Because of the insufficient low-temperature ductility and adhesion of traditional cationic emulsified asphalt, the emulsified asphalt mixture struggles to meet the performance requirements for high-grade pavements. Investigating the performance deterioration mechanism of asphalt during emulsification provides valuable insights for resolving technical challenges in emulsified asphalt materials. This study designed four preparation protocols, including direct-mixing, evaporation, acidification-evaporation, and emulsification, and prepared asphalt binders with different types of cationic emulsifiers. Thereinto, the second and third schemes involve pre-treating the emulsifier before mixing it with asphalt. The influence of evaporation and acidification-evaporation treatment processes on the appearance characteristics of emulsifiers was first investigated. Afterwards, the physical-rheological properties, glass transition, and thermal decomposition behaviors of the asphalt were analyzed. Finally, the intrinsic mechanism of the macro-properties evolution for asphalt was revealed by integrating molecular weight distribution, chemical functional groups, as well as nanoscale morphology and mechanics. Experimental results indicate that emulsifiers themselves cause asphalt softening, particularly the polymeric emulsifier. Following evaporation and acidification-evaporation treatment, the hardening of the emulsifier enhances the high-temperature stability and microhardness of the emulsified asphalt, but significantly compromises its low-temperature crack resistance. Compared to asphalt prepared from pretreated emulsifiers, the emulsified asphalt exhibits superior low- and high-temperature performance, creep recovery ability, and fatigue crack resistance, along with lower glass transition and initial decomposition temperatures. In comparison to low-molecular-weight emulsifiers, the polymeric emulsifier exhibits a much smaller negative impact on the low-temperature deformability of emulsified asphalt. Simultaneously, it significantly enhances high-temperature deformation resistance and adhesion properties. Under acidification, the asphalt system experiences a decline in macromolecular components, resulting from molecular structural changes in the asphaltene and resin. Correspondingly, a greater quantity of “bee structures” is observed in the asphalt from all preparation protocols than in the base asphalt, but the individual structure becomes smaller in area.

The development of multifunctional compound rejuvenator (MCR) that not only can soften the aged asphalt matrix but also is capable of repairing the residual styrene-butadiene-styrene (SBS) copolymer network structure is paramount in achieving a better rejuvenation effect on the SBS polymer modified asphalt (SBSMA) in reclaimed pavement materials. In this research, the rejuvenation efficiency of an MCR that consists of epoxidized polybutadiene resin, epoxidized soybean oil (ESO), and maleic anhydride was evaluated at the scale of asphalt mixture. The comparisons of high-temperature stability, low-temperature anticracking capability, fatigue performance, moisture damage, and aging performance were conducted on original, aged, and rejuvenated SBSMA mixtures. The results indicated that MCR can effectively repair the SBS polymer network, whereas ESO, as a traditional rejuvenator, shows few effects on the damaged SBS polymer structure. MCR has similar rejuvenation effects to ESO in terms of recovering the stiffness, low-temperature cracking, and moisture resistances of aged SBSMA mixture. Notably, MCR shows a huge advantage over ESO when it comes to fatigue lifetime and aging resistance of rejuvenated SBSMA mixture.

Phase change microcapsules (PCMCs) have been developed as asphalt binder additives that can lower the peak road temperatures or extend the time it takes to reach the peak temperatures in hot summer times. However, few studies pay much attention to the possible cooling performance decline of PCMC-modified asphalt (PCMA) caused by the degradation of PCMCs during asphalt binder preparation and service processes. In this research, one type of PCMC with a phase change point of 37 degrees C was chosen for the preparation of PCMA. The impact of PCMCs on performance grade, storage stability and cooling effects of PCMA was evaluated. The degradation of PCMCs in asphalt binder after thin-film oven tests and pressure aging vessel (PAV) aging tests was investigated from both perspectives of PCMCs and PCMA. Additionally, the optimal design and preparation conditions for PCMA were discussed based on the cooling efficiency. The results demonstrate that the introduction of PCMCs can endow asphalt with better cooling performance while not causing adverse effects on binder performance grade and storage stability. The results from morphology and enthalpy of PCMCs to rheological behavior and cooling performance of PCMA consistently illustrate the massive damage of PCMCs and cooling performance deterioration of PCMA caused by aging. Increasing the dosage of microcapsules and reducing the binder preparation temperature contribute to the sustainable cooling performance based on orthogonal experiment results.

