水泥乳化沥青砂浆用乳化沥青的配制与研究

乳化沥青是高速铁路板式无砟轨道弹性垫层专用填充材料水泥乳化沥青砂浆(以下简称"CA砂浆")的关键组成部分,具有与水泥相容性好、黏度大、破乳速度慢、抗冻性和耐久性强等优点,它和水泥等多种原材料在常温下拌合而形成具有混凝土刚性和沥青     

浅析CRTSⅡ型板水泥乳化沥青砂浆充填层施工质量控制

无砟轨道施工具有技术新颖、工艺标准及质量要求高、对安全运营影响大等特点,是维系高速铁路安全质量的核心结构,是保障“和谐号”列车平安运行的关键环节,而CRTSⅡ型板式无砟轨道的核心技术就是水泥乳化沥青砂浆充填层的施工质量控制。本文对水泥乳化沥青砂浆的原材料运输及存储、砂浆拌制及中转、轨道板润湿、封边、限位工艺控制、灌注工艺控制以及砂浆养护工艺等施工质量控制要点进行了相应的阐述。     

CRTSI型板式无砟轨道水泥乳化沥青砂浆施工质量控制

本文根据CRTSI型板式无砟轨道水泥乳化沥青（CA）砂浆设计要求,通过原材料优化选择和现场施工验证,对CA砂浆的施工工艺进行总结和探讨,对类似的施工有一定的借鉴意义。     

CRTS Ⅰ型板式无砟轨道水泥乳化沥青砂浆施工质量控制

本文根据CRTS Ⅰ型板式无砟轨道水泥乳化沥青(CA)砂浆设计要求,通过原材料优化选择和现场施工验证,对CA砂浆的施工工艺进行总结和探讨,对类似的施工有一定的借鉴意义.     

高速铁路无砟轨道CA砂浆施工技术

近年来,CA砂浆在我国高速铁路板式无砟轨道建设中广泛应用,本文着重结合武广客运专线CA砂浆施工的经验,阐述了CA砂浆的施工工艺技术等相关方面的知识。     

CA砂浆的研究现状与问题

<正>1、CA砂浆的概念CA砂浆,即水泥沥青砂浆,由乳化沥青、水泥、骨料和水等混合而成,是一种介于水泥基和沥青基材料之间的半刚性体胶凝材料。作为缓冲充填材料,既是有一定的弹性,又是有一定的强度。水泥砂浆强度高但弹性不足,沥青弹性好但强度不足,且受温度影响大。而CA砂浆固化后,既能提供无碴轨道结构所需的必要强度,又能为结构提供一定的弹性,在无碴轨道结构中起着重要作用,因其良好的工作性能,已逐渐成为无碴轨道道床材料的最佳选择。     

水泥乳化沥青砂浆性能研究现状

水泥乳化沥青砂浆(简称CA砂浆)是无砟轨道的重要层位,近年来关于CA砂浆的研究与应用成为行业热点.通过梳理现有研究成果发现,目前国内外关于CA砂浆的研究主要集中在配合比设计、静动态力学性能、微观结构分析和耐久性等四个方面,形成了基本完善的配合比设计方法,在原材料对力学性能和耐久性的影响规律方面有了基本了解,未来在动态力学性能、宏微观关系及耐久性方面仍需要进一步开展相关研究,以提高CA砂浆的使用性能.     

水泥乳化沥青砂浆微观结构分析

本文通过对水泥乳化沥青砂浆材料的孔结构分析、电子显微分析以及水泥乳化沥青砂浆与混凝土界面结合方式的分析研究,得出材料种类和组成对微观结构的影响,有助于加深水泥乳化沥青砂浆复合材料微观性能的认识,提高该材料的技术开发与应用水平。     

