回收料掺量对温拌再生沥青混合料性能的影响

通过室内试验研究了回收沥青混合料(RAP)掺量(质量分数)对Evotherm温拌再生沥青混合料高温稳定性、低温性能、水稳定性及疲劳性能的影响.结果表明:采用Evotherm温拌技术可将RAP掺量提高到50%;温拌再生沥青混合料的高温稳定性、水稳定性及低温性能均随RAP掺量的增加先升后降,且在RAP掺量为30%~40%时出现峰值;疲劳性能随RAP掺量的增加逐渐降低,且应变水平越高降低幅度越大;温拌再生沥青混合料的高温稳定性、水稳定性较热拌再生沥青混合料差,疲劳性能优于热拌再生沥青混合料;在相同RAP掺量下,温拌再生沥青混合料与热拌再生沥青混合料的低温性能相当.     

温拌再生沥青混合料性能试验

按照热拌再生设计方法配制了废旧沥青混合料（RAP）掺量分别为20%,30%和45%（质量分数）的AC 13F热拌再生沥青混合料.在此基础上,采用干拌法和湿拌法两种制备工艺分别配制温拌再生沥青混合料.利用车辙试验、冻融劈裂试验、低温弯曲和弯曲蠕变试验来评价热拌及温拌再生沥青混合料的高温性能、低温抗裂性能和水稳定性能.结果表明：温拌再生沥青混合料除高温性能优于热拌再生沥青混合料外,其低温抗裂性能和水稳定性能均低于热拌再生沥青混合料;随着RAP掺量的增加,热拌及温拌再生沥青混合料的路用性能除高温性能有所提高外,低温抗裂性能和水稳定性能均有不同程度的降低;制备工艺对温拌再生沥青混合料的性能有一定程度的影响.     

温拌剂在RAP再生混合料中的应用研究

对20%和60%两种RAP掺量Sup-20厂拌热再生沥青混合料与分别掺加Evotherm和Sasowmat再生沥青混合料性能进行综合对比评价分析,结果表明:采用温拌技术的再生混合料抗水损害性能略为较好,添加Sasowma温拌剂再生混合料的高温性能较普通厂拌热再生有较大程度提高,Evotherm温拌沥青混合料和热拌沥青混合料高温性能相当;RAP掺量从20%提高到60%后,再生混合料高温性能有所提高,同时添加温拌剂的再生混合料低温破坏应变要明显大于普通厂拌热再生混合料。     

RAP掺量对温拌再生沥青混合料路用性能的影响

为了评价RAP（Reclaimed Asphalt Pavement）对再生沥青混合料路用性能的影响,选取了2种不同来源的RAP,对其进行了性能评价后,并以不同的掺量（0%、20%、30%和45%）分别添加在不同类型的热拌及温拌再生沥青混合料（AC-13F和SMA-13）中,进行高温车辙试验、低温弯曲试验、浸水马歇尔和冻融劈裂试验。根据试验结果分别评价了热拌及温拌再生沥青混合料的高温性能、低温性能以及水稳定性能,分析了不同类型RAP及其掺量对热拌及温拌再生沥青混合料路用性能的影响规律,确定了RAP在热拌及温拌再生沥青混合料中的最佳掺量。     

基于SMA温拌再生沥青混合料的路用性能试验研究

在我国市政道路工程施工不断增加的新时期,大力加强对市政道路工程质量的控制及检测越来越受到重视和关注。温拌再生是将沥青路面温拌技术与再生技术结合起来,从而大幅提高了再生沥青混合料中废旧沥青路面材料（RAP）的添加比例,高效利用了废旧沥青路面材料。为了评价SMA温拌再生沥青混合料的性能,利用某市政道路某段铣刨下来的废旧沥青混合料（RAP）,按照厂拌热再生设计方法分别配制不同RAP掺量（质量分数分别为0,20%,30%,45%）下的SMA热拌及温拌再生沥青混合料;利用车辙试验、低温弯曲蠕变试验分别评价了混合料高温稳定性和水稳定性能。研究结果表明：温拌再生沥青混合料的高温性能优于热拌再生沥青混合料,但其抗疲劳性能低于热拌再生沥青混合料,水稳定性能与热拌再生沥青混合料基本保持一致。     