Emulsified asphalt, lauded as a new eco-friendly binder, has gained widespread attention and use lately. The characteristics of emulsified asphalt evaporation residues are pivotal for assessing emulsified asphalt quality, highlighting the significance of their recovery methods. This research aims to discern the effect of various recovery methods on the qualities of emulsified asphalt residues, with the goal of selecting an optimal recovery method. Initially, three cationic emulsifiers (SBT, KZW, SHLH) were employed to prepare emulsions, followed by analysis of particle size and storage stability of them. Subsequently, three recovery methods were identified as the direct heat method (DHM), the low temperature heat method (LTHM), and the spin heat method (SHM). Following this, a number of evaluations were carried out on the residues, including physical property tests, temperature sweep test, bending beam rheometer test, multiple stress creep recovery test, and linear amplitude sweep test. Ultimately, aging degree of residues was assessed via Fourier transform infrared spectroscopy (FTIR) test and microstructural analysis was executed utilizing field emission scanning electron microscopy (FESEM) test. Comparing the performance of residues obtained through DHM and LTHM, those obtained via SHM exhibit superior performance in terms of high-temperature rheological and fatigue properties. FTIR results reveal that the emulsified asphalt recovery process only involves physical mixing and minimal aging of residues obtained by SHM among the three recovery methods. Additionally, less residual emulsifier is observed under low-temperature heating condition through FESEM, while abundant residual emulsifier is observed under spin evaporation condition. In summary, the results suggest that SHM can be used as an appropriate method for recovering emulsified asphalt residues.

为探究速生草植物纤维及其沥青胶浆的热性能,采用物理性能试验、热失重试验和差示扫描量热试验测试并比较竹纤维、芦苇纤维及其沥青胶浆的物理性能和热性能,并与木质素纤维及其沥青胶浆进行对比.结果表明:植物纤维的加入可有效提高沥青的高温性能,但对沥青的低温性能有轻微的抑制作用;各路用植物纤维在不同温度范围内的质量损失规律一致;3种植物纤维中,木质素纤维的热稳定性最优,竹纤维次之,芦苇纤维最差;植物纤维可有效改善沥青胶浆的热熔融性,在提高沥青胶浆热稳定性的同时降低温度敏感性;竹纤维沥青胶浆具有最优的低温抗裂性和温度敏感性,速生草植物纤维的低温稳定性优于木质素纤维.

土壤固化剂是一种可以改善和提高土壤结构的新型环保材料,在道路、水利工程等领域得到了较为广泛的应用,而固化土的耐久性是影响其进一步推广应用的关键所在.本文归纳了土壤固化剂和固化土的耐久性能研究现状,总结了提高固化土水稳定性、抗冻性、抗干湿循环、抗收缩开裂等耐久性的研究方法,并提出了部分研究建议,以期为后续固化土耐久性的研究及应用提供部分参考.

In order to study the influence of thermal oxygen aging and photo oxygen aging on the waterborne epoxy emulsified asphalt residues, the changes of rheological properties, chemical structure and micromorphology of emulsified asphalt residues with different epoxy resin contents before and after aging are evaluated by using dynamic shear rheometer（DSR）, Fourier transform infrared（FTIR） spectroscopy and fluorescence microscope. The result shows that（1） Under the same aging condition, with the increase of epoxy resin content, the complex modulus aging index of emulsified asphalt evaporation residue gradually decreases, and the phase angle aging index gradually increases.（2） With the same content of epoxy resin, the complex modulus aging index of the same asphalt in thermal oxygen aging is greater than that in photo oxygen aging, while the phase angle has the opposite trend.（3） The change of sulfoxide group index of evaporation residue of emulsified asphalt without epoxy resin is about 8 times that of evaporation residue of emulsified asphalt with 15% epoxy content after thermal oxygen aging, while the change of sulfoxide group index of the former is about 7 times that of the latter after photooxygen aging.（4） Comparing the change of sulfoxide group index of evaporation residue of emulsified asphalt with 15% epoxy resin content after thermal oxygen aging and photo oxygen aging, it shows that the sulfoxide group index after thermal oxygen aging is 10 times of that after photo oxygen aging, while for evaporation residue of emulsified asphalt without epoxy resin, the sulfoxide group index after thermal oxygen aging is 9 times of that after photo oxygen aging. Compared with photo oxidation aging, thermal oxygen aging is more likely to deepen the aging degree of asphalt.（5） The 3D network structure formed by epoxy resin protects some asphalt from the influence of thermal oxygen and photo oxygen aging. The higher the content of epoxy resin, the better the anti-aging performance of emulsified asphalt evaporation residue.

