Effect of filler on low temperature physical hardening of bitumen

Laboratory investigations of low temperature physical hardening of bitumen using a Bending Beam Rheometer (BBR) are described. The study encompasses five bitumens, three conditions with regard to additives and three testing temperatures (−15, −25 and −30°C). As additives, two fillers, hydrated lime and calcium carbonate, were used. The effect of the fillers on the isothermal low temperature hardening was evaluated with the aid of a physical hardening index. The viscoelastic nature of the bitumens and bitumen/filler mixtures was investigated utilising the Burger model, and the Burger parameters were used to calculate dissipation energy ratios (dissipated energy over stored energy) in each BBR test. The results obtained did not indicate any significant effect of the fillers on low temperature physical hardening. Analyses of the dissipation energy ratio showed a considerable capacity for energy dissipation, even at a temperature as low as −30°C. With few exceptions, more energy was dissipated than stored during a BBR test. It appears that the dissipation energy ratio is not necessarily related to the stiffness of the binder.     

Morphology and image analysis of polymer modified bitumens

This paper presents a laboratory study of styrene butadiene styrene (SBS); ethylene vinyl acetate (EVA) and ethylene butyl acrylate (EBA) based polymer modified bitumen samples (PMBs). The PMBs have been produced by mixing a 50/70 penetration grade unmodified (base) bitumen with copolymers at different proportions. The fundamental characteristics of the PMBs have been determined using conventional methods. The morphology of the samples as well as the percent area distribution of polymers throughout the base bitumen have been characterized and determined by means of fluorescent light optic microscopy and Qwin-Plus image analysis software, respectively. The results indicate that the fundamental properties and morphology of the modified bitumens are dependent on the type of polymer and polymer content. Polymer modification improves the conventional properties of the base bitumen such as penetration, softening point, temperature susceptibility. At low polymer contents, the samples reveal the existence of dispersed polymer particles in a continuous bitumen phase, whereas at high polymer contents a continuous polymer phase is observed. Moreover it is found out that a relationship exists between the polymer content and percent area distribution of polymers.     

Rheological evaluation of ethylene vinyl acetate polymer modified bitumens

The morphological, thermal and fundamental rheological characteristics of ethylene vinyl acetate (EVA) copolymer modified bitumens are studied in this paper. Nine plastomeric EVA polymer modified bitumens (PMBs) have been produced by laboratory mixing bitumen from three sources with an EVA copolymer at three polymer contents. The morphology, thermal properties and rheological characteristics of the EVA PMBs have been analysed using fluorescent microscopy, differential scanning calorometry and dynamic mechanical analysis using a dynamic shear rheometer, respectively. The results of the investigation indicate that EVA polymer modification increases binder stiffness and elasticity at high service temperatures and low loading frequencies with the degree of modification being a function of bitumen source, bitumen–polymer compatibility and polymer concentration. Filler type modification is evident at low temperatures, temperatures above the melting temperature of the semi-crystalline EVA copolymer and for those modified binders that do not exhibit a dominant polymer network.     

Low-temperature properties of styrene–butadiene–styrene polymer modified bitumens

Low-temperature properties of the modified bitumens containing styrene–butadiene–styrene (SBS) polymers were investigated using conventional methods, dynamic mechanical analysis (DMA) and bending beam rheometer (BBR). Effects of the characteristics of base bitumens and polymers and the proportion of the components on these properties were studied. The results indicated that SBS polymers improved low-temperature properties of bitumens. The degree of improvement generally increased with SBS content and were influenced slightly by SBS structure. The study also showed a statistically linear relationships between different low-temperature parameters.     

