The Effects of Road and Other Pavement Materials on Urban Heat Island (A Case Study of Port Harcourt City)

Urban centers are consistently exhibiting higher temperature than its surrounding suburban rural areas. The large amount of heat generated from urban structures such as road materials and pavement materials and other anthropogenic heat sources are the main causes of Urban Heat Island (UHI). The sources of data for this research included primary and secondary sources. Other techniques employed for data collection were direct measurement and readings on the road and pavement materials. The research found out that, there was consistency in rising temperature at different time of the day by the different road and pavement materials. Asphalt has the greatest effect of increasing the urban temperature four degrees higher, followed by concrete, three degree rise in temperature, and earth (ordinary ground) by two degree rise and vegetation (grass) by one degree rise in temperature. The overall effect on the residents of the study area ranges from increase in hotness of the day;44.6% respondents agrees;while 34.3% says it affects the ambient air quality of the area, and other effects such as increased ground level ozone, suffocation, sleeplessness and restlessness as a result of excessive high temperature especially at night are identified in this paper. The research recommends the review or redesigning of the entire Port Harcourt city Master Plan to make provision for creation of more green areas rather than pavements and concreted areas to reduce the effects of (UHI) and ultimately improve the comfort and living conditions of the people in a the garden city Port Harcourt.

Evaluation and Selection of Sealants and Fillers Using Principal Component Analysis for Cracks in Asphalt Concrete Pavements

The objective of this paper was to develop a comprehensive evaluation method and index to evaluate the performance of sealants and fillers for cracks in asphalt concrete pavements using the method of principal component analysis. The performance experiments including cone penetration, softening point, flow, resilience and tension at low temperature respectively were conducted by reference of ASTM D5329 for eight sealants and fillers often used in China. There by a principal component model was developed and weight of every index was calculated. The experimental results show that there are significantly different performances for sealants and fillers often used in China. Principal component analysis is an objective method that evaluates and selects the performance of sealants and fillers for cracks in asphalt concrete pavements.

Solution of pavement temperature field in“Environment-Surface”system through Green's function

In order to simplify the boundary conditions of pavement temperature field,the "Environment-Surface" system which considered the natural environment and pavement surface was established.Based on this system,the partial differential equations of the one-dimensional heat conduction in the pavement were established on the basis of the heat transfer theory.Furthermore,the function forms of the initial and boundary conditions of the equations were created through the field experiments.The general solution of the pavement one-dimensional heat conduction partial differential equations was acquired by using Green's function,and the explicit expression of pavement temperature field under specific constraint conditions was derived.For the purpose of analysis,the pavement temperatures in different seasons were calculated using the explicit expression of pavement temperature field,and the calculation accuracy was analyzed through the comparison between measured and calculated values.Then,the relationship between fitting accuracy and calculation accuracy of pavement temperatures was analyzed.The analysis results show that: the usage of "Environment-Surface" system simplifies the calculation of pavement temperature field; the relative error between calculated and measured values is generally less than 7% and is seldom influenced by seasons; there is a positive correlation between the calculation accuracy and the fitting accuracy of pavement surface temperature; high fitting accuracy would result in less error of pavement temperature prediction.

Advances and development trends in eco-friendly pavements

The major contemporary in road pavement engineering is related to the creation of green and sustainable infrastructures,e.g.,reduction of environmental impacts,increase in traffic safety,and transportation efficiency,etc.This review presents the recent trends in research and the technical solutions developed so far to address these challenges.After the analysis of research status in the past decades,a novel technology system of eco-friendly pavements is proposed considering two solutions,materials modification and structure improvement.The construction of an eco-friendly pavement can be achieved thanks to several different technologies ensuring permeable,noise-reducing,self-luminous,and exhaust-decomposing properties as well as apporting lower heat absorbing and enhanced anti-/de-icing characteristics.A systematic review of these technologies is presented pivoting on four main aspects:technical principle,material and structural composition,performance evaluation,and engineering application.The current trend in road engineering is combining the pavement infrastructure with various eco-friendly functions,e.g.,water permeability,noise reduction,low heat absorption,exhaust gas decomposition,and anti-/de-icing.Finally,the review lists the drawbacks of the existing technologies,including high cost,single function,etc.,and depicts the future developing direction and architecture of the next generation of eco-friendly pavements in which the road infrastructure should have more environmentally friendly functions than the existing technology.