Instead of styrene-butadiene-styrene triblock copolymer (SBS) modified bitumen (SBSMB) being taken as a whole to be investigated in most of previous aging mechanism studies, the respective contributions of SBS and bitumen matrix to SBSMB aging behavior were evaluated in this research. Four bituminous samples including the blend of aged SBS with fresh bitumen matrix (TAS+B), the blend of un-aged SBS with aged bitumen matrix (S+TAB), un-aged and short-term aged SBSMB, were prepared and then compared in terms of physical and rheological properties, molecular size and morphological polymer phase structure. The results indicate the thermal degradation of copolymer and the aging hardening of bitumen matrix jointly determine the SBSMB aging behaviors. The bitumen matrix aging effect outweighs the copolymer aging effect in view of ductility, viscosity and complex modulus results, and the quantitative relationship formulated between these two effects is valid in some cases.

Due to the high water absorption rate,rough surface and multi-angle of recycled aggregate,it is difficult for cement-stablilized recycled aggregate mixture to stir uniformly under conventional stirring method. This paper mainly studies the mechanical properties,anti-scour properties and dry shrinkage of cement stabilized recycled aggregates under different stirring methods. Through the studies,it is concluded that the unconfined compressive strength,splitting strength,elastic modulus,anti-scour performance and dry shrinkage performance of mixture produced by vibration stirring and multi-step stirring have been improved to a certain extent. The use of multi-step with vibration stirring has the best effect on improving the performance of the mixture.Compared with using traditional stirring method,the unconfined compressive strength of the mixture is increased by 8%～20%,the splitting strength is increased by 16%～33%,and the dry shrinkage is reduced by 30%～39%.

为研究建筑固废物再生粒料混合料的永久变形特性,采用天然集料(NA)、再生混凝土集料(RCA)、再生砖渣与混凝土集料(RBCA)3种粒料混合料,开展不同围压、含水率及主应力比对变形的影响研究,确定混合料的永久变形拟合模型.结果 表明:围压越大,3种粒料混合料的变形均显著减小,其在抵抗变形中起着十分重要的作用;相同围压下,变形量与变形速率随主应力比的增大而增大;永久变形在加载初期增加较大,然后逐渐变小;小围压、低主应力比时,永久变形为NA最大,RBCA次之,RCA最小,但大围压、高主应力比时,NA的永久变形最小,RBCA与RCA的相差不大.

In terms of the aging susceptibility of asphalt, the multi-dimensional nanomaterials (MDNMs) have been developed to improve the aging resistance of asphalt. In comparison with most of previous studies that are only based on asphalt binder aging simulation methods to evaluate anti-aging properties of MDNMs modified asphalt, aging resistances of MDNM-modified asphalt were evaluated in this research by extracting and recovering binders from their aged asphalt mixtures and then characterizing the aging degree of the extracted binders in terms of physical, rheological, and chemical properties. Organic expanded vermiculite (OEVMT) and nanoparticles (nano zinc oxide [ZnO], nano titanium dioxide [TiO2], and nano silica [SiO2]) were chosen to compose three kinds of MDNMs. And six types of aging patterns (including mixing aging [MA], short-term aging [STA], compacted and loose long-term aging [CLTA and LLTA], and compacted and loose ultraviolet (UV) aging [CUVA and LUVA]) for asphalt mixtures were conducted. The results indicate that the ranking of aging degree for the six types of aging patterns is LUVA > LLTA > CUVA > CLTA > STA > MA. Regardless of the types of asphalt mixture aging patterns, the aging resistances of extracted MDNM-modified asphalt binders are all better than extracted pure asphalt binder, and the composite form of OEVMT combined with ZnO presents more significant improvements on asphalt aging resistance than the other two composite forms (OEVMT + SiO2 and OEVMT + TiO2).