胶粉改性沥青混合料低温特性试验研究

为研究胶粉改性沥青混合料低温抗裂性能,采用沥青混合料小梁弯曲蠕变试验对胶粉改性沥青混合料的低温性能进行检验,并以SBS改性沥青混合料作为参照,结果表明,胶粉改性沥青混合料的感温性较弱,材料力学性能受温度影响较小,与SBS改性沥青混合料相比低温不易开裂。     

SBS改性沥青低温性能研究

采用低温延度、当量脆点和弹性恢复等指标对SBS1301-1,SBS4303-2改性沥青的低温性能进行了研究,研究结果表明:掺入SBS改性剂,可提高沥青的低温性能,并得出这两种改性沥青最佳掺量均为4%的结论。     

聚合物改性混凝土抗压性能的温度敏感性研究

聚合物改性混凝土(PMC)因其具有较高的变形性能而被用于结构的延性设计和施工中,但其聚合物的物理性能受环境温度影响较大。研究了掺入不同比例聚丙烯酸酯乳液PMC抗压强度与环境温度的关系。试验证明PMC弹性模量、轴心抗压强度和峰值应变存在温度敏感性,并且聚灰比越大温度敏感性越高,并推导出了PMC轴心抗压强度与损伤的函数关系,为PMC在寒冷或炎热地区的设计和施工提供参考。     

低温早强耐久性混凝土施工质量控制

针对青藏高原独特的气候特征,介绍了混凝土耐久性能指标的要求,分析了影响混凝土耐久性的不利因素,重点探讨了为确保混凝土耐久性能所采取的质量控制措施,以供参考。     

Investigation on the performance and detoxification of modified low temperature coal tar pitch

In this paper, studies on the modification on the low temperature coal tar pitch extracted from coal tar residue in Inner Mongolia are conducted. First, the low temperature coal tar pitch in liquid state is solidified with a higher softening point by chemical crosslinking modification. The modified coal tar pitch can achieve the standard pavement performance requirements. Then, the effects of chemical crosslinking agent and physical modification additives on the mechanical performance and toxic properties of coal tar pitch are investigated. The detoxification mechanism is also studied, which further promote the applicability of modified low temperature coal tar pitch in the pavement constructions.     

低温低浊水混凝实验研究

针对石墩子山水厂低温低浊（每年11月份至第二年4月份）的特点,对乌拉泊水库原水和乌拉泊水库原水与滤池反冲洗排水在配水井内的混合水进行混凝实验,实验表明：对于低温低浊水,PAC的最佳投加量为12mg/L,以PAM为助凝剂,除浊效果较好;PAM的投加时间对絮凝效果有较大的影响。     

丁苯橡胶改性沥青低温性能及共混工艺的研究

本文提出丁苯橡胶与沥青的无溶剂共混工艺,并着重探讨丁苯橡胶改性沥青的低温力学性能与改性机理。     

EVA改性沥青混合料路用性能的室内研究

通过室内试验，系统地分析了EVA对沥青性能的影响，介绍了EVA改性沥青的基本性质以及性能，证明了EVA改性沥青不仅具有明显的抗高温稳定性，而且具有一定的低温柔韧性。     

双掺改性聚合物砂浆性能的试验研究

研究了掺增韧剂和纤维进行改性的环氧砂浆抗压、抗弯、抗拉、粘结及弹性模量等性能。结果表明：采用聚硫橡胶和纤维对环氧砂浆进行复合改性，有较好的增韧、抗裂效果；同时，对环氧胶料的固化时间、力学性能、变形性有明显改善。     

弹性体改性沥青涂盖料的低温拉伸性能研究

通过延度试验对弹性体改性沥青涂盖料的低温拉伸性能进行了测试分析,研究了SBS型号、基质沥青、相容剂含量、配合剂种类及含量、填充料种类及含量对改性沥青涂盖料延度性能的影响。结果表明,延度可以比较全面地反映弹性体改性沥青涂盖料的低温拉伸性能,是评价弹性体改性沥青涂盖料低温性能简单有效的方法。     

低碳源改良A~2O工艺低温优化运行模式研究

采用中试规模试验,利用全流程和实验室模拟分析方法,探讨了改良A2O工艺功能段具体运行情况,以期掌握稳定运行的关键性参数,从而建立基于低碳源、低温的污水厂优化运行模式。     

