温拌改性再生剂对不同RAP掺量废旧普通沥青混合料性能影响评价

利用自主研发的复合温拌改性再生剂,对不同RAP掺量(30%、45%、60%)的AC-20型沥青混合料进行了温拌、改性与再生,并对再生沥青混合料进行了路用性能评价.试验结果表明:随着RAP掺量的增加,温拌改性再生沥青混合料的高温性能不断增强,但其低温性能、水稳定性和疲劳性能均呈下降趋势;与SBS改性沥青混合料对比发现,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基本相当;当RAP掺量为45%时,温拌改性再生沥青混合料除高温性能外的各项性能均有下降,但仍能满足规范对改性沥青混合料的要求;当RAP掺量为60%时,温拌改性再生沥青混合料的低温性能和水稳定性已经不满足规范要求.推荐温拌改性再生沥青混合料的推荐RAP掺量为30%~45%.     

发泡用水量对橡胶沥青高低温性能的影响研究

利用DSR试验、弯曲梁流变试验(BBR)对不同发泡用水量条件下橡胶沥青的高低温性能进行测试,并采用车辙试验、低温小梁弯曲试验分别评价混合料的高低温性能。结果表明:泡沫温拌橡胶沥青与橡胶沥青发泡前相比,高温性能显著降低,低温性能明显提高;泡沫温拌橡胶沥青结合料的高温性能随发泡用水量的增加逐渐降低,低温抗裂性能先降低后提高;与未发泡的橡胶沥青相比,泡沫温拌橡胶沥青混合料的高温抗车辙性能降低,低温性能提高,并且随着发泡用水量增加,泡沫温拌橡胶沥青混合料的动稳定度不断降低,破坏应变值逐渐升高。     

不同RAP掺量温拌再生改性沥青抗变形性能研究

为了评价不同RAP （旧沥青混合料reclaimed asphalt pavement）温拌再生沥青混合料的抗变形性能,通过室内试验对SBS改性沥青及4种不同RAP掺量温拌再生改性沥青进行基本性能及不同温度下黏度试验,从活化能角度揭示温拌再生改性机理,并且通过沥青混合料车辙试验对不同RAP沥青混合料抗变形性能进行研究.结果表明：温拌再生改性沥青的活化能较高;温拌再生改性沥青混合料的高温性能优于热拌沥青混合料,RAP建议掺量为40%,再生剂A及B建议掺量分别为沥青质量5%及旧沥青质量4%.     

水泥与消石灰对沥青胶浆性能影响研究

研究掺加水泥和消石灰对沥青胶浆性能的影响.通过测试不同替换量下掺加水泥和消石灰时沥青胶浆的高温、低温性能和施工性能,发现掺加水泥后胶浆的软化点增加,黏度降低,低温性能得到改善.但是替换量超过60%时,胶浆延度改善幅度降低,因而水泥替换量不宜超过60%;当掺加消石灰时沥青胶浆软化点和黏度显著增大,BBR试验显示低温抗裂性能劣化,但是替换量不超过20%时,对低温性能影响较小.     

RAP掺量对再生沥青混合料路用性能影响

使用车辙实验、半圆弯曲实验、四点弯曲疲劳试验、冻融劈裂试验、汉堡车辙试验分别评价不同旧沥青路面材料(RAP)掺量再生沥青混合料的路用性能。结果表明:在较低RAP掺量下,RAP掺量的增加会使再生沥青混合料抗车辙性能、抗疲劳性能、水稳定性明显提高,抗裂性能明显降低;在较高RAP掺量下(大于30%),再生沥青混合料的各项性能均明显降低;RAP掺量的提高会使沥青混合料的抗裂性能明显降低;温拌技术会促进新旧沥青之间的混溶,但不利于再生沥青混合料的水稳定性;再生沥青混合料的抗水损害性能对RAP掺量变化较为敏感;不同RAP掺量对再生沥青混合料的各项路用性能的影响具有一致性,并结合红外光谱分析结果,推荐RAP掺量为30%。     

掺加旧料对温拌沥青混合料疲劳性能的影响分析

温拌再生沥青混合料是基于沥青温拌技术和再生技术发展而来的新型环保型沥青混合料.对掺加旧料（RAP）的温拌沥青混合料的疲劳性能进行了评价,分析了不同旧料掺量对疲劳性能的影响.疲劳试验采用小梁三分点加载方法,进行了旧料掺量为0%、15%、30%、45%以及60%的混合料疲劳试验.试验结果表明,旧料掺量越大,疲劳性能越差;30%为温拌沥青混合料的临界旧料掺量,此掺量为疲劳性能的＂性能拐点＂,超过此掺量后疲劳性能大幅衰减.     

