Ice accumulation on road surfaces poses significant hazards to traffic safety and infrastructure. The mechanism by which salt ions regulate ice adhesion during freezing by altering the structure of water molecules remains poorly understood. This study investigates cation-specific effects on ice adhesion strength (IAS) and the structural evolution of water on asphalt surfaces using experiments and molecular dynamics simulations. At equal mass concentrations, the reduction in IAS among different cations follows the order Li+ > Mg-2(+) > Na+ > Ca-2(+) > K+, indicating that smaller ionic radii and higher charges enhance adhesion suppression. Low-temperature Raman spectroscopy shows that cations disrupt the tetrahedral hydrogen-bond network (DDAA) of water, with the extent of disruption negatively correlated with IAS. The ability to disrupt hydrogen bonds is negatively correlated with IAS. NMR analyses further confirm that strongly hydrated cations (Li+, Mg-2(+)) promote the formation of immobilized water, representing water molecules within the quasi-liquid layer (QLL) that are constrained but not fully frozen. Moreover, ions strongly inhibit the water-ice phase transition, increasing both the thickness and disorder of the quasi-liquid layer (QLL), as revealed by the Q6 order parameter combined with the CHILL+ algorithm. In the Li+ and Mg-2(+) systems, lower diffusion coefficients and higher potentials of mean force (PMF) indicate restricted molecular mobility and hydrogen-bond network rearrangement, resulting in a thicker QLL and weaker ice adhesion. These findings provide fundamental insights into cation-mediated anti-icing mechanisms and offer guidance for the design of effective ion-regulated anti-icing materials for infrastructure.

Understanding the freezing and adhesion properties of de-icing salt solutions is crucial for optimizing de-icing strategies in infrastructure and minimizing damage to the environment and road materials from de-icing salts. This work employed a customized ice-adhesion testing system to investigate the evolution of ice-adhesion strength (IAS) of NaCl and NaCH3COO salts on bitumen surfaces under different concentrations and temperatures. The icing phase transition process and thermodynamic properties of the salt solution were analyzed using multi-channel temperature setting and differential scanning calorimetry (DSC). Moreover, the adhesive mechanisms of salty ice were elucidated based on heterogeneous nucleation kinetics and quasi-liquid layer (QLL) theory. The results show that even a 0.5 wt% salt solution can lower the IAS to approximately 40-50 % of the value observed with pure water. The concentration of salt solution required to achieve adhesive failure is temperature-dependent. Additionally, the latent heat of fusion (hf) of NaCl solutions at concentrations from 0.5 to 2.5 wt% sequentially decreased by 45.3 J/g, 63.1 J/g, 79.9 J/g, 90.0 J/g, and 117.6 J/g compared to pure water. The freezing temperature (TF) of 2.5 wt% NaCH3COO and NaCl solutions dropped by 1.3 degrees C and 1.6 degrees C, respectively. Based on the ice nucleation kinetics, lowering the TF and hf leads to an increase in the nucleation energy barrier (Delta G*), with IAS showing a logarithmic correlation with Delta G*. Furthermore, the QLL transitions from droplets to a thin film as salinity increases, further reducing the contact area and IAS. This work offers novel insights into the freezing progress and adhesion mechanisms of salty ice, aiming to reduce maintenance costs and environmental damage from de-icing salts.

