沥青混合料再生剂的试验研究

应用阿布森法从沥青混合料中回收旧沥青,然后在回收沥青中掺配不同比例的再生剂使沥青再生,通过对再生沥青进行的试验,确定了再生剂的最佳掺配比例和再生剂对沥青性能的影响规律,结果表明,利用选择的再生剂再生后的沥青性能完全满足技术要求。     

A new procedure for measuring geosynthetic friction with an inclined plane

A method for the determination of the friction angle of geosynthetic interfaces (specifically those in contact with soils at very low normal stresses) using an inclined plane is described by the European Standard EN ISO 12957-2. Following this “Standard Displacement Procedure”, the friction angle of a geosynthetic interface is determined using a displacement criterion between the tested geosynthetics. However, the “Standard Displacement Procedure” seems to be poorly suited for many interfaces. Herein, a new procedure is proposed, called the “Force Procedure”, which consists of measuring the force required to restrain a box on top of the interface beyond a limiting value of sliding displacement. With the “Force Procedure”, the friction is determined from the curve of friction mobilization versus plane-inclination. The angle determined with the “Force Procedure” is not sensitive to the conditions of the test and is more representative of real-world conditions, as it takes into account displacements observed in the field. Based on the results of this study, it seems reasonable to suggest a revision of the EN ISO 12957-2 standard testing procedure.     

沥青混合料的施工配合比设计

结合工程实践,对沥青混合料的配合比组成设计进行了总结,从各种材料的准备和选用、沥青混合料的目标配合比设计及生产配合比设计三个方面进行了深入探讨,从而优化沥青混合料的配合比,保证工程质量.     

沥青路面二灰碎石配合比设计的探讨

通过对半刚性基层二灰碎石的反射裂缝的分析，提出对二灰碎石配合比的设计思路，介绍了裂缝的处理措施和防治方法，以减少反射裂缝的数量，保证路面的路用性能。     

SBS改性沥青混合料配合比设计及施工技术

结合工程实例,对沥青混合料的配合比设计进行了阐述,并对其设计过程中的注意问题进行了说明,论述了SBS改性沥青的施工技术要求,供类似工程参考借鉴。     

Influence of surface macro-texture and binder dosage on the adhesion between bituminous pavement layers

The effectiveness of an emulsion applied as a tack coat between bituminous pavement layers is usually analyzed according to the dosage and breakage of the emulsion used on site. In this paper different dosages between different bituminous mixtures were analyzed using shear tests, leading to the conclusion that the optimal application range varies from 250 to 500 g/m². At the same time, the influence of the surface macro-texture of different types of asphalt mixtures on the bond between layers was studied. It was found that the maximum values of shear strength are obtained for a rough texture of 0.17 mm and a dosage of 250 g/m².     

Shear strength of geosynthetic composite systems for design of landfill liner and cover slopes

Torsional ring shear tests were performed on composite specimens that simulate the field alignment of municipal solid waste (MSW) landfill liner and cover system components. Simultaneous shearing was provided to each test specimen without forcing failure to occur through a pre-determined plane. Composite liner specimens consisted of a textured geomembrane (GM) underlain by a needle-punched geosynthetic clay liner (GCL) which in turn underlain by a compacted silty clay. Hydrated specimens were sheared at eleven different normal stress levels. Test results revealed that shear strength of the composite liner system can be controlled by different failure modes depending on the magnitude of normal stress and the comparative values of the GCL interface and internal shear strength. Failure following these modes may result in a bilinear or trilinear peak strength envelope and a corresponding stepped residual strength envelope. Composite cover specimens that comprised textured GM placed on unreinforced smooth GM-backed GCL resting on compacted sand were sheared at five different GCL hydration conditions and a normal stress that is usually imposed on MSW landfill cover geosynthetic components. Test results showed that increasing the GCL hydration moves the shearing plane from the GCL smooth GM backing/sand interface to that of the textured GM/hydrated bentonite. Effects of these interactive shear strength behaviors of composite liner and cover system components on the possibility of developing progressive failure in landfill slopes were discussed. Recommendations for designing landfill geosynthetic-lined slopes were subsequently given. Three-dimensional stability analysis of well-documented case history of failed composite system slope was presented to support the introduced results and recommendations.     

Interface shear strength between geosynthetic clay liner and covering soil on the embankment of an irrigation pond and stability evaluation of its widened sections

Geosynthetic clay liners (GCLs) are typically used for widening sections of an embankment. They are also used as low permeability liners to minimize water leakage from reservoirs such as irrigation ponds. However, few investigations have been carried out on the specific properties of GCLs, such as granulated bentonite sandwiched between geotextiles, their internal shear strength, and the shear strength at the interface between a GCL and an embankment body. In this study, a series of direct box shear tests were performed to determine the shear strength properties of bentonite and compacted soils as well as at the interface between a GCL and bentonite or compacted soil. In addition, a series of field-loading tests were conducted to investigate the failure behaviour of an embankment body containing a GCL when changes in the water content of the bentonite of the GCL in a real embankment occur. Furthermore, the stability of widened embankment bodies that incorporated GCLs were evaluated. The main conclusions of this study are as follows: (1) The shear strength of the interface between the covering soil and geotextiles varied according to the soil type, geotextile type, and the submergence period, (2) the maximum safety factor was observed at the interface between decomposed granite soil and the geotextiles, while the minimum safety factor was observed at the interface between the bentonite and the geotextiles, and (3) the influence of GCLs on the instability of a widened embankment was extremely small.     