泡沫沥青再生混合料劈裂强度影响因素试验

为了研究不同泡沫沥青用量和旧沥青路面铣刨料(简称RAP)掺量两因素对泡沫沥青再生混合料劈裂强度的影响,采用两种不同的沥青路面铣刨旧料RAP1和RAP2,通过变化旧料掺量为0%、20%、40%、60%、80%5种比例,分别与2%、2.5%、3%、3.5%、4%5种用量的泡沫沥青混和,拌制泡沫沥青再生混合料,成型试件后进行干、湿两种条件下的劈裂强度(ITS)和残留劈裂强度比(TSR)测试.结果表明:在沥青旧料掺量比例一定的情况下,混合料的泡沫沥青用量存在最佳值;随着RAP掺量逐渐增大,泡沫沥青再生混合料的最佳沥青用量却逐渐减小,其值由RAP掺量为0时的3.5%减少到掺量为80%时的2%;随着RAP掺量的增大,泡沫沥青再生混合料干、湿ITS呈现减小趋势,但TSR却有所提高.     

生物沥青再生沥青结合料使用性能

为研究生物沥青用作沥青再生剂的可能性,选用蓖麻油生物沥青为再生剂制备再生沥青,并通过试验研究了旋转薄膜烘箱(rolling thin film oven,RTFO)老化前后该种生物沥青掺量对再生沥青相关技术指标的影响.结果表明:随着生物沥青掺量的增加,再生沥青针入度增大,软化点降低,30%掺量的生物沥青可将老化沥青的针入度恢复到原样沥青水平.然而,生物沥青对延度的改善较差.此外,再生沥青135℃黏度、当量软化点和当量脆点降低,针入度指数PI和塑性温度范围逐渐增大,RTFO老化后残留针入度比减小,软化点增量、黏度老化指数逐渐增大.生物沥青的加入改善了再生沥青的感温性能和低温性能,对高温性能表现出不利影响.随着生物沥青掺量的增加,再生沥青抗老化性能逐渐减弱,但在30%掺量范围内,生物沥青再生沥青的抗老化性能仍不低于原样沥青水平.     

添加抗车辙剂的沥青混合料性能试验研究

研究了添加抗车辙剂路孚8000(的沥青混合料的各项性能。对抗车辙剂不同掺量下的沥青胶结料进行了基本性能试验,包括高温车辙、低温弯曲和冻融劈裂。结果表明:改性沥青混合料掺入抗车辙剂掺量后,动稳定度提高显著;对沥青混合料的抗水损害性能变化不大;混合料的低温抗裂性能略有提高。     

SBR-水性环氧-脱色乳化沥青复合胶结料性能研究

为提升脱色乳化沥青的柔韧性和黏附性,探究SBR-水性环氧-脱色乳化沥青复合胶结料的最佳配比,在室内制备了不同配比的SBR-水性环氧-脱色乳化沥青复合胶结料,并采用拉拔试验、拉伸试验、低温韧性试验、荧光显微镜试验等方法,对复合胶结料的黏附性、强度、低温抗裂性等进行了测试。研究结果表明：水性环氧树脂掺量为50%、SBR掺量为4%时,复合胶结料的强度和柔韧性显著提升;水性环氧树脂的掺量为50%、SBR的掺量小于5%范围内,SBR-水性环氧-脱色乳化沥青复合胶结料具有稳定的交联结构体系且稳定性最好;水性环氧树脂掺量不超过40%,其低温抗裂性最好;推荐水性环氧树脂掺量为50%、SBR掺量为4%时为SBR-水性环氧-脱色乳化沥青复合胶结料最佳配比。     

