Effect of aggregate properties on asphalt mixtures stripping and creep behavior

The purpose of this paper is to look at some aspects of the effects of aggregate chemical and physical properties on the creep and stripping behavior of hot-mix asphalt (HMA). Two types of aggregates evaluated in this study were limestone and basalt. The effects of the aggregates type were evaluated on three different aggregate gradations and two types of asphalt used in preparing the HMA. The percent of increase in static creep strain of HMA due to conditioning was utilized in this study to assess the stripping.Test results indicated that unconditioned HMA specimens prepared using basalt aggregate resist creep better than those prepared using limestone. However, after conditioning, mixes prepared using basalt were less resistant to creep strain than those prepared using limestone aggregate. Percent absorbed asphalt was found to be directly related to stripping resistant. Also, mixes prepared using aggregate following ASTM upper limit of dense aggregate gradation presented the highest resistance to stripping. The results of the calculated adhesion work were able to detect the effect of stripping on creep behavior for mixes prepared.     

Effect of glass cullet on the improvement of the dynamic behaviour of asphalt concrete

The stiffness modulus is one of the most important parameters for the prediction of pavement strength against dynamic loads. Previous research indicated that glass can reduce the construction costs of asphalt concrete pavements while providing better dynamic behaviour because of its unique properties. In this research, the behaviour of Hot Mix Asphalt (HMA) in different temperature conditions depending on the variation of the admixture contents and the gradation of the aggregates will be evaluated. Afterwards, for the first time, models for the prediction of the stiffness modulus of waste glass–asphalt in terms of three different parameters including temperature, percentage of additives and the aggregate gradation will be presented. The results of this research are indicative of an improvement in the dynamic behaviour of glass–asphalt mixture in comparison with conventional HMA mixtures.     

沥青混合料配合比设计中的影响因素

沥青混合料是一种比较复杂的复合型材料,它的力学性能与矿料的组成直接相关。介绍了骨架密实型、骨架空隙型和悬浮密实型等3种矿料级配类型的结构特点和工程特性。结合通化市的实际工程经验,指出采用骨架密实型的沥青混合料矿料级配比较理想。在沥青混合料配合比设计中,还应考虑关键性筛孔和最大公称尺寸的影响。     

浅析沥青混合料配合比设计

阐述了沥青混合料配合比设计由矿料配合比设计和最佳沥青用量两部分组成，从原材料、矿质混合料及级配设计、最佳沥青用量等方面，探讨了沥青混合料配合比设计的方法。     

Evaluation of internal resistance in hot-mix asphalt (HMA) concrete

Accurate quantification of aggregate properties is essential for understanding their influence on hot-mix asphalt (HMA) concrete and for selecting aggregates to produce high-quality paving mixture. The objectives of this study are to develop a method to measure internal resistance in HMA mixtures and to evaluate the effect of different gradations on the rutting of mixes. Analysis showed that a HMA mix could be made more resistant to rutting by specifying an adequate range of the fine aggregate passing through the 4.75-mm (No. 4) sieve. The lower the fine aggregate percentage, the greater the difference between the coarse aggregate void volume and the total volume of fines. This indicated that the aggregate interlocking greatly occurred in the coarse aggregate. The image evaluation of aggregate morphological characteristic demonstrated that a stable aggregate skeleton resulted in more internal resistance.     

On SHRP：Twenty Five Years Review and Outlook

夏普计划已经走过了25年,它是沥青科技发展史上极为重要的里程碑.它打破了传统马歇尔设计中要求混合料低沥青含量的限制,     

级配组成与沥青混合料体积参数的关系

通过试验与统计分析，探讨了粗、细集料用量之比对其级配组成和体积参数的影响，进而探讨了粗、细级配混合料体积参数及设计沥青用量的差异及其主要影响因素．研究结果表明：在连续级配组成的沥青混合料中，粗、细集料用量之比虽然对各自的级配组成有影响，但主要影响的是细集料的体积结构组成；在设计空隙率相同的条件下，粗级配混合料较之细级配混合料有着较高的矿料间隙率和设计沥青用量；在粗集料用量未超过70％（质量分数）时，沥青混合料通常呈悬浮密实结构．     

