关于后置发动机式沥青洒布车几个重要技术参数的确定

本分析和讨论后置发动机式沥青洒布车的动力、沥青泵的匹配以及洒布精度、喷洒压力、洒布量等有关重要技术参数的确定，以期对设计和使用提供帮助。     

沥青洒布车作业时洒布高度的探讨

通过理论计算分析,指出了沥青洒布车作业时洒布高度对多重叠洒布效果的影响,阐述了既有计算公式的错误之处,并推导出了正确的计算公式,据此可以对沥青喷洒系统设计及洒布车施工作业参数设定提供参考.     

多重叠洒布对沥青洒布精度的影响分析

运用概率统计理论及试验方法，研究沥青洒布时多重叠洒布的形成原因以及对沥青洒布精度及均匀性的影响，分析影响多重叠洒布质量的各个因素，包括喷嘴距地高度、喷嘴间距、喷洒扇面角度和喷嘴安装角等，提出合理的重叠洒布次数以及提高多重叠洒布质量的方法。设计沥青洒布系统的样机，并进行现场试验。测试结果表明，采用多重叠洒布时的沥青洒布精度明显高于无重叠时的沥青洒布精度。     

美国centennial沥青洒布车

为提高沥青路面的洒布质量，我们利用世界银行贷款购置了一台美国centennial沥青洒布车，通过洒布乳化沥青、改性乳化沥青和钢桥面粘接用改性沥青，洒布质量和洒布效率都十分理想。本文着重分析该沥青洒布车的工作原理。     

三层搭接多级定量沥青洒布车设计要点

随着交通运输事业的发展,公路建筑的铺筑里程在不断的增加,其中为适应我国国情的需要,黑色路面的铺筑量的增大更为突出,为此沥青洒布车也得到了较快的发展,且在自行式沥青洒布车中多属三层搭接洒布。本文对三层搭接多级定量沥青洒布车的设计主要问题加以论述,并介绍如何正确选用国产汽车底盘。     

机械式沥青洒布车作业性能的分析

机械式沥青洒布车工作装置是取力器从汽车变速器取力，通过传动轴驱动沥青泵，本实现沥青洒布的，它具有结构简单，操作维修方便，价格便宜等优点，为此本文对其机械式沥青洒布车的几个主要作业性能参数进行分析，并介绍两种新型沥青洒布车。     

同步碎石封层最佳沥青洒布量室内测评方法的初步探索

选用橡胶沥青和SBS改性沥青作为黏结剂，用4.75～9.5mm和9.5～13.2mm的碎石作为封层集料，通过同步碎石封层室内湿轮磨耗试验评价同步碎石的最佳沥青洒布量，得出洁净碎石预拌料的最佳沥青裹覆量为4‰，4.75～9.5mm碎石的最佳沥青洒布量在1.3kg/m2左右，9.5～13.2mm碎石的最佳沥青洒布量为在1.9kg/m2左右，且改性沥青比橡胶沥青最佳用油量略大，沥青预拌碎石比普通加热碎石黏附性更好。     

沥青洒布车多重叠洒布的参数分析

当前，多数沥青洒布车能够基本满足洒布量的精度要求，但是对沥青洒布的均匀性控制不好，洒布层常常出现纵向条纹(即明显的横向不均匀)。这种现象通常是由于喷嘴未被调整到适当的角度，喷洒管未设置在合适的高度，沥青喷洒的压力不一致或压力不足等原因造成，通过对沥青洒布车多重叠洒布的参数进行分析与计算，得出了实现多重叠洒布的条件。     

超薄磨耗层Novachip沥青混合料设计方法研究

针对超薄磨耗层Novachip沥青混合料与普通沥青混合料界面粘结力的问题以及粘层油的洒布量的问题,试验选用Nova Bond作为粘结材料,进行了相关室内试验,分析了Novachip混合料空隙率、粘层油洒布量、冻融循环对界面粘结力的影响;新旧路面粘层油洒布量与剪切强度的关系。发现Novachip沥青混合料空隙率、粘层油洒布量、原路面状况对界面剪切强度具有显著的影响,针对Novachip沥青混合料设计方法提出了一些参数和建议。     

基于DSP的沥青洒布量控制系统设计

介绍同步碎石封层车沥青洒布量的控制原理,选用DSP2000系列的TMs320LF2407作为主控制器,对沥青洒布量控制系统进行硬件、软件设计.将所设计的控制系统安装在同步碎石封层车上,进行现场空载试验,试验结果表明沥青泵转速在100-700r/min时,实际转速与理论转速的偏差范围为±1%,沥青洒布量精度可控制在±2%以内,达到设计要求.     

