混凝土标准芯样抗压强度的测量不确定度分析

表征合理地赋予测量之值的分散性、与测量结果相联系的参数称为测量不确定度。测量不确定度是对测量结果的可疑程度进行量化,不确定度越小,则测量结果可信程度越大。混凝土标准芯样是用钻芯机从结构中钻取的公称直径为100 mm、高径比为1∶1的混凝土圆柱体试件,混凝土标准芯样抗压强度试验是在压力试验机上,将芯样压至破坏,芯样的抗压强度值（fcu,cor）即芯样破坏时的最大压力所对应的强度值,是推定结构混凝土强度的重要指标。以下根据《测量不确定度评定与表示》.JJF1059-1999、对某花园商住楼一设计强度等级为C25的混凝土构件钻取的一个芯样的抗压强度（fcu,cor）测量结果的不确定度进行评定。分析中考虑了仪器设备、人为因素及修约等影响因素。     

混凝土抗压强度试验结果的不确定度分析

根据混凝土抗压强度计算公式，建立数学模型，分析C20、C25、C30混凝土立方体抗压强度试验结果不确定度的主要影响因素，并进行评定、计算各强度等级混凝土立方体抗压强度的不确定度。通过结果分析知：影响不确定度大小的主要因素依次为破坏荷载测量结果的重复性、压力机本身的准确度等级，再次是试件尺寸的数据修约。     

铝单板涂层厚度测量不确定度分析

不确定度是指由于测量误差的存在,对被测量值的不能肯定的程度,反过来也表明该结果的可信赖程度。它是测量结果质量的指标。涂层厚度测量是一个重要内容,涡流测厚仪是目前使用最为广泛的涂层测厚设备。通过分析铝单板涂层厚度测量时影响不确定度的各种因素,结合测量结果给出合成不确定度,并对影响其测量不确定度的分量进行了简单的分析,得出铝单板涂层厚度不确定度。     

钻芯法芯样混凝土强度检测的测量不确定度评定

以钻芯法混凝土强度检测为例对芯样试件抗压强度试验测量不确定度进行评定和表示,简述建筑工程质量检测机构出具的检测报告中测量结果的不确定度评定方法和结果报告。     

回弹法检测混凝土强度不确定度分析

介绍回弹法检测混凝土强度的特点和方法,阐述不确定度的原理和评定不确定度的主要步骤,并结合具体实例对回弹法推定混凝土强度的主要影响因素进行分析.引入不确定度对结构混凝土强度合格性评定进行了探讨,以期完善回弹法检测混凝土强度施工工艺.     

混凝土抗压强度检测结果的不确定度评定

测量结果的不确定度,表示在重复性或复现性条件下测量结果的分散性,仅与测量方法有关.本文根据JJF1059-1999《测量不确定度评定与表示》,对采用WYH-2000型微机控制数显全自动压力试验机进行混凝土抗压强度试验的测量结果进行了不确定度评定.     

评定回弹法检测普通混凝土强度不确定度的工程实践

混凝土回弹法作为检测普通混凝土强度的无损检测方法,被广泛应用于工程质量验收、工程质量控制、验证设计要求、房屋鉴定等,是目前检测混凝土强度一项主要方法;不确定度作为国际公认的评价检测结果可信程度的指标,被广泛应用于测量和检测行业;本文通过工程实例对回弹法检测混凝土强度的不确定度进行评定,并对评定的实践应用进行了探讨。     

钻芯法检测混凝土强度及其不确定度评价

在介绍了钻芯法检测混凝土强度的特点和方法的基础上,阐述了不确定度的原理和评定测量不确定度的主要步骤,并结合具体实例进行了钻芯法推定混凝土强度的不确定度评价,以期完善钻芯法检测混凝土强度施工工艺。     

钢筋保护层厚度测量不确定度的评定

根据JGJ/T 152-2019《混凝土中钢筋检测技术规程》中的检测技术要求,对同一点混凝土剪力墙钢筋保护层厚度进行10次重复性检测,综合分析相关标准检验检测过程以及日常检测过程,建立数学模型,进行不确定度分量的确定.依据JJF 1059.1-2012《测量不确定度评定与表示》进行A类不确定度和B类不确定度计算,最终得到钢筋保护层厚度的测量不确定度,保证日常检验检测活动的准确性,维持实验室的不确定度评价能力.     

