PSI - Issue 28

N.A. Kosheleva et al. / Procedia Structural Integrity 28 (2020) 1883–1891 Author name / Structural Integrity Procedia 00 (2019) 000–000

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Based on the analysis of the obtained data, the maximum difference between the sensor measurements along the length of the samples for the considered moment of time was 28.5 and 27.3% for the first and second samples, respectively. The strain distribution along sample 1, in contrast to sample 2, is symmetric. For sample 2, there is a noticeable disturbance in strain distribution along the length, which can be caused by a violation of the straight-line position of the optical fiber during the casting of the sample. 5. Conclusions In the presented paper, the evolution of process-induced strains in samples made from cement mixture with different geometric shapes using embedded fiber-optic sensors based on Bragg gratings is investigated. To accomplish this task, an experimental stand was designed and manufactured, equipped with the necessary sensors to control the temperature and humidity of both the environment and inside the created samples. In addition, the installed laser displacement sensors allow to measure the shrinkage of the samples. The history of process-induced strains during first 72 hours after casting was recorded with the help of embedded fiber Bragg grating sensors. The analysis of the obtained experimental data showed that FOSs make it possible to register qualitatively and quantitatively the level of process-induced strains from the moment of the initial setting of the cement mixture. In addition, the possibility of placing point sensors along the entire length of the samples under study makes it possible to better investigate the processes that occur during the cement samples formation, as well as their further evolution. It should be noted that the embedded fiber-optic sensors did not have additional coatings, except for the polyimide coating. Despite the fragility and obvious limitations of the implemented technology for full-scale construction objects, in laboratory conditions this method allows to obtain the experimental data that can be useful for constructing and validating models of the concrete mechanical behavior. Acknowledgements This work was supported by the grant of the President of Russian Federation for support of young Russian scientists and leading scientific schools (МК-2401.2019.1). References Hong, C. Y., Zhang, Y. F., Zhang, M. X., Leung, L. M. G., Liu, L. Q., 2016. Application of FBG sensors for geotechnical health monitoring, a review of sensor design, implementation methods and packaging techniques . Sensors and Actuators, A: Physical 244, 184– 197. Huang, Y., Huang, Y., Bao, Y., Chen, G., Zhou, Z., 2019. A constrained cylinder model of strain transfer for packaged fiber Bragg grating sensors embedded in inelastic medium. Structural Control and Health Monitoring 26(5), e2335. Kablov, E. N., Sivakov, D. V., Gulyaev, I. N., Sorokin, K. V., Fedotov, M. Yu., Dianov, E. M., Vasil’ev, S. A., Medvedkov, O. I., 2011. Application of optical fiber as strain gauges in polymer composite materials. Polymer Science Series D 4(3), 246–251. Kara, P., Korjakins, A., 2013. Investigation of Thermal Properties of Cement Paste with Fluorescent Lamp Glass Waste, Glass Cullet and Coal/Wood Ashes. Journal of Sustainable Architecture and Civil Engineering 2(3), 46– 53. Khadour, A., Waeytens, J., 2018. Monitoring of concrete structures with optical fiber sensors. Eco-Efficient Repair and Rehabilitation of Concrete Infrastructures. Elsevier, 97–121. Kosheleva, N., Serovaev, G., Gusev, G., 2020. Process-induced strain measurement by fiber optic sensors in a cylindrical concrete sample. AIP Conference Proceedings 2216, 040011. Lammens, N., Luyckx, G., Degrieck, J., De Waele, W. , 2011. Experimental determination of the multi-axial strain transfer from CFRP-laminates to embedded Bragg sensor., Smart Structures and Materials, 5th ECCOMAS thematic conference, Proceedings, 482–485. Leng, J. S., Winter, D., Barnes, R. A., Mays, G. C., Fernando, G. F., 2006. Structural health monitoring of concrete cylinders using protected fibre optic sensors. Smart Materials and Structures 15(2), 302–308. Lin, Y. B., Pan, C. L., Kuo, Y. H., Chang, K. C., Chern, J. C., 2005. Online monitoring of highway bridge construction using fiber Bragg grating sensors. Smart Materials and Structures 14(5), 1075–1082. Majumder, M., Gangopadhyay, T. K., Chakraborty, A. K., Dasgupta, K., Bhattacharya, D.K., 2008. Fibre Bragg gratings in structural health monitoring—Present status and applications., Sensors and Actuators A: Physical 147(1), 150–164. Mao, J., Xu, F., Gao, Q., Liu, S., Jin, W., Xu, Y., 2016. A Monitoring Method Based on FBG for Concrete Corrosion Cracking. Sensors 16(7), 1093. Ramakrishnan, M., Rajan, G., Semenova, Y., Farrell, G., 2016. Overview of Fiber Optic Sensor Technologies for Strain/Temperature Sensing Applications in Composite Materials . Sensors 16(1), 99.