Optimizing the bituminous pavement constructions with waste plastic materials improved the road constructions performance and their future applications

The yearly production of plastic garbage is rising in the current environment as a result of the fast population rise.Recycling and reusing plastic trash is essential for sustainable development.The need of the hour is to utilize waste polythene for various supporting reasons since it is not biodegradable.These materials are made of polymers like polyethylene,polypropylene,and polystyrene.Due to the enhanced performance and elimination of the environmental issue,adding plastic waste to flexible pavement has emerged as a desirable choice.A composite material known as bituminous concrete(BC)is often utilized in construction projects such as road paving,airport terminals,and stopover areas.It includes mineral aggregate and black top or bitumen,which are combined,laid down in layers,and then compacted.The bituminous mixture in this research article was combined with plastic to use a chemical stabilizer.The ideal bitumen content is replaced by 0,15%,27%,and 36%plastic,as well as the bitumen’s weight,stability,and Marshall value to create hypothermal.A linear scale is used to compare the flow rates to the bituminous mixture.The characterization of plastics contains bituminous materials are done by the SEM-EDX,XRD,FTIR and BET analysis.There have been several studies on the addition of trash to bituminous mixes,but this one is focused on the use of plastic waste as a modification in a bitumen binder for flexible pavement.According to research,bituminous mixes containing up to 4 percent plastic waste are excellent for sustainable development.

聚氨酯改性乳化沥青冷拌重复再生集料路面修补料的试验研究

本文利用聚氨酯改性沥青技术和水泥浆处理技术弥补第二次重复再生集料的缺陷,将其再配制成冷拌重复再生集料路面修补料。通过黏附性试验、贯入试验、黏聚性试验、车辙试验、浸水马歇尔试验和冻融劈裂试验,分析了冷拌重复再生集料路面修补料的施工性能、早期强度、成型强度、高温稳定性、水稳定性等路用性能,研究结果显示聚氨酯改性乳化沥青冷拌重复再生集料路面修补料的各项性能均优于乳化沥青冷拌重复再生集料混合料,与聚氨酯改性乳化沥青冷拌天然集料混合料相差不大,缩短了路面修补后的养生时间,在实现建筑废弃物资源化利用的同时落实了“双碳”行动。

Review on evolution and evaluation of asphalt pavement structures and materials

The purpose of this study was to summarize the wide-range literatures on asphalt pavements, explore the evolution of road pavements, analyze typical asphalt pavement structures, highlight current trends in research and industry, and to recommend future areas of research and development. In this research, road pavement evolution was explored from the earliest roads to the modern pavements. A new method was recommended to categorize asphalt pavement materials into the three large families which may be further sub-divided according to their mechanical parameters. A unified asphalt pavement classification(UAPC) method was proposed and the worldwide asphalt pavements could be divided into six types through the new method. Based o n the UAPC method, 1087 asphalt pavement structures were classified and analyzed to explore the asphalt thickness variation. In order to evaluate asphalt pavement performance, the Chinese design specification was employed for analyzing lives of 29 high-volume pavements and 28 low-volume pavements. Through this research, it was found that:(1) in the past 100 years, asphalt pavement materials and structures had been becoming more and more strong;(2) asphalt layer thicknesses were various from 5 to 60 cm and the overall pavement thicknesses were various from 28 to 160 cm;(3) the long-life pavements in the other countries may become"shorter-life" pavements according to the prediction based on the Chinese specification.