预应力混凝土用钢绞线拉伸强度试验结果不确定度的评定

本文通过对预应力混凝土用钢绞线拉伸强度试验结果进行了不确定度评定和分析,为同类试验结果的不确定度评定提供了参考依据。     

保护涂料对混凝土渗透性能的研究

利用AUTOCLAM和RCM方法研究了两种混凝土保护用涂料(分别属于成膜型涂料和渗透型涂料)的性能,测试了涂刷涂料后混凝土试件吸水性、透水性、以及氯离子渗透性,定量说明两类混凝土结构防护用保护涂料对混凝土抗渗透能力的影响。结果表明:涂刷涂料的混凝土的抗水渗性能和抗氯离子渗透性明显比没有涂刷涂料的混凝土好,渗透型涂料和成模型涂料的抗氯离子渗透性相差不大,但渗透型涂料比成膜型涂料的抗水渗透性能优越。     

防水涂料检测中若干影响因素浅析

分析了防水涂料检测中应注意的几个问题,影响膜片物理性能的因素包括实验室温湿度条件、涂膜的涂覆次数以及涂膜厚度、拌和方式、养护条件、拉伸速度等;粘结强度测试过程中应注意水泥基材、涂刷厚度以及涂刷次数等因素。最后,提出了一些关于防水涂料性能检测的可行性建议。     

膨胀结晶型防火材料对混凝土耐火性能的影响

为了研究结晶型防火涂层对混凝土耐火性能的影响,设计了4个体积分数（1%、2%、3%和4%）的结晶型防火涂层用于混凝土耐火性能的改良,然后开展了混凝土试件的质量、渗透性能和力学性能的测试,同时开展SEM试验,研究其微观结构。结果表明：燃烧试验对混凝土造成了严重的损伤,质量损失率随防火涂料浓度的增大呈先降低后稳定的特点;当防火涂料体积分数为0~3%时,混凝土渗水高度随浓度增加而减小,超过3%后变化幅度较小;表面防护作用加速了混凝土早期强度的形成,养护28 d后混凝土强度几乎不受防火涂料浓度的影响;结晶型防火材料改变了混凝土内部的孔隙结构,体积分数3%和4%的防火涂层可以形成连续状晶体膜结构。     

聚氨酯防水涂料评述(上)

对当前市场上几类聚氨酯防水涂料的组成、性能、特点作了评述,认为聚氨酯防水涂料应按外露型和非外露型分类并分别制定标准;剖析了“911”和“991”等所谓非焦油聚氨酯防水涂料的实质,指出其不能作为外露型涂料使用,也不宜用在地下防水中;分析了聚氨酯涂膜厚度与涂膜抗拉强度及延伸率的关系,指出施工中保证厚度的重要性;提出了单组分聚氨酯防水涂料在我国不可能成为主流品种的观点,并认为将聚氨酯防水涂料宣传为绿色建材是一种误导。     

Evaluating a polymer concrete coating for protecting non-metallic underground facilities from sulfuric acid attack

Deteriorating underground facilities built with cement concrete and clay bricks require rapid in situ rehabilitation, and using coating as a corrosion protectant is one method currently being adopted. The performance of a polymer concrete coating was evaluated using a combination of full-scale and laboratory tests. The polyester-based polymer concrete coating had a density of 1.75 g/cm³ (109 lb/ft³) and hardness in the range 38–45 (Barcol hardness). A full-scale test on coating applicability and performance on the concrete substrate was performed under an external hydrostatic pressure of over 103 kPa (15 psi) of water, simulating the groundwater condition. Coated concrete cylinders and clay bricks with holidays (pinholes) were used to study the chemical resistance of the coating under acidic environments to represent the worst sewer and accelerated test conditions (ASTM G 20). Bond strength between the coating and the concrete/clay brick substrates were determined using the modified ASTM D 4541 test. The performance of the polymer concrete coating material was studied for over 3 years. The polymer concrete coating was applied with ease on dry and wet concrete surfaces. Test results showed that the polymer concrete coating had good bond strength with clay bricks and wet concrete surface. No failure was observed in 3 years with coated clay bricks. The coating extended the lifetime of dry and wet concrete by a factor of 29 and 71, respectively. The weight change of coated concrete was modeled using a film model.     

