回收沥青瓦在沥青路面再生应用中的研究进展

为了将建筑行业所产生的大量废旧沥青瓦材料再生应用于道路建设中,促进循环利用,阐述了利用回收沥青瓦再生沥青混合料的可行性及相应再生方法,综述了回收沥青瓦改性沥青胶结料的粘度、抗车辙和低温抗开裂等性能以及回收沥青瓦再生沥青混合料的路用性能,指出未来进一步的研究建议。现有研究表明,沥青瓦改性沥青胶结料表现出更好的抗车辙性和低温性能,且低沥青瓦含量对其低温抗裂性能并未有明显影响,沥青瓦改性后因胶结料粘度提高而出现的硬化问题可通过引入生物改性技术来消除。回收沥青瓦材料加入沥青混合料中能有效降低脆化温度,提高混合料的抗车辙性能、抗疲劳开裂性及水稳定性。采用发泡工艺和添加剂可将回收沥青瓦材料再生技术与温拌技术相结合,从而表现出良好的环境和经济效益,为我国环保型路面研究提供了参考价值。     

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。     

废旧玻璃在沥青混合料中的应用研究进展

近年我国公路建设迅速发展,2016年高速公路总里程达到13.10万公里,其中沥青路面占95%以上。沥青路面的建设使沥青和石料等自然资源大量消耗,给环境资源带来较大负担。为缓解道路建设对天然石料的消耗,国内外学者开展了固体废弃物在沥青混凝土中的回收再利用研究。与此同时,鉴于废旧玻璃的不断增多和处理方法的缺陷,寻求废旧玻璃的有效处理途径已是当务之急。利用废旧玻璃这种常见生活及工业废弃物替代部分天然石料进行沥青混凝土的制备则是有效的解决方法之一。已有研究表明,废旧玻璃破碎后具有耐磨、抗滑、反光、渗水性强等特性,替代部分集料制备废旧玻璃沥青混凝土作为面层,可一定程度改善路面耐磨、抗滑、透水等路用性能。当前,废旧玻璃在沥青混凝土中的应用面临一系列问题。废旧玻璃材料质脆,主要成分SiO2为亲水性材料,掺入后沥青混凝土的强度及耐久性受到一定程度的影响。废旧玻璃来源丰富,多为生活垃圾,其回收、筛选、破碎等处理过程复杂,在我国回收利用率较低,且道路工程中对原材料杂质含量要求较高,这就抬高了废旧玻璃回收利用的技术要求及成本。基于以上问题,研究者对废旧玻璃的工程特性和材料组成以及废旧玻璃沥青混凝土的路用性能和力学特性开展了进一步研究。研究结果表明,玻璃颗粒尺寸、掺量保持在一定范围内,在一定掺入方式下,沥青混凝土强度及路用特性均满足规范要求。加入抗剥落剂或使用改性沥青,废旧玻璃沥青混凝土的水稳定性明显提升。混合料疲劳寿命不易受废旧玻璃集料影响,在一定掺量及颗粒尺寸下,抗疲劳特性较好;蠕变特性与普通沥青混合料相似,在一定应力与温度范围内,蠕变变形小于普通沥青混合料,且可用常见流变模型来描述其永久变形特性。本文归纳总结了废旧玻璃材料作为沥青混合料集料的物理力学性能,废旧玻璃沥青混合料的材料组成设计方法,废旧玻璃对沥青混合料的路用性能和表面特性的影响规律,并展望了该领域未来的发展趋势。     

泡沫沥青路用性能试验

道路的改扩建过程中会产生大量的废旧沥青路面材料，而这些材料是可以再生利用的资源，如果废弃，不仅会造成浪费，同时也会污染环境。泡沫沥青就是一种利用新技术再生废旧资源的产物，本文通过试验，重点研究了泡沫沥青的路用性能。     