刚柔复合式路面结构与材料及发展趋势

刚柔复合式路面作为一种耐久性路面结构,广泛应用于重载交通、特殊地质条件、桥隧铺装等工程。为进一步推动耐久性刚柔复合式路面的应用,明确研究中的关键问题及发展方向,该文综述了国内外刚柔复合式路面的相关研究进展。在梳理刚柔复合式路面结构设计理论及施工技术的基础上,首先阐述了刚柔复合式路面的结构力学行为特征,分析了沥青面层和刚性基层的荷载应力、温度应力及其交互影响,刚性基层上的沥青面层一方面直接承受荷载和环境作用,另一方面可以改善下卧结构层的应力场和温度场,是影响刚柔复合式路面服役性能及使用寿命的关键;明确了刚柔复合式路面的病害主要出现在沥青面层,由于沥青面层与刚性基层之间的模量差异巨大,刚性基层上的沥青面层更倾向于产生压剪破坏,刚性基层的开裂以及刚‒柔层间的结合状态对沥青路面的性能也有着显著影响;最后,分别从沥青面层抗剪、基层板整体性、刚‒柔层间结合3个方面归纳了刚柔复合式路面性能的提升技术。基于刚柔复合式路面的结构力学特性,开展结构‒高性能材料一体化设计是提升刚柔复合式路面使用性能和耐久性的有效途径。

基于微波加热的沥青混合料自愈合性能研究

微波加热作为一种全新的体积加热形式,因其快速、均匀和节能的加热特性,已广泛应用于食品、陶瓷等行业,但在道路早期养护领域尚处于探索研究阶段。本研究归纳了基于微波加热的沥青混合料自愈合性能研究进展,针对沥青材料自愈合理论、微波加热机理、微波加热材料、微波加热沥青混合料自愈合影响因素等方面研究现状进行了总结。综述分析表明:由于沥青成分、微观结构以及复杂的相互作用,沥青材料的愈合机制尚未完全清楚,但裂缝表面分子扩散理论、裂缝表面能理论和毛细流动理论在一定的限定条件下能够很好地表征沥青材料的自愈合特性;微波加热是一种高效、环保的沥青混合料自愈合热诱导形式,通过掺入钢屑、钢渣、炭黑、铁素体颗粒等微波加热材料,可提高沥青混合料的自愈合性能;沥青混合料的自愈合性能受到微波特性、沥青性能及沥青混合料类型、外部环境等因素的共同影响,外部环境对沥青混合料自愈合性能的影响最为显著,当超过最佳加热时间、含水率过高、损伤程度较大时,沥青混合料的自愈合性能显著下降。最后,从实际工程的角度,分析了微波加热沥青混合料自愈合性能工程应用面临的问题,并展望了其应用前景。

水泥稳定碎石拉压不同力学特性研究

为解决现行路面结构设计参数及其取值与材料实际力学特性不匹配的问题,选取典型水泥稳定碎石开展了不同水泥剂量与加载速度下的单轴压缩及直接拉伸试验,研究了其应力应变特性,并分析了压拉强度、模量及泊松比的变化规律及其相互关系,揭示了水泥稳定碎石的拉压不同力学特性.结果表明:水泥稳定碎石拉压受力状态下的应力应变性质符合双模量理论的双线性特征,2%~3%水泥剂量范围为水泥稳定碎石力学本质特性发生变化的过渡区;水泥稳定碎石的拉压力学参数与加载速度和水泥剂量均呈良好的非线性变化关系;就影响因素而言,水泥剂量对材料拉压参数的影响程度远大于加载速度;就力学参数而言,模量受水泥剂量和加载速度的影响最大,其次为强度,最后为泊松比,且相较于抗压,抗拉力学参数受这2种因素的影响更为显著;压拉模量比及压拉泊松比的比值受加载速度和水泥剂量的影响较小,压拉强度比随水泥剂量的增大而逐渐减小,当水泥剂量超过3%时,压拉强度比趋于稳定,据此建立了水泥稳定碎石的拉压力学参数量化取值模型.研究结果可为基于双模量理论的路面结构设计参数取值提供依据.

