温拌沥青混合料的路用性能研究

沥青混合料组成设计方法的目标是获得具有优良路用性能的沥青混合料,因此可通过研究沥青混合料的路用性能评价级配组成设计与胶浆改善措施的效果。通过研究发现对温拌沥青混合料（WMA）进行设计时,除了如同热拌沥青混合料（HMA）的级配的选择以外,还得兼顾到矿粉在沥青混合料中的使用比例。所以在选择外加剂之后,确立了胶粉的比例,在合适的粉胶比下验证温拌沥青混合料的性能。     

掺生物沥青的乳化沥青冷再生混合料强度特性及路用性能研究

再生剂对老化沥青混合料的改善作用,可使老化沥青混合料的路用性能在一定程度上恢复还原。在进行再生沥青路面混合料设计之前,必须对旧料中沥青的含量及性质、旧料的级配组成及技术指标等进行全面了解,以确定回收的废旧沥青和旧集料性质,为新添集料性质、级配提供掺量依据。本文分析了掺生物沥青的乳化沥青冷再生混合料的概况,对原材料配比和乳化沥青制备情况进行了阐述,接着对不同的生物重油掺量乳化沥青再生混合料力学强度进行实验分析,最后总结了不同生物质重油掺量乳化沥青冷再生混合料路用性能,旨在为提高高速公路的质量以及延长其使用寿命提供保障。     

浇筑式沥青混凝土性能影响因素研究

浇筑式沥青混凝土具有较高的变形随从性而在钢桥面铺装上得到了很多的应用,为研究浇筑式沥青混凝土的性能影响因素,采用4种合成级配、3种沥青用量,系统评价了各因素对浇筑式沥青混凝土性能的影响。通过流动度试验和贯入度试验确定最佳含油量,由高温车辙试验和低温弯曲试验进行路用性能检验。研究表明,级配形式和沥青含油量变化对混合料的性能指标的影响较大,因此,实际施工时应严格控制混合料的级配和沥青用量。     

沥青混合料级配类型研究

本文分析了目前高速公路沥青路面常用的几种不同级配类型的混合料,对比了其各自的特点。并指出具有良好集料级配组成的沥青混合料将具有优良的力学性能和路用性能。     

级配对冷补沥青混合料路用性能的影响

用冷补沥青混合料修补路面坑洞具有方便、快捷等优点,为许多道路工作者所使用.但在多年的使用中经常发现冷补沥青路用性能欠佳,修补后很快出现路面病害.为了探讨级配对冷补沥青混合料性能的影响,采用3种不同矿料级配来配制冷补沥青混合料,并对其进行性能测试,包括初始强度测试、成型强度测试、黏聚性试验、抗水剥离试验、耐水性试验及低温工作性和抗冻性.通过以上室内试验与在实验路上的路用性能相比较,得出矿料级配对冷补沥青混合料路用性能有重要影响.     

粗集料棱角性对OGFC多孔沥青混合料性能的影响

采用洛杉矶磨耗机对粗集料进行不同程度磨耗后,按照OGFC-10、OGFC-13和OGFC-16等3种级配制备了12种OGFC沥青混合料。在室内借助集料图像测量系统得到了不同OGFC沥青混合料的粗集料棱角性综合值Ic,并测试了各沥青混合料的相关路用性能。结果表明,当集料级配相同时,粗集料棱角性下降会造成OGFC沥青混合料马歇尔稳定度、动稳定度、空隙率和抗滑性能均有明显下降,但对渗水性能影响不大。当集料级配不同时,3种OGFC沥青混合料中,随着粗集料棱角性综合值Ic的下降,OGFC-16的马歇尔稳定度、动稳定度和抗滑性能下降最明显,OGFC-10的空隙率下降最明显。     

两种硬质沥青混合料配比设计及路用性能对比分析

为了研究和分析"东海牌"30#和50#硬质沥青的特性,分别对两种硬质沥青进行混合料设计与性能分析。按照我国现行规范要求,对两种沥青进行全指标检测评价;采用马歇尔设计方法对两种沥青进行悬浮密实型沥青混合料AC-20C级配设计与优化,确定沥青混合料级配曲线与最佳沥青含量;对两种沥青混合料进行性能验证,性能验证包括抗渗性能、高温稳定性、水稳定性、-10℃低温抗弯性能;并具体对比分析每种沥青的路用性能效果。     

基于CAVF级配设计方法的环氧沥青混合料路用性能研究

为研究环氧沥青混合料耐久性不足、易脆裂等问题,优化其路用性能质量,采用CAVF级配设计方法和常规马歇尔方法进行了环氧沥青混合料高温稳定性试验、低温抗裂性试验、低温蠕变试验及水稳定性试验;通过调整级配、环氧沥青类型和温度等因素对其进行研究分析。结果显示:CAVF级配显著改善了环氧沥青混合料的高温力学稳定性和抗车辙能力,并且降低了温度对环氧沥青混合料高温力学强度的劣化作用;低温弯曲试验发现环氧沥青混合料具有较强的温度敏感性(与普通沥青混合料相比),最大弯拉应变值随温度的降低呈线性下降趋势,采用CAVF级配在一定程度上能够弥补温度对其的劣化作用;水稳定性试验显示随试验浸泡时间的延长和循环次数的增加,其高温水稳定性能和低温水稳定性能均出现显著劣化作用,这与低温蠕变应变变形影响规律相同。汇总研究成果,表明CAVF级配较适用于环氧沥青混合料,能够降低或避免常规级配设计方法出现的缺陷性问题,可为实体工程应用提供技术支持。     

