Method for Evaluation of In-place concrete Strength using Concrete Temperature History.

由于混凝土存在于结构中，因此获取有关混凝土现场强度的信息变得更加重要，特别是对于高强度混凝土的使用。按照标准程序进行的测试，仅在圆柱体上进行测试，表示交付到现场的混凝土的潜在强度。在此基础上提出了混凝土现场强度评价体系。(1)水化热积累促进混凝土强度发展的评价。由于水化热，高强混凝土构件内的温度上升了约40度。通过不同的实验来阐明早期高温史对早期加速强度发展和后期强度退化的影响。在此基础上，提出了混凝土强度发展的实用评价方法。(2)混凝土水化热温升分析。对试验得到的混凝土构件内温度分布的检验表明，水化速率对温度的依赖关系是存在的，并可用Arrhenius方程表示。提出了考虑这种相关性的分析方法。(3)超高强混凝土抗拔试验的应用。使用特别改进的测试设备对超高强度混凝土进行了拔出试验。推导出了适用于混凝土强度全范围的强度预测公式。(4)提出了现场强度的评估方法。将强度法与温升分析相结合，提出了配合比设计中目标强度的确定方法。应用强度发展理论和混凝土施工过程中的拉拔试验，提出了一种现场强度评定的推荐方法.

It becomes more important to obtain information about the in-place strength of concrete as it exists in a structure especially for the use of high-strength concrete. As carried out in accordance with standard procedures, the test on cylinders only r13EA\ : epresents the potential strength of concrete as delivered to a site. A system for evaluation of in-place strength of concrete is proposed based on the methods developed in this research.(1) Evaluation on strength development accelerated by the hydration heat accumulation. The temperature in the high-strength concrete member rises about 40 degrees due to hydration heat. Various experiments were performed to clarify the effect of the13EA\ : high temperature histories during early age on accelerated strength development in early age and strength degradation in later age. On the basis of these test results, the practical method for evaluation of strength development was derived.(2) Analysis for temperature rise in concrete due to hydration heat. The examination on the temperature distribution in the concrete member obtained from tests shows that the dependency of hydration rate on temperature exists and it can be expressed13EA\ : by using Arrhenius equation. An analytical method considering this dependency was developed.(3) Application of pull-out tests for very high strength concrete. Pull-out tests on very high strength concrete were performed using specially improved test devices. The strength-predicting equation applicable for whole range of concrete strength w13EA\ : as derived.(4) Proposed method for evaluation of in-place strength. A method for determination of target strength at mix design is proposed based on the combination of the strength method and the analysis of temperature rise described in this study. A recommen13EA\ : ded method for evaluation of in-place strength is shown by applying the strength development theory and the pull-out test on concrete during construction.