桥上CRTSII型道岔板砂浆离缝影响特性研究

水泥乳化沥青砂浆离缝是桥上纵连板式无砟轨道主要伤损型式之一。参考18号无砟道岔的结构形式,简化建立桥梁-纵连板式道岔垂向耦合静力和动力分析模型,应用有限单元法,计算分析了不同程度的道岔板下砂浆离缝对道岔结构变形及受力影响。研究表明,板下砂浆层发生离缝,对道岔板及钢轨的影响较底座板更明显。不同离缝形式对结构的影响程度不同,当离缝发生在板端时,道岔结构受力与变形最不利;发生在板中时,道岔板的翘曲位移变化不明显。依据计算结果得出板底砂浆离缝尺寸对道岔结构的影响规律,同时从无砟轨道稳定性角度出发,初步提出砂浆离缝尺寸限值,道岔板下砂浆离缝垂向高度低于1.8mm,沿线路纵向离缝长度小于0.7mm。     

墩台沉降对桥上纵连板式无砟轨道线路动力影响

基于耦合动力学理论,考虑纵连板式无砟轨道-桥梁系统各部件间非线性接触,建立高速列车-纵连板式无砟轨道-桥梁三维非线性有限元耦合动力学模型。运用建立的模型,研究高速列车在桥上纵连板式无砟轨道线路墩台不均匀沉降区段行驶时,墩台沉降对高速列车-纵连板式无砟轨道-桥梁耦合系统动力特性的影响。研究结果如下:①墩台不均匀沉降对高速列车、纵连板式无砟轨道各部件振动特性有很大影响,但对桥梁振动影响相对较小;②墩台不均匀沉降对最大垂向轮轨力、扣件最大压力影响较小,而对钢轨最大正弯矩、扣件最大拉力、轨道板和底座板纵向最大拉应力、CA砂浆最大压应力影响较大;③墩台不均匀沉降对耦合系统振动特性及无砟轨道动应力特性的影响不是简单的单调线性增加,而与墩台不均匀沉降引起的无砟轨道各部件间、无砟轨道与桥梁间局部脱空有关。     

A novel method to evaluate the setting process of cement and asphalt emulsion in CA mortar

Cement and asphalt mortar (CA mortar) is the key component in the structure of Shinkansen slab track and serves as the elastic shock-absorber. A new method was put forward to evaluate the setting process of cement and asphalt emulsion (CAE) in CA mortar. It was noted that the setting process was governed by several factors such as cement types, cement/asphalt emulsion ratios (C/AE ratio). Results also indicated that the setting process of CAE was faster, the higher proportion of cement content was; the early age strength and the separation rate of CA mortar could be improved by using cement of high early age strength and rapid hydration rate, or a blended cement with ordinary Portland cement partially replaced by sulfoaluminate cement, or by increasing C/AE ratio. Nevertheless, the replacement ratio of ordinary Portland cement by sulfoaluminate cement should not exceed 15% and C/AE ratio should be not less than 0.8.     

基于高速铁路路基冻胀的轮轨动力响应研究

季节性冻土区高速铁路无砟轨道路基冻胀,影响了列车运行的安全性、舒适性以及无砟轨道主体结构的服役性能。为研究路基冻胀和高速行车荷载组合效应下的轮轨动力响应,建立了车辆-轨道-路基冻胀耦合动力学模型,对路基不同冻胀幅值、冻胀位置和行车速度下CRTSⅠ型板式无砟轨道轮轨动力响应及轨道结构受力进行分析。结果表明:冻胀发生区段轮轨动力响应增大,列车以350 km/h运行时的安全性和舒适性满足冻胀管理标准要求,但轮轨力随冻胀幅值和速度的增加而增大;轨道板和底座板振动加剧,在计算冻胀波长和幅值范围内,离缝处轨道板振动加速度峰值超过动态验收标准要求,容易引起离缝处CA砂浆层及路基基床表层伤损破坏,且轨道板、底座板振动加速度随行车速度增加而增大;轨道结构动应力和列车荷载传递关系密切,路基冻胀状态下列车荷载引起轨道板和底座板处于交替和交变的拉压受力状态,需要在设计中提出控制裂纹的措施,行车速度对短波冻胀时轨道结构受力影响较小。     

Study on the mechanical performance and application of the composite cement–asphalt mixture