就地热再生沥青混合料配合比优化设计及性能研究

为了避免在沥青路面就地热再生中由于级配设计不良导致的沥青混合料出现离析、松散、粘接性能不佳和路 用性能等问题。通过对原路面材料进行调查,掌握原材料级配及老化程度,根据调查结果对沥青路面就地热再生材料进行 级配优化设计,控制再生剂用量、级配和最佳油石比,得到室内配合比。在此基础上对再生沥青混合料进行水稳定性和高 温稳定性能检测。试验结果表明通过对原有沥青路面情况调查和就地热再生沥青混合料配合比优化设计,可以得到路用性 能优良的再生沥青混凝土路面。     

基于矿料间隙率的预估最佳油石比经验计算法

基于矿质混合料的级配,可用经验计算法预估矿料间隙率;基于矿料间隙率,可用经验计算法预估最佳油石比,将沥青混凝土设计为密实结构;用预估的最佳油石比做马歇尔试验,可验证沥青混凝土是否为骨架结构,若为空隙结构,则增加粗集料,重复以上步骤。经工程实践证明,基于矿料间隙率的预估最佳油石比经验计算法准确可靠,使上述级配优化方法具有可行性,为设计骨架密实结构的沥青混凝土提供捷径。     

沥青路面沥青混合料针对性设计

由于沥青混合料设计不合理,造成沥青路面产生严重的车辙,因此沥青混合料原材料选择和配合比设计要充分考虑其对路面高温稳定性能的影响。从矿料的颗粒形状和化学性质、沥青性质、矿料级配、沥青混合料空隙率、矿料间隙率、路面中面层沥青混合料性能等方面对沥青路面车辙产生的原因进行了分析,提出了针对车辙产生原因的沥青混合料设计措施。     

Laboratory evaluation of incorporating waste ceramic materials into Portland cement and asphaltic concrete

Laboratory tests were conducted to evaluate the feasibility of incorporating fired ware scrap, a waste ceramic material from automobile manufacturing, into pavement material. In this study, crushed fired ware scraps were added into Portland cement concrete (PCC) and hot-mix asphalt (HMA) to replace fine aggregates.The results of this study indicated that the fired ware scraps can be potentially used in the Portland cement concrete and HMA mixture. The compressive strength of PCC was improved by adding crushed scrap. However, due to the high water absorption of the crushed scrap, crushed scrap content is recommended to be less than 10% and a water reduction additive is recommended to provide adequate workability. For HMA, the test results indicated that adding a certain amount (up to 15% by weight) of ground scrap improved the binder’s total resistance to deformation. The dynamic modulus, flow number and indirect tensile strength of the HMA mixture were all improved by adding “filler” made of ground scrap. 2.5% “filler” content was recommended for a dense-graded HMA surface mixture.     

布敦岩矿料的沥青混合料路用性能

以70号A级道路石油沥青为依据,实施了6种不同布顿岩矿料掺量的6种AC20矿料级配的布顿岩沥青混合料路用性能研究。结果表明,布敦岩沥青原材料中的岩矿料对矿料级配组成与路用性能均影响较大;合理选择布敦岩沥青油石比可显著提高综合路用性能,较优油石比为0.7%～1.3%时的路用性能接近于SBS 改性沥青混合料,但对提高水稳定性能力有限;布敦岩沥青最佳掺量为23.7%,与布敦岩沥青原材料自身的油石比几乎相同。     

上海林海公路新建工程中Super-19沥青混合料的生产质量控制

介绍了上海林海公路新建工程沥青路面中面层上,采用的Super-19沥青混合料的生产质量控制。它采用Superpave方法成型旋转压实试件,进行混合料设计,确定混合料级配和沥青用量。通过对原材料、拌和工艺、混合料旋转试验和马歇尔试验等进行过程质量控制,有效地改善了沥青混合料的路用性能,提高了林海公路新建工程路面质量。     