沥青再生过程中新-旧沥青界面混溶行为综述

随着公路里程的迅速增长,废旧沥青混合料(RAP)逐年增多,研究者开展了废旧沥青混合料回收技术的研究,发现随着RAP掺量的增大,再生沥青路面整体路用性能急剧下降。探讨其原因,废旧沥青混合料再生过程中,新-旧沥青局部融合。鉴于RAP不断增多,寻求RAP的有效处理途径成为当务之急,高掺量RAP对再生沥青路面路用性能的影响有待商榷。为解决一系列再生沥青路面的难题,需形成完整的新-旧沥青融合理论体系,探讨新沥青以及相容渗透剂在旧沥青中的扩散影响区域和扩散途径。迄今为止,国内外学者以宏观到微观的纵深演进思维,从宏观、细观、微观以及分子尺度分析新-旧沥青的混合效率,由部分融合的定性评价到融合程度量化分析的研究拓展,建立理论模型与评价指标。基于Fick扩散理论和分子动力学理论,运用混合效率和扩散速率等评价指标,探讨新-旧沥青融合影响因素及扩散机制。研究表明,影响新-旧沥青融合的因素有拌和温度、拌和时间以及材料参数,其中温度是主要因素。为满足再生沥青混合料的路用性能,研究者探讨施工参数(RAP掺量、拌和温度、拌和时间)与路用性能的关联性,从而提高废旧沥青混合料的回收利用效率。本文综合国内外的研究成果,介绍扩散理论与模型,归纳研究手段及对应的评价指标。试验研究方面,分析存在的问题及不足,详细介绍了分子示踪、分层抽提、凝胶渗透色谱(GPC)、傅里叶红外光谱(FTIR)以及原子力显微镜(AFM)等技术在新-旧沥青融合中的运用。鉴于目前研究现状,研究者仅在宏观层面上利用再生沥青、再生沥青混合料的流变性能以及预估性能,通过对比分析以确定混合效率存在的缺陷,故研究者常借助细微观研究手段来验证试验的可靠性,并指出了影响新-旧沥青融合程度的诸多因素。     

基于核壳结构缓释剂和抗氧化剂的新型复合沥青抗老化剂研究

我国每年的沥青路面回收料已经接近亿吨,同时回收料的使用率不断提高。沥青旧料回收利用的关键步骤是老化沥青的再生过程,而其中添加剂的选择和使用是影响再生后沥青混合料工程性质和沥青路面路用性能的关键因素。传统的沥青再生剂可以得到瞬时的沥青还原效果,但是无法延长再生后沥青的使用寿命。相较而言,用于回收沥青的长效抗老化剂是提高再生沥青路面耐久性的有效解决方案,但目前鲜有抗老化剂在沥青再生工艺中的实验室研究和实际应用。本研究探索了利用一种抗氧剂和一种缓释剂作为复合抗老化添加剂,通过实验室模拟沥青长期老化,评价其对典型回收沥青的抗氧化老化效果。选用的抗氧化剂分别为Irganox和木质素磺酸盐,同时合成的缓释剂分别为包裹食用植物油和商业再生剂油的聚苯乙烯微胶囊。未改性的基础回收沥青和四种抗氧化剂改性沥青通过压力反应釜进行60 h的长期高温高压老化,并利用动态流变剪切仪(DSR)对未改性沥青和抗老化剂改性沥青老化前后的粘度、衍生延度和SHRP流变指标进行分析。结果表明,本研究采用的四种复合抗老化剂均可以有效控制沥青老化过程中的物理性质变化。商业再生剂微胶囊和木质素磺酸钠的复合添加剂表现出最好的效果,可以减缓22.4%的沥青老化硬化速率和27%的延度下降速率,而商业再生剂微胶囊和Irganox的复合抗老化剂次之,可以减缓21.3%的沥青老化速率和19.5%的延度下降速率。相比之下,由植物油再生剂微胶囊和抗氧化剂组成的抗老化剂只减缓了10%的沥青粘度上升速率并且加快了沥青延度的下降趋势,但可以提供相对较高的车辙因子。最后,通过对沥青老化过程中红外光谱的变化研究,发现抗老化剂对羰基和亚砜产物的生成控制是抑制沥青物理老化的驱动力,四种抗老化剂均显示了瞬时的亚磺酰基氧化反应控制作用。本工作所建议的抗老化剂方案解决了以往沥青抗老化剂缺乏长效性的缺点,能够有效延长再生后沥青路面的路用寿命。同时本研究提供的复合抗老化剂组成思路可以选用其他环保材料,以帮助推广新型抗老化剂在沥青回收路面可持续再生过程中的应用。     