The rigidity of matrix mixture asphalt (MMA) is increased by the combination with cement mortar, and the performance of asphalt pavement has been better changed in the stabilities of high temperature rut and low temperature cracking and water damage. The research problems in this project mainly focus on the combinations among cement mortar and MMA and mechanical performance of composite cement–asphalt mixture (CCAM), etc. In the project, the CCAM is produced by pouring cement mortar into MMA, and the mechanical performance of CCAM has been researched. The research contents include the production technology and mechanical performance and construction technology of CCAM. Through the test data of CCAM in the mechanical performance, and compared with the performance of AC-16 MMA, the paper has analysed the mechanical performance and application of CCAM in high temperature rut and low temperature cracking and water damage, the components design and production technology and construction technology of CCAM have been put forward. The rigidity of MMA has been improved and the mechanical performance of CCAM has also met the design standards, it is suggested that CCAM can be applied as a new composite pavement materials.     

Modelling calcium leaching kinetics of cement asphalt paste

Calcium leaching is an important durability problem for cement asphalt (CA) mortar used in ballastless slab track which is under the coupled action of train-induced dynamic load and rainwater erosion. In this paper, a model based on the calcium mass conservation and the thermodynamic equilibrium of calcium was developed to describe the calcium leaching of CA paste in both deionized water and ammonium nitrate solution. In this model, the spatial–temporal distribution of solid calcium content in skeleton, porosity and diffusivity, which are directly or indirectly relevant to the calcium concentration in pore solution, were considered. Finite difference method was utilized to solve this model, and a three layer Crank–Nicolson differential scheme was applied to improve the stability. The model was experimentally verified using the Ca/Si molar ratio in solid and the calcium leaching rate characterized by SEM–EDX and potentiometric titration respectively. It was found that asphalt content does not change the spatial distribution of solid calcium in CA paste. Asphalt affects the leaching rate by reducing solid calcium concentration and changing the activation energy of micro-pore wall. Accelerating factors by ammonium nitrate solution were experimentally determined and predicted by the model.     

老化对水泥乳化沥青胶结料动态力学性能的影响

基于分数导数修正Burgers模型,建立了水泥乳化沥青胶结料（简称复合胶结料）的本构方程。结合不同材料配比的复合胶结料的老化试验及频率扫描试验,分析了老化时间及材料配比等因素对复合胶结料黏弹性力学参数的影响。研究表明,复合胶结料的存储模量与损耗模量均随老化时间的增加而增大,在老化时间为0~8 h时,存储模量及损耗模量增加较快,当老化时间超过8 h后,其增长趋势减缓。对于乳化沥青与水泥的质量比（m_A/m_C）为1.2和1.4的复合胶结料,在不同的加载频率下,其相位角均随老化时间的增加而减小。对于m_A/m_C为1.0的复合胶结料,其相位角随着老化时间的增加呈现先增加后减小的变化规律。随着老化时间的增加,复合胶结料趋向于弹性材料的力学性质。分数导数修正Burgers模型可以较好的描述老化后复合胶结料的黏弹性动态力学行为,模型参数弹性模量E₁、黏度η₁和分数导数r可以描述老化情况下材料黏弹特性的变化规律。     

Interaction mechanism of cement and asphalt emulsion in asphalt emulsion mixtures

The interaction characteristics of cement asphalt composite mastic (CAM) and performance properties of cement asphalt emulsion mixtures (CAEM) were evaluated in this work using chemical and mechanical test methods to investigate the effect of the presence of cement on asphalt emulsion mixtures (AEM). The chemical composition of the CAM was obtained through use of X-ray diffraction, Fourier-transform infrared spectroscopy, and environmental scanning electron microscopy (ESEM) as a means to describe the interactions between the cement and asphalt in the composite materials. Test results demonstrated that cement can hydrate with the water phase of the asphalt emulsion. Asphalt droplets can simultaneously enclose cement particles and delay the hydration reaction process of cement. The interaction mechanism of cement particles or hydration products and residual asphalt is a physical compound process. The influence of these findings on asphalt emulsion mixture design and performance properties was assessed using varying mix design components and conducting laboratory-based mechanical test methods for rutting resistance and moisture susceptibility. Mix design components varied including added water content, emulsion content, and cement dosage levels. The optimum fluids content was determined based on the dry indirect tensile strength. It was found that the cement content significantly impacts the optimum fluids content for both added water and emulsion. Furthermore, the presence of cement improves the dry tensile strength, rutting resistance, and moisture susceptibility. Based on microstructural analysis of CAM and CAEM, the mechanism by which cement improves the performance of AEM is attributed to the ability of hydration products to increase both the stiffness of the asphalt binder and the adhesion at the mastic–aggregate interface. In practical applications, this study recommends a mix design method for cement-modified asphalt emulsion mixes (CAEM) based on selection of optimum cement and emulsion contents using indirect tensile strength and verification of the design through evaluation of the moisture susceptibility and rutting resistance of the CAEM mix. Threshold values of CAEM mix mechanical properties to determine the quality of the design are proposed.     