SMA的施工控制与监理措施

改性沥青是加入外掺剂的沥青或沥青混合料,某一方面的性能够得到改善的。沥青玛蹄脂碎石混合料是一种由沥青、纤维稳定剂、矿粉及少量的细集料组成的沥青马蹄脂,填充间断级配的粗集料骨架问隙而形成的密实结构混合料。通过使用情况发现,SMA路面结构不仅在高温、重载时车辙变形量小,而且在低温时性能良好。本文通过介绍某市政工程改性沥青路面的施工及监理,探讨其具体施工控制及监理措施。     

岩沥青对沥青混合料路用性能的研究

文章针对国产岩沥青的特性,对不同掺量的岩沥青改性沥青混合料和复合改性沥青混合料SMA-10的水稳定性,高温稳定性和低温抗裂性分别进行室内对比试验研究。结果表明,随着岩沥青掺量的增加,岩沥青改性混合料和复合改性沥青混合料的水稳定性,高温稳定性和低温抗裂性等路用性能改善明显,其中,以岩沥青掺量为沥青混合料质量的4%时,综合路用性能改善效果最好。     

柔性基层沥青路面车辙性能的影响因素

为解决柔性基层沥青路面车辙问题,采用室内试验和数值模拟对柔性基层沥青路面车辙性能的影响因素进行了研究。结果表明,空隙率是影响柔性基层沥青混合料抗车辙能力最关键的因素,宜为4%左右;级配形成骨架嵌挤结构能明显提高柔性基层混和料的抗车辙能力,但级配不宜太粗;对SBS改性沥青,可根据基质沥青的高温性能指标来选择改性沥青;温度、荷载、行车速度对柔性基层沥青路面车辙性能有显著影响。     

浇注式沥青混凝土现状与发展

为进一步确定浇注式沥青混凝土科学合理的性能评价指标及要求,全面梳理了国内外浇注式沥青混凝土相关规范,对比评价了不同规范中的技术指标要求及级配范围,系统地调查了大量实体工程及研究动态,厘定了浇注式沥青混凝土钢桥面铺装结构层组合、原材料类型和技术指标要求及级配类型,为浇注式沥青混凝土规范完善与质量控制奠定了基础.结果表明:推荐钢桥面铺装结构层组合为30~35 mm GA-10+35~40 mm SMA-10,GA基础沥青为SBS改性沥青+TLA(15%~30%),采用2%降粘剂;推荐性能评价指标要求范围为油石比7.9%~8.5%、流动度10~17 s、贯入度1.4~2.5 mm、贯入度增量不超过0.25 mm、弯拉应变不小于7 000με、动稳定度不小于1 000次/mm(参考指标);疲劳性能试验以控制应变模式进行,结果以实测为准.     

Reconsideration of the fatigue tests for asphalt mixtures and binders containing high percentage RAP

When applying reclaimed asphalt technology in a flexible pavement project, most performance concerns are related to low temperature and fatigue cracking since the stiffness of the HMA mixture could dramatically increase through adding a high percentage of reclaimed asphalt pavement (RAP) material. The purpose of this study is to evaluate asphalt mixtures with high RAP contents, prepared using two RAP addition methods, for their performance based on fatigue-cracking resistance rather than relying on volumetric properties. Asphalt mixture samples were prepared with three RAP binder content replacement percentages (30, 40 and 50%) using two preparation methods: the as-is RAP gradation (traditional method) and the splitting of the RAP gradation into coarse and fine fractions (fractionated method). Asphalt mixture beam fatigue and binder fatigue time-sweep tests were performed. Beam fatigue samples also underwent freeze–thaw cycling for freeze–thaw damage evaluation. Rather than basing the performance based solely on S–N_f curves to illustrate the fatigue performance, the beam fatigue test data was analysed through a dissipated energy approach. Faster fatigue degradation was observed for the 40% RAP binder and beam mixture when subjected to repeated loading. From a morphology aspect, this can be explained by the binder’s phase separation and physical hardening effects.     

The use of asphalt low shear viscosity to predict permanent deformation performance of asphalt concrete

The permanent deformation performance of asphalt concrete is strongly dependent on the rheological properties of the asphalt binder. It has been recognized that the asphalt’s low shear viscosity (LSV) characterizes the mixture’s rutting resistance. At the same time, the pavement temperature is one of the main factors that significantly affect the mixture performance. In this work the rutting performance of mixtures prepared with the same aggregate gradation and different binders [conventional (C), multigrade (M) and polymer modified (PM) asphalts] were evaluated by using wheel tracking tests (WTT) performed at 50, 60, 70 and 80°C; in parallel, the LSV of asphalts were measured at the same temperatures. The relationship between the asphalt’s LSV and rutting, to predict asphalt mixture performance, was discussed and a criterion to consider the effect of LSV is proposed.     

