沥青混合料水损害的室内研究

在级配确定的基础上选取对沥青混合料水稳定性有影响的几种典型因素:集料种类、沥青种类、空隙率、老化程度掺加抗剥落剂种类等,通过正交试验,以一次冻融劈裂强度比、多次冻融劈裂强度比作为沥青混合料水稳定性的评价指标。通过室内试验,定量地探讨了这些影响因素各个水平变化所引起的对沥青混合料水稳定性的影响;采用正交试验极差分析法分析试验数据,最后得出了如下结论:对于沥青混合料水稳定性能,影响最大的因素是沥青种类,剥落剂种类及集料种类次之。     

硅藻土改性沥青及其混合料路用性能研究

对硅藻土改性沥青及其混合料进行了一系列室内试验研究，包括沥青的技术性能试验，沥青混合料的高温车辙试验，低温弯曲劈裂试验，残留稳定度和冻融劈裂试验以及弯曲疲劳试验。研究结果表明硅藻土能改善沥青的高温、低温和抗老化性能；且硅藻土改性沥青混合料能显著提高混合料的水稳定性、低温性能，高温稳定性和抗疲劳性能，具有良好的路用性能，是一种值得推广的改性沥青混合料。     

冷拌冷铺乳化沥青混合料压实时机确定方法室内模拟研究

冷拌冷铺乳化沥青混合料的强度形成受多种因素的影响,导致其压实时机难以把握,而现行规范中缺少冷拌冷铺乳化沥青混合料压实时机的判定标准,制约了该材料的推广应用。为此,对冷拌冷铺乳化沥青混合料压实时机的确定方法和判据开展室内模拟研究。首先,通过室内试验建立了乳化沥青混合料劈裂强度、高温稳定性、低温抗裂性及水稳定性与试件成型时机的关系方程,相关性分析表明,劈裂强度与高温稳定性、低温抗裂性及水稳定性之间的相关性极显著,可以用劈裂强度作为代表性指标来确定压实时机。在此基础上,以路用性能满足热拌改性沥青混合料的规范要求为判据,确定了乳化沥青混合料压实时机的判定指标和标准,即判定指标为劈裂强度,判定标准为劈裂强度Q≥0.69 MPa。该成果对乳化沥青混合料压实时机的确定具有参考价值。     

岩沥青改性沥青及沥青混合料路用性能研究

为了了解新疆岩沥青的路用性能,在沥青胶结料中掺入不同量的岩沥青,进行针入度、延度扣软化点试验,对加入岩沥青后的沥青混合料进行了车辙试验、低温弯曲试验、浸水马歇尔试验、冻融劈裂试验、疲劳试验,并与SBS改性沥青及沥青混合料的试验结果进行了比较。结果发现掺入岩沥青后,沥青胶结料的的高温稳定性和抗老化性得到了较大程度的提高,掺入量为15%的岩沥青改性沥青混合料动稳定度、冻融劈裂强度比、劲度模量较基质沥青分别提高了3.5倍、0.34倍、2.89倍,说明其高温稳定性、水稳定性、抗疲劳性有了较大的提高,而低温弯曲破坏强度提高了0.18倍,反映出其低温抗裂性也得到了一定程度的改善,表明掺入岩沥青的沥青混凝土具有良好的路用性能。     

花岗岩沥青混合料水稳定性问题的研究

研究了沥青混合料内部组成对粘附性和水稳定性的影响.从级配、集料、沥青和抗剥落剂的选择角度入手,综合解决花岗岩在沥青路面中的应用.通过对两种典型级配的研究,确定出适用于花岗岩沥青混合料的级配类型;对不同酸性的集料和同种类沥青之间的粘附性试验和冻融劈裂试验,发现集料和沥青之间的粘附是有选择性的.因此,在选择材料时可以优先选择粘附性和水稳定性较好的集料和沥青进行组合;通过不同抗剥落剂对水稳定性的提高程度,确定了最佳的抗剥落剂类型.     

