Submission of proposals
U.S. Army Construction Engineering Research Laboratory (CERL)
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A00-053 TITLE: Electro-Osmotic Pulse Technology to Control Leaching and Groundwater Intrusion in Containment Sites TECHNOLOGY AREAS: Materials/Processes OBJECTIVE: To develop an economically feasible prototype seepage prevention system based on electro-osmotic pulse technology to be used primarily in landfill and hazardous waste containment applications. DESCRIPTION: Electro-osmosis is the transport of cations due to the application of an external electric field. Because of the molecular binding nature of water molecules, water molecules are transported along with the cations. This technique has been used in civil engineering to dewater dredgings and other high-water content waste solids, consolidate clays, strengthen soft sensitive clays, and increase the capacity of pile foundations. Electro-osmosis has received significant attention in the last 5 years as a method to remove hazardous contaminants from groundwater or to arrest water flow. Although results have shown the technique to be feasible, they have not been remarkable. One limitation of the present application is the use of a constant direct current, not a pulsating current. Currently, electro-osmotic pulse (EOP) technology is being applied to concrete structures. A system has been developed that uses a pulsating direct electric field. The system consists of an electronic control unit that delivers electric pulses to positive electrodes (anodes) inserted into the concrete structure. The negative electrode (cathode) is driven into the exterior soil or buried within the concrete structure outside of the protected area. The pulsating electro-osmosis system consists of a pulse of positive voltage (as seen from the dry side of the concrete wall) and a period of rest when no voltage is applied. The pulse of positive voltage has the greatest duration and amplitude. The electrical pulse causes cations (e.g., Ca++) and associated water molecules to move from the structure's dry side towards the wet side, counter to the direction of flow induced by the hydraulic gradient, thus preventing water penetration through buried concrete structures. By using a pulsating excitation; electrode polarization, cation depletion, and overdrying of the concrete are prevented. The application of pulsating electro-osmosis and semi-conductive anodes to soils may overcome some of the limitations of the present direct current method. PHASE I: A theoretical model detailing the similarities and differences in the application of the EOP system to soil compared to those previously used in concrete would be developed. The theoretical developments would be complemented by small and large scale laboratory testing. Some issues to be addressed are: optimization of the pulse pattern for various soils and contaminants, e.g. number of cations available, and; selection of anode and cathode materials based on soil and contaminant type. PHASE II: The design construction and installation of three full scale prototype systems would be completed, based on the previous phase I design work. The test sites would include a normal landfill, a hazardous waste containment site, and a remediation barrier site. Prior to system installation, guidelines would be developed for applicable sites, operating procedure and monitoring, installation methodology and technical specifications, and reliability monitoring. PHASE III DUAL USE APPLICATIONS: The technology for seepage prevention system is applicable to landfills and hazardous waste containment applications within the DoD, other Federal agencies, State agencies and private sector foundations. There are extremely high benefits in terms of cost savings through this environmental technology. REFERENCES: K. Utklev, "Method and Apparatus for Controlling the Relative Humidity in Concrete and Masonry Structures," U.S. Patent No. 5,368,709.
A00-054 TITLE: Advance Anode Materials for Electro-Osmotic-Pulse Technology to Control Water Intrusion in Porous Structures TECHNOLOGY AREAS: Materials/Processes OBJECTIVE: To develop new anode technology and materials that can be used on non-homogeneous structures such as masonry block, brick and stone. DESCRIPTION: Electro-osmosis is the transport of cations due to an external electric field. Because of the molecular binding nature of water molecules, water molecules are transported along with the cations. Currently, electro-osmotic pulse (EOP) technology is being commercially applied to concrete structures. A system has been developed that uses a pulsating direct electric field. The system consists of an electronic control unit that delivers electric pulses to positive electrodes (anodes) inserted into the concrete structure. The negative electrode (cathode) is driven into the exterior soil or buried within the concrete structure outside of the protected area. The pulsating electro-osmosis system consists of pulses of positive voltage (referenced to the dry side of the concrete wall), negative voltage, and zero voltage. The positive voltage pulse, which has the greatest duration and amplitude, causes cations (e.g., Ca++) and associated water molecules to move from the structure's dry side towards the wet side, counter to the direction of flow induced by the hydraulic gradient, thus preventing water penetration through the concrete structure. By using a pulsating excitation; electrode polarization, cation depletion, and overdrying of the concrete are prevented. EOP technology provides installation cost savings of over 40% compared to conventional methods. Additionally EOP has a much longer lifetime. Unfortunately, present technology limits its use to poured concrete structures, which comprise less than 30% of the basements. Development of new anode technology can extend EOP application to virtually all below-grade structures by including masonry block, brick and stone. PHASE I: Develop a methodology to apply EOP technology to non-homogenous structures. The methodology may include anodes in the form of a wall coating, which, in order to function as a reliable anode, must have excellent adhesion and good electrical conductivity. Tests will be performed in the laboratory on scale-model systems. Base materials of masonry block, brick and stone will be used. PHASE II: Develop an economically feasible prototype for efficient field application of the new anode materials. Tests will be conducted on full size structures. PHASE III DUAL USE APPLICATIONS: The anode technology will serve to improve the efficiency and use of EOP technology. EOP technology will offer cost savings of over $500 million to the DoD. These cost savings can be drastically increased by applying EOP technology to below-grade structures constructed of masonry block, brick and stone. Since water intrusion in buildings is not limited to DoD facilities, the market for this technology is worldwide. EOP technology can be applied to any below-grade structure constructed of standard building materials (e.g., concrete or masonry) regardless of use or ownership. OPERATING AND SUPPORT COST (OSCR) REDUCTION: In 1999 a cost comparison was done using two adjacent and identical buildings at Ft. Bragg. The cost per lineal foot for EOP treatment of water intrusion was $133.53/foot and the cost per lineal foot for conventional waterproofing was $262.60/foot - an up front cost savings of 49%. These savings will be further increased through the development of new anode materials. The Honorable Tommy G. Thompson, Governor of Wisconsin expressed his appreciation to LTG Ballard, Commander, Corps of Engineers, for the Corps of Engineers' role in developing EOP technology. In this letter, he estimates that cost savings resulting from the use of EOP technology will be in excess of $100 million nationwide. REFERENCES: V.F. Hock, M.K. McInerney, and E. Kirstein, "Demonstration of Electro-Osmotic Pulse Technology for Groundwater Intrusion Control in Concrete Structures," FEAP Technical Report 98/68, U.S. Army Center for Public Works, April 1998. M.K. McInerney and V.F. Hock, "Electroosmotic Pulse Technology for Groundwater Intrusion Control in Concrete Structures, presented at the 21st Army Science Conference held 15-17 June, 1998 in Norfolk, Virginia. KEYWORDS: electro-kinetics, anode, masonry, moisture, structures, water Download 1.22 Mb. Share with your friends:
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