SBS改性沥青的黏温特性研究

SBS改性沥青的黏温特性与普通沥青不同。用目前的黏度测试方法测试SBS改性沥青黏度,根据黏温曲线确定的SBS改性沥青混合料的拌和与压实温度过高,过高的拌和与压实温度会引起SBS改性沥青的老化、环境和生产安全问题。从改性沥青的高温流变特性入手,分析改性沥青的黏度试验方法,研究SBS改性沥青的黏度变化规律。由试验结果可知,当温度低于150℃时,黏度对温度的依赖性很大,但是当温度高于150℃时,黏度对温度的依赖性逐渐减小;随着温度的升高,SBS改性沥青的黏度值对剪切速率的依赖性逐渐减弱。因此在测试SBS改性沥青的黏度时,必须在试验温度下规定相应的剪切速率,这对合理确定SBS改性沥青的拌和与压实温度至关重要。     

低温柔性优良的聚合物水泥防水涂料的研制

低温柔性优良的聚合物水泥防水涂料，以纯丙烯酸乳液、水泥为主要原料，填料全部采用工业废料，再加入自制的复合增塑剂、干燥促进剂以及适当助剂配制而成该涂料低温柔性可达-35℃，一次涂刷干膜厚度可达1-2mm。     

聚合物黏度及温度对透水混凝土性能影响的试验研究

采用3种改性效果较好的聚合物改性剂,研究聚合物黏度随浓度和温度的变化规律及聚合物黏度对透水混凝土的力学性能及透水性的影响,得出利于施工拌合的混凝土最佳温度范围。结果表明:HPMC、EP及PVA聚合物溶液的浓度与黏度成正相关,温度与黏度成负相关;3种聚合物对透水混凝土的力学以及透水性能具有明显的提高作用,其中HPMC对抗压强度的改善效果最好,PVA聚合物透水混凝土的抗折强度最高但变化幅度大,EP聚合物透水混凝土的透水效果最佳且满足设计要求;在最长浇筑时间范围内,HPMC、EP及PVA聚合物透水混凝土的出机温度应分别高于55、45、40℃,其坍落度及流动性都满足设计与实际施工要求。     

Laboratory study of an injected granular soil with polymer grouts

Soil or rock mass with low strength or high permeability may not be appropriate for an excavation project or for use as a structural support. These soils or rock mass can cause severe damages to overlying structures, because of their considerable distress. Therefore, a suitable ground improvement technique is needed for deep excavations in order to confront these problems. The increase in strength and durability, as well as the reduction in compressibility and porosity are the main aims of a ground improvement technique. Grouting is the commonly used method to meet the above requirements. In recent years, various types of water soluble polymers are used as additives in cement grouts to improve the soil properties. The main objective of this laboratory project was to investigate the use of such materials for the improvement of physical and mechanical properties of a granular soil. Grouts were prepared by using cement, clay, water in different percentages along with an amount of acrylic resin or methyl methacrylate co-polymer emulsion. These two substances are the most widely used non-toxic additives in concrete structures and applications due to their significant contribution to the improvement of physical and mechanical properties of mortars or concretes. Grouting experiments were performed through 10-cm diameter and 150-cm height columns, filled with granular soil with particle size distribution of 2 – 12.7 mm. The experimental results reveal that the addition of latexes in thick pure cement grouts improves substantially the physical and mechanical properties of the injected soil.     

Mineralogical study of polymer modified mortar with silica fume

Experimental investigation on the effects of styrene acrylic polymer and silica fume on the mineralogical composition of pastes of high-early-strength portland cement after 28 days of casting are presented in this paper. Thermogravimetry and derivative thermogravimetry were used to study the interaction between polymers and cements, and the extent of pozzolanic reaction of mortars with silica fume. Differential scanning calorimetry and X-ray diffraction were also used to investigate the cement hydration according to the additions. The results showed that the addition of silica fume and polymer reduces the portlandite formation due to delaying of portland cement hydration and pozzolanic reaction.