基于振动传递率函数的水泥混凝土铺面脱空识别方法

为提高水泥混凝土铺面脱空识别的准确性和便捷性,提出一种基于振动传递率函数的板底脱空识别方法。首先,建立了九块板全尺寸铺面结构三维有限元模型,获取冲击荷载作用下铺面板的多点加速度响应;其次,在2个振动传递方向上,分别计算相邻2个测点间的振动传递率函数,分析特定频段内传递率函数的差异,并提出传递率损伤指标(transmissibility-damage indicator,TDI)及其矩阵表达式;最后,计算分析11种不同脱空形式、程度下TDI矩阵的差异,并分析测点布设方式、信号噪声水平对TDI矩阵的影响。结果表明:该脱空判定指标能较好识别定位板角和板边局部脱空。所得TDI矩阵在板角脱空的2个传递方向均十分显著,在板边脱空的垂直脱空边方向较为显著;对于板中脱空,2个传递方向上的TDI矩阵均无法有效识别。板中脱空的分布与TDI矩阵的分布一致性较差;对于多区域脱空,其计算得到的TDI矩阵与单区域脱空类似,对于板角和板边局部脱空均能有效识别;测点布设越密,TDI矩阵的分布与脱空分布的一致性越高。然而,该识别方法对噪声水平较为敏感,噪声水平越高,识别精度越低,需要较高精度的传感器或设备予以支撑。

沥青路面用复合相变材料研究进展

为缓解夏季热岛效应和减少路面病害,“凉爽路面”已从概念得到落实,其中相变材料因其自动控温的特性受到了道路工程研究人员青睐。介绍了相变材料的分类及其特点,概述了路面传热机理模型和影响因素。针对直掺相变沥青性能劣化的问题,提出了复合相变材料技术并展开介绍其应用效果。还总结归纳了相变改性沥青控温效果测试方法的优缺点,综述了复合相变材料对沥青及沥青混合料的降温效果和性能影响,最后指出了当前路用相变材料应深入研究的方向,并对复合相变材料泄漏问题提出了改进方法与展望。

考虑正交异性的粒料压实特性及其结构力学行为研究

粒料的正交异性与其压实过程密切相关,对路面的结构力学行为具有显著影响。为研究压实过程对粒料正交异性的影响,采用不同的压实方式及压实功对路用粒料进行击实成型,开展改进的动态回弹力学试验研究,得到典型粒料的正交异性系数α^(2);采用有限元方法,开展考虑粒料正交异性的沥青路面结构力学分析。结果表明:对于旋转压实成型的试件,其干密度略大于冲击压实成型;增大压实功,在增加粒料干密度的同时也会增加其正交异性;在低压实功下,旋转压实成型的粒料正交异性更显著,但在高压实功下,冲击压实成型的正交异性更加显著;粒料的正交异性对沥青路面结构关键响应具有显著影响,忽略粒料的正交异性,存在低估路面结构损坏的风险;考虑粒料的正交异性,能够改善路面结构计算中粒料层的底部受拉,且更符合实际情况。

铁尾矿在沥青路面中的资源化利用研究进展与展望

铁尾矿的大量堆积,不仅浪费了宝贵的土地资源,还造成了严重的环境污染,与此同时,沥青路面建设需消耗大量天然资源,铁尾矿在沥青路面中的资源化利用可有效缓解这一矛盾。本文概述了不同地区的铁尾矿的物理化学特性及环境安全性,总结归纳了铁尾矿在沥青面层的路用性能、界面黏附性能以及微波加热自愈合性能方面的研究进展及难点,分析提炼了铁尾矿作为路面基层集料及补充胶凝材料的研究现状及关键技术,详细阐述了基于水化反应和聚合反应制备的铁尾矿基胶凝材料的活化工艺及反应机理,最后指出了铁尾矿在沥青路面应用中存在的问题及未来应深入研究的方向。

PEG/漂珠复合相变材料的表征及性能研究

为了研发适用于高温环境下沥青路面的复合相变材料,本研究以PEG2000作为相变材料,漂珠作为载体,利用PEG2000优良的相变特性及漂珠的高强度特性,制备出一种高强度且耐高温的复合相变材料(composite phase change materials,CPCMs)。制备的CPCMs在相变储热性能上表现较好,同时具有优良的化学稳定性、兼容性及热稳定性。当CPCMs的掺量达到60%时,测温试件之间的最高温差仅为2.8℃,峰值温度出现的时间延迟了2.1 min,对路用性能也产生了不利影响。因此,适量CPCMs能够有效调控沥青混合料温度。该研究结果为沥青路面的降温调控提供了参考。

