Starch as a modifier for asphalt paving materials

This paper investigates the viability of using starch (ST) as a new modifier for asphalt paving materials. Different ratios of ST (2.5, 5.0, and 7.5% by weight of asphalt) were blended with 70/100 paving grade asphalt. Unmodified and modified asphalt binders were subjected to physicochemical, alkali, acid and fuel resistance tests. The performance tests including, Marshall stability, Marshall Quotient (MQ), tensile strength, tensile strength ratio, flexural strength, rutting resistance and resilient modulus (MR) were carried out on unmodified and modified stone matrix asphalt (SMA) mixtures. The analyses of test results show that the performance of ST-modified asphalt mixtures are better than conventional and styrene–butadiene–styrene (SBS)-modified mixtures. The rutting potential, moisture susceptibility and temperature susceptibility can be reduced by the inclusion of ST in the asphalt mixture. The laboratory MR values are lower than the calculated ones using the empirical equations. The results also revealed that this modifier can be used as anti-stripping agent. It also shows resistance to fuels and most common chemicals. A ST content of 5% by weight of asphalt is recommended for the improvement of the performance of asphalt concrete mixtures similar to that investigated in this study.     

不饱和树脂改性沥青裂缝修补材料的性能研究

裂缝是沥青路面常见的病害形式之一,裂缝不仅影响路面的平整度和安全性,还影响路面结构的完整性。不饱和树脂(UP)改性沥青具有较好的黏性和流动性,本文将UP改性沥青用作裂缝修补材料。通过抗渗试验、黏度试验、抗拉强度试验和粘结强度试验评价(UP)改性沥青的性能,并与SBS改性沥青进行对比。试验结果表明:在抗渗能力方面,UP改性沥青与SBS改性沥青相差无几;UP改性沥青的粘度、抗拉强度和粘结强度优于SBS改性沥青,UP性沥青的拉伸强度比SBS改性沥青的高16.4%。     

Laboratory comparison of the crumb-rubber and SBS modified bitumen and hot mix asphalt

The use of crumb rubber (CR) recycled from waste tires using an ambient grinding process was evaluated at two stages in asphalt formulation. First, bitumen modified with crumb rubber was evaluated by rotational viscometery (RV), dynamic shear rheometry (DSR) and conventional binder tests. Hot asphalt mixtures including crumb-rubber-modified bitumen were then evaluated by determining the permanent and fatigue characteristics and stiffness moduli of control and modified mixtures. The properties of the crumb-rubber-modified bitumen and asphalt mixtures were compared to different contents of styrene–butadiene–styrene (SBS) modified-bitumen and asphalt mixtures. The tests showed that to achieve the same performance, as with SBS-modification, the CR-content must be used at much higher than SBS. 8%-CR modification was determined as the most suitable content according to both binder and mixture tests.     

Investigation of rutting performance of asphalt mixtures containing polymer modifiers

The purpose of this study is to evaluate mechanical properties of control and modified asphalt mixtures. Conventional and five modified asphalt mixtures were studied on hot mix asphalt permanent deformation resistance. Amorphous polyalphaolefin, cellulose fiber, polyolefin, bituminous cellulose fiber and styrene butadiene styrene were used as modifiers. Indirect tensile strength, indirect tensile, static and repeated creep and LCPC wheel tracking tests were used for different loading conditions and temperatures. Research was focused on comparing the interaction between LCPC wheel tracking and other mechanical tests. According to the LCPC wheel tracking and repeated creep test results SBS mixtures were found as the most resistance mixtures in view of the rutting. Additives performed different performance levels but showed more resistance to permanent deformation according to the conventional mixtures. As far as the static creep test results are concerned there are controversial results because conventional mixtures are better. It is thought that this result may stem from the static behavior of the load and rheological change of bitumen with modifiers.     

