泡沫沥青分散性状及其与矿料相互作用研究

采用简便的筛分分析法,分别考虑沥青发泡特性、矿料温度、矿料级配组成及矿料拌和水量等材料设计参数,对泡沫沥青混合料中沥青分散性状及沥青与矿料的相互作用进行了分析评价。结果表明:沥青发泡性能及矿料温度的提高有助于提升泡沫沥青的分散均匀性,并在一定程度上增大泡沫沥青裹覆的矿料粒径范围;泡沫沥青在混合料中均匀分散时,其主要裹覆矿料为小于1.18mm、尤其是小于0.3mm的细料颗粒,为确保泡沫沥青混合料性能优良,矿料组成中必须具有足够的小于0.3mm的细料,且细料部分应为连续级配;矿料拌和水量不合理将导致泡沫沥青结团,对泡沫沥青混合料强度及稳定性不利,混合料组成设计中需通过试拌方式确定合适的矿料拌和水量。     

泡沫沥青再生混合料劈裂强度影响因素试验

为了研究不同泡沫沥青用量和旧沥青路面铣刨料(简称RAP)掺量两因素对泡沫沥青再生混合料劈裂强度的影响,采用两种不同的沥青路面铣刨旧料RAP1和RAP2,通过变化旧料掺量为0%、20%、40%、60%、80%5种比例,分别与2%、2.5%、3%、3.5%、4%5种用量的泡沫沥青混和,拌制泡沫沥青再生混合料,成型试件后进行干、湿两种条件下的劈裂强度(ITS)和残留劈裂强度比(TSR)测试.结果表明:在沥青旧料掺量比例一定的情况下,混合料的泡沫沥青用量存在最佳值;随着RAP掺量逐渐增大,泡沫沥青再生混合料的最佳沥青用量却逐渐减小,其值由RAP掺量为0时的3.5%减少到掺量为80%时的2%;随着RAP掺量的增大,泡沫沥青再生混合料干、湿ITS呈现减小趋势,但TSR却有所提高.     

Optimal percentage of reclaimed asphalt pavement in central plant hot recycling mixture

For determining the optimal percentage of RAP material in central plant hot recycling, binder was recovered from RAP by means of Abson recovery method, and properties tests of mixed binders consisting of recovered asphalt and fresh asphalt at different ratios were performed. In addition, the performances of mixture with different percentages of RAP such as rutting resistance, anti-cracking, moisture susceptibility and fatigue resistance were tested. The binder test results showed that the high temperature performance was improved with the increase of the percentage of the RAP, while the low temperature performance was declined. When the percentage of the recovered binder was less than 30%, the mixed binder could match the technical standards for fresh asphalt. Tests on the mixtures showed that rutting resistance increased gradually as RAP percentage increased, while thermal anti-cracking at low temperature and fatigue properties declined. The effect of the percentage of RAP on moisture susceptibility was limited. It is indicated that low temperature performance and fatigue properties are important for selecting the optimal percentage of RAP. Based on data obtained from binders and mixtures, it is concluded that the maximum percentage of RAP is approximately 30% without the addition of rejuvenating agent.     

Estimation of rheological properties of RAP binder

The low-temperature rheological properties of binders in the recycled asphalt pavement (RAP) material without the damaging effects of solvent extractions were analyzed. The developed procedure is based on testing of bitumen-RAP mortars produced by mixing the fresh (virgin) binder with RAP material smaller than # 8 sieve. Different mortars were prepared, containing RAP material passing the #8 sieve and 15% by weight of fresh binder. Low temperature properties of these mortars were investigated by using the bending beam rheometer (BBR) test procedure that is specially modified for testing of the RAP mortars. The modification involved the development of a new kind of mold and different testing parameters. The RAP material used in the experimental study were both extracted from real reclaimed pavement and prepared in the laboratory, by aging binder through repeated PAV cycles. The results indicate the new procedure can capture the effect of aged properties of bitumen in the RAP and can be used to estimate the PG low temperature grade of the blended binder. Although data is limited in size, the modification of the BBR appears to be simple and provide repeatable data.     

Mixture Performance of Bitumen Modified with Cocamide Diethanolamide

Bituminous binders have been modified by using cocamide diethanolamide.The chemical material used in this study is used for the first-time on the purpose of modification of the bitumen.In addition to the conventional bitumen tests (penetration,softening point and ductility tests),adhesion and peeling tests (Vialit,Nicholson and California tests) were carried out on the bituminous binders which are modified with different ratios of cocamide diethanolamide.According to the results of the tests,the most appropriate additive ratio has been determined.Samples containing the reference bituminous binder and the bituminous binder modified with the most appropriate cocamide diethanolamide ratio were prepared using the superpave volumetric mix design method (SuperpaveTM).In accordance with standard method of test for resistance of compacted asphalt mixtures to moisture-induced damage (AASHTO T 283),the moisture susceptibility of prepared samples has been examined.In order to observe the changes in strength due to the temperature difference,prepared samples were subjected to the freeze-thawing test in accordance with standard test method for resistance of concrete to rapid freezing and thawing (ASTM C 666).     