通过制备SBS改性剂掺量为0～5.0％的改性沥青并测试针入度、软化点、5℃延度、弹性恢复以及旋转黏度,研究了改性沥青宏观指标与SBS改性剂掺量间的联系.改性沥青再生试验表明:含SBS改性剂成分的B再生剂比普通A再生剂对老化改性沥青再生效果更好,抗老化能力也更为优异.采用红外光谱测试以及荧光显微镜成像对改性沥青中SBS改性剂含量进行定量以及定性的测定,并与改性沥青宏观指标相对应.改性沥青老化后其SBS改性剂含量降低,仅使用再生剂对其进行再生并不能恢复SBS改性剂含量,A/B新旧混合沥青中SBS改性剂含量进一步提升,可以达到3.05％的较高含量.采用动态剪切流变(DSR)试验研究改性沥青的高温抗车辙能力,老化后回收沥青的高温稳定性增强,掺入再生剂会降低其高温抗车辙能力,再生沥青、新旧混合沥青与新改性沥青的高温特性相似.

为了提高钢-超高性能混凝土组合桥面沥青铺面层的使用寿命,利用聚氨酯/环氧树脂对沥青结合料进行改性.通过红外光谱试验、荧光显微镜试验对聚氨酯/环氧树脂改性沥青的固化进程进行了表征.分别采用了聚合物改性沥青离析试验、布氏旋转黏度试验、拉伸试验测试了改性沥青的储存稳定性、黏时特性和力学性能.借助动态剪切流变仪试验和低温弯曲梁流变仪试验研究了改性沥青的高低温性能.试验结果表明:在固化过程中,聚氨酯/环氧树脂与复配胺类固化剂发生开环反应并逐步形成了聚合物互穿网状(IPN)结构,聚氨酯/环氧树脂相由分散相转变为连续相,改性沥青的黏度先缓慢增长至凝胶点后快速拉升并且受固化温度和改性剂掺量的影响较大;聚氨酯/环氧树脂改性沥青因IPN结构的骨架作用具有超高的拉伸强度和较好的柔韧性,而且相较于普通环氧沥青,低温性能得到改善;聚氨酯/环氧树脂能够大幅提高沥青的高温抗车辙能力,其改善效果随着掺量的增加而增强;35％改性剂掺量的聚氨酯/环氧树脂改性沥青拥有最好的储存稳定性.

环氧沥青混合料因胶结料具有热固性而导致其在重复荷载与低温状态下变形能力不足,前期大量研究结果表明聚氨酯的加入可使环氧沥青形成互穿聚合物网状(IPN)结构进而提高胶结料的弹性恢复性能.为了研究聚氨酯/环氧树脂改性沥青混合料的路用性能,对不同聚氨酯/环氧树脂掺量的改性沥青混合料进行了马歇尔稳定度试验、车辙试验、低温劈裂试验、浸水马歇尔试验、冻融劈裂试验和抗滑性能试验,得到了马歇尔模数、动稳定度、破坏劲度模量和残留强度比等性能评价指标结果,并与SBS改性沥青混合料进行了对比分析.结果表明:聚氨酯/环氧树脂改性沥青混合料的马歇尔模数和动稳定度是SBS改性沥青混合料的2～6倍,并且随着改性剂掺量的增加而提高,说明聚氨酯/环氧树脂大幅提升了沥青的高温抗车辙性能;聚氨酯的加入使环氧沥青的劲度模量降低至800 MPa左右,其中聚氨酯/环氧树脂掺量为35％的改性沥青混合料的降幅最大,但依然高于SBS改性沥青混合料,意味着聚氨酯/环氧树脂改性沥青混合料的低温抗裂性能比SBS改性沥青混合料差;不同改性剂掺量的聚氨酯/环氧树脂改性沥青混合料的水稳定性和抗滑性能与SBS改性沥青混合料相差不大,都能够满足钢-超高性能混凝土组合桥面结构的使用要求.

Aging simulation methods for asphalt materials can be generally classified into two types: for asphalt binder and for asphalt mixture. Nevertheless, there exists the aging effect difference between aging patterns for asphalt binder and mixture due to differences in aging experimental conditions. The comparison of the aging effect difference between aging patterns for asphalt binder and mixture contributes to building the relationship and thus achieving a conversion of asphalt aging degree between its binder and mixture aging patterns. In this research, aging effect differences between aging patterns for binder and mixture were investigated in terms of short-term aging, long-term aging, and ultraviolet radiation (UV) aging. The binders were collected before and after different aging patterns and then characterized by physical, rheological, and chemical tests. The results indicate that the aging effect difference between thin film oven test and short-term oven aging test is slight, whereas the aging effect of pressure aging vessel test significantly outweighs the effects of long-term aging patterns with loose or compacted specimens. As for photo oxidation aging, the aging effect ranking from the highest to the lowest is UV aging with loose specimen, UV aging for binder, and UV aging with compacted specimen. In addition, regardless of long-term or UV aging pattern for mixture, the aging degree of binder in loose specimen is more serious than that in compacted specimen.

