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A temperature prediction model in new concrete pavement and a new test method for concrete fracture parameters.

机译：新型混凝土路面温度预测模型及混凝土断裂参数试验方法

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摘要

The interaction between temperature development within concrete pavement within the first few days after placement and the ambient temperature conditions can influence the long-term quality of the concrete. The thermal behavior of concrete can be characterized from a knowledge of concrete temperature, environmental conditions (air temperature, wind velocity, and solar radiation), and cement hydration in the mixture. To account for those interactions, a computer model is developed for predicting the temperature profile in hardening concrete pavement in terms of material and environmental factors.; A concrete pavement structure is unlike most other structures because it manifests a very large surface to volume ratio causing significant variations in temperature and moisture within the structure. Also, thermal properties such as concrete conductivity and specific heat affect the heat transfer of the concrete pavements at an early age. Since conductivity is an important property, a unique approach is suggested by which concrete conductivity is back-calculated from the best fit value between the computed and measured laboratory process. Concrete conductivity can be represented in terms of the degree of hydration.; Boundary conditions were also considered in the modeling process; such as the use of polyethylene sheets as an insulating material. It was determined, based on historic experiments, heat loss by convection through the polyethylene sheets can be represented in terms of wind velocity. Specially, solar radiation absorptivity can be increased as the polyethylene sheets are covered on the concrete pavement sections.; Also developed is an experimental laboratory procedure which measures the fracture properties of concrete material. Fracture properties are important in characterizing the crack potential of concrete pavements at saw cut notch locations. The procedure suggested provides a method to measure the fracture toughness of concrete in terms of the temperature and curing conditions in the field. Using the maturity concept, temperature-dependent fracture toughness of concrete could be estimated and used to control thermal cracking in the concrete pavement.
机译：浇筑后头几天内混凝土路面内温度的升高与环境温度之间的相互作用会影响混凝土的长期质量。混凝土的热行为可通过了解混凝土温度，环境条件（气温，风速和太阳辐射）以及混合物中水泥的水化来表征。为了解决这些相互作用，开发了一种计算机模型，用于根据材料和环境因素预测硬化混凝土路面的温度曲线。混凝土路面结构与大多数其他结构不同，因为它显示出非常大的表面积与体积比，从而导致结构内的温度和湿度发生明显变化。而且，诸如混凝土的电导率和比热之类的热性能在早期就影响混凝土路面的热传递。由于电导率是重要属性，因此建议采用一种独特的方法，即根据计算出的和测量的实验室过程之间的最佳拟合值对混凝土的电导率进行反算。混凝土的电导率可以用水合度来表示。在建模过程中还考虑了边界条件。例如使用聚乙烯片作为绝缘材料。根据历史性实验确定，通过对流通过聚乙烯片的热损失可以用风速表示。特别地，当聚乙烯板覆盖在混凝土路面部分上时，太阳辐射吸收率可以增加。还开发了一种实验性实验室程序，用于测量混凝土材料的断裂性能。断裂特性对于表征锯齿形切口位置处混凝土路面的裂缝可能性非常重要。建议的程序提供了一种根据现场温度和固化条件测量混凝土断裂韧性的方法。使用成熟度概念，可以估算混凝土随温度变化的断裂韧性，并将其用于控制​​混凝土路面的热裂。

著录项

  • 作者

    Yang, Sungchul.;

  • 作者单位

    Texas A&M University.;

  • 授予单位 Texas A&M University.;
  • 学科 Engineering Civil.; Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 1996
  • 页码 176 p.
  • 总页数 176
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 建筑科学;工程材料学;
  • 关键词

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