自应力弹性沥青混合料路面除冰效果研究

采用在车辙试件上洒水并在低温环境下凝冰的方法,模拟了沥青路面结冰情况,并在不同温度、橡胶颗粒掺量以及凝冰厚度的条件下,用车辙仪对凝冰试件进行了碾压,通过计算不同条件下的冰层破损率,评价了自应力弹性沥青混合料路面的除冰效果,结果表明,SEAM的除冰效果随橡胶颗粒掺量的增加而提高,随温度的降低和冰层厚度的增加而下降。     

沥青含量对多孔隙沥青混合料性能的影响

本文通过旋转压实试验分析沥青结合料含量与沥青混合料体积性能的关系。结果表明:多孔隙沥青混合料密度随沥青含量的增加而增加;混合料的空隙率随沥青含量的增加而减小;孔隙率随沥青含量的增加而降低;沥青饱和度随沥青含量的增加呈线性递增关系;沥青含量越低,多孔隙沥青混合料渗透性越高;多孔隙沥青混合料磨损损失随沥青含量的增加而降低。     

国产环氧沥青混合料强度增长规律研究

选取国产环氧沥青进行试验研究,重点研究了国产环氧沥青混合料在常温下的强度发展规律,并由此确定了国产环氧沥青混合料铺装层在常温下需要养生30 d以上方能开放交通。     

浅析热拌冷铺沥青混合料的强度形成机理

介绍了热拌冷铺沥青混合料技术的应用及优越性，通过试验分析了冷铺沥青混合料的组成特点与强度形成机理，论证了冷铺沥青混合料的强度与矿粉用量、粘聚力、骨料的摩擦角的关系。     

Effect of bitumen wax on asphalt mixture performance

This paper mainly deals with waxes which are naturally present in bitumens, and does not include synthetic waxes that sometimes are proposed as bitumen additives. The main objectives were to study the rheological effect of bitumen waxes and the impact of waxy bitumens on asphalt mixture performance, such as rutting, low temperature cracking, and water sensitivity. In the rheological characterisation of bitumens, a dynamic shear rheometer (DSR) and bending beam rheometer (BBR), as well as various conventional methods, were used. For asphalt mixtures, rutting, low temperature cracking and water sensitivity were evaluated by wheel tracking test (WTT), thermal stress restrained specimen test (TSRST), and modified Lottman test, respectively. It was found that, at high service temperatures and within the same bitumen grade, differences in rutting between the asphalt mixtures made with waxy and non-waxy bitumens were relatively small. However, the presence of wax in bitumen resulted in physical hardening at low temperatures. Using waxy bitumens, asphalt mixtures tended to show higher fracture temperature. As regards water sensitivity, no effect of the wax content in bitumen was seen. The water sensitivity was however heavily influenced by type of aggregate and to less extent by bitumen type. The present study implies that the effect of wax on bitumen quality and asphalt mixture performance depends on many factors. Those may include the chemical composition of the bitumen and particularly the nature of the wax.     

添加剂对凝灰岩沥青混合料粘附性能影响

为改善凝灰岩沥青混合料的粘附性能,以掺水泥和抗剥落剂凝灰岩沥青混合料为研究对象,选取石灰岩沥青混合料为对比试样,通过水煮法试验、老化前后水稳定性试验,对凝灰岩沥青混合料的粘附性能研究。结果表明:掺入适量添加剂可使凝灰岩集料的粘附等级显著提高,并接近石灰岩集料等级;掺水泥对凝灰岩沥青混合料老化后残留稳定度和冻融劈裂强度比的提升效果均优于掺抗剥落剂,与不掺添加剂的凝灰岩沥青混合料相比,水泥掺量2%、3%下,凝灰岩沥青混合料的老化后残留稳定度分别提高了21.5%、21.7%,冻融劈裂强度比分别增大了16.7%、15.3%,均接近于石灰岩沥青混合料。掺液体抗剥落剂对凝灰岩沥青混合料的冻融劈裂强度比提升效果欠佳。     

The effects of porosity,asphalt content and fiberglass incorporation on the tensile strength and resilient modulus of asphalt concrete blends