Evaluation of Mixture Performance Recycled Asphalt Pavement Materials as Base Layer with or without Rejuvenator into the Asphalt

The binder properties were determined in accordance with Chinese standard such as ductility test,which allowed to measure the distance in centimeters that a standard briquette of asphalt had been stretched before breaking.Then,penetration test was carried out in order to know some properties of the asphalt,which are the hardness and the softness.Finally,softening point test was carried out in order to determine the temperature at which the bitumen attains a particular degree of softening under the specification of the test.According to Chinese standard for performance tests,firstly,Marshall test was carried out in order to measure the theoretical density,air voids,voids filled with asphalt,stability,flow,and voids in mineral aggregate of asphalt specimens.Secondly,Freeze-thaw splitting test was carried out in order to determine Splitting strength ratio.Finally,dynamic stability (rutting) test was carried out to determine average dynamic stability.Beside the tests carried out,the gradation of the extracted aggregate in accordance with American Association of State Highway and Transportation Officials was carried out to determine the dimensions of the particles weight distribution.Furthermore,both the percentage of recycled asphalt pavement materials and binder in mixture were determined to know how much of the new material during the mixture was needed.However,two specimens were used to evaluate the performance of recycled asphalt pavement materials.One specimen of recycled asphalt pavement materials was ten years old,and another one of recycled asphalt pavement materials was five years old.The results show that the conditions of the environment such as moisture,temperature,and age,decrease the ductility and penetration properties of binder when increase the softening point property of binder.Then the gradation of recycled asphalt pavement aggregate is of the required values to reuse in the mixture,while the flow ratio,the splitting strength ratio,and the dynamic stability ratio,are less than the required value test.With regard to the properties of mixture of recycled asphalt pavement material binder with rejuvenator,the results show that when the penetration and ductility versus percentage of rejuvenator increase,softening point versus percentage of rejuvenator decreases.Also,when the bitumen and rejuvenator percentage increase,the air voids decrease.Consequently,voids filled with asphalt and voids in the mineral aggregate increase.Moreover,the theoretical density and stability values decrease in a mixture containing four-point fifty percent to six percent of bitumen and rejuvenator,whereas the flow values increase.More interestingly,with four percent to four-point fifty percent mixture ratio of bitumen and rejuvenator,density,stability,and flow values increase.The splitting strength ratio values of mixtures and the dynamic stability test (rutting test) values of mixtures with forty percent of specimen one and specimen two respectively are greater than the required value of the standard test.In addition,the high percentage of rejuvenator increases the rut of pavement,in the same manner,the low percentage of rejuvenator induces low rut.In conclusion,the binder content from recycled materials without rejuvenator seems not be sufficient to be reused on the new pavement while the aged recycled material seems to be performed better than no aged recycled material with rejuvenator into bitumen.Then,the rejuvenator can influence the bitumen properties and performance of the pavement.Finally,the pavement made by only recycled pavement materials as a base layer appears to be more economical but cannot be more effective than the pavement made by mixture of new and recycled pavement materials as a base layer.     

Road performances of mesoporous nano-silica modified asphalt binders

The objective of this paper was to find new modifier to improve the aging resistance and low temperature cracking resistance of asphalt. To investigate the aging resistance of modified asphalt binders, mesoporous nano-silica(doping Ti~(4+)) was used as a asphalt modifier. Some physical properties including penetration, ductility, and softening point of asphalt were analyzed with RTFO(Rotating thin film oven) aging and ultraviolet aging. Moreover, the performances of high and low temperature of modified asphalt binders with pressure aging were tested by dynamic shear rheometer(DSR) test and bending beam rheometer(BBR) test. These results showed that the penetration decreased, low temperature ductility, and softening point increased when adding mesoporous nano-silica to base asphalt. After ultraviolet radiation aging, the penetration loss and ductility loss of modified asphalt decreased than that of original asphalt, the increase of softening point was also significantly reduced than that of base asphalt. Furthermore, The test results of DSR and BBR showed that the G*sinδ and creep modulus‘s' of pressure aged asphalt decreased, but the creep rate ‘m' increased. It can be concluded that the aging resistance and cracking resistance of modified asphalt are improved by adding mesoporous nano-silica, especially the doping of Ti~(4+) could improve the aging resistance obviously.     