泡沫沥青温拌再生混合料试验研究

动态剪切流变试验评价不同拌和工艺下沥青结合料的老化程度,并提出老化因子量测指标。试验结果表明,泡沫沥青老化程度较低,沥青混合料路用性能受到影响。拟设计中粒式沥青混凝土HMA-AC-20、FWMA-20-RAP、FWMA-20同级配的三组混合料,进行性能检测。结果表明,泡沫沥青再生混合料可压实性好、抗水损害较好;泡沫沥青混合料抗疲劳开裂、抗低温开裂效果好;加入RAP料后压实沥青混合料的动稳定度提升很多,但仍然赶不上热拌沥青混合料。     

Evaluation of reclaimed asphalt pavement binder stiffness without extraction and recovery

A new testing procedure to estimate the low-temperature stiffness of the reclaimed asphalt pavement(RAP) binder was developed.In the testing procedure,the SuperpaveTM Bending Beam Rheometer(BBR) with special modifications and binder blending charts by Asphalt Institute were utilized.Modifications involved the development of a new kind of sample mold and different testing parameters were made to BBR testing procedure to capture the rheological properties of bitumen mortars produced by mixing fresh binder wit...     

Evaluation of Mixture Performance Recycled Asphalt Pavement Materials as Base Layer with or without Rejuvenator into the Asphalt

The binder properties were determined in accordance with Chinese standard such as ductility test,which allowed to measure the distance in centimeters that a standard briquette of asphalt had been stretched before breaking.Then,penetration test was carried out in order to know some properties of the asphalt,which are the hardness and the softness.Finally,softening point test was carried out in order to determine the temperature at which the bitumen attains a particular degree of softening under the specification of the test.According to Chinese standard for performance tests,firstly,Marshall test was carried out in order to measure the theoretical density,air voids,voids filled with asphalt,stability,flow,and voids in mineral aggregate of asphalt specimens.Secondly,Freeze-thaw splitting test was carried out in order to determine Splitting strength ratio.Finally,dynamic stability (rutting) test was carried out to determine average dynamic stability.Beside the tests carried out,the gradation of the extracted aggregate in accordance with American Association of State Highway and Transportation Officials was carried out to determine the dimensions of the particles weight distribution.Furthermore,both the percentage of recycled asphalt pavement materials and binder in mixture were determined to know how much of the new material during the mixture was needed.However,two specimens were used to evaluate the performance of recycled asphalt pavement materials.One specimen of recycled asphalt pavement materials was ten years old,and another one of recycled asphalt pavement materials was five years old.The results show that the conditions of the environment such as moisture,temperature,and age,decrease the ductility and penetration properties of binder when increase the softening point property of binder.Then the gradation of recycled asphalt pavement aggregate is of the required values to reuse in the mixture,while the flow ratio,the splitting strength ratio,and the dynamic stability ratio,are less than the required value test.With regard to the properties of mixture of recycled asphalt pavement material binder with rejuvenator,the results show that when the penetration and ductility versus percentage of rejuvenator increase,softening point versus percentage of rejuvenator decreases.Also,when the bitumen and rejuvenator percentage increase,the air voids decrease.Consequently,voids filled with asphalt and voids in the mineral aggregate increase.Moreover,the theoretical density and stability values decrease in a mixture containing four-point fifty percent to six percent of bitumen and rejuvenator,whereas the flow values increase.More interestingly,with four percent to four-point fifty percent mixture ratio of bitumen and rejuvenator,density,stability,and flow values increase.The splitting strength ratio values of mixtures and the dynamic stability test (rutting test) values of mixtures with forty percent of specimen one and specimen two respectively are greater than the required value of the standard test.In addition,the high percentage of rejuvenator increases the rut of pavement,in the same manner,the low percentage of rejuvenator induces low rut.In conclusion,the binder content from recycled materials without rejuvenator seems not be sufficient to be reused on the new pavement while the aged recycled material seems to be performed better than no aged recycled material with rejuvenator into bitumen.Then,the rejuvenator can influence the bitumen properties and performance of the pavement.Finally,the pavement made by only recycled pavement materials as a base layer appears to be more economical but cannot be more effective than the pavement made by mixture of new and recycled pavement materials as a base layer.     