公路旧沥青路面材料热再生技术及机理研究

通过添加不同含量的再生剂,对公路旧沥青路面材料进行回收再生,制备了再生沥青及再生沥青混合料。研究了再生沥青混合料的毛体积相对密度、空隙率、稳定度和流值等混合料指标;分析了不同掺杂量的再生剂对回收沥青的针入度、延度和软化点的影响;并通过弯曲实验和傅里叶红外光谱研究了回收沥青的力学性能及再生机理。结果表明,掺入3%(质量分数)再生剂时,再生沥青针入度、延度和软化点分别为44(0.1 mm)、14.9 cm和54.5℃,可达到盘锦50~#沥青的标准要求,满足路面用再生沥青指标要求;添加3%(质量分数)再生剂时,再生沥青混合料的空隙率为5.9%,稳定度为13.43 kN,流值为26(0.1 mm),满足高速和一级公路对沥青的使用要求;弯曲实验表明,再生沥青混合料老化后的力学性能良好,其耐久性和普通沥青混合料没有明显区别;FT-IR分析显示,回收沥青再生前后组分大致相同,回收沥青的再生机理为再生剂中的饱和烃通过溶解和分散沥青质,改善了回收沥青的流变性能;再生剂中的芳香族化合物补充了回收沥青长时间老化过程中芳香族小分子物质的损失。     

废旧三元锂离子电池正极材料回收技术研究进展

三元锂离子电池因其性能优越,在国内外便携式电子设备和新能源汽车中得到广泛应用.随着对锂离子电池需求量的不断增大,大量的锂离子电池将迎来"退役"高峰期.为实现有价金属资源的循环利用,降低固体废物处理对环境的影响,废旧锂离子电池的回收利用受到了广泛的关注.通过对三元锂离子电池进行资源化回收利用,可以获得有价金属或直接制备电池材料.为了提高物料的有效回收率,通常采用预处理的方法来分离集流体和正极活性材料,实现物料的有效分离及进一步的后处理.然后,采用冶金处理的方法从正极活性材料中提取金属和分离杂质,其包括高温冶金和湿法冶金处理工艺.最后,结合材料合成的方法进一步制备得到电池材料或化合物.在现阶段的研究中,高温冶金过程面临着物料损耗大、能耗高、环境不友好等问题;湿法冶金过程存在酸耗大、除杂效率低、工艺流程长等问题.正极材料的再生过程、回收成本以及再合成材料的性能是限制其应用的重要因素.本文主要介绍了废旧三元锂离子电池回收过程及方法,包括预处理、高温冶金、湿法冶金、正极材料再生等,分析比较了其存在的主要问题,为废旧三元锂离子电池的资源化技术发展提供参考.最后,提出了废旧三元锂离子电池正极材料的回收应向绿色环保、短流程和低能耗的方向发展.     

水性含磷功能性聚合物的制备及应用

水性含磷功能性聚合物是一种环境友好材料,且具有阻燃、耐热、防腐、生物相容性好以及改善粘接性能等多种特性.本文介绍了水性含磷功能性聚合物的结构和制备方法,综述了其在粘合剂、涂料以及生物医用材料等方面的应用报道,并展望了其发展前景.     

公路废旧沥青混合料再生利用的探讨

本文对公路废旧沥青材料的回收再生利用做了深入的分析，在成功经验上进行了经济比较，阐述了其中的施工工艺和技术要点，供广大公路技术人员参考。     

Pavement performance evaluation of recycled styrene–butadiene–styrene-modified asphalt mixture

More and more styrene–butadiene–styrene (SBS)-modified asphalt waste materials are being discarded with the increase in road service life. The recycling of these waste pavement materials can reduce environmental pollution and help save resources. However, the low-temperature performance and the fatigue resistance of recycled asphalt mixture are significantly affected by the addition of reclaimed asphalt pavement (RAP). In order to evaluate the low-temperature performance and the fatigue resistance of recycled SBS-modified asphalt mixture, three points bending test, Fénix test and Ensayo de BArrido de DEformaciones test were conducted. Additionally, the differences of recycling between SBS-modified RAP with different ageing conditions and ordinary unmodified RAP were compared. The results showed that fatigue resistance of modified recycling of asphalt mixture with different RAPs did not vary much under low temperature (?5 °C) while displaying an obvious difference under higher temperature. SBS-modified RAP under light ageing condition was suitable for modified recycling. However, the SBS-modified asphalt from RAP under serious ageing condition would lose modification effect resulting in a great reduction of the low-temperature crack resistance and the fatigue resistance. Therefore, it is necessary to evaluate the ageing degree of RAP before recycling SBS-modified asphalt mixture. The SBS-modified RAP under serious ageing condition (SM-RAP) is not recommended for directly modified recycling. But considering for further utilisation, the SM-RAP used for unmodified recycling as ordinary unmodified RAP can be regarded as a good choice and the RAP content should be restricted to less than 30%.     