研究了轻质砖再生细集料掺量对水泥稳定砖混再生集料混合料无侧限抗压强度、劈裂强度、抗压回弹模量、抗冲刷性能与收缩性能的影响.结果表明:随轻质砖再生细集料掺量增加,混合料的最佳含水率大幅增大,最大干密度大幅降低,无侧限抗压强度、劈裂强度、抗压回弹模量与抗冲刷性能均下降;混合料的干缩应变和温缩应变随轻质砖与水泥掺量的增加而增大,轻质砖再生细集料掺量对混合料干缩影响较大,而水泥掺量对混合料温缩影响较大,粗型级配混合料的上述性能均优于其它2种级配混合料.全砖混再生集料水泥稳定混合料可用于各等级公路路面基层,当需要掺入轻质砖再生细集料时,其掺量应控制在20％以内.

该文主要研究聚酯纤维对水泥稳定再生骨料性能的改善作用,在不同的聚酯纤维掺量条件下,测试水泥稳定再生骨料力学性能、抗冲刷性能与干缩性.研究结果表明:在一定聚酯纤维掺量范围内,随聚酯纤维掺量增加,水泥稳定再生骨料无侧限抗压强度先增加后减少,劈裂强度不断提高,抗压弹性模量变化规律与无侧限抗压强度变化规律类似,扫描电镜结果能较好地解释上述规律.另外,掺入聚酯纤维能显著提高水泥稳定再生骨料抗冲刷性能,并降低其干缩变形.

为探究木焦油基再生沥青混合料的耐久性能,采用老化试验、四点弯曲疲劳试验和冻融劈裂试验对基质沥青混合料、木焦油基再生沥青混合料和RA-102再生沥青混合料的疲劳耐久性、冻融循环耐久性和老化耐久性进行试验研究.研究结果表明:木焦油基再生剂有利于减缓疲劳应力、冻融循环和老化作用对沥青混合料性能的劣化作用;木焦油基再生沥青混合料具有良好的疲劳耐久性、冻融循环耐久性和老化耐久性,其水稳定性能优越,可有效延长道路使用寿命;木焦油与生物质纤维的协同作用可有效缓和沥青与集料间的黏附失效,提高混合料的力学强度和抗渗性能,从而提高混合料的耐久性.

将废弃黏土砖制成再生集料,代替部分天然集料制备再生混凝土,研究了4种强化剂对废砖再生粗集料基本性能和再生混凝土性能的影响,利用扫描电镜观察了再生混凝土的微观形貌.结果表明,水泥类浆液对再生集料基本性能的影响具有相似的规律;水玻璃溶液不仅能增大再生集料的表观密度,降低压碎值,还能降低再生集料的吸水率,水玻璃溶液浓度为15％最宜;废砖再生集料取代率超过40％后,再生混凝土28d抗压强度达不到设计标准,经过强化的再生集料混凝土抗压强度最多可提高3.1MPa,水玻璃溶液的强化效果最好.经水玻璃溶液处理后的再生集料混凝土,其内部水化反应更完全,水化产物较多,强度也更高.

传统路桥用防水黏结剂主要为沥青类材料,但在夏季高温环境下会发生软化,导致黏结强度和防水性能下降,最终导致路面和桥面铺装层的损坏.环氧树脂是一种热固型材料,具有良好的黏结强度和防水性能,但未经改进的环氧树脂黏度高,而韧性、抗冲击性和抗剥离性差.选取环氧树脂用稀释剂、增韧剂、促进剂和固化剂,并配置成环氧树脂防水黏结剂A和助剂B.A剂和B剂的应用比例为100∶40～45,使防水黏结剂具有适合施工的黏度和优良的韧性.通过路用性能试验对防水黏结剂分别用于水泥块、沥青块、钢块之间的黏结强度测定,测试中水泥块和沥青块均有不同程度的损坏,而黏结层未出现开裂现象,表明黏结层的黏结强度均高于试样本身强度;在测试钢块之间的黏结强度时,黏结强度达到14.3 MPa.通过低温柔韧性和耐高温性能测定,在低温达到-20℃和高温140℃环境下,低温柔韧性和耐高温性能依然满足要求.研究结果表明,研制的环氧树脂防水黏结剂具有优良的黏结强度、低温柔性和耐高温性能.