混凝土碱骨料反应浅析

<正>混凝土碱骨料反应是混凝土原材料中的水泥、外加剂、混合材和水中的碱(Na2O或K2O)与骨料中的活性成分发生的反应。混凝土碱骨料反应对建筑物的危害很大,此反应会在混凝土浇     

重盐碱地区钢筋混凝土结构腐蚀原因分析与防腐措施

本文介绍了在重盐碱地区混凝土腐蚀的主要因素,氯化物的侵蚀、碱-骨料反应等因素。并在分析原因的基础上论述了基本的防腐措施,主要有添加钢筋阻锈剂、喷涂环氧树脂、改善施工工艺、介绍工程实例等方法。通过防腐措施可以有效改善混凝土结构物使用的耐久性和安全性。     

混疑土碱骨料反应浅析

混凝土碱骨料反应是混凝土原材料中的水泥、外加剂、混合材和水中的碱（Na20或K20）与骨料中的活性成分发生的反应。混凝土碱骨料反应对建筑物的危害很大，此反应会在混凝土浇筑成型后若干年逐渐进行，反应后的生成物吸水膨胀使混凝土产生内部应力。从而膨胀开裂使混凝土失去设计性能。     

浅谈碱骨料在水工混凝土中反应的预防

水泥中的碱与骨料中的活性成分发生反应，由于活性骨料在混凝土拌制中大体呈均匀分布，所以一旦发生碱骨料反应，混凝土内部产生膨胀应力，对混凝土的破坏将是严重的。     

小议影响混凝土结构耐久性的因素及改善措施

介绍了混凝土结构的耐久性的概念,从常见的混凝土耐久性破坏如冻融破坏、渗透破坏、碱骨料反应、混凝土的碳化和化学侵蚀这五个方面对混凝土结构发生耐久性失效的原因及影响因素进行简单分析和介绍,并提出了提高混凝土结构耐久性的措施。     

混凝土裂缝控制技术在闸室工程中的应用

裂缝是混凝土建筑物主要的老化病害之一,主要由干缩、砼自身质量、水泥水化热、温度、钢筋锈蚀、地基变形、荷载、碱骨料反应、地基冻胀等引起。     

浅谈混凝土的施工温度与裂缝

一、裂缝的原因 混凝土中产生裂缝有多种原因,主要是温度和湿度的变化,混凝土的脆性和不均匀性,以及结构不合理,原材料不合格(如碱骨料反应),模板变形,基础不均匀沉降等.     

复掺粉煤灰和矿渣对高性能混凝土抑制骨料碱活性效能及其强度的影响研究

在这次实际研究的过程中,主要使用正交试验的方式进行分析,获取最终的试验结果。主要在以往的工艺方式之下,分析粉煤灰材料以及粒化类型高炉矿渣在实际施工中的应用情况,了解具体的性能影响特点,明确骨料的碱活性抑制情况,为后续的施工提供帮助。     

高碱混凝土影响建筑寿命

混凝土是现代建筑的基本材料,在使用混凝土时,人们普遍注意的是高强度、高标号,很少有人强调它的含碱量问题。但是在中国工程院最近举行的一次研讨会上,化工、冶金与材料工程原部的几位院士以大量的事例与研究报告说明,高碱混凝土使建筑物出现开裂破坏,使用寿命缩短。专家们提供的事例触目惊心。北京市的三元立交桥建成于1984年,在80年代末已发现开裂,目前盖梁及桥台开裂十分严重,裂缝宽度最大已达1.4厘米。有关部门不得不采取措施将桥墩扩大以支撑悬臂盖梁。三元桥的水泥用量每立方米约300至400公斤,使用北京地区含碱较高的砾石做集料,施工中为了防冻剂和缩短凝固时间,又掺人了防冻剂和早强剂,使部分混凝土中碱的含量高达每立方米15公斤。碱与混凝土骨料中的某些成分发生反应,从而导致混凝土的膨胀开裂与破坏,专家们把这种反应叫做碱集料反应。     

提取啤酒废酵母中β-葡聚糖的工艺研究

采用自溶-酶-碱法对啤酒废酵母中的β-葡聚糖进行提取,分别对酶用量、酶添加时间、碱液浓度和反应温度进行研究,确定了最佳提取工艺.结果表明:在自溶6h后,添加0.8%的木瓜蛋白酶,碱提时碱液浓度为2%,温度为80℃,β-葡聚糖粗糖得率10.41%,β-葡聚糖含量83.84%.     

Incumplimiento del salario mínimo en Europa central y oriental

En este estudio se analiza el incumplimiento del salario mínimo durante el periodo 2003–2012 en diez países de Europa central y oriental con salario mínimo obligatorio nacional. A partir de los datos de EU‐SILC y la metodología propuesta por Bhorat, Kanbur y Mayet (2013), se cuantifica la incidencia y magnitud del incumplimiento. Se realizan análisis de regresión sobre determinantes individuales, laborales y macroeconómicos. Aunque la incidencia permanece relativamente baja, los trabajadores a los que se dirigen las políticas de salario mínimo parecen los más expuestos a su incumplimiento. Con el tiempo, una mayor incidencia se asocia a una razón más alta entre salario mínimo y salario medio.     