Predicting stripping and moisture induced damage of asphalt concrete prepared with polymer modified bitumen and hydrated lime

Many highway agencies have been experiencing premature failures that decrease the performance and service life of pavements. One of the major causes of premature pavement failure is the moisture damage of the asphalt concrete layer. Many variables affect the amount of water damage in the asphalt concrete layer such as the type of aggregate, bitumen, mixture design and construction, level of traffic, environment, and the additive properties that are introduced to the bitumen, aggregate or bitumen–aggregate mixture.This study is aimed to determine the effect of additives such as hydrated lime as well as elastomeric (SBS) and plastomeric (EVA) polymer modified bitumen (PMB) on the stripping potential and moisture susceptibility characteristics of hot mix asphalt (HMA) containing different types of aggregate (basalt–limestone aggregate mixture and limestone aggregate). The stripping properties and moisture susceptibility characteristics of the samples have been evaluated by means of captured images and the Nicholson stripping test (ASTM D 1664) as well as the modified Lottman test (AASHTO T 283), respectively.The results indicated that hydrated lime addition and polymer modification increased the resistance of asphalt mixtures to the detrimental effect of water. Moreover, it was found out that samples prepared with SBS PMB exhibited more resistance to water damage compared to samples prepared with EVA PMB.     

Effect of polyethylene on life of flexible pavements

The present study investigates the potential use of pyrolysis low density polyethylene (LDPE) as a modifier for asphalt paving materials. Five different blends including conventional mix were subjected to binder testing such as rheological tests, as well as to some other tests related to the homogeneity of the system. Further, its effect on the moisture sensitivity and low temperature performance of stone matrix asphalt (SMA) mixtures was studied. Research results indicate that modified binders showed higher softening point, keeping the values of ductility at minimum range of specification of (100⁺ cm), and caused a reduction in percentage loss of weight due to heat and air (i.e. increase durability of original asphalt). The results indicated that the inclusion of LDPE in SMA mixtures can satisfy the performance requirement of high-temperature, low temperature and much rain zone. In addition, the horizontal tensile strain at the bottom of asphalt concrete layer (Ε_t) and the vertical compressive strain at the top of subgrade layer (Ε_c) were calculated using multi-layer elastic analysis program, BISAR under 50KN set of dual tires with 106.5 mm contact radius. These responses were used for estimating the improvement in service life of the pavement or reduction in thickness of SMA and base layer for the same service life due to modification the SMA mixtures.     

A model for dynamic creep evaluation of SBS modified HMA mixtures

The specimens, according to the Marshall Stability testing procedure, of hot mix asphalt (HMA) containing bitumen modified with styrene–butadiene–styrene (SBS) have been constructed in the laboratory and tested under dynamic loading for permanent deformation using Suleyman Demirel University Asphalt Tester equipment (SDU-Asphalt Tester). Analysis of data shows that the permanent deformation of the samples may be modeled in terms of the specimen’s characteristics in a very satisfactory manner. Benefits of adding styrene–butadiene–styrene (SBS) in variant quantities and in variant types of additive to asphalt cement (AC-60/70) were investigated. Initial research was done to determine the physical properties of asphalt cement and modifiers. Fifteen asphalt binder recipes were prepared with two types of gradation, six different contents of bitumen, four different contents of polymer, three different types of polymer. After that, Marshall samples were prepared by using the modified and unmodified control asphalt binders. The results of investigation indicate that asphalt mixtures modified by any SBS additive gives the best permanent deformation resistance in the tests carried out in this study, so that, this modification increases physical and mechanical properties of asphalt binder. In this study, total deformation of each sample was calculated using a newly developed equation containing variables of mixture characteristics. In addition to these, to develop a model that could fit the creep curve a new logarithmic model derived from first 100 preconditioning loading was developed instead of power law function model for first stage of permanent deformation curves.     

纳米复合改性沥青混合料路用性能研究

为评价纳米复合改性沥青混合料的路用性能,对纳米ZnO改性沥青混合料、纳米ZnO/TiO_2改性沥青混合料以及纳米ZnO/TiO_2/SBS复合改性沥青混合料进行了高温性能试验、小梁弯曲试验、劈裂试验及相关耐久性试验,并与基质沥青混合料和SBS改性沥青混合料进行对比分析.结果表明:上述3种纳米改性沥青混合料的高温稳定性、低温抗裂性、间接抗拉性和耐久性均优于基质沥青混合料,其中纳米ZnO/TiO_2/SBS复合改性沥青混合料的上述性能优于SBS改性沥青混合料.由此可见,纳米材料可显著改善沥青混合料的性能,纳米复合改性沥青的性能优于聚合物改性沥青,将其应用于道路是可行的.     