硅藻土改性沥青混合料水稳定性的试验研究

将硅藻土掺配在沥青混合料中，可以改善沥青混凝土的性能，提高路面工程的质量。使用冻融劈裂试验，采用不同剂量的硅藻土来研究硅藻土对沥青混合料水稳定性能影响。试验结果表明硅藻土能较好地改善沥青混凝土水稳定性能，其最佳剂量为15％。     

岩沥青改性沥青路用性能试验研究

通过车辙试验、冻融劈裂试验及汉堡轮辙试验对两种不同岩沥青改性沥青混合料的路用性能进行试验研究;并与70号普通道路石油沥青混合料进行了汉堡轮辙试验对比。在试验研究的基础上对使用岩沥青改性沥青后沥青混合料的路用性能进行了分析。     

粗集料对乳化沥青冷再生混合料性能的影响

粗骨料多用于形成骨架空隙结构,依靠粗集料相互嵌挤及其间的内摩阻力形成强度,进而使得结构坚实,促进排水。为了研究乳化沥青冷再生混合料中粗集料是否形成骨架结构,是否有助于提高乳化沥青冷再生沥青混合料的稳定性和耐久性,选取4种级配的混合料,通过马歇尔试验、车辙试验、冻融劈裂试验等,分析了4种不同含量粗集料对沥青混合料空隙率、高温稳定性、水稳定性能的影响。     

再生SBS沥青混合料的性能提升措施

采用车辙试验、低温弯曲试验、冻融劈裂试验、应力控制模式下的间接拉伸疲劳试验,在分析RAP掺量(质量分数)对再生SBS沥青混合料各项性能影响的基础上,探究了高RAP掺量(60%)再生SBS沥青混合料的性能提升措施,此外,还通过旋转压实成型试验,研究了两种性能提升措施对再生SBS沥青混合料压实性能的影响。     

彩色半柔性混合料路用性能研究

彩色半柔性混合料是一种在开级配沥青混合料中填充水泥胶浆而形成的兼具沥青路面与水泥混凝土路面优点的彩色复合路面。利用车辙试验来评价彩色半柔性混合料的高温稳定性,用残留稳定度和冻融劈裂试验评价半柔性混合料的水稳定性。结果表明,半柔性混合料具有优良的高温稳定性和疲劳性能,水稳定性较好。     

Manufacture of High Softening Waxy Asphalt for Use in Road Paving

This research aims to manufacture a special type of high softening waxy asphalt of penetration grade 60/70 to be used as a suitable binder in production of a hot mix asphalt (HMA) consisting of low quality aggregate (high absorptive type). This type of aggregate is found in Egypt on a large scale, especially in Sharkia governate. To achieve this aim, crude microcrystalline wax, which is characterized by its high congealing point, kinematic viscosity, and its low penetration, was mixed with the normal penetration grade asphalt 60/70 in percentage ranging from 2 to 6% by weight. The resultant asphalt samples were found to have high softening point ranging from 58°C to 75°C and penetration values within the current specifications. The produced waxy asphalt samples were used in preparing the HMA using the high absorptive aggregate. The mixes were evaluated using the Marshall method and tested for rutting resistance. The laboratory results show that the prepared mixes are suitable for use as a wearing or base course for the medium and low traffic roads.     

Moisture susceptibility of warm mixed-reclaimed asphalt pavement containing Sasobit and Zycotherm additives

In this research, the influence of Sasobit and Zycotherm on the properties of reclaimed asphalt pavement (RAP)-warm mix asphalt (WMA) was investigated. Moisture susceptibility was evaluated applying the resilient modulus ratio, the indirect tensile strength ratio, and the fracture energy ratio. Laboratory testing results indicated that Zycotherm mixtures had more resistance to moisture damage than Sasobit WMA and hot mix asphalt (HMA) mixtures. The stiffness of mixtures increased dramatically by increasing the amount of RAP and using Sasobit exacerbated this problem.     

Rutting behavior of hot mix asphalt modified by polyvinyl chloride powder

In this experiment, at first, waste polyvinyl chloride was used as an additive in an attempt to improve the performance of bitumen and hot mix asphalt (HMA) in order to minimize the amount of rutting. To further these aims, conventional and rheological tests were conducted on bitumen and all HMA specimens were tested by Marshall stability, flow, and repeated load axial tests. After investigating rutting resistance of HMA samples, the results demonstrated that this waste material could improve the rheological properties of bitumen, and the HMA samples, manufactured by this particular type of bitumen, are more resistant to rutting.     

Environmentally friendly road construction

Environmental pollution is a major problem in developing countries like Egypt. Reuse of waste polymers is considered an attractive solution for environmental white pollution and reducing of the costs of road pavement and maintenance. This research aims to prepare environmentally friendly hot mix asphalt (HMA) for paving using some industrial wastes as polypropylene and polyester fibers. The solid materials in the mix include normal and highly porous aggregates. 5% and 10% of waste polymers by weight of the asphalt were used to prepare special binders. The samples were tested for their physical properties, chemical properties, aging, scanning electron microscopy (SEM) and thermo-gravimetric analysis (TGA). The results revealed that the prepared HMA using 5% of waste polymer had high performance as compared to the ordinary one and the waste polymer could be used in road construction.     