沥青混合料中矿料组成特征及其性能研究综述

介绍了国内外的研究人员利用数字图像处理技术构建的许多描述集料颗粒形态的方法和指标,以及对集料颗粒形态特征的有效评价。在对矿料组成特征的描述中,基于试验的体积法仍是当前的主要手段,矿料组成的理论模型鲜有报道,认为矿料组成特性及其性能的评价可以改善沥青混合料性能的控制和优化。     

Material-specific effects of hydrated lime on the properties and performance behavior of asphalt mixtures and asphaltic pavements

This study evaluates hydrated lime-treated hot-mix asphalt (HMA) mixtures through various laboratory tests, including the dynamic modulus test and performance tests to characterize permanent deformation and fatigue damage resistance both in displacement-controlled and force-controlled modes. Two different asphalt mixtures — the asphalt concrete mixture and the fine aggregate asphalt matrix mixture — which differ only in the amount of additional hydrated lime (0.5–3.0%), are tested. Test results demonstrate material-specific damage characteristics of hydrated lime and the existence of a more appropriate amount of hydrated lime to be added to the HMA mixtures than the current typical application rate such as the addition of 1.0% lime to dry or pre-moistened aggregates. In addition, the newly released Mechanistic-Empirical Pavement Design Guide (MEPDG) is used for predicting pavement performance related to hydrated lime content. The MEPDG analysis results show that damage prediction models implemented in the current MEPDG are limited to accurately predicting material-specific damage characteristics. Mechanistic models that consider material-specific crack phenomenon and fracture behavior should be pursued.     

Laboratory evaluation of WMA mixture for use in airport pavement rehabilitation

The concept of warm mix asphalt (WMA) gives a promise for rehabilitating airport pavement to realize quick turnover to traffic after construction, however, laboratory and field data in terms of the performance-related properties are significantly lacking for using WMA in airfield in Japan. To fill this gap, three WMA mixtures (different gradations) were systematically investigated compared with the conventional airfield used hot mix asphalt (HMA) through a series of laboratory tests in terms of wheel tracking test, submerged wheel tracking test, raveling test, static bending and fatigue bending test. These WMA mixtures were made at two production temperatures (30 and 50 °С lower than the normal, respectively) by incorporating a commercially sold additive. Results showed that overall, the WMA mixture with a coarse gradation produced at the temperature 30 °С lower than the normal exhibited a comparable performance compared with the control HMA mixture, and it was further recommended for use in airport pavement rehabilitation.     

自编EXCEL程序设计沥青混合料的矿料级配

矿料级配是沥青混合料配合比设计中关键环节。传统的矿料级配方法费时、费力、精度差。采用自编的EXCEL程序代替传统方法,可以提高矿料级配精度及效率。以目标配合比设计为例,介绍了矿料级配曲线、优化矿料级配曲线的形成过程,以及生产配合比设计、生产配合比设计验证阶段的程序应用。     

GTM沥青混合料低温性能影响因素研究

论述了以GTM设计的AC-16C改性沥青混合料为基础,在级配、油石比、粉油比变化的条件下,分别对混合料进行低温弯曲破坏试验。试验结果表明,对于沥青混合料的低温抗裂性能,4.75mm通过率、油石比、粉油比均存在最佳值。采用BBR试验进一步分析消石灰及水泥对胶泥低温性质的影响时发现,以部分水泥替代矿粉有利于提高沥青胶泥的低温性能。研究结论对道路沥青混合料配合比设计和施工控制具有一定的参考价值。     

Superpave沥青混合料组成设计研究

采用旋转压实方法对安山岩集料Superpave25沥青混合料进行配合比设计。通过级配优选和油石比优选及性能验证等步骤,最终设计出级配合理、性能优良的Superpave25沥青混合料。     

沥青混合料级配特征与路用性能的相关性

为了定量分析沥青混合料级配特征,揭示级配与沥青混合料路用性能的关系,通过分形理论方法量化了级配曲线特征,采用分形维数表征级配曲线特征,通过对比分析试验级配的分维数和沥青混合料路用性能指标变化趋势,得到了两者的变化规律。