基于非线性疲劳损伤的沥青路面轴载换算

为了建立沥青混合料的非线性疲劳损伤演化方程, 同时为完善沥青路面的轴载换算方法, 首先进行沥青混合料的配合比设计, 确定矿料级配及最佳油石比, 然后从损伤力学基本理论出发, 定义模量衰减为其疲劳损伤参量, 由此推导得到了疲劳损伤方程, 并以此方程对小梁直接拉伸疲劳试验结果进行拟合, 得到了模型参数和损伤随应力比的变化规律, 建立了沥青路面轴载换算新方法。结果表明:沥青混合料的疲劳损伤演化具有明显的非线性, 用Miner线性疲劳损伤理论来描述沥青路面疲劳损伤演化过程不合适, 由此推导得到的轴载换算方法偏不安全, 建立在非线性疲劳损伤演化基础上的轴载换算方法考虑了加载历史和损伤历史的影响。     

新型硅藻土改性剂对沥青混合料路用性能的影响

本文研究了复合型硅藻土改性剂的特点及其改性沥青混合料的路用性能,并从各项技术性能上进行了分析研究,结果发现该复合型硅藻土改性剂对沥青混合料的高温稳定性、疲劳耐久性与水稳定性均有不同程度的改善,结果表明复合型硅藻土改性沥青混合料有着较好的应用发展前景.     

Wheel tracking rutting performance estimation based on bitumen Low Shear Viscosity (LSV), loading and temperature conditions

The development of new technologies and road pavement materials require the evaluation of the asphalt mixture performance. Rutting is one of the main modes of failure of asphalt mixtures; it is typically studied at the laboratory through the wheel tracking test (WTT). Weather and traffic conditions (temperature, loads) significantly affect the pavement rutting performance. The bitumen rheological properties also have a main role in mixture rutting response; they can adequately characterized by the bitumen Low Shear Viscosity (LSV). The estimation of rutting performance appears as a useful decision tool to optimize pavement design process. This paper studies the rutting performance of asphalts mixtures utilising the WTT. The specimens were tested at different temperatures and loading levels to simulate different climatic and traffic pavement conditions. A performance estimator was developed including temperature and traffic load on the pavement, and LSV of the binder as input data.     

Experimental investigation of basic oxygen furnace slag used as aggregate in asphalt mixture

Chinese researchers have commenced a great deal of researches on the development of application fields of basic oxygen steel making furnace slag (BOF slag) for many years. Lots of new applications and properties have been found, but few of them in asphalt mixture of road construction engineering. This paper discussed the feasibility of BOF steel slag used as aggregate in asphalt pavement by two points of view including BOF steel slag's physical and micro-properties as well as steel slag asphalt materials and pavement performances. For the former part, this paper mainly concerned the mechanochemistry and physical changes of the steel slag and studied it by performing XRD, SEM, TG and mercury porosimeter analysis and testing method. In the second part, this paper intended to use BOF steel slag as raw material, and design steel slag SMA mixture. By using traditional rutting test, soak wheel track and modified Lottman test, the high temperature stability and water resistance ability were tested. Single axes compression test and indirect tensile test were performed to evaluate the low temperature crack resistance performance and fatigue characteristic. Simultaneously, by observing steel slag SMA pavement which was paved successfully. A follow-up study to evaluate the performance of the experimental pavement confirmed that the experimental pavement was comparable with conventional asphalt pavement, even superior to the later in some aspects. All of above test results and analysis had only one main purpose that this paper validated the opinion that using BOF slag in asphalt concrete is feasible. So this paper suggested that treated and tested steel slag should be used in a more extensive range, especially in asphalt mixture paving projects in such an abundant steel slag resource region.     

Effect of crumb rubber gradation on a rubberized cold recycled mixture for road pavements

Cold recycling technique represents the most environmental friendly solution for pavement rehabilitation nowadays. In fact, this technique allows the use of the highest percentage of reclaimed asphalt avoiding the energy consumption related to aggregates heating required by the traditional hot mix asphalt design. The mix design represents a key phase of the cold mix production. The study of workability and compactability properties combined with a deep laboratory investigation is required. The idea of introducing crumb rubber in the cold mixtures was developed based on the concept of maximizing the valorization of recycled materials together with the goal of achieving high performance. In the present research project, two different gradations of crumb rubber, processed with the traditional grading method, have been adopted for the production of a cold recycled mixture stabilized with bitumen emulsion and cement. The spring-back effects of the rubber particles, which occur after compaction, together with the Indirect Tensile Strength and the Indirect Tensile Stiffness Modulus have been studied. The results show that the gradation of the adopted crumb rubber sensibly affects the compaction and mechanical properties of the cold recycled mixture.