The effects of using lime and styrene–butadiene–styrene on moisture sensitivity resistance of hot mix asphalt

This study focuses on determining the effects of styrene–butadiene–styrene (SBS) and using mineral filler with lime on various properties of hot mix asphalt especially moisture damage resistance. The asphalt cement was modified with 2%, 4% and 6% SBS. The lime treated mixtures containing 2% lime by weight of the total aggregate as filler. The physical and mechanical properties of polymer modified binder and binder–aggregate mixes were evaluated through their fundamental engineering properties such as dynamic shear rheometer (DSR), rotational viscosimeter (RV) for binders, Marshall stability, stiffness modulus, indirect tensile strength and moisture susceptibility for mixes. The retained Marshall stability (RMS) and tensile strength ratio (TSR) values were calculated to determine the resistance of mixtures to moisture damage. To investigate clearly the effective of SBS and lime seven freeze–thaw cycle was applied to specimens at TSR test. The results indicate that application of SBS modified binders and lime as mineral filler one by one improves the stability, stiffness and strength characteristic of hot mix asphalt. According to retained Marshall stability it is concluded that addition of only 2% lime have approximately same effect with addition of 6% SBS. Using lime together within the SBS modified mixes exhibit high accordance and exacerbates the improvement of properties. Specimens containing both 2% lime and 6% SBS, have the highest stiffness modulus which is 2.3 times higher than those of the control mixture and showed the least reduction in tensile strength ratio while maintaining 0.70 tensile strength ratio after seven freeze–thaw cycle.     

老化作用下沥青混合料的疲劳及自愈合性能

通过四点弯曲疲劳试验,分析了老化作用下苯乙烯-丁二烯-苯乙烯三嵌段共聚物(SBS)改性沥青混合料和基质沥青混合料的疲劳及自愈合性能.结果表明:老化作用显著削弱了沥青混合料的抗疲劳性能,SBS改性沥青混合料的抗疲劳性能优于基质沥青混合料;老化程度和损伤程度对沥青混合料的自愈合能力影响最为显著;适当延长愈合时间和适宜的愈合温度可以提高沥青混合料的愈合率,但老化程度和损伤程度会削弱其自愈合能力;未老化条件下,基质沥青混合料的自愈合能力大于SBS改性沥青混合料,而老化条件下SBS改性沥青混合料表现出较强的自愈合能力.因此选用SBS改性沥青混合料作为路面材料可以提高沥青路面的抗疲劳及自愈合性能.     

SBS改性沥青混合料疲劳极限拉应变研究

为了证实和确定SBS改性沥青混合料疲劳极限标准,通过控制应变的小梁疲劳试验,研究了SBS改性沥青混合料疲劳寿命随拉应变水平的变化规律,拉应变水平的变化模拟了实际路面沥青层厚度变化对层底拉应变的影响.结果表明:当拉应变水平较高时,沥青混合料疲劳寿命有限;随着拉应变水平降低,疲劳寿命逐渐增大,且拉应变水平越低,增幅越大;当拉应变水平由400×10-6向100×10-6变化时,疲劳曲线在200×10-6处有明显的转折,此后,随着拉应变水平进一步降低,疲劳曲线明显变得平缓,呈现典型的渐近线特征,这证实了SBS改性沥青混合料存在疲劳极限这一假设;基于交通发展、设计年限和经济性,通过理论计算,建议SBS改性沥青混合料疲劳极限拉应变可以采用140×10-6.     

SBS改性沥青玛脂石屑混合料配合比设计

结合某沥青加铺层项目,研究了旧水泥混凝土路面加铺沥青层时设置的应力吸收层材料———SBS改性沥青玛脂石屑混合料的配合比,并通过马歇尔试验和路用性能检验了该混合料配合比,结果表明:所配制的SBS改性沥青玛脂石屑混合料的各项技术指标均满足要求。     

罩面工程中SBS改性沥青防水粘结层的研究

结合江西昌樟高速公路沥青路面维修罩面工程,对比分析了各种沥青路面防水粘结层的特点,探讨了沥青路面SBS改性沥青防水粘结层在高速公路沥青路面罩面工程中的应用技术,提高了沥青路面的使用寿命,具有良好的经济效益和社会效益。     

环氧树脂下封层在钢混叠合梁桥面防水中的应用研究

以无锡江海西路快速化改造工程钢混叠合梁桥面铺装工程为例,分析了浇注式沥青混凝土铺装体系在施工过程中出现鼓包的原因及危害,并针对性地提出了设置环氧树脂下封层的设计方案。研究结果表明,添加环氧树脂下封层后,其与混凝土桥面板间的粘结强度最高可达5.9 MPa,降低了浇注式沥青混合料和改性沥青SMA施工过程中鼓包出现的概率,有效保证了桥面铺装的施工质量。     

