ABSTRACT

For safe construction practise, it is important to monitor the hardening process of concrete during the construction stage itself. Moreover, with the increasing use of supplementary cement-based materials (SCM) in concrete construction which adversely alters (significantly delays) the setting and strength gain in concrete, it becomes highly imperative to closely monitor and examine the development of properties of cement composite in the structural system during hardening. In view of this, the present study investigates the efficacy of the non-invasive wave propagation methods employing Acoustic Emission (AE) and electromechanical impedance (EMI), through passive and active signatures, respectively, in monitoring the hardening process of just poured SCM incorporated cement system. Results showed that AE parameters combined with the frequency analysis could be able to qualitatively provide the information on the hardening process in cement mixtures made with varying levels of flyash replacements. AE results are further correlated with the properties such as stiffness of the material system obtained through EMI measurement and strength property. Correlations are found to be very consistent and will be helpful for continuous monitoring of strength and stiffness gain in cement composite during the construction stage, through non-invasive, non-destructive, in-situ technique combining AE and EMI.

摘要

为了安全的施工实践，重要的是在施工阶段本身监测混凝土的硬化过程。此外，随着在混凝土施工中越来越多地使用补充水泥基材料 (SCM)，这会不利地改变（显着延迟）混凝土的凝结和强度增加，因此密切监测和检查水泥复合材料性能的发展变得非常必要。硬化过程中的结构体系。有鉴于此，本研究分别通过无源和有源特征，研究了采用声发射 (AE) 和机电阻抗 (EMI) 的非侵入性波传播方法在监测刚浇注的 SCM 的硬化过程中的功效。水泥系统。结果表明，AE 参数与频率分析相结合，能够定性地提供有关用不同水平的粉煤灰替代物制成的水泥混合物的硬化过程的信息。AE 结果与通过 EMI 测量获得的材料系统的刚度和强度特性等特性进一步相关。发现相关性非常一致，将有助于在施工阶段通过结合 AE 和 EMI 的非侵入性、非破坏性、原位技术连续监测水泥复合材料的强度和刚度增益。AE 结果与通过 EMI 测量获得的材料系统的刚度和强度特性等特性进一步相关。发现相关性非常一致，将有助于在施工阶段通过结合 AE 和 EMI 的非侵入性、非破坏性、原位技术连续监测水泥复合材料的强度和刚度增益。AE 结果与通过 EMI 测量获得的材料系统的刚度和强度特性等特性进一步相关。发现相关性非常一致，将有助于在施工阶段通过结合 AE 和 EMI 的非侵入性、非破坏性、原位技术连续监测水泥复合材料的强度和刚度增益。