Asphalt concrete is the prevailing material used for road surface construction. Its adequate characteristics in providing stability, durability and driving safety are controlled by complex interactions between its components. Thus, it is important to estimate the sensitivity of asphalt concrete mechanical properties as a function of its volumetrics. For this study, different combinations between asphalt content (3.5, 5 and 7.5%) and porosity values (above 4%) were used in order to disassociate these properties. The influence of mixing in fiberglass (0.5%) was also analyzed. It was found that porosity is significantly more relevant than the asphalt content in the prediction of tensile strength and resilient modulus of fiber-free asphalt concretes. In fiber-reinforced mixtures, the mechanical properties are improved by increasing the asphalt content, which suggests a better bonding between fibers and aggregates. For both cases, decreasing porosity is beneficial. By grouping both sets of results, it was possible to create a unique theoretical curve for both the tensile strength (q_t) and the resilient modulus (RM). The RM/q_t ratio was 5800 for the fiber-free group, and 3900 for the fiber-reinforced group - suggesting a better fatigue life indicator for asphalt concretes when fibers are added.     

溶剂型冷补沥青混合料强度参数评价及指标研究

基于冷补沥青混合料强度变化规律,从冷补混合料的初始强度、成型强度以及强度成型速度等方面,探讨了冷补沥青混合料强度参数的评价方法及指标要求,通过设置不同试验条件下的改进型马歇尔试验,同时结合冷补沥青混合料性能要求,提出了适合于冷补沥青混合料使用要求的强度指标。     

新型高效阻燃剂对沥青混合料体积指标的影响

采用内掺法与外掺法将自制的新型高效阻燃剂按照沥青质量的6%、9%、12%、15%、18%、21%添加到沥青混合料中,检测其毛体积密度、空隙率、流值、稳定度、VWA、VFA等体积指标,探讨阻燃剂添加方式及掺量对沥青混合料体积指标的影响。结果表明:阻燃剂的加入对沥青混合料体积指标影响较大;添加方式不同,对阻燃沥青混合料的各项指标影响不同;当阻燃剂添加量在10%以内时,采用外掺法较为合适;当添加量在10%~15%时,内掺法较为合适;当添加量在20%以上时由于其对沥青混合料体积指标影响较大,不建议使用如此高的添加量。     

Effect of discrete fibre reinforcement on soil tensile strength

The tensile behaviour of soil plays a significantly important role in various engineering applications. Compacted soils used in geotechnical constructions such as dams and clayey liners in waste containment facilities can suffer from cracking due to tensile failure. In order to increase soil tensile strength, discrete fibre reinforcement technique was proposed. An innovative tensile apparatus was developed to deter- mine the tensile strength characteristics of fibre reinforced soil. The effects of fibre content, dry density and water content on the tensile strength were studied. The results indicate that the developed test apparatus was applicable in determining tensile strength of soils. Fibre inclusion can significantly in- crease soil tensile strength and soil tensile failure ductility. The tensile strength basically increases with increasing fibre content. As the fibre content increases from 0% to 0.2%, the tensile strength increases by 65.7%. The tensile strength of fibre reinforced soil increases with increasing dry density and decreases with decreasing water content. For instance, the tensile strength at a dry density of 1.7 Mg/m^3 is 2.8 times higher than that at 1.4 Mg/m^3. It decreases by 30% as the water content increases from 14.5% to 20.5%. Furthermore, it is observed that the tensile strength of fibre reinforced soil is dominated by fibre pull-out resistance, depending on the interracial mechanical interaction between fibre surface and soil matrix.     

沥青混合料劈裂强度与压实度及路用性能相关性研究

为评估15℃劈裂强度作为沥青路面交工验收指标的合理性,选择Sup-13、Sup-20、ATB-25和SMA-13四种沥青混合料,研究15℃劈裂强度与芯样压实度及沥青混合料路用性能的相关性。结果表明,沥青混合料15℃劈裂强度与芯样压实度呈正相关,当压实度为最大理论密度的93%时,Sup-13、Sup-20、SMA-13和ATB-25的劈裂强度分别为1.260MPa、1.423MPa、1.066MPa和1.470MPa。15℃劈裂强度与60℃动稳定度、冻融劈裂强度比和残留稳定度呈正相关,与低温破坏应变呈负相关,相关系数不低于0.6241。     

沥青路面沥青混合料针对性设计

由于沥青混合料设计不合理,造成沥青路面产生严重的车辙,因此沥青混合料原材料选择和配合比设计要充分考虑其对路面高温稳定性能的影响。从矿料的颗粒形状和化学性质、沥青性质、矿料级配、沥青混合料空隙率、矿料间隙率、路面中面层沥青混合料性能等方面对沥青路面车辙产生的原因进行了分析,提出了针对车辙产生原因的沥青混合料设计措施。     

