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Laboratory evaluation of performance and durability of polymer grouts for subsurface hydraulic/diffusion barriers. Informal report, October 1993--May 1994

Description: Contaminated soils, buried waste and leaking underground storage tanks pose a threat to the environment through contaminant transport. One of the options for control of contaminant migration from buried waste sites is the construction of a subsurface barrier. Subsurface barriers increase the performance of waste disposal sites by providing a low permeability layer that can reduce percolation water migration into the waste site, minimize surface transport of contaminants, and reduce migration of volatile species. Also, a barrier can be constructed to envelop the site or plume completely, there by containing the contaminants and the potential leakage. Portland cement grout curtains have been used for barriers around waste sites. However, large castings of hydraulic cements result invariably in cracking due to shrinkage, thermal stresses induced by the hydration reactions, and wet-dry cycling prevalent at and sites. Therefore, improved, low permeability, high integrity materials are under investigation by the Department of Energy`s (DOE) Office of Technology Development, Integrated Demonstrations and Programs. The binders chosen for characterization include: an acrylic, a vinylester styrene, bitumen, a polyester styrene, furfuryl alcohol, and sulfur polymer cement. These materials cover broad ranges of chemical and physical durability, performance, viscosity, and cost. This report details the results of laboratory formulation, testing, and characterization of several innovative polymer grouts. An appendix containing a database of the barrier materials is at the end of this report.
Date: May 1, 1994
Creator: Heiser, J.H. & Milian, L.W.
Partner: UNT Libraries Government Documents Department

Liquid return from gas pressurization of grouted waste

Description: The ability to force pore liquids out of a simulated waste grout matrix using air pressure was measured. Specimens cured under various conditions were placed in a permeameter and subjected to increasing air pressure. The pressure was held constant for 24 hours and then stepped up until either liquid was released or 150 psi was reached. One specimen was taken to 190 psi with no liquid release. Permeability to simulated tank waste was then measured. Compressive strength was measured following these tests. This data is to assess the amount of fluid that might be released from grouted waste resulting from the buildup of radiolytically generated hydrogen and other gasses within the waste form matrix. A plot of the unconfined compressive strength versus breakthrough pressures identifies a region of ``good`` grout, which will resist liquid release.
Date: May 1, 1994
Creator: Powell, W. J. & Benny, H. L.
Partner: UNT Libraries Government Documents Department

A TOUGH2 equation-of-state module for the simulation of two-phase flow of air, water, and a miscible gelling liquid

Description: The injection of grout into the subsurface can be used to encapsulate contaminated regions of an aquifer, or to form underground barriers for the isolation of contaminant sources and to prevent the spreading of existing plumes. This requires identifying grouts, or barrier fluids, which when injected into the subsurface exhibit a large increase in viscosity and eventually solidify, sealing the permeable zones in the aquifer. Simulation and modeling analysis are indispensable tools for designing the injection and predicting the performance of the barrier. In order to model flow and transport in such systems, the thermophysical properties of the fluid mixtures have to be provided, and the governing mass- and energy-balance equations for multiphase flow in porous media have to be solved numerically. The equation-of-state module EOS11 described herein is an extension of the EOS7 module of the TOUGH2 code for flow of saline water and air. In the modeling approach, the chemical grout is treated as a miscible fluid the viscosity of which is a function of time and concentration of the gelling agent in the pore water. If a certain high viscosity is reached and the movement of the grout plume ceases, the gel is assumed to solidify, leading to a new porous medium with changed soil characteristics, i.e. reduced porosity and permeability, increased capillary strength for a given water content, and changed initial saturation distribution.
Date: May 1, 1994
Creator: Finsterle, S.; Moridis, G. J. & Pruess, K.
Partner: UNT Libraries Government Documents Department