Waste rubber modified bitumen has gained significant attention as a sustainable and innovative material in the field of pavement engineering. This study aims to evaluate the performance of rubber modified bitumen mastic by considering its rheological properties, specifically focusing on preparation parameters, i.e., rubber content, mesh number, and filler to bitumen ratio. From the experimental results, the rheological properties of rubber modified bitumen mastic were significantly influenced by preparation parameters. Increasing the rubber powder content in bitumen mastic results in higher viscosity. Increasing the rubber content improves high-temperature rutting resistance to a certain extent, however, excessive rubber powder content would result in weakened high-temperature performance improvement. The rutting factor decreases gradually with an increase in the rubber mesh number. A ratio of filler to bitumen of 0.95 exhibits the best resistance to rutting at high temperatures. Higher rubber content and larger mesh number correspond to stronger low-temperature crack resistance in bitumen mastic. As the ratio of filler to bitumen increases, the low-temperature deformation capacity gradually decreases, resulting in weaker low-temperature crack resistance. Based on the grey relation analysis, the ratio of filler to bitumen has the greatest impact on the high and low-temperature rheological properties of bitumen mastic, followed by the rubber content. The rubber mesh number has a relatively lower impact. It is crucial to control the ratio of filler to bitumen to avoid excessive values. When possible, a higher rubber powder content should be used while meeting process requirements. These findings provide valuable insights into the design and optimization of rubber modified bitumen mastic, which can contribute to the development of sustainable and high-performance bitumen mixtures, promoting the use of recycled rubber in pavement engineering.

为改善建筑垃圾再生砂浆的性能,选用水洗法和纳米材料掺入法复合强化再生砂浆的力学性能,通过再生砂浆标准稠度试验、表观密度试验、保水性试验、抗压试验和SEM对再生砂浆基础指标、抗压能力与微观形貌进行了综合评价.稠度、表观密度以及保水性试验结果表明:水洗强化后,再生砂浆流动性变好、表观密度和保水性下降;在复合强化中,随着纳米材料掺量的增加,再生砂浆流动性逐渐变差,表观密度提升,保水性逐渐变好.抗压强度试验结果表明:随着龄期的增长,抗压强度明显变大;水洗强化后,抗压强度在不同龄期中,均随着纳米材料掺量的增加呈现出先升高后降低的趋势,并且得出纳米材料的推荐掺量为1.5％.扫描电镜结果表明:未进行水洗强化和纳米材料强化的再生砂浆水化反应遭到抑制;复合强化中,随着纳米材料掺量的增加,再生砂浆水化反应程度加深.

从胶粉活化机理、胶粉活化改性方法、胶粉活化对改性沥青性能影响3个方面,对目前活化胶粉的研究进展进行了分类总结.研究发现,活化胶粉改性沥青的低温性能、储存稳定性、感温性能等比未处理胶粉改性沥青更优.该研究成果可为后续活化胶粉改性沥青的研究和应用提供参考.

A large number of waste tires are in urgent need of effective treatment, and breaking waste tires into crumb rubber powder for modifying asphalt has been proved as a good idea to solve waste tires. Crumb rubber modified asphalt not only has good high and low temperature performance, durability, and aging resistance but can also reduce pavement noise and diseases, which has wide application prospects. In this study, crumb rubber powder was desulfurized by mechanochemical method to prepare desulfurized crumb rubber modified asphalt. During the desulfurization process of crumb rubber, the effects of desulfurization process variables including desulfurizer type, desulfurizer content, and desulfurization mixing temperature and time were considered, and then the physical properties of modified asphalt were tested. The test results showed that after mixing crumb rubber powder with desulfurizer, the viscosity of crumb rubber powder modified asphalt can be reduced. Moreover, the storage stability of crumb rubber powder modified asphalt could also be improved by mixing crumb rubber with desulfurizer. Based on the physical properties of crumb rubber powder modified asphalt, the desulfurization process of selected organic disulfide (OD) desulfurizer was optimized as follows: the OD desulfurizer content was 3%, the desulfurization mixing temperature was 160 °C, and the mixing time was 30 min. In addition, Fourier infrared spectroscopy analysis was carried out to explore the modification mechanism of desulfurized crumb rubber powder modified asphalt. There is no fracture and formation of chemical bonds, and the modification of asphalt by crumb rubber powder is mainly physical modification.