耐久性混凝土的组分优化及配合比设计研究

混凝土耐久性是影响钢筋混凝土结构使用性能和寿命的主要指标,对于沿海、地下等环境恶劣的工程结构,必须考 虑按混凝土耐久性指标进行配合比的设计和施工.结合依托工程,分析了耐久性混凝土的成分组成,对各组分的技术指 标进行了优化,提出了基于多目标控制的耐久性混凝土配合比设计原则和方法,经依托工程验证可以满足工程各项指标要求.     

SBS改性乳化沥青温拌混合料路用性能评价研究

采用特制改性乳化沥青对温拌沥青混合料进行了配合比设计和路用性能（水稳性、高温稳定性）测试,并将其与相同类型的改性沥青混合料的路用性能进行了对比,结果表明,改性乳化沥青温拌沥青混合料和改性沥青混合料的路用性能基本相同且能满足改性沥青混合料的规范要求．由于改性乳化沥青温拌沥青混合料拌和及压实时所需的温度比改性沥青混合料低30℃以上,因此是一种高节能低排放的环保路面材料．     

Effect of ageing on fatigue properties of asphalt

The fatigue properties of asphalts were investigated after various laboratory simulation ageing tests and outdoor natural exposure ultraviolet radiation ageing,by dynamic shear rheometer(DSR) time sweep fatigue test in constant strain model and a new type of specimen which was introduced to avoid the problem of adhesion failure between rotor and asphalt binder.The results show that outdoor natural exposure ageing(NEA) causes the decrease of retained fatigue life distinctly,and photodegradation caused by outdoor NEA of 1 250 μm thin films asphalt for three months,is found to be severer than pressure ageing vessel(PAV) with respects to retained fatigue life.The effect of photodegradation increases as the time of outdoor NEA increases.DSR time sweep fatigue test in constant strain indicates that the aged styrene-butadiene-styrene(SBS) modified asphalt still displays better fatigue properties than the corresponding base asphalt after ageing.     

厂拌热再生过程中旧矿料颗粒的迁移行为

为提高热再生混合料的均匀性与生产质量,设计一种以回收沥青路面材料(reclaimded asphalt pavement, RAP)模拟制备、利用磁铁分离新旧矿料及迁移程度测试为关键步骤的室内试验,并通过该试验分析了RAP掺量、拌和时间及沥青用量对不同规格旧矿料颗粒迁移程度的影响。试验结果表明:热再生沥青混合料中旧矿料颗粒不能全部脱离原矿料,其迁移程度约为55%~75%;RAP掺量对迁移程度影响不大,随着拌和时间和沥青用量的增加,迁移程度不断增大;适当延长拌和时间,掺加新沥青或再生剂以及增加沥青用量可以促进旧矿料有效迁移,提高热再生沥青混合料的均匀性。     

锰渣掺合料对海工混凝土耐久性的影响

研究了锰渣的组成、结构等基本性能及其对海工混凝土耐久性的影响.所用水淬锰渣碱度系数1.09、质量系数1.71,具有潜在水硬活性.含α′-C2S胶凝矿物,其玻璃体含量和活性指数均约为80％.从水胶比、浆集比、水泥用量等配合比设计参数优化出发,使用锰渣掺合料和萘磺酸甲醛高效减水剂配制了力学性能良好的C40海工混凝土.用5倍正常海水浓度的模拟海水溶液对掺锰渣混凝土进行了侵蚀试验,以考察其耐海水腐蚀性.研究发现,掺锰渣混凝土在人工海水侵蚀及50次冻融循环后质量损失、强度损失均较小,抗渗性有所改善.由于所用水淬锰渣对改善混凝土耐久性有重要作用,其可作为矿物掺合料应用于近海及海洋环境混凝土工程.     

掺加RAP的骨架密实型级配碎石性能

为了解决沥青路面回收料(reclaimed asphalt pavement,RAP)在级配碎石中应用的问题,研究了RAP对骨架密实型级配碎石性能的影响.在室温(22℃)条件下,采用UTM-100对纯碎石及掺加RAP的骨架密实型级配碎石进行了动态模量、抗剪强度和永久变形对比试验.依据试验结果,分析了RAP对级配碎石性能的影响.研究表明,掺加RAP后,骨架密实型级配碎石动态回弹模量显著增大,平均增幅9.3%,模量增幅受围压和偏压围压比不同程度的影响,其中偏压围压比的影响较围压更为显著.抗剪强度有所减小,且应力软化阶段应力下降速率较慢.在发生剪切破坏时,与不掺加RAP的级配碎石具有相似的剪胀特征.轴向永久变形随RAP的加入显著增大,表明抵抗永久变形能力有所下降.     

再生SBS改性沥青混合料再度老化性能的研究

主要研究再生SBS改性沥青混合料的抗老化性能.对沥青进行24 h、48 h TFOT老化,分别模拟沥青的中度和重度老化,然后将老化沥青再生,对再生沥青拌制的混合料及新鲜沥青混合料进行室内短期与长期老化,并对老化后的沥青混合料进行性能试验与对比评价,分析了再生沥青混合料的抗老化性能及其老化规律,评价再生沥青混合料的耐久性.     