热拌沥青混合料:21世纪展望与挑战--材料与混合料设计

针对材料与混合料设计,展望了21世纪热抖沥青工业界面临的挑战与机遇,论述了设计系统方法、热抖沥青混合料、胶结料、集料等方面正在进行今后将重点进行研究解决的问题,如与性能有关的规范、力学性能预测模型、水敏感性和耐久性试验、Superpave混合料使用、废料、抖与压实温度、更厚更稠的沥青层、改性沥青等,这些对我国道路和沥青工业界均有一定的参考价值。     

Tack coats for asphalt paving

Poor bonding between two layers of hot mix asphalt (HMA) is the cause of many highway pavement problems. Normally, hot asphalt cements, emulsified asphalts or cutback asphalts are used as tack coat. The objective of this study was to evaluate the practice of using tack coat through controlled laboratory simple shear tests and determine the optimum application rate. The influences of tack coat types, application rates, viscosity and temperatures on the interface shear strength were examined. Test results indicated that latex modified asphalt emulsion has the highest interface bond strength. It was also found that applying low viscosity tack coat asphalt emulsion at two layers is more effective than a tack coat asphalt emulsion high viscosity one layer coat.     

取样位置对质量控制参数的影响评价

热拌沥青混合料（HMA）的取样质量对试验结果有着显著的影响。研究利用工地生产的混合料对运料车、摊铺机后及路面钻芯三种不同的取样方式进行了比较研究。结果表明，虽然三种取样方式获取的混合料试验的实验室特性在数学理论统计意义上没有显著的差别（沥青用量除外），但运料车上取样时很容易发生离析现象，导致获取的级配偏细、沥青用量偏高及空隙率偏低。     

集料在沥青混合料中的状态对其体积指标的影响

沥青混合料的体积特征参数对沥青路面路用力学性能具有重大影响，在采用体积设计方法时各种集料的密度参数设计的成功与否起着决定性的作用。其空隙率（VV）、矿料间隙率（VMA）、沥青饱和度（VFA）等各项体积指标的影响，得出了三种不同的计算模式下混合料体积指标变化规律。     

Investigating the influence of using nano-composites on storage stability of modified bitumen and moisture damage of HMA

In this study, a composite of styrene butadiene rubber (SBR) and nano-clay was made with different ratios and used for bitumen modification. The results show that using nano-composites improves storage stability at high temperature. However, pure SBR modified bitumen is proved not to be stable at high temperature. Investigating the results of indirect tensile strength and indirect tensile strength ratio also indicates that nano-composites improve moisture sensitivity of hot mix asphalt (HMA). Further, according to the results, increasing the content of nano-clay enhances the resistant of asphalt mixtures against moisture damage.     

ABSORPTION OF ASPHALT INTO POROUS AGGREGATES: TEST OF A SIMPLE PHYSICOCHEMICAL MODEL

ABSTRACT

Absorption is the process in which asphalt flows into a porous aggregate, under the driving force of capillary pressure. Asphalt absorption is of interest because it represents an economic loss of effective binder, and because it may change the properties of the resulting asphalt film and lead to premature pavement distress. Incorrect air voids estimation may also result from failure to properly account for asphalt absorption in pavement design. The objective of this research was to determine the temporal dependence of absorption upon asphalt and aggregate properties and to test a rational model for this dependence.

Absorption data were obtained for several model liquids and asphalts with synthetic alumina aggregates and a natural limestone aggregate. The data were used to test a simple absorption model incorporating the effects of asphalt and aggregate properties into a single dimensionless time variable.

While quantitative agreement was not obtained in all aspects of the model, certain predictions of the model were verified. The general shape of the absorption data followed the model prediction for synthetic alumina spheres. The effect of viscosity and surface tension was correlated fairly well by the surface tension/virosity factor in the dimensionless time variable

The use of the dimensionless time variable was able to reduce the time span for absorption from ca. four order of magnitude to only ca. one order of magnitude; although, there remained a significant variation in some of the absorption data, probably caused by differences in the contact angles for the various Liquids.

The absorption behavior with a natural Iowa limestone did not follow the shape of the theoretical curve predicted by the model. This deviation is thought to be c a d by the presence of air in the pores coupled with the large and polydisperse pore size of this aggregate