Early age volume change of cement asphalt mortar in the presence of aluminum powder

Cement asphalt mortar (CA mortar) is a highly flowable grouting material used in the slab track structure. CA mortar is required to possess a volume expansion rate of 1.0–3.0% after 24 h to guarantee a desired filling effect. This is achieved by the incorporation of aluminum powder (AP). The article investigates the volume change of CA mortar under various AP dosages, temperatures and asphalt emulsion/cement ratio (A/C). Results indicate that when AP is absent, volume shrinkage of 1.8–3.0% is noted at temperatures of 10–30°C; upon the addition of 0.013–0.021% AP, CA mortar undergoes slight volume shrinkage before 4 h, and then keeps expanding until about 24 h after which volume expansion slows down gradually; the expansion rate of CA mortar is greater, the lower the temperature is, and also the higher A/C is.     

轨道结构建模精细化程度对高速铁路连续梁桥地震易损性的影响

为探究CRTS Ⅱ板式无砟轨道结构建模精细化程度对高速铁路连续梁桥地震易损性曲线的影响,以一座48 m+80 m+48 m高速铁路预应力混凝土连续梁桥为例,采用有限元分析软件OpenSEES分别建立四个轨道结构建模精细化程度不同的线桥一体化模型,进行了非线性时程分析和易损性分析,构造了桥梁各关键构件和轨道结构各部件的易损性曲线。计算结果表明,在建立轨道-桥梁一体化模型研究高铁连续梁桥抗震性能时,轨道结构建模精细化程度对滑动层的地震易损性曲线影响很大。随着轨道结构建模的精细化程度降低,滑动层发生地震破坏的概率变大。同时,轨道结构建模越简单,滑动支座发生破坏的概率略微增加,桥墩发生破坏的概率略微减小。此外,轨道结构建模的精细化程度对CA层、扣件、桩基等构件的地震易损性曲线基本上没有影响。     

CRTS Ⅱ型轨道板/CA砂浆界面内聚力模型研究

轨道板与CA砂浆层间离缝是CRTS Ⅱ型板式无砟轨道结构的主要病害之一。为描述轨道板-CA砂浆层间界面本构行为、揭示层间离缝机理,该文提出了一种改进指数型界面内聚力模型,并基于理论分析和试验数据确定了改进模型的参数取值。该模型为含有指数系数的分段函数,可以表征层间界面拉力-位移关系的非线性特征。研究结果表明:改进指数型内聚力模型可以高效计算轨道板-CA砂浆界面内聚强度、损伤萌生时界面相对位移和界面临界断裂能,结果与试验值基本一致;改进指数型模型可以较为准确地模拟轨道板-CA砂浆界面的法向和切向开裂行为。     

Ⅰ型双块式无砟轨道传力杆受力研究

随着我国高速铁路的不断发展,Ⅰ型双块式无砟轨道结构得到了广泛应用。由于Ⅰ型双块式无砟轨道是连续结构,当铺设在温度变化较大的线路上时,会出现严重的开裂和上拱问题。为了适应兰新二线大温度跨度、大温差的线路条件,考虑将道床板断开为单元板,并在伸缩缝处设置传力杆,以保证轨道结构竖向和横向的稳定性。该文主要用有限元法计算不同传力杆数目时轨道结构的应力和变形,来研究传力杆的力学性能并确定传力杆最佳数目,最终建议传力杆数目不少于4根。