高比例RAP温拌再生沥青混合料研究

基于沥青温拌技术与热再生技术的结合,试验分析得到高比例RAP温拌再生混合料配合比设计,且获得了不错的路用性能指标。横向对比试验确定再生剂最佳掺量为8%;通过热拌对比试验确定温拌剂最佳掺配比为0.7%;拌合温度降低15℃的混合料性能不低于热拌混合料,大比例掺加RAP的情况下,温拌剂的降温效果会有所下降,但再生沥青混合料的高温稳定性能良好,低温抗裂性较热拌一致,水稳定性有所下降但依然满足规范要求。     

温拌改性再生剂对AC-13废旧普通沥青混合料的性能影响评价

利用自主研发的温拌改性再生剂对不同废旧普通沥青混合料(RAP)掺量的AC-13进行了温拌、改性与再生,并对再生沥青混合料进行了路用性能评价。结果表明,随着RAP掺量的增加,温拌改性再生沥青混合料的高温性能提高,但其低温性能、水稳定性和疲劳性能均下降;当RAP掺量为30%时,温拌改性再生沥青混合料的各项路用性能与SBS改性沥青混合料基本相当;当RAP掺量为45%时,温拌改性再生沥青混合料各项性能仍能符合JTG F40—2004的要求。     

温拌再生沥青混合料性能试验

通过将温拌再生沥青同热拌再生沥青混合料进行对比,从低温性能、高温性能、疲劳性能、水稳定性能四个方面进行比对,对利用温拌技术提高再生混合料中RAP比例的可行之处进行讨论。试验表明:就疲劳性能以及低温性能而言,温拌再生沥青混合料胜于热拌再生沥青混合料;但是在水稳定性和高温性能方面,温拌再生沥青混合料和热拌再生沥青混合料性能相比差距不大,同时利用温拌再生技术有助于改善再生混合料中RAP的比例。     

泡沫温拌再生沥青混合料性能试验研究

为了控制废旧沥青回收料(RAP)级配及沥青含量的变异性,保障泡沫温拌再生沥青混合料的性能,将RAP料"分档"处理,并研究了RAP掺量对泡沫温拌再生沥青混合料高温性能、劈裂强度及短期抗水损害能力的影响。结果表明:RAP"分档"处理有利于降低RAP级配及沥青含量的变异性;随着RAP掺量增加,泡沫温拌再生沥青混合料的高温稳定性和劈裂强度提高;当RAP掺量为30%～50%时,泡沫温拌再生沥青混合料的短期抗水损害能力高于热拌沥青混合料,随着RAP掺量的增加,泡沫温拌再生沥青混合料的冻融劈裂强度比(TSR)逐渐减小。     

矿物发泡温拌再生沥青混合料性能研究

通过设计不同RAP掺量的矿物发泡温拌再生沥青混合料,对再生沥青混合料的降温效果、老化性能以及路用性能进行试验研究。研究结果表明:在达到相同的压实效果前提下,矿物发泡温拌再生沥青混合料能够降低压实温度20℃;随着RAP掺量的增加,再生沥青混合料的高温性能逐步提高,水稳定性能降低,低温抗裂性能降低,老化后水稳定性能也逐步衰减。     

SBR胶乳高旧料热再生沥青混合料性能研究

为了能够制备高性能高RAP料掺量(高达50%)的厂拌热再生沥青混合料,本文基于改性再生的理念,研究了SBR胶乳作为改性剂对于含有再生剂的老化沥青以及50%RAP料掺量的热再生沥青混合料的性能的影响,并与再生剂的作用效果进行了对比分析。室内性能试验结果表明,再生剂的软化效应对再生混合料的高温性能不利。在含有再生剂50%RAP料掺量的再生沥青混合料中加入SBR胶乳能够明显改善再生沥青混合料的高温性能,弥补再生剂的不足,同时SBR胶乳能够提升再生混合料的低温抗裂性能和抗水损害性能,使其达到或者超过全新沥青混合料的水平。     

