浅谈公路工程中沥青混合料离析的控制方法

从原材料和沥青混合料的施工等方面全面分析了沥青路面混合料离析产生的原因及过程,提出了在施工中防止沥青混合料离析的技术措施,以有效控制离析,提高沥青路面的质量,从而延长路面的使用寿命。     

公路工程中沥青混合料离析的控制方法

从材料、运输和施工等方面全面分析了沥青路面混合料离析的产生原因及过程,提出了在施工中防止沥青混合料离析的技术措施,以有效控制离析,提高沥青路面的质量,从而提高路面的使用寿命。     

沥青混合料离析的原因及防治措施研究

混合料离析是造成沥青路面早期损坏的原因之一,本文在收集分析路面离析研究资料的基础上,介绍了沥青混合料、沥青路面离析的类型,路面离析的检测与判定方法;结合沥青混合料的离析类型及原因,采用视觉观察法、铺砂法、核子密度仪法、红外线摄像法等方法对混合料离析进行了检测,并提出了沥青混合料的离析判别标准及防治措施。     

公路路面沥青混合料离析问题探讨

介绍了公路路面沥青混合料存在的离析现象,分析了造成沥青混凝土路面离析的原因,提出了预防沥青混合料离析的措施。     

沥青混合料集料离析的数值模拟与分析

采用颗粒力学的基本理论分析了颗粒相互作用时的运动规律及沥青混合料集料离析的机理,提出以混合料中滚落距离大的集料颗粒比例判断集料离析的模型。利用离散元颗粒流计算软件PFC2D对沥青混合集料离析进行数值模拟,验证了集料离析模型的合理性。以沥青混合料集料料仓的实际尺寸为依据,对AC-13、AC-20沥青混合料集料进行下落试验,试验结果与理论分析及数值模拟结果吻合,并表明密级配沥青混合料集料粒径分布范围广、公称粒径大,集料易产生离析。沥青混合料生产过程中,应严格控制粗、细颗粒粒径大小及其级配含量,以避免混合料集料离析的产生。     

沥青混合料离析的离散元模拟

针对沥青混合料堆积时出现的离析现象,以颗粒离散单元法为基础,通过编制数值模拟程序对沥青混合料的离析进行数值模拟计算,并通过室内料堆法对沥青混合料进行离析试验,归纳了离析的大致规律。将试验结果与数值模拟结果进行比较,验证数值模拟程序的效用性,为今后沥青混合料的离析提供了一种更方便快捷的方式。     

谈热拌沥青混合料离析原因及控制措施

热拌沥青混合料的离析是沥青路面早期损坏的一个重要原因,在沥青混合料生产过程中的任一环节控制不当,都有可能造成沥青混合料的离析,从而对沥青路面留下质量隐患。论文通过对离析成因分析,提出有效的控制措施,以避免沥青混合料离析现象的产生。     

沥青离析问题浅析

对沥青混合料离析类型及检测方法进行了论述,通过对沥青离析原因的分析,从沥青混合料的级配设计及施工过程中的管理与控制等方面提出了沥青路面离析的预防和补救措施,从而有效控制沥青的离析问题.     

沥青混合料离析成因及控制

从沥青路面水损害破坏出发，指出沥青混合料的离析是造成水损害破坏的根本原因，分析造成离析及不均匀的原因，提出了防止离析及不均匀的技术措施。     

沥青路面离析对路面面层技术指标的影响

在路面施工时,沥青混合料离析是较为常见的问题。沥青混合料的离析会使路面技术指标受到较大的影响。本文先对沥青混合料离析出现的原因以及离析的种类进行分析,再对因沥青混凝土离析所引起的路面面层平整度、抗滑指标、压实度以及渗水系数等技术指标的变化进行研究,为今后沥青路面离析的研究提供理论依据。     

水泥碎石混合料离析的成因及处治措施

对水泥碎石混合料的离析及其危害进行了论述,从原材料的级配组成、混合料的拌和、运输和摊铺等方面分析了水泥混合料离析的成因,并详细地阐述了解决离析问题的对策,以保证水泥稳定碎石基层的质量.     

沥青路面混合料离析的控制与预防

沥青混合料的离析是沥青路面铺筑过程中经常出现的问题,是引起沥青路面早期破坏的主要原因之一,该文结合离析产生的原因,阐述了在施工各个环节控制和预防沥青路面离析的有效措施。     

The investigation on the workability of fibre cocktail reinforced self-compacting high performance concrete

The workability, the strength and the toughness are the significant factors for self-compacting-high performance concrete (SCHPC). The workability is a significant precondition for application of the Fibre Reinforced SCHPC. This paper presents research results on the workability of Monofibre and Fibre Cocktail (hybrid steel-polypropylene fibre) Reinforced SCHPC. Lots of mixtures made with steel fibres, PP-fibres and fibre cocktail of various dosages have been investigated. The mixtures were tested using various new methods for evaluating the flowability, filling ability and segregation risk of the fresh mortar/concrete. Based on the results of the workability, the suitable fibre types (steel fibres, PP-fibres and fibre cocktail) and the upper level of the fibre dosages for Fibre Reinforced SCHPC have been selected for study of the mechanical behaviour and the failure patterns in the next phase.     

