补偿收缩混凝土在不同限制条件下的变形特性及力学性能试验研究

模拟工程中补偿收缩混凝土受钢筋约束的情况,通过对纵向、侧向不同限制条件下补偿收缩混凝土的变形特性及力学性能进行研究,力求使补偿收缩混凝土在工程中得到更好的应用效果.     

补偿收缩混凝土的施工技术

补偿收缩混凝土得到广泛的应用,如何才能保证混凝土工程的质量是人们非常关心的问题。本文从补偿收缩混凝土的配合比设计、生产、浇筑、养护及工程后期保护等方面介绍补偿收缩混凝土的施工技术。     

收缩补偿砂浆及其应用

工程应用中混凝土和水泥砂浆由于收缩导致开裂，严重影响其应用性能。本文分析了混凝土和砂浆体积收缩的内外因素，研究探讨了收缩补偿砂浆的原理及其在工程中的应用前景。所得结果对收缩补偿混凝土及砂浆的研究及其在工程中的应用具有一定的指导意义。     

浅析补偿收缩混凝土施工控制要点

补偿收缩混凝土,是指在混凝土中掺入一定剂量膨胀剂或用膨胀水泥作为胶凝材料配制的混凝土,是一种适度膨胀的混凝土,其利用膨胀能来做功,主要起到补偿收缩作用及产生预加应力作用,从而达到减轻或避免混凝土因体积收缩引起的结构开裂问题.工程中补偿收缩混凝土在结构设计、施工、质量监管过程中存在以下问题:补偿收缩混凝土设计标准不统一,...     

补偿收缩混凝土在天津芥园道水厂的应用

本文介绍了补偿收缩混凝土在天津市芥园道水厂的工程应用,工程实践证明补偿收缩混凝土可以减轻或消除有害裂缝的产生,达到结构自防水的目的。     

补偿收缩混凝土在工程中的应用

补偿收缩混凝土在工程中的应用赵五一（石家庄市建筑工程局，０５００１１）补偿收缩混凝土是用膨胀水泥或在普通混凝土中掺入适量膨胀剂配制而成的一种微膨胀混凝土。它可以针对普通混凝土收缩变形大、易产生裂缝的弊病，起到相应的补偿效果。１补偿收缩混凝土的配制配制...     

补偿收缩混凝土施工技术研究

普通混凝土由于收缩在大体积混凝土结构中容易形成有害裂缝,影响结构安全,加入适量膨胀剂后的补偿收缩混凝土可以有效的解决这一问题,通过介绍补偿收缩(微膨胀)混凝土在中央商务区地下空间工程中的应用,结合现场浇筑情况,充分说明了补偿收缩混凝土在缩短工期的同时有效地控制了裂缝的形成。     

补偿收缩混凝土与膨胀加强带在超长混凝土结构中的应用

结合京沪高铁南京南站北广场,从超长无缝施工技术,补偿收缩混凝土的配合比设计及其施工与养护控制3个方面论述了补偿收缩混凝土应用注意要点。实际工程证明补偿收缩混凝土在良好合理的使用条件下可以有效抑制超长混凝土结构的开裂问题。     

膨胀剂为什么有时不好用

在混凝土中掺入适量膨胀剂可以补偿混凝土的收缩,是防止或减小混凝土开裂的有效方法,但使用效果不佳和使用失败的工程实例也屡见不鲜.一些工程虽然采用了补偿收缩混凝土,有时也产生不同程度的渗漏和开裂.为此,有必要对其使用失败的原因进行分析和归纳,以求使膨胀剂及补偿收缩混凝土的应用得以健康发展.     

补偿收缩混凝土在合肥地铁大东门站场中的应用

补偿收缩混凝土主要用于钢管混凝土结构中,通过膨胀组分对抗混凝土自生收缩,确保钢管柱与内部混凝土密贴共同受力,并对内部混凝土起到约束作用。运用高性能混凝土配制技术,将高效减水剂、粉煤灰和膨胀剂复合在一起掺入到混凝土中,以在建工程为依托,通过筛后砂浆对硬化混凝土收缩补偿性能研究分析,探讨补偿收缩混凝土实用配合比。     

The effects of changing water flow velocity on the formation of biofilms and water quality in pilot distribution system consisting of copper or polyethylene pipes

We studied the effects of flow velocity on the formation of biofilms and the concentration of bacteria in water in copper and plastic (polyethylene, PE) pipes. The formation of biofilms increased with the flow velocity of water. The increase in microbial numbers and contents of ATP was clearer in the PE pipes than in the copper pipes. This was also seen as increased consumption of microbial nutrients in the pipeline system. This indicates that the mass transfer of nutrients is in major role in the growth of biofilms. However, the increased biomass of biofilms did not affect microbial numbers in the water. Rapid changes in water flow rate resuspended biofilms and sediments which increased the concentrations of bacteria and copper in water. The disturbance caused by the changing water flow was also seen as an increase in the particle counts and water turbidity recorded with online instrumentation.     