橡胶沥青水老化试验研究

沥青路面的长期使用过程中,水是影响沥青老化的主要因素之一。为研究水老化作用方式及水量对橡胶沥青老化性能的影响,本文以橡胶沥青和TOR橡胶沥青两种材料为例,通过改变水作用阶段和用水量试验研究不同水老化方式对橡胶沥青老化后软化点、粘度、疲劳因子、蠕变劲度、蠕变速率的影响。试验结果表明：选择在压力老化前三分之一时间（400min）进行加水压力老化试验,后三分之二时间进行无水压力老化试验的水老化作用方式最具可行性;对比无水压力老化试验和加水压力老化试验可知,水的存在促进了橡胶沥青的热氧老化;随水量的增加,TOR橡胶沥青的高温稳定性能降低,抗疲劳开裂能力和低温性能降低,沥青老化加剧。     

超硬质沥青改性结合料流变性能分析

为研究超硬质沥青(super hard asphalt,SHA)对超硬质沥青结合料的高、低温流变的影响效果,采用SHA作为改性剂对AH-90道路石油沥青进行改性,制备了不同质量分数（5%、6%、7%和8%）的SHA改性结合料,并进行动态剪切流变试验、多应力蠕变恢复试验及小梁弯曲蠕变试验. 试验结果表明:其适用于时温等效原理;SHA的掺入会有效提高沥青结合料的车辙因子G^*/sin δ,沥青混合料的高温性能得到明显改善;随着SHA掺量的增加,沥青结合料的平均应变恢复率R逐渐升高,不可恢复蠕变柔量J_nr逐渐降低,掺加SHA有利于提高沥青结合料高温抗变形能力与变形恢复能力;随着SHA的掺入,沥青结合料的蠕变劲度S与蠕变劲度变化率m变化幅度不大,对沥青结合料的低温抗裂性能影响不大. SHA改性沥青结合料高温抗车辙性能优异,低温性能相对于基质沥青PG分级保持不变.     

基于室内环境模拟的再生沥青混合料老化影响因素

为了解决不同环境因素对路面工程中未经压实的再生沥青混合料(recycled asphalt mixture,RAP)老化程度影响的问题,以松散的再生沥青混合料为研究对象,利用特制的室内模拟老化试验装置,通过控制温度、湿度、老化时间、氧气浓度等因素,对新制备密级配沥青混合料AC-13进行特定环境条件下模拟老化试验.结果表明:松散RAP混合料的老化程度随试验温度升高而增加,随空气湿度增加和氧气浓度下降而降低;不同试验温度下,沥青老化的成长速度和试验终值均不相同,表明老化过程中的化学反应因温度不同而有所差异;在通入纯氮气的试验中,沥青没有发生任何老化作用,表明沥青的老化只受氧化作用影响;环球法测软化点的试验结果对温度变化较为敏感,动态剪切流变仪(dynamic shear rheometer,DSR)测定的动态复数剪切模量在表征沥青老化程度时存在一定迟滞效应;老化后沥青混合料低温性能出现衰减,主要原因是沥青长期老化作用导致.     

SBR改性沥青老化动力性能

目的通过研究SBR改性沥青的老化动力性能,进一步探讨在动力因素的影响下沥青和骨料的黏附性.方法通过旋转薄膜烘箱试验,研究SBR改性沥青和基质沥青在不同老化温度、老化时间下的软化点变化规律,并以软化点为参数建立了SBR改性沥青老化动力学模型,以此研究SBR改性沥青的老化动力性能.结果与基质沥青相比,SBR改性沥青在150℃、163℃、180℃三个老化温度下的老化反应速率常数分别降低了26.8%、51.9%、21.4%;SBR改性沥青的反应活化能达到48.863 kJ·mol^-1,比基质沥青提高了13.1%.结论以软化点为参数建立的沥青老化动力学方程能够较好的反映沥青的老化过程,SBR改性沥青比基质沥青具有较好的抗老化性能.