Nanoparticle and Surfactant-Modified Smart Cement and Smart Polymer Grouts

Cement and polymer grouts are being used in various construction and rehabilitation applications related to oil wells, piles, structures, leaking pipelines and ground improvement. In this study oil well cement (Class H), Portland cement (Type 1) and poly acrylamide were used as representative cement and polymer grouts. The smart cement and smart polymer grouts were developed using conductive fillers to make them piezoresistive materials. The highly sensing properties of the smart grouts will help with the real-time monitoring of the performance of the grouts from the time of installation to the entire service life. A series of experiments were conducted to evaluate the smart grout behavior with and without 1% nano silica (NS) and 0.5% biosurfactant (BS) to determine the sensitivity in terms of piezoresistivity. The Marsh Funnel flow time and the viscosity increased by addition of NS and BS for both types of grouts. Addition of 1% NS improved the compressive strength and piezoresistivity of both smart cement grouts. For the smart oil well cement grout the piezoresistivity at compressive peak stress varied from 155 to 179% and it increased to 209-237% with 1% nano-silica. With 1% nano-silica and 0.5% biosurfactant the piezoresistivity reduced to 64 to70%. For the Portland cement grout with with 1% NS and 0.5% BS the piezoresistivity varied from 124% to 178%. For the acrylamide grout the resistivity changed by 25% at a compressive stress of 100 kPa and the addition of nano silica and biosurfactant reduced the peiezoresistivity of the grout. A nonlinear piezoresistive model predicated the compressive stress–change in resistivity relationship of the smart cement grouts with and without NS and BS very well.