Comparison of Alkali-Silica Reaction Gel Behavior in Mortar at Microwave Frequencies
Comparison of Alkali-Silica Reaction Gel Behavior in Mortar at Microwave Frequencies
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DOI：
10.1109/tim.2014.2367771
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发表时间：
2015-07-01
影响因子：
5.6
通讯作者：
Zoughi, Reza
中科院分区：
文献类型：
--
作者：
Hashemi, Ashkan;Horst, Matthew;Zoughi, Reza
碱-硅反应（ASR）是混凝土劣化的常见原因之一，几十年来一直受到越来越多的关注。水在用于制造混凝土的活性骨料的存在下，在该反应的形成、维持和促进中起主要作用。在这个过程中，游离水被束缚在ASR凝胶中，导致混凝土的膨胀和劣化。设计一种对水的状态（游离或结合）敏感的测试方法有可能成为ASR检测和评估的首选方法，因为这些措施可用于检测ASR并可能量化反应进展。微波信号对水的存在敏感，因为水弛豫频率出现在该频率范围内。最近，微波无损评价技术已显示出巨大的潜力，以评估和区分ASR影响的砂浆样品和那些没有ASR凝胶。考虑到ASR产品的复杂化学性质，预计它们的行为在不同的微波频带下会有所不同。为了评估不同频率对ASR存在的敏感性，在R波段（1.7-2.6 GHz）、S波段（2.6-3.95 GHz）和X波段（8.2-12.4 GHz）进行介电常数测量。本文介绍了用活性和非活性骨料制成的砂浆样品的测量结果。测量结果和随后的分析有助于更好地理解微波信号与受ASR影响的水泥基材料的相互作用。此外，结果表明，S波段似乎是最合适的频带ASR评估在微波政权。
Alkali-silica reaction (ASR) is one common cause of concrete deterioration and has been a growing concern for decades. Water, in the presence of reactive aggregates used to make concrete, plays a major role in the formation, sustainment, and promotion of this reaction. In this process, free water becomes bound within ASR gel, resulting in expansion and deterioration of concrete. Devising a test approach that is sensitive to the state of water (free or bound) has the potential to become a method-of-choice for ASR detection and evaluation, since such measures can be used to detect ASR and potentially quantify reaction progression. Microwave signals are sensitive to the presence of water, since the water relaxation frequency occurs in this frequency range. Recently, microwave nondestructive evaluation techniques have shown great potential to evaluate and distinguish between ASR-affected mortar samples and those without ASR gel. Given the complex chemistry of ASR products, their behavior is expected to differ at different microwave frequency bands. To evaluate the sensitivity of different frequencies to the presence of ASR, dielectric constant measurements were conducted at R-band (1.7-2.6 GHz), S-band (2.6-3.95 GHz), and X-band (8.2-12.4 GHz). This paper presents the measured results for mortar samples made with reactive and nonreactive aggregates. The measurement results and subsequent analyses aid in a better understanding of the microwave signals interaction with ASR-affected cement-based materials. Moreover, the results indicate that S-band appears to be the most appropriate frequency band for ASR evaluation in the microwave regime.