| Permeable bituminous pavement is a key technique for “sponge” city construction.OGFC(Open Graded Friction Course)as a structural form of permeable bituminous pavement has such advantages as skid resistance,noise reduction and water drainage.However,due to relatively low strength and irreversible silting behavior of OGFC,the durability thereof becomes the key factor that restrains such pavement development.By virtue of relying on NSFC(National Natural Science Foundation of China)project----Study of Key Technology for Water Damage of Bituminous Pavement with Strengthened Asphalt-aggregate Ratio Fixation and Improved Integrity and Project of Jilin Provincial Department of Science and Technology----Study of Key Technology for Comprehensive Silting Control of Permeable Bituminous Pavement in Sponge City Construction,the paper aims at deeply studying the application of oil shale waste residues in pavement performance and permeability function of permeable bituminous pavement on the basis of climatic characteristics of snow-melting springtime in seasonal frozen region,thus providing theoretical basis and technical support to the structural design and construction of permeable bituminous pavement in seasonal frozen region.The main research contents are as follows:1.Study of performance of oil shale waste residues and silane coupling agent modified asphaltFirstly,the oil shale residue powder and silane coupling agent modified asphalt sample is prepared through two processes----surface pretreament method an direct mixing method,and the optimum preparation of the two process are respectively determined on the basis of the fundamental performance test.Then the two preparation process----surface pretreament method and direct mixing method are compared with each other according to needle penetration,softening point,ductility,aging test in rotating film oven,TG(Thermogravimetric Analysis),infrared spectroscopy,differential scanning calorimetry,etc.In order to determine the optimum preparation process and performance strengthening mechanism of the oil shale waste residue powder and silane coupling agent modified asphalt.According to the basic performance test,the oil shale waste slag powder/silane coupling agent composite modified asphalt prepared under the two preparation processes have good low temperature performance,high temperature performance,temperature sensing performance and anti-aging performance.The method has better modification effect than the surface pretreatment method.Infrared spectroscopy tests show that the modification mechanism of oil shale waste slag powder/silane coupling agent composite modified asphalt is not only physical blending,but also certain chemical modification.2.Study of pavement performance of permeable bituminous pavement with fine aggregate replaced by oil shale waste residuesOn the basis of the study of the performance of the oil shale waste residue powder and silane coupling agent modified asphalt,a preparation method of high-strength,environment-friendly and economical OGFC bituminous mixture(NM-OGFC)is proposed in the paper: the sieved oil shale waste residues is adopted to replace the aggregates with particle size less than 4.57 mm in the bituminous mixture at an equal proportion,and meanwhile silane coupling agent is adopted for auxiliary modification.Asphalt-aggregate ratio,silane coupling agent dosage,mixing temperature and compbehavior times influencing factor are optimized on the basis of externally tangent center composite design method,thus determining the optimum preparation process of NM-OGFC bituminous mixture.Moreover,through such pavement performance tests as Marshall test,wheel tracking test,low temperature splitting test,low temperature small-beam bending test,immersion Marshall test,snow-melting springtime stability test and looseness test,the pavement performance of NM-OGFC bituminous mixture is verified.The test data shows that the NM-OGFC asphalt mixture has good road performance,confirms the feasibility of replacing the fine aggregate in the oil shale waste residue,and also shows that the oil shale waste is used to replace the fine aggregate ratio.Bitumen has better economics and road performance.3.The study of strengthening mechanism in replacement of fine aggregate by oil shale waste residuesFirstly,the stress mechanism of the permeable bituminous pavement structure is discussed through discrete-element numerical simulation in order to determine the structural stress characteristics and the main bearing particle size of the permeable bituminous pavement.Then,the adsorption behavior of the oil shale waste residues and asphalts is deeply researched through performance test of bituminous mortar filled with oil shale waste residues,BET test,electron microscopy scanning test,asphalt absorbing and enduring rate test,interface asphalt saturation rate test and adhesion interface in-situ observation test system.The test results show that the enhancement mechanism of the oil shale waste residue replacing the fine aggregate permeable asphalt pavement is due to the development of the pore structure of the oil shale waste slag,the mesoporous shape,the unique layered column structure and the cellular structure antennae,which improves.The adsorption area of asphalt and aggregate forms a “paw membrane” structure at the adhesion interface,which changes the combination of asphalt and aggregate,and causes the performance of asphalt mortar to improve itself,thus making the macroscopic mechanics of permeable asphalt mixture.Significantly improved performance.4.Study of silting behavior of permeable bituminous pavement in seasonal frozen regionThe particle size characteristics of siltation materials in spring and summer were studied according to the sieving method.It was found that the particle size distribution of siltation materials was closely related to the daily average traffic volume,region,environment,weather,season and the type of pavement surface material.The difference of particle size distribution between spring and summer is particularly obvious,which is due tothe slipping of the non-slip sand in winter in the cold season.Then,on the basis of the spring-summer silting behavior simulation test system for seasonal frozen region and the entropy weight method,the comprehensive evaluation index----silting coefficient of the indoor silting behavior simulation test is proposed in the paper.It is found that the fouling coefficient obtained by fitting the three evaluation indexes has good objectivity,order and rationality by comparing the permeability loss rate,void loss rate and mass increase rate curve.5.Study of silting characteristics of permeable bituminous pavement with fine aggregate replaced by oil shale waste residuesAccording to the different siltingbehaviors in the spring and summer season,the silting characteristics of base permeable asphalt mixture,SBS modified permeable asphalt mixture and NM-OGFC were discussed in spring and summer season based on the siltation behavior simulation test system.The Mescherlich growth model was used to study the permeable asphalt mixture in the double-season environment,the Mescherlichsiltation model of the permeable asphalt mixture was established to quantify the siltation process of the permeable asphalt pavement.Among them,the maximum siltation degree and the siltation rate can be used as the evaluation index to quantify the siltation process of the permeable asphalt pavement.By comparing the two indexes,it is found that the oil shale waste can replace the fine aggregate in the permeable asphalt mixture to effectively improve the pore distribution,reduce the probability of free asphalt blocking the voids,and effectively improve the performance of permeable asphalt pavement against siltation behavior.By comparing the siltation models of the two seasons,it is found that there are two kinds of siltation modes ofpermeable asphalt pavement in spring and summer: one is the rapidsiltation behavior in spring,and the other is slow siltation in summer.Finally,based on the entropy-grey correlation theory,it is determined that the siltation materials whose particle size range150?m-1180?m has the greatest impact onthe siltation behavior,this provide a reference for the design of the permeable asphalt pavement. |
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