Laboratory evaluation of fatigue characteristics of recycled asphalt mixture

This paper presents the results of a laboratory study of evaluating the fatigue characteristics of hot-mix asphalt (HMA) mixtures using different testing methods. In this study, the fatigue performance of HMA mixtures was evaluated with the Superpave indirect tension (IDT) tests and beam fatigue test. The HMA mixtures containing 0%, 10%, 20%, and 30% of recycled asphalt pavement (RAP) were plant prepared with one source of aggregate, limestone, and one type of binder, PG 64–22. The fatigue properties tested included indirect tensile strength (ITS), failure strain, toughness index (TI), resilient modulus, DCSE_f, energy ratio, plateau value, and load cycles to failure. The results from this study indicated that both Superpave IDT and beam fatigue tests agreed with each other in ranking the fatigue resistance of mixtures when proper procedures were followed.     

Experimental study of recycled asphalt mixtures with high percentages of reclaimed asphalt pavement (RAP)

This paper presents an experimental study to characterize the mechanical behaviour of bituminous mixtures containing high rates of reclaimed asphalt pavement (RAP). Two semi-dense mixtures of 12 and 20 mm maximum aggregate size and containing 40% and 60% RAP, respectively (S-12 and S-20, in accordance with Spanish specifications), which were used for rehabilitation of a highway section, were evaluated. First, the effect of RAP variability on the recycled mixtures was analyzed. Their mechanical properties were then studied by determining the stiffness modulus and indirect tensile strength and cracking and fatigue behaviour. Results show that high rates of recycled material can generally be incorporated into bituminous mixes by proper characterization and handling of RAP stockpiles.     

Mechanistic-empirical mixture design for hot mix asphalt pavement recycling

Mixture design of six asphalt mixtures containing Reclaimed Asphalt Pavement (RAP) were evaluated by using a mechanistic-empirical approach. The testing methodology involved determination of the key mechanical properties and durability of wearing course and base course materials containing RAP at three different levels of addition (i.e. 10%, 30% and 50%), manufactured to a supplied specification, and the rheological properties of binder used in, and recovered from, these materials. In order to optimise both rutting and fatigue resistance, the recycled mixtures were manufactured by using 80/100 pen virgin bitumen (which is one grade softer than the 60/70 pen bitumen conventionally used for the respective parent asphalt materials), with or without added rejuvenating oil. This paper demonstrates that the asphalt mixtures containing RAP performed at least similar to, or better than, that of conventional asphalt materials.     

浇注式沥青混凝土疲劳寿命的能量法

根据应变控制模式下的4点弯曲疲劳试验方法,用能量法研究了浇注式沥青混合料抗疲劳性能。通过多个应变水平下的疲劳试验,得出浇注式沥青混凝土的疲劳寿命与累积耗散能在双对数坐标下的线性关系。并回归出了浇注式沥青混合料在不同应变水平下疲劳寿命预测方程。用Maxwell模型分析了浇注式沥青混合料疲劳破坏与能量耗散的关系,并将滞后回线和滞后角引入到浇注式沥青混合料疲劳性能研究中,得出滞后角大的混合料有更好的抗疲劳性能。     

Fatigue behavior of rubberized asphalt concrete mixtures containing warm asphalt additives

