Evaluation Of Durability Of Concrete Materials Based On Fuzzy Extension Analytic Hierarchy Process

The anti-freezing melt erosion is an important aspect of the durability of concrete materials.Especially in the northwest in our country,because of the special geographical environment and climatic conditions,land salinization degree is high,the hydraulic buildings,Bridges and other concrete often occur because of freeze-thaw erosion surface spalling,internal damage such as cracking,seriously affect the normal use of concrete structures.This article selects the northwest scenery electric irrigation area of hydraulic concrete structure as the research object,through field investigation,chemical composition analysis,X-ray diffraction spectrum means to clear the main erosion medium concrete buildings.According to the relevant specification design of experiments for different water/cement ratio and different air content and 7 groups of dosage of fly ash concrete specimens,3%water,3%NaCl and Na₂SO₄,5%Na₂SO₄+3%NaCl mixture four different freezing and thawing medium,collection and quality loss rate,the relative dynamic elastic modulus,compressive strength and ultrasonic wave velocity of 4 kinds of durability evaluation indexes,through the index changes of drawing with the increase of freeze-thaw cycles trend curve and concrete internal defects sketch,reveals the coupled action of freeze-thaw cycle and salt ions of hydraulic concrete material degradation damage law.For further proved the various influencing factors of hydraulic concrete durability of the importance of its material,this paper USES the fuzzy extension analytic hierarchy process?ahp?,with rate range instead of a single index,select the freeze-thaw cycle,chlorine salt corrosion,reinforcement corrosion,JianJiLiao reaction,carbonation 5 indexes and 20secondary indicators established the comprehensive evaluation index system of the durability of concrete material,to calculate the index weight sorting at all levels,the membership degree for each indicator,and at the same time,adopt the secondary fuzzy comprehensive evaluation method for comprehensive evaluation of each index,finally obtains an aqueduct material durability evaluation level.Based on the two parameter weibull distribution theory,on the basis of test data from,to any loss characterization of concrete dynamic elastic modulus,by least squares fitting of weibull distribution parameter values,and according to the relationship between the indoor and outdoor freeze-thaw cycles to compute each material service life prediction of concrete specimens.Compared with the preliminary design of concrete antifreeze safety,the optimized design of concrete material and ratio was carried out.The project is supported by the"study on the durability attenuation law of hydraulic concrete structures based on the erosion freezing and thawing composite effect?174200510020?"by the outstanding talent program of Henan science and technology innovation.The following conclusions are drawn by the indoor accelerated test and theoretical analysis.?1?The water glue ratio and air content have a great influence on the frost resistance of concrete,and a moderate amount of fly ash can improve the degree of chamber of concrete,but not too much.The effect of freeze-thaw medium on the durability of concrete's frost resistance was ranked by the strong to the weak:3%NaCl>5%Na₂SO₄+3%NaCl>5%Na₂SO₄>water.?2?The weight ranking of durability damage of concrete materials is classified as:reinforcement corrosion?0.399?>freezing and thawing damage?0.298?>chlorine salt corrosion?0.185?>alkaline aggregate reaction?0.093?>carbonation?0.025?.Comprehensive weight sorting various influencing factors of concrete durability in order,Cl-concentration?0.32?>water cement ratio?0.20??0.19?>>temperature humidity air content?0.10?>PH?0.05?>mineral admixture?0.04?>alkali content?0.031?>aggregate activity?0.03?>freezing temperature?0.02?>satisfied degree of water?0.01?>electrical impedance?0.01?>CO2 concentration?0.01?>layer thickness?0.00075?.?3?Using the comprehensive evaluation method of second-level fuzzy mathematics,it is concluded that the durability grade of concrete material of a aqueduct is second grade,that is,the quality is better.?4?Based on the theory of weibull distribution,the life prediction model of concrete material under the condition of freezing and thawing,and according to the relationship between the indoor and outdoor freeze-thaw cycles to compute each material service life prediction of concrete specimens.Compared with the preliminary design of concrete antifreeze safety,the optimized design of concrete material and ratio was carried out.