相变材料在冬季沥青路面中的应用分析

沥青路面在冬季低温雨雪气候下易发生结霜、结冰现象,致使路面抗滑性能降低,从而导致事故发生率上升,给行车安全及路面使用性能带来严重影响。传统的被动式除雪法效率低,且须占用行车道影响道路正常运行,化学融雪剂还会造成土壤和水污染。本文通过文献调研,总结常见的主动融雪化冰路面类型,分析相变材料在沥青路面中的应用研究重点,提出将相变材料掺入沥青路面中,以预防或减少冬季沥青路面冰冻病害。

一种新型环氧乳化沥青桥面防水材料制备及粘附性能试验

针对传统桥梁防水粘接层材料存在粘接强度不足,温度敏感性大的问题,提出一种新型环氧乳化沥青防水材料的制备,并对环氧乳化沥青的应用性能进行分析。试验结果表明,当固化剂用量为水性环氧树脂的50%,水性环氧树脂用量为15%时,制备的水性乳化沥青性能最优。该环氧沥青在160℃的高温条件下也不出现流淌和滑动;在-15℃下冷冻2 h后,不出现开裂;附着力为1.15 MPa;耐碱性和耐盐性均满足防水粘接层材料要求;渗水试验后也不出现透水现象,表现出良好的综合性能。

水性环氧树脂修复材料路用性能研究

为提高路面坑槽修复材料早期强度和稳定性,本文提出了一种冷拌冷铺型水性环氧树脂基(EAC)复合快速修复材料,通过劈裂试验、车辙试验、小梁弯曲试验及浸水马歇尔试验评价了EAC材料的路用性能。结果表明:相对于传统热拌沥青混合料,EAC材料耐高温性能及水稳定性得到了较大的提升,但低温性能略差;与冷再生修复材料相比,EAC材料的力学性质及适用性有所提升。

全地面起重机用工程机械轮胎不同特征路面力学性能分析

建立了全地面起重机用385/95R25工程机械轮胎带花纹轮胎有限元模型,在验证了模型准确性的基础上分析轮胎在不同特征路面(平面路、横向凸台和纵向凸台)上的力学性能。轮胎充气外缘尺寸和接地数据有限元仿真结果与实测结果一致,表明有限元模型准确、可靠。有限元仿真结果表明:胎肩部位的应力集中于2^(#)带束层端点,应变极值也在此处,横向凸台条件下应力和应变较大;横向凸台条件下,1^(#)带束层帘线张力明显增大,胎体帘线张力在凸台接触区域减小;纵向凸台条件下,1^(#)带束层端点近纵向凸台的接触区域的帘线张力增大,胎体帘线张力变化不大;轮胎的包络刚度约为3000 N·mm^(-1);轮胎在破坏案例中的极限撕裂能为672 J,撕裂能指标对于配方设计有重要的参考意义。

RAP精细分离效果评价及其再生沥青混合料性能研究

采用精细分离技术对沥青混合料回收料(RAP)进行处理,可减小RAP的变异性,提高再生沥青混合料的路用性能。通过对不同工艺处理的精细分离RAP试验,分析了精细分离RAP的矿料级配、沥青含量变化规律及变异性。采用精细分离RAP制备再生沥青混合料,研究分析了精细分离工艺对再生沥青混合料路用性能的影响。结果表明:未经过精细分离的RAP,矿料级配、沥青含量变异性较大;精细分离后的RAP,矿料级配、沥青含量的变异性明显减小,提升了RAP的稳定性;精细分离工艺有利于提升再生沥青混合料的路用性能,尤其是动稳定性和最大弯拉应变;精细分离有利于提高RAP在再生沥青混合料中的掺量,保证再生沥青混合料的质量,提升RAP在沥青路面中再生利用水平。