Evaluation of low temperature viscoelastic properties and fracture behavior of bio-asphalt mixtures

The overall national emphasis on sustainability in pavement construction has led to the promotion of recycled materials such as reclaimed asphalt pavement (RAP) and reclaimed asphalt shingles. In general, the inclusion of these materials has led to reduced performance at low temperatures leading to thermal cracking. Previous research by the authors showed that the application of bio-binder from swine manure could alleviate the effect of RAP while improving the overall low temperature bulk viscoelastic and fracture properties of the asphalt mixture. The current paper expands on the previous research on bio-modified asphalt mixtures by investigating three additional bio-asphalts produced by introducing wood, miscanthus and corn stover based bio-oils to a neat asphalt. These bio-asphalt mixtures were introduced in both virgin and reclaimed asphalt pavement mixtures to evaluate interaction between the bio-oils and reclaimed asphalt pavement, with a focus on properties related to low temperature pavement performance. Low temperature characterization was conducted using disk-shaped compact tension fracture (DC(T)) and indirect tension (IDT) bulk viscoelastic characterization tests. The IDT test, completed in accordance with AASHTO T-322, evaluated the creep compliance of mixtures at 0, ?12 and ?24 °C to examine the ability of the mixture to relax thermal stress development. The DC(T) test was completed according to ASTM D-7313 to determine the fracture energy of the mixtures at ?12 °C. Test results demonstrate that the bio-asphalt mixtures had superior physical properties in terms of fracture resistance and creep compliance. Furthermore, the effect of increased RAP contents was less detrimental to low temperature properties in the bio-asphalt mixtures as compared to the reference hot-mix asphalt mixture.     

Time dependent viscoelastic rheological response of pure,modified and synthetic bituminous binders

Bitumen is a viscoelastic material that exhibits both elastic and viscous components of response and displays both a temperature and time dependent relationship between applied stresses and resultant strains. In addition, as bitumen is responsible for the viscoelastic behaviour of all bituminous materials, it plays a dominant role in defining many of the aspects of asphalt road performance, such as strength and stiffness, permanent deformation and cracking. Although conventional bituminous materials perform satisfactorily in most highway pavement applications, there are situations that require the modification of the binder to enhance the properties of existing asphalt material. The best known form of modification is by means of polymer modification, traditionally used to improve the temperature and time susceptibility of bitumen. Tyre rubber modification is another form using recycled crumb tyre rubber to alter the properties of conventional bitumen. In addition, alternative binders (synthetic polymeric binders as well as renewable, environmental-friendly bio-binders) have entered the bitumen market over the last few years due to concerns over the continued availability of bitumen from current crudes and refinery processes. This paper provides a detailed rheological assessment, under both temperature and time regimes, of a range of conventional, modified and alternative binders in terms of the materials dynamic (oscillatory) viscoelastic response. The rheological results show the improved viscoelastic properties of polymer- and rubber-modified binders in terms of increased complex shear modulus and elastic response, particularly at high temperatures and low frequencies. The synthetic binders were found to demonstrate complex rheological behaviour relative to that seen for conventional bituminous binders.     

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.     

粗骨料对沥青混凝土开裂阻力影响分析

沥青混凝土是典型的非均匀材料,在进行力学分析时通常是将其视为均匀、各向同性体,但是理论分析结果很难与实际相符合。同时均质化假设也很难解释含大粒径骨料的沥青碎石作为防裂层的抗裂性能优于小粒径沥青混凝土的现象。笔者通过在均质的沥青混凝土引入一个粗骨料,应用断裂力学平面有限元程序系统地分析了粗骨料对沥青混凝土抗裂性能的影响,分析结果可以较好地解释大粒径沥青混凝土的抗裂性能优于小粒径沥青混凝土的机理。因此,使用大粒径骨料沥青混泥土能够改善路面的使用寿命。     

Thermal stresses of asphalt pavement under dependence of material characteristics on reference temperature

This thesis presents an analytical study of thermal stresses of asphalt pavement under dependence of material characteristics on reference temperature. In the analysis, flexible pavement is regarded as a multi-layered elastic half-space axisymmetrical system. Firstly, thermo-elastic theory is used to describe thermal stresses of a multi-layered system, while the temperature-dependent material characteristics are considered. Then Laplace transformation and Hankel transformation with respect to time and radial, respectively, are utilized for thermo-elastic equations of equilibrium. In addition, the transfer matrix method is applied to derive general solutions for the multi-layered problem. Finally, the resulting formulation is applied to calculate thermal stresses in the low temperature cracking problem of asphalt pavement. Thermal stress is calculated and compared with the case that material characteristics are supposed to be constant to show the remarkable impact of temperature-dependent material characteristics on thermal stresses of asphalt pavement.     

