Moisture plays a critical role in reinforced concrete corrosion, underpinning structural degradation which costs the global economy a staggering $350 bn per year (0.5% GDP). Both moisture sensors and repair materials that limit water ingress are required, but monitoring and maintenance are often viewed as separate challenges. This paper outlines a first-time demonstration of moisture sensors based on low calcium fly ash geopolymers — a class of cementitious, electrolytically conductive repair materials. Electrochemical impedance spectroscopy and equivalent circuit models are used to understand and optimize the electrical response of geopolymer sensors to water content and temperature. Moisture and temperature precisions of 0.1 wt% and 0.1 ° C are demonstrated respectively, and sensor drifts over 20 minute periods were found to be within 1–3%. Sensor responses were also shown to be repeatable to within 3% between wetting and thermal cycles. Results from spectrometry and chromatography analyses link this repeatability to the minimal ion leaching from the sensors. The study demonstrates the feasibility of moisture sensing using geopolymers, and furthers our current understanding of the role of moisture in the ionic conductivity of alkali-activated materials. This work is anticipated to be the first stage in developing 2D, distributed sensor-repairs for concrete structures, and other chemical sensors that support concrete structural health monitoring and prognostics.

水分在钢筋混凝土腐蚀中起着关键作用，加剧了结构退化，每年给全球经济造成的损失高达3500亿美元（占GDP的0.5％）。既需要水分传感器，又需要限制进水的修补材料，但是监视和维护通常被视为独立的挑战。本文概述了基于低钙粉煤灰地质聚合物（一种胶凝，电解导电修复材料）的湿度传感器的首次演示。电化学阻抗谱和等效电路模型用于了解和优化地聚合物传感器对水含量和温度的电响应。水分和温度精度分别为0.1 wt％和0.1°C，在20分钟的时间内传感器漂移在1-3％之内。还显示出传感器响应在润湿和热循环之间可重复至3％以内。光谱分析和色谱分析的结果将这种可重复性与传感器中最少的离子浸出联系起来。这项研究证明了使用地质聚合物进行湿度感测的可行性，并进一步加深了我们目前对水分在碱活化材料的离子电导率中的作用的理解。预计这项工作将是开发用于混凝土结构的二维，分布式传感器修复以及支持混凝土结构健康状况监测和预测的其他化学传感器的第一步。这项研究证明了使用地质聚合物进行湿度感测的可行性，并进一步加深了我们目前对水分在碱活化材料的离子电导率中的作用的理解。预计这项工作将是开发用于混凝土结构的二维，分布式传感器修复以及支持混凝土结构健康状况监测和预测的其他化学传感器的第一步。这项研究证明了使用地质聚合物进行湿度感测的可行性，并进一步加深了我们目前对水分在碱活化材料的离子电导率中的作用的理解。预计这项工作将是开发用于混凝土结构的二维，分布式传感器修复以及支持混凝土结构健康状况监测和预测的其他化学传感器的第一步。