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Effects of Curing Temperature and Pressure on the Chemical, Physical, and Mechanical Properties of Portland Cement.

机译：养护温度和压力对硅酸盐水泥化学，物理和力学性能的影响。

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摘要

This dissertation mainly focuses on studying the fundamental hydration kinetics and mechanisms of Portland cement as well as the effects of curing temperature and pressure on its various properties.;An innovative test apparatus has been developed in this study to cure and test cement paste specimens under in-situ conditions, such as down-hole in oil wells with high temperature and high pressure. Two series of tests were performed using cement pastes prepared with four different classes of oilwell cement (namely Class A, C, G, and H cements). Specimens in groups of four were cured at temperatures ranging from ambient to 60 °C and pressures ranging from 0.69 to 51.7 MPa for a period of 48 or 72 hours. The density and w/c ratio of the specimens at the time of casting as well as at the end of the curing period were recorded. Total chemical shrinkage of the cement paste was measured continuously during the entire hydration period while tensile strength was obtained at the end of the curing period using both water pressure and splitting tension test methods. Due to capacity limitations of the test equipment, in-situ tensile strength was obtained for only one test series with a highest curing pressure of 13.1 MPa. Specimens from the other test series were depressurized before the tensile strength tests.;Chemical shrinkage test is an important method of measuring cement hydration kinetics in that the normalized total chemical shrinkage is approximately equal to the degree of cement hydration. By studying the correlations between the chemical shrinkage and the non-evaporable water content of cement during hydration, a multi-linear model is first proposed to estimate the normalization factors for different types of cement under different curing conditions. Based on the hydration kinetics data obtained from chemical shrinkage test results, a new approach of modeling the effect of curing temperature and pressure on cement hydration kinetics is proposed. It is found that when a hydration kinetics curve is represented by an unknown function, the effect of curing condition on the curve can be modeled by incorporating a simple scale factor in this function. The relationship between this scale factor and curing condition is described by chemical kinetics laws.;While the proposed new approach of modeling cement hydration kinetics has the advantage of being widely applicable to different types of cement, it only explains one influence factor of cement hydration (i.e. the curing condition). In order to take into account other influence factors and to further understand the fundamental mechanisms of cement hydration, a more complex particle-based numerical hydration model is developed by combining the two well-known cement hydration mechanisms, namely the nucleation and growth controlled mechanism and the diffusion controlled mechanism. The model is applied to experimental data of both C3S hydration in dilute suspensions and Class H cement paste hydration. Excellent agreement is observed between experimental and modeled results. Three rate-controlling parameters with clear physical meanings can be identified from the proposed model. Fitted model parameters are found to be in reasonable agreement with experimental observation. The dependencies of these parameters on particle size, cement composition, w/c ratio, and curing condition are also investigated.;Finally, the importance of cement hydration kinetics is illustrated by showing their close correlations with the physical and mechanical properties. The various influence factors, including the curing temperature and pressure, of physical and mechanical property test results (particularly density and tensile strength) are evaluated. Potential damage mechanisms of cement paste specimens during depressurization are studied by analyzing the deformation behavior of the entire system consisting of the cement paste and pressurizing water.
机译：本论文主要研究了硅酸盐水泥的基本水化动力学和机理，以及固化温度和压力对其各种性能的影响。现场条件，例如高温高压油井的井下。使用由四种不同类型的油井水泥（即A，C，G和H类水泥）制备的水泥浆进行了两个系列的测试。将四个一组的样品在环境温度至60°C，压力0.69至51.7 MPa的范围内固化48或72小时。记录在铸造时以及在固化阶段结束时的样品的密度和w / c比。在整个水化期间连续测量水泥浆的总化学收缩率，同时在固化阶段结束时使用水压和劈裂张力测试方法获得抗张强度。由于测试设备的容量限制，仅在最高固化压力为13.1 MPa的一个测试系列中获得了现场拉伸强度。在拉伸强度测试之前，对其他测试系列的样品进行降压。化学收缩率测试是衡量水泥水化动力学的重要方法，因为归一化的总化学收缩率大约等于水泥水合度。通过研究水化过程中水泥的化学收缩率与非挥发水含量之间的相关性，首先提出了一个多线性模型来估计水泥在不同固化条件下的归一化因子。基于化学收缩试验结果获得的水化动力学数据，提出了一种模拟固化温度和压力对水泥水化动力学影响的新方法。发现当水合动力学曲线由未知函数表示时，可以通过在该函数中加入简单的比例因子来模拟固化条件对该曲线的影响。该比例因子与固化条件之间的关系由化学动力学定律描述。虽然所提出的水泥水化动力学建模新方法具有可广泛应用于不同类型水泥的优势，但仅解释了水泥水化的一个影响因素（即固化条件）。为了考虑其他影响因素并进一步了解水泥水化的基本机理，通过结合两种众所周知的水泥水化机理，即成核和生长控制机理，以及两种方法，建立了一个更复杂的基于颗粒的数值水化模型。扩散控制机制。该模型适用于稀悬浮液中C3S水化和H类水泥浆水化的实验数据。实验结果和模型结果之间观察到极好的一致性。可以从提出的模型中识别出三个具有清晰物理意义的速率控制参数。发现拟合的模型参数与实验观察结果合理吻合。还研究了这些参数对粒度，水泥组成，w / c比和固化条件的依赖性。最后，通过显示水泥水化动力学与物理和机械性能的密切关系，说明了水泥水化动力学的重要性。评估了物理和机械性能测试结果（特别是密度和拉伸强度）的各种影响因素，包括固化温度和压力。通过分析由水泥浆和加压水组成的整个系统的变形行为，研究了水泥浆试样在降压过程中的潜在破坏机理。

著录项

  • 作者

    Pang, Xueyu.;

  • 作者单位

    Columbia University.;

  • 授予单位 Columbia University.;
  • 学科 Engineering Civil.;Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2011
  • 页码 239 p.
  • 总页数 239
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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