Preparation and recipe optimization of water-based architectural heat insulation coatings

Water-based architectural heat insulation coatings were studied to overcome the drawbacks of conventional inorganic silicate heat insulation coatings. The heat insulation coatings were prepared with the method of mechanical agitation when the mixed organic polymer emulsions were used as binder of the coatings and the mixed heat insulating aggregates were applied as powder, and some assistants were also added. Water temperature difference in the plastic container, which was coated with heat insulation coatings, represented the heat-insulating property of the coatings. The influences of components of mixed polymer emulsion, mass ratio of polymer emulsion to powder, particle size of heat insulating aggregates, added amount of air entraining admixture and the match of thickeners on the properties of the coatings were studied. The experimental results show that the heat insulation coatings with good finishing, heat-insulation property and artificial weathering can be prepared when the binder is composed of 66.92% styrene-acrylic emulsion, 16.59% elastic emulsion and 16.49% silicone-acrylic emulsion, the mass ratio of polymer emulsion to powder is 0.45, the particle size of heat insulating aggregates is in the rang of 200 and 250 mesh size, the added amount of sericite is 15%, and the added amount of air entraining admixture is in the range of 1.0% and 1.5% and the thickeners are the mixtures of ASE-60 and RM-5000.     

Long-term Durability of Cement-based Materials with Very Low w/b

To investigate the durability, especially the long-term stability of cement-based materials with very low w/b, the air permeability test, carbonation test, capillary absorption rate test and dilation Dotential test were adopted under long-term heat treatment condition. Microstructure of these materials is also analyzed by scannmg electronic microscopy (SEM) and mercury intrusion porosimeter (MIP) in order to further unveil its mechanism and interrelation between microstructure and its properties. The results indicate that in the area investigated, cement-based material with w/b 0.17, like RPC, possesses low porosity and excellent durability. Moreover, its porosity will further decrease under long-term heat treatment compared with normal heat treatment. Its long-term durability is much superior to that of other cement-based materials with w/b 0.25 or 0.35 as high strength concrete (HSC).     

Performance evaluation of open-graded epoxy asphalt concrete with two nominal maximum aggregate sizes

Open-graded friction course(OGFC) is applied to pavement surfaces to increase driving safety under wet conditions, and recently, to reduce tire/pavement noise. The durability of OGFC, however, has been a concern since conventional OGFC mixes last typically less than ten years before major maintenance or rehabilitation is needed. This work investigates a new open-graded asphalt mixture that uses epoxy asphalt as binder to improve mix durability. One type of epoxy asphalt that has been successfully applied to dense-graded asphalt concrete for bridge deck paving was selected. A procedure of compacting the mix into slab specimens was developed and a series of laboratory tests were conducted to evaluate the performance of the new mix, including Cantabro loss, permeability, friction, shear strength, and wheel rutting tests. Results show superior overall performance of the open-graded epoxy asphalt mix compared to conventional open-graded asphalt mix. There are also preliminary indications that the OGFC mix with 4.75-mm NMAS gradation can improve the resistance performance to raveling, while the OGFC mix with 9.5-mm NMAS gradation can improve the performance of surface friction at a high slip speed.     

磷石膏生产墙体材料可行性研究

通过正交试验获得磷石膏—矿渣—粉煤灰—石灰—水泥胶凝体系的优化配合比为磷石膏∶矿渣∶粉煤灰∶生石灰∶水泥=30∶25∶24.5∶10.5∶10,并通过XRD、SEM微观分析手段和宏观测定强度的方法探讨了养护制度对该胶凝体系性能的影响。研究结果表明：该胶结料90℃下蒸养7 h,然后自然养护,28 d抗压强度高达43.9MPa,凝结时间正常,耐水性良好。胶结料强度随养护温度的升高而增加;90℃下,胶结料强度随蒸养时间的增加而增加,此温度下蒸养13 h所得制品,7 d抗压强度便达到39.6 MPa。利用最优配比成型的免烧砖能达到非烧结粘土砖15级的要求。     

泡沫沥青稳定旧沥青路面混合料冷再生试验分析

以回收的废旧路面材料(RAP)为基础,从材料的选取与级配的组成、沥青的最佳发泡条件、混合料拌和方法及养护方案等几个方面初步得出一套基于水稳性的泡沫沥青混合料配合比设计方法.并对该材料的物理性质和强度特性进行了研究,提出了路用泡沫沥青的最佳含量,进行泡沫沥青再生混合料与乳化沥青混合料性能的比较,得出了泡沫沥青再生的使用范围.