沥青混合料级配特征与路用性能的相关性

为了定量分析沥青混合料级配特征,揭示级配与沥青混合料路用性能的关系,通过分形理论方法量化了级配曲线特征,采用分形维数表征级配曲线特征,通过对比分析试验级配的分维数和沥青混合料路用性能指标变化趋势,得到了两者的变化规律。     

温拌阻燃混合料生产配合比设计及优化

依据拌合场热料筛分结果,确定了基准沥青混合料配合比,并根据施工现场状况提出了两个优化的生产配合比。在此基础上,对比了不同温度时各细温拌阻燃沥青混合料的体积指标,并切开成型试件观察试件矿料分布情况及空隙布置,最终确定了温拌沥青混合料生产配合比和最低成型温度。     

密级配沥青混合料集料分形分维与路用性能的关系

从集料结构本身出发,利用分形几何的基本理论,建立沥青混合料集料的粒径分布分形模型、集料体积分形模型和集料孔隙分形模型。集料的体积分形维数是一个饱含丰富信息的重要参数,其与沥青混合料的空隙率存在强相关性,建立AC-16密级配沥青混合料集料体积分形维数与沥青混合料空隙率的回归模型。通过大量路用性能试验,得到AC-16密级配沥青混合料集料的体积分形维数与路用性能指标之间的相关变化规律。集料的体积分形维数增大,沥青混合料的高温性能、抗滑性能呈下降趋势,水稳定性、低温抗裂性呈上升趋势。根据密级配沥青混合料集料体积分形维数与各项路用性能的关系,可对具有不同集料体积分形维数的沥青混合料的路用性能进行预估。     

砂砾卵石混合料干密度与碾压的关系研究

针对砂砾卵石混合料压实特性离散的特点,对其干密度与碾压速度的关系、干密度与碾压遍数的关系进行了深入的压实研究,通过对碾压前、碾压4遍、碾压6遍的筛分试验,对到粗粒填料压实前后的粒度成分的变化规律进行了研究。     

沥青混合料不均匀性的原因分析及防治措施

从原材料、生产配合比、拌和、运输、摊铺等几个环节详细分析了沥青混合料不均匀性产生的原因及所采取的有效防治措施,以期最大限度减少沥青混合料不均匀性的产生。     

A thermal theory for estimating the flammability limits of a mixture

Because it is difficult to treat the contributions of diluents explicitly using Le Chatelier's rule, a methodology based on thermal balance is proposed for estimating the flammability limits of a mixture. This method converts the flammability information of a mixture into a binary domain of heating/quenching potentials and, after some simple manipulations, converts them back into the flammability domain. The advantage of this conversion is the separation of the heating and quenching potential sums. The dual contribution (heating and quenching) of each species is stressed, while the simplicity of hand calculation is preserved. This method is equivalent to Le Chatelier's rule but has increased flexibility in dealing with various fuel/oxygen/diluents combinations. It will help safety engineers gain more confidence in the hazard analysis of flammable mixtures involving diluents.     

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。     

Soil-cement mixture properties and design considerations for reinforced excavation

soil-cement is a mixture produced by grouting or mixing cement with soils. This paper reviews and discusses the general classifications of grouting techniques and the suitability of their applications. The mechanical properties of soil-cement mixture and the influence of sodium silicate added are discussed. Design considerations for deep soil mixed wall (DSMW) for excavation support and vault arch for tunnelling stabilisation are presented. Parameters for the numerical analysis of soil-cement mixture are evaluated and recommended.     

沥青混合料温度场及有效压实时间分析

结合试验路的现场测试,研究了沥青混合料在碾压过程中温度的变化情况,探讨了各环境因素对温度场的影响关系,进而分析了其有效压实时间,对指导施工、保证施工质量具有重要意义。     

浅谈沥青混合料面层的施工方法及质量控制

结合工作实践,以阳冀高速公路工程为例,对沥青混合料面层的施工方法及质量控制进行了介绍,分别对拌和、摊铺、碾压及工作缝的处理等工序作了具体阐述,对今后同类工程项目具有一定指导意义。     

木焦油基再生沥青及其混合料性能研究

测试分析了木焦油基再生沥青结合料及基质沥青混合料、木焦油基再生沥青混合料、RA-102再生沥青混合料的性能。结果表明:木焦油基再生剂可将老化沥青的针入度、软化点、延度和黏度恢复至符合JTG F40-2017《公路沥青路面施工技术规范》技术要求;木焦油可使老化沥青充分软化,提升老化沥青的延展性和塑性;与RA-102再生沥青混合料相比,木焦油基再生沥青混合料具有良好的高温稳定性、低温抗裂性、水稳定性和抗老化性能;木焦油与生物质纤维协同作用可显著提高再生沥青混合料的强度和韧性,在改善沥青路面使用性能的同时延长其使用寿命。