Monitoring hydration characteristics of cement paste by EMI method
A monitoring system, which employs a piezoelectric ceramic as an active sensing transducer, is proposed for monitoring hydration characteristics of cement paste based on the electromechanical impedance (EMI) method. An impedance analyzer was used to obtain the electrical response of the sensor and the EMI measurements were performed by an online technique. The obtained data were analyzed using root mean square deviation (RMSD), a common statistical algorithm used for comparative processing of EMI spectra. The results show that the developed monitoring system is able to effectively detect physical changes of cement paste during the initial hydration.
Multiple Crack Detection of Concrete Structures Using Impedance-based Structural Health Monitoring Techniques
This paper presents a feasibility study for practical applications of an impedance-based real-time health monitoring technique applying PZT (Lead–Zirconate–Titanate) patches to concrete structures. First, comparison between experimental and analytical studies for damage detection on a plain concrete beam is made. In the experimental study, progressive surface damage inflicted artificially on the plain concrete beam is assessed by using both lateral and thickness modes of the PZT patches. Then, an analytical study based on finite element (FE) models is carried out to verify the validity of the experimental result. Secondly, multiple (shear and flexural) cracks incurred in a reinforced concrete (RC) beam under a third point bending test are monitored continuously by using a sensor array system composed of the PZT patches. In this study, a root mean square deviation (RMSD) in the impedance signatures of the PZT patches is used as a damage indicator.
People and Society in Scotland
People and society in Scotland: a social history ofmodern Scotland, vol. I, 1760-1830, ed. T. M. Devine and R. Mitchison (John Donald in association with the Economic and Social History Society of Scotland, Edinburgh, 1988), pp. xii, 316. £10.00; vol. II, 1830-1914, ed. W. Hamish Fraser and R. J. Morris (Edinburgh, 1990), pp. xvi, 362. £12.50; vol. Ill, 1914-1990, ed. T. Dickson and J. H. Treble (Edinburgh, 1992), pp. xi, 287. £15.00.