为研究砖混再生细骨料对砖混再生砂浆力学性能、耐久性能及微观形貌的影响,以再生砂浆为研究对象,采用抗折与抗压试验直接与间接地研究了砖混再生细骨料不同取代率下砖混再生砂浆的力学性能、抗冻性能、抗硫酸盐侵蚀性能,并结合微观试验进一步验证了其性能影响.研究结果表明:砖混再生细骨料由于高孔隙率导致其本身具有一定的缺陷,它的掺入会降低砖混再生砂浆力学性能;砖混再生细骨料在低取代率下(≤30％)能够一定程度上提高砖混再生砂浆的抗折和抗压强度,使其整体较为密实,抗冻融循环能力与抗硫酸盐侵蚀性能均有所提高;当取代率≥50％时会明显降低砖混再生砂浆的力学性能.取代率越高,强度损失率和质量损失率越大;扫描电子显微镜试验显示,砖混再生细骨料掺量越高,其水泥石内部横向和纵向裂缝越显著.

The rubber molecular chain in waste vulcanized tire rubber will be crosslinked to form a network structure that would be difficult to degrade in asphalt. Crumb rubber treated by desulfurization activation could form active groups on the surface by interrupting the crosslinking bond to improve the compatibility between crumb rubber powder and asphalt. To explore the influence of activation modes on crumb rubber powder and the corresponding rubber-modified asphalt binder, crumb rubber powder was firstly activated through three commonly used activation methods and asphalt binder samples modified by activated crumb rubber powder were also prepared. The basic properties of activated crumb rubber powder were characterized by infrared spectroscopy, and conventional tests were used to study the conventional physical properties of the asphalt binder. The infrared spectroscopy and elemental analysis showed that the crumb rubber powder was mainly composed of alkanes, alkenes, sulfonic acids, aromatics, and a little silica rubber and antioxidant zinc oxide, which is suitable for asphalt modification. The simple heat activation treatment method is not enough to greatly destroy the cross-linking structure of crumb rubber powder, but the “C=C” bond was destroyed more seriously. Under the action of adjuvants, the polysulfide cross-linking bond could be broken in crumb rubber powder. The heat treatment and chemical treatment could not achieve the purpose of reducing the viscosity and improving the compatibility of rubber asphalt binder through desulfurization activation. The mechanochemical treatment would help to improve the performance of crumb-rubber-powder-modified asphalt binder. The data correlation analysis based on the grey relational degree can provide a reference for the selection of activated crumb rubber powder for different application requirements in the asphalt modification procedure.

通过分析集料中含量较多的锈染颗粒、重结晶方解石颗粒的特性,研究了特殊骨料颗粒对沥青混合料性能的影响,提出了特殊集料的质量控制标准.结果表明:锈染颗粒、重结晶方解石颗粒与沥青的粘附性比普通灰岩颗粒低两个等级;锈染颗粒及重结晶方解石颗粒降低了沥青混合料的高温抗变形性能及抗水损害性能,对低温抗开裂性能影响较小.在集料生产过程中,建议将锈染颗粒、重结晶方解石颗粒含量控制在5％以下.

为了研究基质沥青的化学组分对橡胶沥青性能的影响,基于基质沥青四组分及橡胶沥青路用性能试验数据,利用灰关联方法分析了饱和分、芳香分、胶质、沥青质、胶质与沥青质含量之和、饱和分与芳香分含量之和等因素对橡胶沥青的针入度、延度、软化点、180℃黏度和48 h离析软化点差的作用关系,得出影响橡胶沥青性能的关键因素.通过对比各因素与不同目数橡胶粉制备的橡胶沥青路用性能的灰关联分析结果,阐明了橡胶粉目数对各因素与橡胶沥青性能关联度的影响.研究结果表明:胶质对橡胶沥青软化点的影响程度最高,饱和分与芳香分含量之和对橡胶沥青针入度的影响程度较深,二者之间的关联度接近0.9;饱和分对橡胶沥青5℃延度的影响程度最高,而胶质与沥青质含量之和对橡胶沥青的180℃黏度和48 h离析软化点差的影响程度最高.橡胶粉目数不会影响各因素与橡胶沥青的路用性能关联度的排序,但增大橡胶粉目数会降低各因素与橡胶沥青的路用性能之间的关联度.