沥青混合料再生技术研究

论述了沥青混合料再生技术研究现状,阐明了沥青再生的机理,按照再生方式对再生技术进行了分类和论述,指出了不同再生技术的特点和适用性,并对再生混合料的设计提出了相应的要求。     

硬质沥青富油混合料的性能研究

针对硬质沥青富油混合料的性能进行了研究,分别介绍了硬质沥青的性能及硬质沥青富油混合料配合比设计,并通过对比试验来评价富油沥青混合料的各种性能,从而得出了一些指导性结论。     

孔隙率对沥青混合料性能的影响

阐述了孔隙率的定义,讲述了孔隙率对沥青混合料性能的综合影响,介绍了实际工程中沥青混合料孔隙率控制应用时的注意事项,得出了高速公路沥青面层的最佳孔隙率。     

再生沥青混合料应用探讨

简要介绍了沥青的再生机理,依据再生剂的功能与技术要求,分析了再生沥青混合料的配合比设计方法,并对再生沥青混合料的力学性能、高温性能、抗裂性能及水稳性能等进行了试验验证,为再生沥青路面的设计、施工及推广提供了理论依据。     

浅析针片颗粒含量对沥青混合料性能的影响

通过对海南省东西部石场实际生产状况的调查,分析了针片状颗粒含量对集料性能的影响,并根据试验验证了针片状颗粒含量对沥青混合料路用性能的影响,对针片状颗粒产生的机理进行了研究,以寻求解决针片状颗粒含量的途径。     

Laboratory investigation of indirect tensile strength using roofing polyester waste fibers in hot mix asphalt

The vast quantity of waste materials (such as roofing polyester waste fibers) accumulating throughout the world is creating costly disposal problem. The use of these materials was proved to be economical, environmentally sound and effective in increasing the performance properties of the asphalt mixture in recent years. The primary objective of this research was to determine whether homogeneously dispersed roofing waste polyester fibers improve the indirect tensile strength (ITS) and moisture susceptibility properties of asphalt concrete mixtures containing various lengths and percentages of the fiber in various aggregate sources. The experimental design included the use of three aggregate sources, two lengths (0.635 cm (1/4 in.) and 1.270 cm (1/2 in.)) of this fiber, and two fiber contents (0.35% and 0.50% by weight of total mixture). The results of the experiments found that, in general, the addition of the polyester fiber was beneficial in improving the wet tensile strength and tensile strength ratio (TSR) of the modified mixture, increasing the toughness value in both dry and wet conditions, and increasing the void content, the asphalt content, the unit weight, and the Marshall stability.     

含水率对层状砂岩劈裂抗拉强度影响研究

为了研究含水率对层状岩体劈裂抗拉强度的影响,特选取层理显著的砂岩为研究对象,考虑5种含水率,进行顺层理弱面的劈裂抗拉强度试验,结合岩样劈裂破坏面的微观形貌特征和能量参数变化规律进行综合分析。研究结果表明:(1)随着含水率的增加,层状砂岩的抗拉强度逐渐减小,总体呈现先陡后缓的降低趋势,在饱水度低于80%左右时,抗拉强度降低幅度明显较大,而后抗拉强度降低趋势逐渐趋于缓慢;(2)岩样劈裂破坏面的高度参数和纹理参数都随着饱水度的增加而逐渐增大,呈先陡后缓的增长趋势,岩样抗拉强度与劈裂面微观形貌参数存在较好的线性相关性;(3)随着含水率的增加,加载过程中岩样吸收的总能量、弹性应变能逐渐减小,呈现与抗拉强度类似变化趋势,弹性应变能占总能量的比值逐渐减小,耗散能占总能量的比值逐渐增大;(4)层理弱面既是层状岩体结构的薄弱面,也是水分吸收和运移的主要空间和通道,含水率增加,首先是影响岩样层理弱面力学性状和孔隙水的分布,改变岩样加载过程中的裂纹扩展规律,进而影响加载过程中的弹性应变能和耗散能的分配比例,从而导致岩样劈裂破坏面形态趋于复杂,抗拉强度降低,水对岩样抗拉强度的影响是一个从微观结构变化导致宏观力学特性劣化的过程。     

沥青混合料集料级配选择研究

分析了沥青混合料集料级配理论，从理论方法、试验方法等方面介绍了级配评价方法，并从级配曲线的走向、各档集料的组成等，阐述了矿料级配的选择分析，以确保沥青混合料的路用性能。