氡在破碎花岗岩巷道及围岩中的运移机制解析

依托某破碎花岗岩巷道工程,以多孔介质中气体的渗流理论为基础,综合考虑影响氡在破碎花岗岩山体及巷道中运移和析出的多种因素,构建了氡的数值计算模型,给出了山体和通风巷道中的氡浓度计算公式,模拟并比较了自然状态和微正压通风状态下山体中氡浓度分布的变化情况,并对微正压通风状态下巷道中氡浓度的变化情况进行模拟和验证。研究结果表明:扩散作用和渗流作用是巷道围岩中氡运移的主要机制;微正压通风条件下巷道中氡的运移主要受通风作用、围岩的射气作用和氡的衰变作用共同影响;微正压通风能够改变围岩中氡的渗流方向,是巷道降氡的有效手段。     

Health assessment of artisanal gold miners in Indonesia

Small scale miners use mercury to extract gold from ore in many countries. An environmental and health assessment was performed in Indonesia in two regions, Galangan in Central Kalimantan and Talawaan in Northern Sulawesi. The environmental assessment showed severe mercury contamination of the sediments, and increased mercury levels in local fish. For the health investigation 281 volunteers were recruited and examined by a standardized questionnaire, a neurological examination and neuro-psychological tests. A medical score was used consisting of significant factors of mercury intoxication. Mercury exposed workers showed typical symptoms of mercury intoxication, such as movement disorders (ataxia, tremor, dysdiadochokinesia, etc.). Blood, urine and hair samples were taken from any participant and analyzed for mercury. The mercury concentration in the biomonitors was high, partly extreme high in the working population, increased in the population living in the same habitat and low in the control group. By a standard protocol which includes a combination of threshold values of mercury in the biomonitors and a medical sum score the diagnosis of chronic mercury intoxication was made for highly burdened workers (amalgam smelters) in 55% in Sulawesi and in 62% in Kalimantan. Less exposed mineral processors and the general population in the mining areas were also intoxicated to a high percentage.     

Alteration of arsenopyrite in soils under different vegetation covers

The weathering of arsenopyrite (FeAsS) has been monitored in soils using an in situ experimental approach. Arsenopyrite in nylon experimental bags was placed in individual horizons in soils in spruce (litter, horizons A, B, and C), beech (litter, horizons A, B, and C) and unforested (horizons A, B, and C) areas and left in contact with the soil for a period of 1 year. The individual areas on the ridge of the Krušné hory Mts., Czech Republic, had the same lithology, climatic and environmental conditions. Scorodite (FeAsO₄·2H₂O) was identified as a principal secondary mineral of arsenic (As) formed directly on the surface of the arsenopyrite. Scorodite was formed in all the areas in all soil horizons. The amount of scorodite formed decreased in the series beech, spruce and unforested areas. In forested areas, there was a larger amount of scorodite on arsenopyrites exposed in organic horizons (litter, A horizon). The greater rate of arsenopyrite alteration in organic horizons in the beech stand compared to spruce stand is probably a result of faster mineralization of organic material with resulting production of nitrate and better seepage conditions of soil in this area. Speciation of As determined using the sequential extraction technique demonstrated that As was bonded in the soils primarily in the residual fractions prior to the experiment. The As content in the mobile fractions increased in the organic horizon in the forested areas after the experiments.     

Heterotrophic and mixotrophic growth of Micractinium pusillum Fresenius in the presence of acetate and glucose: effect of light and acetate gradient concentration

The main objective of this study was to determine the importance of secondary mechanism of organic carbon utilization (mixotrophic and heterotrophic modes) in addition to CO2 fixation (photoautotrophic mode) in the green alga, Micractinium pusillum Fresenius (chlorophyta), isolated from a waste stabilization pond. The growth was studied in the presence of acetate and glucose. The incorporation rate of 14C- acetate was measured in the light and in the dark at different concentrations. Finally, in order to underline the role of photosynthesis and respiration processes in the acetate assimilation, the effect of two specific metabolic inhibitors, a specific inhibitor of photosystem II (DCMU) and an uncoupler respiratory (DNP), has been studied. The obtained results showed that M. pusillum grows in the presence of organic substrates, i.e., glucose and acetate, in the light (mixotrophic growth) as well as in the dark (Heterotrophic growth). The growth was much more important in the light than in the dark and more in the presence of glucose than of acetate. In the light, the presence of acetate led to a variation of growth parameters mumax, iotaopt, and beta. The effect of acetate gradient on the growth of the microalga was severe as soon as its concentration in the medium was higher. The acetate uptake followed a Michaelis-Menten kinetic in the light as well as in the dark. The capacity of assimilation was slightly higher in the dark. The utilization of DNP and DCMU indicates that acetate incorporation is an active process depending on both anabolic (photosynthesis) and catabolic (respiration) metabolisms, corroborating the model of the Michaelis-Menten kinetic.     