Cultural Economy Planning in Creative Cities: Discourse and Practice

While a growing body of research analyses the functional mechanisms of the cultural or creative economy, there has been little attention devoted to understanding how local governments translate this work into policy. Moreover, research in this vein focuses predominately on Richard Florida's creative class thesis rather than considering the wider body of work that may influence policy. This article seeks to develop a deeper understanding of how municipalities conceptualize and plan for the cultural economy through the lens of two cities held up as model ‘creative cities’ — Austin, Texas and Toronto, Ontario. The work pays particular attention to how the cities adopt and adapt leading theories, strategies and discourses of the cultural economy. While policy documents indicate that the cities embrace the creative city model, in practice agencies tend to adapt conventional economic development strategies for cultural economy activity and appropriate the language of the creative city for multiple purposes.     

Input/output ranges and performance: an examination of US machine tool producers

Despite the establishment of high-tech multinational enterprises (MNEs) in Ireland since the late 1950s, the country did not succeed in closing the technological gap with most of its EU counterparts. The weak National System of Innovation (NSI), and in particular low business and government R&D levels, combined with a lack of research and technology linkages between MNEs and indigenous firms, explain these poor results. However, the Shannon region in the West of the country presents some specific institutional characteristics that could theoretically make the region a strong technological enclave. The various actors in the region - i.e. the administrative, financial, political and research institutions, as well as the business organizations - have indeed infused a new type of economic development. After a brief review of the available concepts and models articulated around these actors and their interrelationships, the paper analyses whether the Shannon region, taken as an illustrative example, mirrors a specific economic and technological localized setting. The study is based on a survey of indigenous and foreign firms.     

Sixty years of discrimination and diversity research in human resource management: A review with suggestions for future research directions

This article reviews discrimination and diversity research published in Human Resource Management (HRM) over the past 60 years. While discrimination and diversity are very different constructs, it is often informative to study them together, because when people recognize each other's diversity, this can result in bias, stereotyping, and discrimination. We conducted bibliographic searches for terms related to discrimination and diversity as well as a manual search through every title and abstract published in HRM over the last 60 years to assess article relevance. The search resulted in 135 research articles with 136 unique studies (i.e., samples) which are reviewed in this article. Sex and race are the demographics that have been examined the most in HRM, while religion has been examined the least. Moreover, the number of studies examining lesbian, gay, bisexual, transgender, and queer (LGBTQ) employees in the workplace in HRM has grown quickly within the past 10 years, culminating in a recent meta‐analysis. Our review looks at some of the earliest research published, the most recent research published, and the overall trends we identified in the research over the years for both discrimination and diversity articles. We then make future research suggestions and recommendations to advance the study of discrimination and diversity in the coming years.     

The Early History of the Cumulants and the Gram-Charlier Series

The early history of the Gram-Charlier series is discussed from three points of view: (1) a generalization of Laplace's central limit theorem, (2) a least squares approximation to a continuous function by means of Chebyshev-Hermite polynomials, (3) a generalization of Gauss's normal distribution to a system of skew distributions. Thiele defined the cumulants in terms of the moments, first by a recursion formula and later by an expansion of the logarithm of the moment generating function. He devised a differential operator which adjusts any cumulant to a desired value. His little known 1899 paper in Danish on the properties of the cumulants is translated into English in the Appendix.     

Capturing the Implications of Services Trade Liberalization

This paper evaluates the impact of service sector trade liberalization on the world economy by a ten-region, eleven-sector CGE model with import embodied technology transfer from developed countries to developing countries. Simulation results show that service sector trade liberalization not only directly affects world service production and trade, but also has significant implications for other sectors in the economy. The major channel of the impact is through inter-industry input-output relations and TFP growth induced from services imported by developing countries from developed countries, which may be embodied with new information and advanced technology.     

City Children and Genderfied Neighbourhoods: The New Generation as Urban Regeneration Strategy

Former industrial cities in the West are employing gentrification as urban policy. In these policies, women and families currently play an important role as gentrification pioneers. In my analysis of Rotterdam in the Netherlands, I propose the term genderfication to understand the gender dimensions of this process. Genderfication refers to the production of space for different gender relations. I analyse Rotterdam's urban planning program for becoming a ‘child‐friendly city’, which entails replacing existing urban dwellings with new, larger and more expensive ‘family‐friendly homes’ as a strategy for urban re‐generation. Urban re‐generation supplements regeneration in the form of material and economic restructuring, and refers to the replacement of part of the current population by a new and better suited generation. The ‘child‐friendly city program’ is considered in tandem with punitive ‘youth policies’.     

Hierarchical Models in Environmental Science

Environmental systems are complicated. They include very intricate spatio-temporal processes, interacting on a wide variety of scales. There is increasingly vast amounts of data for such processes from geographical information systems, remote sensing platforms, monitoring networks, and computer models. In addition, often there is a great variety of scientific knowledge available for such systems, from partial differential equations based on first principles to panel surveys. It is argued that it is not generally adequate to consider such processes from a joint perspective. Instead, the processes often must be considered as a coherently linked system of conditional models. This paper provides a brief overview of hierarchical approaches applied to environmental processes. The key elements of such models can be considered in three general stages, the data stage, process stage, and parameter stage. In each stage, complicated dependence structure is mitigated by conditioning. For example, the data stage can incorporate measurement errors as well as multiple datasets with varying supports. The process and parameter stages can allow spatial and spatio-temporal processes as well as the direct inclusion of scientific knowledge. The paper concludes with a discussion of some outstanding problems in hierarchical modelling of environmental systems, including the need for new collaboration approaches.