采用机械力化学法对橡胶粉进行脱硫处理,制备脱硫胶粉改性沥青并测试其基础性能指标,研究脱硫工艺对胶粉改性沥青路用性能及微观结构的影响.结果 表明:将胶粉与脱硫助剂混炼后,可以降低胶粉改性沥青的黏度;胶粉与活化剂8501及再生剂RVS混炼还可以改善胶粉改性沥青的储存稳定性;基于胶粉改性沥青路用性能指标,优选出活化剂8501的脱硫工艺为活化剂掺量3％,混炼温度160℃,混炼时间30 min.微观试验结果表明,胶粉对沥青的改性主要以物理改性为主.胶粉经脱硫处理后具有明显的颗粒核心,而且其表面粗糙程度明显增加,与沥青的相容性优于未处理的胶粉.

为研究再生剂-老化沥青界面扩散行为及其影响因素,采用Wilhelmy吊片法测试了不同温度下再生剂的表面张力及其与老化沥青间的接触角,计算得到润湿过程中的热力学参数浸润功和动力学参数润湿速度(润湿时间),研究了再生剂自身性质、环境温度及沥青老化程度对界面扩散行为的影响.结果表明:环氧大豆油(ESO)的掺入降低了再生剂的接触角,增大了浸润功,加快了润湿速度,缩短了润湿时间,提升了再生剂的润湿性能,促进了再生剂-老化沥青的界面扩散,而十二烷基苯磺酸(DBSA)的掺入则对再生剂-老化沥青的界面扩散有不利影响;温度对再生剂-老化沥青界面扩散行为影响显著,随着温度升高,再生剂的黏度降低,接触角减小,润湿速度加快,再生剂在较短时间内即可充分包裹老化沥青表面;再生剂表面张力越大,其在老化沥青表面浸润功越大,界面扩散动力越大,扩散过程更易自发进行;再生剂在老化沥青表面的接触角越小,其在老化沥青表面的润湿速度越快,再生剂液滴更容易形成包裹老化沥青表面的再生剂膜;再生剂的黏度越低,流动性越好,其在老化沥青表面的润湿速度越快,有利于再生剂-老化沥青界面的扩散;沥青的老化对再生剂-老化沥青的界面扩散有不利影响,随沥青老化程度的加深,再生剂在其表面的润湿性能下降,界面扩散程度降低.故为保证再生剂对老化沥青的再生效果,在再生剂选择及研发时,应优先选用表面张力更大、黏度更低且与老化沥青间接触角更小的再生剂.

The roads’ renovation and reconstruction not only requires a lot of economics, but also causes serious environmental problems. Preventive maintenance has significant economic and environmental benefits. Therefore, as an effective preventive maintenance material, rejuvenator has received extensive attention from researchers in the past three decades. However, there is few concerns about single component’s impact on the regeneration effect of aged asphalt. In this study, four kinds of mono-component modifiers including ethanol, acetaldehyde, ethylenediamine and acetone was used to prepare mono-component modified rejuvenators. The regeneration effect of mono-component modified rejuvenators was then characterized and compared by fundamental physical properties and viscoelastic properties to study the effective contributions of different chemical functional groups on regenerative process of aged asphalt. The results show that the change of asphalt properties caused by aging and regeneration differ obviously depending on the type of aged binder and mono-component. Therefore, it is necessary to examine the aging degree and conditions of asphalt material, in the case where it is considered to use rejuvenators to maintain the asphalt pavement, thereby selecting the types of rejuvenator material accordingly.

通过使用二氧化钛,二氧化硅,硅藻土以及其它辅助基料(分散剂,消泡剂,树脂等)成功制备了一种新型的沥青路面热反射涂层.其中二氧化钛填料所占比例在15％～25％,四种主体填料二氧化钛、二氧化硅、硅藻土、成膜物质体积的最佳配比为1:0.25:0.05:4.565.通过涂层降温效果中的实验数据分析,该种新型沥青路面热反射涂层对其覆盖物的降温效果能达到12～15℃.