纤维自密实高性能混凝土工作度的试验研究

工作度、强度、韧性及耐久性是自密实高性能混凝土(SCHPC)的主要性能指标,而工作度是保证混凝土具有高性能的重要前提。本文参照目前国际上的最新发展趋势,使用流变仪(rheometer)、流动槽(flow channel)、坍落流动板(slump flow panel)、J型环(J-Ring)和L槽(L-Box)等方法研究纤维自密实高性能混凝土(FR-SCHPC)的工作度。通过大量试验分析了不同掺量的钢纤维、PP纤维及组合纤维对新拌混凝土流动性、抗离析性、流经钢筋的间隙通过性能以及自流平能力的影响;为在实际工程中应用FRSCHPC提供了依据。     

自密实钢管混凝土的研究与应用

采用自密实混凝土作为钢管核心混凝土．针对钢管混凝土的受力特点和施工工艺．进行自密实混凝土材料的选择和配合比优化。为了确保自密实钢管混凝土的顺利施工和硬化后良好的力学、变形性能，进行了自密实钢管混凝土与普通泵速铜管混凝土拱的现场模拟施工对比试验，以及钢管混凝土短柱的轴心受压对比试验。试验结果表明．自密实混凝土作为钢管核心混凝土，其施工性能明显优于普通泵送混凝土。在施工过程中不泌水、不离析。硬化的混凝土能在各截面上均匀分布；自密实钢管混凝土短柱的组合弹性模量、极限承载力和延性以及后期承载能力方面均与普通泵送混凝土短柱相似。在此基础上．成功地将自密实混凝土应用于莆田市一钢管混凝土拱桥工程，应用结果表明，采用自密实混凝土技术，钢管混凝土拱桥施工顺利、快捷。且更好地保证了工程质量，同时混凝土材料造价与普通泵送混凝土基本持平。     

Temperature segregation and its impact on the quality and performance of asphalt pavements

Temperature segregation is non-uniform temperature distribution across the uncompacted asphalt mat during paving operations and may have detrimental effects on the quality and performance of asphalt pavements. However, many research studies conducted across the US have reported mixed observations regarding its effects on the initial quality and long-term performance of asphalt pavements.The objective of this study was to determine the effects of the temperature segregation on the density and mechanical properties of Louisiana asphalt mixtures. Seven asphalt rehabilitation projects across Louisiana were selected. A multisensor infrared bar (Pave-IR) system and a hand-held portable thermal camera were used to measure the temperature of asphalt mats. Field core samples were collected from various areas with varying severity levels of temperature segregation and tested for the density, fracture resistance (J_c) by semi-circular bending (SCB), rut depth by wheel tracking, and dynamic modulus (|E*|) by indirect tension (IDT) devices.Two distinctive patterns of non-uniform temperature distribution were observed: a cyclic and irregular temperature segregations. Laboratory test results showed that highly temperature segregated asphalt pavements (i.e., temperature differentials ≥41.7°C) can have significantly lower densities and the mechanical properties than the non-segregated area, especially when the temperature differentials are measured at compaction.     

Cartography of the segregation as a tool of decision-making aid for the fight against poverty: case of the town of Yaounde (Cameroon)

The urban demographic explosion in the developing countries (DC) is generally accompanied by segregative phenomenon for the populations with low income and exposes them to several types of risks. This phenomenon of segregation, object of this study, is the result of the containment of the poor city dwellers in zones which are difficult to arrange, and in which the risks are numerous. This paper proposes a method of identification of the segregations and their domains of appearance, the analysis of the explanatory factors and their evaluation, using suitable mathematical tools. An application to the case of the town of Yaounde is used as illustration with our study. We charted the socio-spatial segregation in the town of Yaounde and implemented the characteristic elements of cartography of segregation in a given environment. We defined also the existence of the threshold of segregation and the intensity of a segregation associated with a domain.     

Performance of high strength concrete made with copper slag as a fine aggregate

This research study was conducted to investigate the performance of high strength concrete (HSC) made with copper slag as a fine aggregate at constant workability and to study the effect of superplasticizer addition on the properties of HSC made with copper slag. Two series of concrete mixtures were prepared with different proportions of copper slag. The first series consisted of six concrete mixtures prepared with different proportions of copper slag at constant workability. The water content was adjusted in each mixture in order to achieve the same workability as that for the control mixture. Twelve concrete mixtures were prepared in the second series. Only the first mixture was prepared using superplasticizer whereas the other eleven mixtures were prepared without using superplasticizer and with different proportions of copper slag used as sand replacement. The results indicated that the water demand reduced by almost 22% at 100% copper slag replacement compared to the control mixture. The strength and durability of HSC were generally improved with the increase of copper slag content in the concrete mixture. However, the strength and durability characteristics of HSC were adversely affected by the absence of the superplasticizer from the concrete paste despite the improvement in the concrete strength with the increase of copper content. All concrete mixtures did not meet the strength and durability design requirements due to the segregation and dryness of the concrete paste. Therefore it can be concluded that the use of copper slag as sand substitution improves HSC strength and durability characteristics at same workability while superplasticizer is very important ingredient in HSC made with copper slag in order to provide good workability and better consistency for the concrete matrix.