Abstract:
Cement grouts are used in number of applications including construction, maintenance and repairing of bridges, highways, airport runways, buildings, tunnels, pipelines, piles and wells (oil, gas and water). Also cement grouts are used in soil stabilization, repairing rocks, stabilizing slopes and tunnels and solidifying contaminated soils. With the wide spectrum of applications, there is a need to make the cement grouts sensing so that it can be monitored from the time of mixing to the entire service life and also make the repaired sections highly sensing for real-time monitoring. In this investigation highly sensing smart cement grout was developed using 0.8 water-tocement (w/c) ratio. A two probe monitoring method has been developed to not only characterize the material to identify the monitoring electrical property but also monitor the changes in the cement grout properties. During the hardening process the change in the resistivity with curing time was continuously monitored to better understand the process. The sensing grout showed change in resistivity with applied stress (piezoresistive) and the changes in the behavior were very much depended on the curing time up to 28 days of investigation. The piezoresistive axial strain was over 100% at the failure stress, which was over 500 times (50, 000%) higher than the compressive failure strain of cement. The sensing grout was also used to repair damaged piezoresistive smart cement cured under room condition. Vipulanandan p-q models were used to predict the curing and also the piezoresisitive behavior of the sensing grout and the models predicted the behavior very well. The grout strengths and secant piezoresistivity modulus varied with time and Vipulanandan correlation model predicted the changes very well. Also twenty 2 eight days old smart cement samples with piezoresistivity in the range of 250% were failed and then repaired using the newly developed smart cement grout in one day. The recovered repaired strength and piezoresistive axial strain at failure have been tested, verified and also modelled.