Research On The Durability Of Eco Porous Concrete

Ecological Porous Concrete(EPC)is a new type of concrete structure material,whose strength is between C5 to C15 and the effective opening porosity is in 20%-30%.EPC can meet the vegetation growth and it is of great significance to beautify the living environment,realize harmonious symbiosis between human and natural environment,and achieve sustainable development.In order to meet the chemical compatibility of vegetation and EPC,Oxalic acid was used to reduce the alkali treatment of EPC,and the solid alkali treatment was carried out by carbonization technology.Considering that the low alkaline environment has a significant influence on the mechanical properties of concrete structure material,and then significantly affects its durability,therefore,after alkali treatment with reducing alkali and solid alkali technology of EPC,the research results of domestic and foreign scholars in the field of mechanical properties deterioration and durability are less.In addition,given the serious environmental pollution in our country,the corrosion of concrete materials by acid rain could not be ignored.Therefore,based on the basic theory of material science and chemistry,this thesis draws lessons from ordinary concrete durability test method,the oxalic acid resistance,carbonation resistance,frost resistance and sulfate resistance of EPC were discussed in depth.Finally,the evaluation index system of durability of EPC was established,which lays the theoretical foundation for the practical application of the EPC.The main conclusions are as follows:(1)The research results of EPC resistance to oxalic acid erosion based on immersion corrosion method:The strength of EPC decreased after oxalic acid erosion;with the time going on,the strength decreased significantly;When the content of adding single fly ash or slag in the range of 10%-30%,the effect to improve the anti-oxalate corrosion performance of EPC was not obvious and its strength decreased significantly with the increase of mineral admixture;When the mineral admixture content is same,the strength of the samples mixed with slag decreased more significant than that of the fly ash.(2)The research results of EPC carbonation resistance based on rapid carbonization method:The strength of EPC was slightly higher than that of the standard curing concrete specimens after 7 days of rapid carbonation,but the strength decreased gradually with the extension of carbonization age;After rapid carbonation,the corrosion resistance coefficient decreases with the extension of carbonization age,however,the mass growth rate increased;When the content of adding single fly ash or slag in the range of 10%-30%,the effect on carbonation resistance of EPC was not obvious.(3)The research results of EPC frost resistance based on the rapid freezing thawing method for wet condition of specimen:With the increase of the number of freeze-thaw cycles,the strength loss rate and mass loss rate increased,but the relative dynamic modulus decreased;When the content of adding single fly ash or slag in the range of 10%-30%,the effect on the strength loss rate of EPC was not obvious,but improvement in mass loss rate.(4)The research results of EPC resistance to sulfate corrosion based on the accelerated sulfate dry-wet circulation and immersion corrosion method:The compressive strength of EPC was obviously reduced after 4 times accelerated sulfate dry-wet circulation,and compared with sulfate immersion corrosion,the damage degree was more serious;The quality of EPC increased at the early age of sulfate corrosion,but its quality decreased with the extension of corrosion age;When the content of adding single fly ash or slag in the range of 10%-30%,the effect on the sulfate corrosion resistance of EPC was not obvious.However,when the fly ash or slag content was 20%,the corrosion resistance coefficient increased slightly.(5)The evaluation index system of EPC durability was established,besides,4 criteria layer index and 9 index layer index were presented.4 criteria layer index are:frost resistance,resistance to sulfate corrosion,resistance to oxalic acid erosion and carbonation resistance.Eventually,based on evaluation index system of EPC durability,the AHP model was founded and realized quantitative evaluation.