Development and Characterization of Grouts for Sealing and Sensing Applications
Sunder, Shiva 1986-
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Greater use of cement and polymeric grouts in sealing applications demands further enhancement in the physical, mechanical and sensing properties from the time of mixing through pumping, final setting and entire service life. Hence, the cement and polymeric grouts (acrylamide, acrylic and polyurethane) were modified using various solutions and particle fillers. The self sensing capabilities for the grouts and grouted sands have been developed (resistivity and dielectric parameters) with applied stress. For the purpose of enhancing piezo-resistive and dielectric sensing capabilities of the grouts, a small amount of conductive fibers were used in the grout mix. Test protocols were developed to evaluate the sealing of leaking waste water pipe joints and decommissioning oil pipelines. The addition of surfactants had a significant effect on the polymeric grouts (maximum increase up to 4 hrs with the addition of Cationic surfactant). The bleed in the cement grout was reduced to zero with the addition of 10% clay. The pullout test developed was sensitive to the addition of admixtures in the grout and grouted sand. The compressive strength of the polymeric grout increased by over 50% with the addition of anionic surfactant. The optimum clay content was 5% based on the strength enhancement of cement grout. The dielectric constant of the chemically grouted sand varied from a value of 4 to 1200 with the addition of conductive fibers. With stress application on grouted sand with fibers, the dielectric constant varied from 1200 to 4200, a 250% increase as compared to a variation of 4.3 to 5.8 which was a 34% increase for the sample without fibers. The dielectric constant of the cement grout decreased by about 25% with the addition of clay. Application of polymeric grout was studied in large scale model tests. The polymeric grout was effective in sealing the lateral leaking joint with a leak of 1220 gpd to 0 gpd. The use of polyurethane grout was effective in sealing material in the decommissioning of simulated oil pipelines. A phenomenological model based on gas production and hardening properties of grout was developed to predict the confined expansion pressures developed during the curing of polyurethane grout. Also non-linear stress strain models were used to predict the behavior of grouted sand. Effect of additives on stresses on the sensing properties of the grouts and grouted sand were quantified.