河西戈壁地区沥青路面裂缝处治技术应用研究

基于G30连霍高速公路嘉安段养护工程,分析了河西戈壁地区沥青路面裂缝典型类型及成因,提出了设置橡胶沥青应力吸收层后,采用橡胶粉与SBS复合改性沥青混凝土罩面的裂缝处治技术。研究应用结果表明:橡胶粉与SBS复合改性沥青混合料具有优良的低温抗裂性和高温稳定性,在延缓反射裂缝、延长路面使用寿命等方面具有独特的优势。     

Performance of the SMA mixes made with the various binders

This paper compares the performance of the stone mastic asphalt (SMA) mixes made with the various binders. Three types of binders namely: 20–30, 40–50 and 70–100 penetration grade were considered. The performance tests including, Marshall stability, tensile strength, tensile strength ratio, resistance to permanent deformation, flexural strength and resilient modulus were carried out on the SMA mixes. The safe pavement design criteria of the SMA mixes based on the anisotropic elasticity analysis through finite-element simulation were obtained and reported herein. In addition, an optimization table was prepared to select the type of SMA mixture for any field applications.     

Effect of carbon black on the dynamic moduli of asphalt mixtures and its master curves

Modulus is one of the main parameters during the design of asphalt pavement structure, the newest specifications of China gives the dynamic moduli ranges of commonly used asphalt mixtures with base asphalt (BA) or styrene-butadiene-styrene modified asphalt (SBS MA), while the moduli ranges of mixtures with carbon black modified asphalt (CB MA) are not recommended. To investigate the CB effect on the dynamic moduli of CB MA mixtures, one commonly used asphalt mixture (AC-20) was designed with BA, SBS MA, and CB MA, respectively. Then, the uniaxial compression dynamic modulus tests were conducted at different temperatures and loading frequencies, the master curves of asphalt mixtures were analyzed based on the time-temperature equivalence principle. The results show that with increasing loading frequency, the temperature dependence of dynamic moduli of all asphalt mixtures tend to be less obvious. Both SBS and CB can decrease the temperature sensitivity of asphalt mixture, the SBS MA mixture has the lowest temperature sensitivity, followed by CB MA and BA mixture. In addition, CB and SBS can obviously improve the dynamic modulus of the BA mixture, enhance the anti-deformation performance of pavement structure, and the improvement effect of CB is almost the same with SBS.     

Laboratory evaluation of HMA with high density polyethylene as a modifier

This paper investigates the viability of using high density polyethylene (HDPE) as a modifier for asphalt paving materials. Different ratios of HDPE by weight of asphalt were blended with 80/100 paving grade asphalt. Unmodified and modified asphalt binders were subjected to physicochemical and homogeneity tests. The performance tests including, Marshall Stability, Marshall Quotient (MQ), tensile strength, tensile strength ratio, flexural strength and resilient modulus were carried out on unmodified and modified hot asphalt mixtures. The analyses of test results show that the performance of HDPE-modified asphalt mixtures are better than conventional mixtures. The moisture susceptibility and temperature susceptibility can be reduced by the inclusion of HDPE in the asphalt mixture. A HDPE content of 5% by weight of asphalt is recommended for the improvement of the performance of asphalt concrete mixtures similar to that investigated in this study.     

水性环氧树脂改性乳化沥青作为雾封层材料的应用性能研究

沥青路面雾封层预养护主要选用普通乳化沥青、SBS改性乳化沥青等材料,本研究采用水性环氧树脂乳液作为改性剂对乳化沥青进行改性,将其试用于沥青路面雾封层施工,经检测路面防水抗渗功能明显提高,松散细集料得到有效固结。结果表明,水性环氧树脂改性乳化沥青作为沥青路面雾封层材料,具有良好的路用性能。     

环氧沥青混凝土桥面薄层铺装性能研究

为了研究环氧沥青混凝土在薄层铺装中的性能优势,通过马歇尔试验、浸水马歇尔试验、车辙实验、弯曲试验、劈裂试验,分析比较了环氧沥青混凝土与SBS改性沥青混凝土、沥青玛脂碎石SMA的路用性能。研究结果表明:环氧沥青混凝土桥面薄层铺装路用性能优于当前普遍采用的SBS改性沥青混凝土和沥青玛脂碎石SMA,是一种良好的桥面铺装材料。