious eco concrete in different environments is determined to provide an intuitive evaluation.5.The application and structural form of pervious eco-concrete slope protection and road are introduced.Combined with the ecological control work of Huanyan River in Lianyungang,the pervious eco-concrete applied to the road and slope protection in the actual project is introduced.