洒布车沥青泵流量的计算方法

准确地计算沥青泵流量是提高沥青洒布车作业质量的关键步骤。对沥青泵转速和流量的检测试验数据进行拟合处理。传统的计算方法，将沥青泵的实际容积效率看作常量，其计算所得沥青泵流量的绝对误差大于6L／min，相对误差大于23％。提出基于绝对误差和相对误差的沥青泵流量二元最小二乘线性拟合方法，并分别进行计算，结果表明：基于绝对误差的拟合方法所得沥青泵流量计算精度较传统方法有很大提高，但仍不理想，而利用基于相对误差的拟合方法所得相对误差的最大值较基于绝对误差的回归方法几乎减少了一半，仅为5．66％，是具有较高合理的计算精度的方法。     

基于动态老化过程的沥青抗老化性能对比研究

旨在运用动态表征模型评价沥青的老化过程,并采用多指标评价方法对比不同沥青的优劣。对4种沥青进行不同时间的RTFOT老化试验,采用动态表征模型拟合,得到沥青针入度、延度、软化点和粘度的老化参数和老化方程;采用灰色关联决策评价方法,以沥青针入度、延度、软化点和粘度的老化参数L和r为评价指标,综合对比不同沥青的抗老化性能。研究结果表明：沥青针入度、软化点、延度和粘度与老化时间存在非线性关系,在开始时刻,老化速率大,后期随着时间的推移,老化速率趋于缓慢,最后达到平衡;沥青的老化过程可用动态模型表征,参数L和r能很好地表征沥青老化过程的老化度和老化速率,不同沥青的不同指标的老化参数排序不一致;采用灰色关联决策评价四种沥青的抗老化性能排序为：室内制备改性沥青优于90号A级基质沥青优于成品改性沥青优于70号A级基质沥青。     

Investigation into the properties of asphalt mixtures containing magnesium hydroxide flame retardant

In this study, horizontal burning, limiting oxygen index (LOI) and direct burning tests were conducted to evaluate the effects of magnesium hydroxide (MH) on flame retardancy for asphalt. The influence of MH on the mechanical properties of the asphalt mixtures was also evaluated using a Marshall stability test and an indirect tensile strength test. The results indicate that MH improves the thermal stability of asphalt. The presence of MH reduces the horizontal burning classification of asphalt from FH-3 to FH-1, and the LOI is also increased. Reductions in the average burning time and mass loss were observed. The volume of flammable volatiles released from asphalt was reduced. By replacing some of the mineral filler in asphalt with equal quantities of MH, the Marshall stability was increased, its loss decreased. Similarly, the indirect tensile strength (ITS) was increased, but the ITS loss increased slightly. It is concluded that MH can be used as flame retardant for asphalt mixtures without significantly reducing the original pavement performance. This may provide a novel and safer road material, especially for use in tunnel roadways.     

橡胶沥青衬垫式碎石封层黏结性能

针对旧水泥混凝土路面加铺改造工程的层间黏结问题,选择适用于该工程的碎石封层结构,通过室内直接剪切试验对比分析了橡胶沥青衬垫式碎石封层与橡胶沥青单层碎石封层的黏结性能,利用正交试验优化了橡胶沥青衬垫式碎石封层的配合比.结果表明:单层碎石封层及衬垫式碎石封层为最佳碎石封层结构;橡胶沥青衬垫式碎石封层第1层沥青洒布量为2.4 kg/m2,第1层碎石撒布量为9 m3 /km2,第2层沥青洒布量为2.0 kg/m2,第2层碎石撒布量为12 m3/km2时,层间抗剪强度最优;橡胶沥青衬垫式碎石封层黏结性能较橡胶沥青单层碎石封层提高30％左右.     

