Accelerated tests for assessing the potential exhibited by concrete aggregates for alkali-aggregate reaction

A number of tests are available for assessing the potential of aggregates for alkali-aggregate reaction. These are listed, for example, in ASTM C33-93. The majority of these test procedures have been widely used in researching aggregates, but there are serious reservations concerning the application of some of these tests to the selection of materials for structures. In recent years, many papers have been published detailing investigations of the tests. An examination of the literature shows that most of the tests are of little value for making engineering decisions. This paper reviews the literature relating to three commonly used tests, the ASTM C-289 Rapid Chemical Test, the ASTM C-227 Mortar Bar Test and what has become ASTM C-1260-94 Accelerated Mortar Bar Expansion Test. Attention has been given to a detailed practical study of the accelerated mortar bar tests since these are becoming very widely used. The experimental work, in essence, represents a determination of the errors to be expected from application of the test to a single aggregate and the factors that influence these errors. The repeatability of the tests suggests an upper bound standard deviation of 0.0365% expansion. This figure is used to establish discriminant criteria for the recognition of potentially damaging materials. It is evident that diagnosis of potentially highly reactive materials can be made with confidence, but that a large number of tests are required to assess marginal types. Petrographic evaluation of the mortar following the test is essential, particularly where the results are borderline, though the presence of traces of gel has to be interpreted with caution. Much of the uncertainty in the test results derives from inherent aggregate variability. A test schedule can be designed that has small contributions to the error from the experimental steps, but the error due to aggregate variability remains. This can lead to the requirement for the manufacture of multiple batches of mortar for establishing acceptance criteria for even a single aggregate batch, and further consideration is needed as to the procedures necessary for the assessment of aggregate sources.     

大型电站锅炉刚性梁的挠度分析

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苏北盆地码头庄油田阜一段、阜二段湖泊—三角洲沉积模型

通过分析各种沉积体的岩性、结构、沉积构造、沉积序列和电性特征，划分了苏北盆地码头庄油田阜一段、阜二段沉积相；根据滩和坝在剖面、平面以及岩性上所呈现的特征，划分了滩和坝的类型,建立了各种相的沉积模式，分析了沉积模型的演化历史。据此指出：阜一段发育三角洲前缘亚相沉积，至下而上发育前缘席状砂、河口坝、水下分流河道、水下分流间湾和水下天然堤微相，呈现出三角洲进积的特点，三角洲前缘亚相在阜一段沉积末期消失；阜二段发育滨浅湖亚相沉积，分为生物滩、鲕粒滩、灰质滩、浅湖砂坝和滨浅湖泥微相，有开阔浅湖砂坝和水下隆起区碳酸盐岩滩2种沉积模式。     

泊松公式的应用

从泊松公式的物理学意义出发，借助降维法推出二维波动方程柯西问题的积分表达式，并通过举例给予证明。     

宝珠寺水电站左岸高边坡处理综述

宝珠寺电站左岸边坡开挖垂直高度２００余ｍ，地质情况复杂，存在多处断层及夹泥层，构成１０余组不稳定楔形岩体。施工中，根据不同的地质情况，分别采取了混凝土抗剪置换洞，锚筋桩，系统锚杆及爆破控制等综合处理措施。确保了施工期间的稳定及安全，保证了施工工期。本文以该工程为例，简要介绍了边坡处理的施工方法，以供借鉴。     

棒材倍尺飞剪的控制与优化

对棒材生产线上倍尺飞剪系统配置及控制方法进行分析，并对优化剪切提出解决方案，提高了倍尺飞剪的剪切精度。     

发酵香肠中葡萄球菌快速"两步一补"鉴定

介绍一种凝固酶阴性葡萄球菌(CNS)快速鉴定方法:"两步一补法"。并用此方法鉴定传统发酵香肠中CNS的分布情况。CNS菌株先经二步鉴定:第一步4h,包括:蕈糖、尿素酶、碱性磷酸酶;第二步24h,包括:鸟氨酸脱羧酶、新生霉素敏感性、磷霉素敏感性、厌氧生长。极少数不能鉴定的CNS菌株,用补充试验完成结果。能鉴定出发酵香肠中CNS的22个种及2个亚种,本文两步法能鉴定出发酵香肠中64%以上常见CNS菌种,仅36%的菌株需用补充实验证实。     

两树和图的Cordial性问题

两个图的和图Cordial性的研究结果甚少且方法单一.本文采用粘接边或删除边的方法,给出了两树和图为Cordial图的充分必要条件:两树不都是奇度图.     

φ8 mm热轧带肋钢筋工艺实践

介绍了长钢三轧厂Φ8mm热轧带肋钢筋的工艺设计及试生产情况，该产品各项指标均符合GB1499要求，并用于山西万家寨引黄工程（国家重点 工程），受到使用单位的好评，该产品的开发，填补了省内空白，开拓了市场，创造了较好的经济效益和社会效益。     

趋零计量法在经编产品设计及分析中的有效应用

在经编产品设计、分析过程中，确定正确的垫纱运动是至关重要的环节，同时对产品生产也有决定性影响。介绍了趋零计量法在经编产品组织结构分析中的应用，指出这对于快速有效地设计、分析出正确的垫纱运动图，以提高经编产品设计、分析效率，进而提高生产效率是一种有效的途径。