城外造景：清末广州景园营造与岭南 园林的近代转型

清末广州中西交汇,景园营造新旧共存互动,推 动岭南园林的近代转型。其中,在繁荣的中西贸易和文化交 流,以及书院文化、士绅文化等的影响下,清末岭南形成了 以广州为中心、十三行行商为代表、官商士绅竞相造园的特 殊历史时期,其造园数量、规模、意匠等均在该时期达到岭 南古典园林发展的巅峰。这一时期也是岭南园林近代转型的 关键时期。在西方文化和清末洋务运动思想的影响下,广州 开始出现洋务花园、公园、市政绿化,以及校园绿地等新型 园林形式。这些具有公共性质的城市景致与新建私园一道广 泛分布在城墙以外,成为清末广州城市空间拓展与风景体系 形成的重要参与者。由于清末广州城外造景的繁荣,从时间 上开启了岭南园林的近代转型,在空间上使岭南园林的地域 性特征得以形成和辨识,其空间性与时间性界定了清末岭南 园林近代转型的物质及文化维度。梳理了清末广州具有代表 性的景园营造活动,在分析其动力机制的同时,探讨城外造 景之于岭南园林近代转型的意义。     

Bacteriological, virological and chemical evaluation of a wastewater-aquaculture system

Levels of fecal coliforms (FC), fecal streptococci (FS), Salmonella spp and enteric viruses were monitored in the water, sediment and fish in experimental wastewater-fish ponds near Benton, Arkansas, U.S.A. Concentrations of five heavy metals were also monitored in the fish and wastewater. Concentrations of indicator bacteria were reduced by as much as 99.7% through the series of six ponds which had a calculated total retention time of 72 days. Two filter-feeding species of Chinese carp, Hypophthalmichthys molitrix (silver carp) and Aristichthys nobilis (bighead carp), grown in the last three ponds accumulated FC and FS in their digestive tracts and skin at levels as great or greater than in the surrounding water and sediment. Only low levels of FC and FS were found in the fish muscle tissue (maximum of 25 FS per 100 g) even when concentrations of bacteria in the gut exceeded 10⁵ per 100 g. Concentrations of bacteria in the water and sediment were not good predictors of concentrations in the fish. No Salmonella and no enteric viruses were isolated from the fish, but this lack of isolates was attributed to the extremely low levels which were present in the influent wastewater. Higher levels of copper and mercury were found in the fish flesh than in the surrounding water, with three of eleven fish samples containing higher than acceptable levels of mercury in the edible portion. Based on the efficiency of wastewater treatment, an aquaculture system using silver and bighead carp was judged to be a viable treatment system for domestic sewage resulting in a product suitable for animal or human consumption if proper precautions are taken in harvesting and processing the fish.     

The potential for gender equality in architecture: an Anglo-Spanish comparison

The practice of architecture is very similar in different national settings despite what may be very different sociological and cultural origins of the profession, the attendant variances in how work is organized and distinctions in equality and gender roles. The aim of this paper is to examine the quest for equality in architecture for women in the UK and Spain reporting the findings of a comparative study into women architects’ careers in the two countries. Within the qualitative paradigm, semi-structured in-depth interviews were carried out with a total of 55 women architects in the UK and Spain. Findings indicate surprising differences in levels and terms of equality for women in the two countries and marked differences in women’s experiences of working as an architect. Women have come to the profession in Spain much later than their British counterparts and, somewhat surprisingly, are present in greater numbers. However, despite there being more of a ‘critical mass’ this has not served to improve their situation; they report much higher levels of discrimination and find it difficult to progress in their careers. Conclusions argue for a stronger approach by the professional bodies to help improve the position of women.     

Polycyclic aromatic hydrocarbons (PAHs) in agricultural soil and vegetables from Tianjin

Several types of vegetables were collected from two contaminated sites in Tianjin, China. The bulk soil and the rhizosphere soil samples were also collected from the same plots. Sixteen PAHs in the samples were measured. The total concentrations of PAH16 in the bulk soil from the two sites were 1.08 and 6.25 microg/g, respectively, with similar pattern. The concentrations of PAH16 and individual compounds in the rhizosphere were significantly higher than those in the bulk soil with mean values of 2.25 and 7.82 microg/g for the two sites, respectively. The contents of both total and dissolved organic matter in the rhizosphere were also higher than those in the bulk soil. Almost all PAH compounds studied were detected in both roots and aerial parts of the vegetables studied. Abundance of higher molecular weight PAHs in vegetable, however, was lower than that in soil. Concentrations of PAH16 in vegetable were higher than those reported in the literature for other areas. It appears that agricultural soils and vegetables in Tianjin, especially those from the site located immediately next to an urban district and irrigated with wastewater for several decades, are severely contaminated by PAHs. Among the eight types of vegetable studied, the highest concentration of PAHs was found in cauliflower. By average, the concentration of PAH16 in the aerial part of vegetables was 6.5 times higher as that in vegetable root, suggesting that foliar uptake is the primary transfer pathway of PAHs from environment to vegetables.     

未来高校图书馆建筑空间构成及设计特点初探

从高校图书馆发展的外部动因,使用主体的心理、行为特征和现代化设备对图书馆的影响三个方面来分析研究图书馆建筑发展的趋势和特点,归纳出未来高校图书馆建筑的功能布局及空间组织结构特点,总结出设计中要考虑的诸多因素,以期更好地指导高校图书馆的设计与建设。