Comparative life cycle assessment (LCA) of bio-modified binder and conventional asphalt binder

This study is a life cycle assessment (LCA) of conventional asphalt binder versus bio-modified binder that is produced by mixing asphalt binder with bio-binder obtained from swine manure. Both processes were evaluated and compared in terms of their contribution to global warming, using a global warming potential index and energy consumption. This LCA study uses a cradle-to-gate approach for the binder and includes a comparison between the environmental impacts of swine manure in lagoons and the production of bio-binder. The results show the energy consumption and global warming potential improvements after using bio-binder as a sustainable additive.     

钢渣沥青混凝土技术及其应用研究进展

钢渣常被当成工业废弃物处置,但其碱性强、棱角丰富,兼具有优异的力学特性,可以改善沥青混凝土的抗水损害、抗高温变形以及耐磨和抗滑等性能,被认为是可替代天然矿质集料的理想筑路材料。近年来道路建设对集料用量的高需求与天然集料短缺之间的矛盾越来越突出,钢渣沥青混凝土技术因而成为备受关注的热点。概述了钢渣的材料特性以及钢渣沥青混凝土的设计与性能,介绍了钢渣沥青混凝土的实际应用情况,研究了钢渣沥青混凝土长期应用后的路面性能变化,最后对钢渣沥青混凝土未来的发展趋势进行了展望。     

Asphalt concrete modification with waste PMMA/ATH

This paper presents recycling of waste PMMA/ATH powder in asphalt concrete mixture. Waste PMMA/ATH is generated in large amounts during shaping process of acrylic sheets. Recycling waste polymers rationally and efficiently has become one of the priorities of road pavement industry in recent years. Therefore, in this study waste PMMA/ATH powder was incorporated in an asphalt mixture. In one case waste PMMA/ATH was used as an asphalt binder modifier and in other case as a partial replacement for fine aggregate fraction. Basic performance characteristics of asphalt mixtures were evaluated by measuring material properties such as rutting potential and stripping resistance. Binder characteristics were determined also on artificially aged samples. With both modification methods, improved performance characteristics of asphalt mixture were achieved which can increase road pavement durability. Finally, waste PMMA/ATH allowed us to prepare an asphalt mixture that had strongly enhanced mechanical properties regarding to the wheel tracking test and could also have less negative effects on the environment as indicated by moisture susceptibility test results.     

A multiscale model for predicting the viscoelastic properties of asphalt concrete

It is well known that the accurate prediction of long term performance of asphalt concrete pavement requires modeling to account for viscoelasticity within the mastic. However, accounting for viscoelasticity can be costly when the material properties are measured at the scale of asphalt concrete. This is due to the fact that the material testing protocols must be performed recursively for each mixture considered for use in the final design.In this paper, a four level multiscale computational micromechanics methodology is utilized to determine the accuracy of micromechanics versus directly measured viscoelastic properties of asphalt concrete pavement. This is accomplished by first measuring the viscoelastic dynamic modulus of asphalt binder, as well as the elastic properties of the constituents, and this comprised the first scale analysis. In the second scale analysis, the finite element method is utilized to predict the effect of mineral fillers on the dynamic modulus. In the third scale analysis, the finite element method is again utilized to predict the effect of fine aggregates on the dynamic modulus. In the fourth and final scale analysis, the finite element method is utilized to predict the effect of large aggregates on the dynamic modulus of asphalt concrete. This final predicted result is then compared to the experimentally measured dynamic modulus of two different asphalt concretes for various volume fractions of the constituents. Results reveal that the errors in predictions are on the order of 60 %, while the ranking of the mixtures was consistent with experimental results. It should be noted that differences between the “final predicted results” and the experimental results can provide fruitful ground for understanding the effect of interactions not considered in the multiscale approach, most importantly, chemical interactions.