Minimum voids in mineral aggregate in hot-mix asphalt based on asphalt film thickness

This study is aimed at determining the relationship between asphalt film thickness and aging characteristics of various hot-mix asphalt (HMA) mixtures. Resilient modulus and indirect tensile strength tests were conducted on the Superpave Gyratory-compacted specimens with five different asphalt film thicknesses in order to determine an optimum asphalt film thickness. From the relationships between the asphalt film thickness and resilient modulus and indirect tensile strength test values of the short and long-term aged samples, optimum asphalt film thickness has been determined about 9–10 μm. The minimum void content of mineral aggregate (VMA) to obtain this optimum asphalt film thickness can be calculated as 15.2%.     

邢临高速公路沥青路面透层处理技术与施工

结合工程概况,介绍了沥青路面透层的作用,并对透层沥青的选择进行了分析,着重从施工准备、喷撒透层沥青、养生几方面详细阐述了透层的施工工艺,并指出了施工应满足的几个问题,以保证施工质量。     

Effect of asphalt film thickness on the moisture sensitivity characteristics of hot-mix asphalt

Temperature, air and water are the common factors that profoundly affect the durability of asphalt concrete mixtures. In mild weather conditions, distresses such as permanent deformation, fatigue cracking can be encountered on the pavements due to traffic loading. But when a severe climate is in question, these stresses increase in poor materials; under inadequate control; with traffic as well as with water which are key elements in the degradation of asphalt concrete pavements. Many variables affect the amount of water damage in asphalt concrete layer. Among them, mixture design properties such as air void level, permeability, asphalt content and asphalt film thickness are the ones that must be investigated carefully.     

The effects of porosity,asphalt content and fiberglass incorporation on the tensile strength and resilient modulus of asphalt concrete blends

Asphalt concrete is the prevailing material used for road surface construction. Its adequate characteristics in providing stability, durability and driving safety are controlled by complex interactions between its components. Thus, it is important to estimate the sensitivity of asphalt concrete mechanical properties as a function of its volumetrics. For this study, different combinations between asphalt content (3.5, 5 and 7.5%) and porosity values (above 4%) were used in order to disassociate these properties. The influence of mixing in fiberglass (0.5%) was also analyzed. It was found that porosity is significantly more relevant than the asphalt content in the prediction of tensile strength and resilient modulus of fiber-free asphalt concretes. In fiber-reinforced mixtures, the mechanical properties are improved by increasing the asphalt content, which suggests a better bonding between fibers and aggregates. For both cases, decreasing porosity is beneficial. By grouping both sets of results, it was possible to create a unique theoretical curve for both the tensile strength (q_t) and the resilient modulus (RM). The RM/q_t ratio was 5800 for the fiber-free group, and 3900 for the fiber-reinforced group - suggesting a better fatigue life indicator for asphalt concretes when fibers are added.     

Strain distribution along geogrid-reinforced asphalt overlays under traffic loading

While there is significant field evidence of the benefits of geosynthetic-reinforced asphalt overlays, their use has focused on minimizing the development of reflective cracks. Yet, geogrids in asphalt overlays are also expected to develop reinforcement mechanisms that contribute to the pavement structural capacity. Specifically, the use of geosynthetics in asphalt overlays may also improve the mechanical behavior of paved roads by controlling permanent displacements and reducing strains in the pavement layers. While relevant advances have been made towards identifying the mechanisms in geosynthetic stabilization of base courses, such mechanisms may differ from those that develop in geosynthetic-reinforced asphalt overlays. This paper investigates the development and distribution of tensile strains along geogrids used to reinforce asphaltic layers. Experimental data was collected from large-scale paved road models subjected to the repeated loading imparted by wheel traffic. Specifically, the study examines both the elastic and permanent components of displacements induced in geogrids by using mechanical extensometers attached to the geogrids. The testing program includes a number of geosynthetic-reinforced paved road models, as well as a control (unreinforced) section that was also instrumented for comparison purposes. Asphalt strain gauges were used to measure strains within the asphalt concrete layer, providing an additional source of information that proved to be highly consistent with the results obtained from the extensometers. The experimental results showed a progressive mobilization of permanent geogrid strains that reached a final profile beyond which additional traffic loading did not result in additional straining. In comparison, higher strains developed in the unreinforced model, which showed a continuously increasing trend. Elastic tensile strains in the asphalt mixture and rutting under the wheel load were comparatively smaller when using geogrids. Overall, the results generated in this study indicate that the presence of geogrids in asphalt overlays results in a lateral restraining mechanism that influences on the mechanical behavior of flexible pavements.