The long-term performance of pavement is associated with various factors such as pavement structure, materials, traffic loading, and environmental conditions. Improving the understanding of the fatigue behavior of the specific rubberized warm mix asphalt (WMA) is helpful in recycling the scrap tires and saving energy. This study explores the utilization of the conventional fatigue analysis approach in investigating the fatigue life of rubberized asphalt concrete mixtures containing the WMA additive. The fatigue beams were made with one rubber type (?40 mesh ambient crumb rubber), two aggregate sources, two WMA additives (Asphamin^® and Sasobit^®), and tested at 20 °C. A total of eight mixtures were performed and 29 fatigue beams were tested in this study. The test results indicated that the addition of crumb rubber and WMA additive not only reduced the mixing and compaction temperatures of rubberized asphalt mixtures offset by crumb rubber but also effectively extended the long-term performance of pavement when compared with conventional asphalt pavement. In addition, the exponential function forms are efficient in achieving the correlations between the dissipated energy and load cycle as well as mixture stiffness and load cycle.     

盐冻融循环对温拌胶粉改性沥青混合料疲劳性能的影响

为了研究冻融循环次数、盐质量分数和表面活性剂型温拌剂(SDYK)对胶粉改性沥青混合料疲劳性能的影响,采用小梁四点弯曲疲劳试验得到了冻融循环次数和弯曲劲度模量的关系,并结合疲劳寿命和能耗理论进行了分析.结果表明:胶粉改性沥青混合料的疲劳寿命随着冻融循环次数的增加而降低;当盐质量分数为8%时,水的冻胀与盐的侵蚀耦合作用最强,混合料疲劳寿命最低;当盐质量分数超过8%时,会对水的冻胀有一定的抑制作用;加入温拌剂的胶粉改性沥青混合料的疲劳性能更好.     

Utilization of municipal solid waste incineration ash in stone mastic asphalt mixture: Pavement performance and environmental impact

The objective of this study is to the use of municipal solid waste incinerator (MSWI) fly ash as a partial replacement of fine aggregate or mineral filler in stone matrix asphalt (SMA) mixture. For saving natural rock and reusing solid waste, basic oxygen furnace slag (BOF slag) was used as part of coarse aggregate. And this makes SMA mixtures contain more than 90% solid waste materials by mass. A comparative study of the performance of two mixes designed using superior performance asphalt pavements (SUPERPAVE) and Marshall mix design procedures was carried out in this research. Samples from both mixes were prepared at the design asphalt contents and aggregate gradations and were subjected to a comprehensive mechanical evaluation testing. These tests included Marshall stability, water sensibility, resilient modulus, fatigue life and rutting. In all the performed tests SUPERPAVE mixtures proved their superiority over Marshall mixtures. TCLP test for environmental impact indicated that asphalt is an effective stabilization and solidification agent for heavy metal in MSWI ash. The heavy metal leachates in TCLP tests have great positive correlation with their initial concentration in waste. But Ni is an exception that lower initial concentration leaded to higher cumulative leaching rate.     

Laboratory comparison study for the use of stone matrix asphalt in hot weather climates

Stone matrix asphalt (SMA) is a hot mixture asphalt consisting of a coarse aggregate skeleton and a high binder content mortar. It was developed in Germany during the mid-1960s and it has been used in Europe for more than 20 years to provide better rutting resistance and to resist studded tyre wear. The main objective of this research study was to compare the performance of the normally used dense graded asphalt mixtures, named in this research as control mixtures, and SMA mixtures. Samples from both mixtures were fabricated at their optimum asphalt contents that were 5.3% for control mixtures and 6.9% for SMA mixtures. Comparison performance tests that included Marshall stability, loss of Marshall stability, split tensile strength, loss of split tensile strength, resilient modulus, fatigue, and rutting testing were performed on both mixtures. Test results showed that although the control mixtures have higher compressive and tensile strengths, SMA mixtures have higher durability and resilience properties. In addition, although the research could not prove the superiority of SMA in rutting resistance because of the limited sample sizes, field performance of SMA mixtures proves its superiority. Therefore, especially in hot weather climates, these properties, (durability, resilience and rutting resistance) give SMA mixtures advantages over dense graded mixtures.