The use of inorganic conversion coatings to enhance the corrosion resistance of reinforcement and the bond strength at the rebar/concrete

The performance of concrete specimens reinforced with uncoated rebars or rebars coated with inorganic conversion coatings was investigated. The corrosion resistance of rebars and the bond strength at the rebar/concrete interface for uncoated rebars as well as rebars coated with three different inorganic conversion coatings were evaluated according to the corresponding ASTM G109 standard. The results showed that different inorganic conversion coatings give significant enhancements of corrosion resistance and increased interface bond strength compared to uncoated ordinary steel rebars. However the extent to which each conversion coating improves the corrosion resistance of the rebars and the interface bond strength inevitably depends on the chemical composition of the applied inorganic conversion coating.     

Evaluation of the durability of mortar and concrete applied with inorganic coating material and surface treatment system

Various surface coatings are used to prevent the degradation of durability of concrete structures. Most of them are constituted of organic coatings using volatile organic compound. However, such organic coatings have the decisive shortcoming of being air-polluting during manufacturing process as well as during coating works. Calcium-silicate compound, an inorganic coating which exhibits composition similar to cement, is adopted to compensate this disadvantage. So far clear results are still lacking for the evaluation of durability of concrete using inorganic coating.This study intends to assess the durability of concrete applied with inorganic coating material and concrete surface treatment. The diffusivity of chloride has been evaluated using mortar specimens, and concrete specimens were used to assess the durability performance related to inorganic coating materials via carbonation test and frost resistance test.Experimental results reveal that the resistances against the penetration of chloride, freezing–thawing and carbonation are improved in the hardened mortar and concrete specimens coated with special cement coating compared to non-coated ones. Especially, cases where concrete surface treatment is applied as level III exhibit the most remarkable performances.     

膨胀型防火涂层膨胀尺寸非线性传热模型

膨胀型防火涂层在膨胀过程中孔隙存在的对流传热和辐射传热会降低涂层的防火性能。考虑到孔隙之间存在涂层分解产生的气体,因此通过理想气体状态方程,描述了涂层在不同升温条件下的膨胀行为。建立了以膨胀尺寸为输出项,并考虑孔隙对有效导热系数增强作用的有限元传热模型,探究不同厚度的涂层在不同升温环境下的防火性能。结果表明：膨胀尺寸模型能够较为准确地预测涂层在不同温度场下的膨胀行为,涂层最大膨胀率随干膜厚度增大而减小;基于膨胀尺寸和多孔有效导热系数的有限元传热模型模拟的钢管温度变化与试验结果吻合较好;膨胀型防火涂层在高升温速率环境中能够明显延缓钢管升温,并降低其最大受火温度;不同升温环境中,涂层的防火能力和厚度呈非线性变化。     

隧道防火涂料配方设计和性能研究

试验研究了隧道防火涂料的配方设计,讨论了粘结剂、隔热材料、引气剂、可再分散乳胶粉对隧道防火涂料性能的影响。试验结果表明,研制的隧道防火涂料具有良好的物理化学性能,施工和易性好,粘结强度高,导热系数低,抗龟裂性和耐候性优良。当干膜厚度为10mm时,其耐火极限达2.5h。     

防水涂料拉伸强度检测结果不确定度分析

用测量不确定度表示检测结果是当前国际上约定的做法．然而如何对测量结果的不确定度进行合理评定，一直是困扰检测实验室的一个难题．依据JJF 1059-1999《测量不确定度评定与表示》的评定原则，通过实例，简要地阐述了防水涂料拉伸强度检测不确定度评定方法，对力学检测领域测量不确定度的评定具有借鉴意义。