Abstract:
A system and method for treating porous material, e.g., concrete, brick, or other masonry material, via electro-osmosis. One application carries dehydration to an extent that it weakens a structure for demolition by significantly dehydrating its structural material. A durable, dimensionally stable anode is affixed to the structure and attached to a wire from a DC power supply. The anode is composed of a valve metal substrate with a semiconductive coating of a precious metal, cermet or ceramic. Connection to a cathode through the power supply completes the circuit. A DC voltage is applied to the concrete structure by cycling a pre-specified pulse train from the power supply. One pulse train consists of an initial positive pulse followed by a shorter duration negative pulse and ends with a short off period before the pulse train is reinitiated. The cycle continues until the porous material has been determined to be sufficiently treated.

Description:
STATEMENT OF GOVERNMENT INTEREST  
       [0001] The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention relates to a method of treating a porous structure by using durable, dimensionally-stable anodes to effect electro-osmosis within the structure. One purpose for treating a structure may be to remove moisture to weaken it for demolition.  
         BACKGROUND  
         [0003]    Groundwater intrusion through a building&#39;s foundation can cause serious damage. In addition to increased concrete deterioration and accelerated rebar corrosion, basement dampness can ruin expensive electrical and mechanical equipment, which is often located in basement space, and can increase maintenance requirements through frequent repainting or cleaning to combat mold growth. Furthermore, the intruding water raises the interior relative humidity thereby accelerating the corrosion rate of mechanical equipment in the area and creating unacceptable air quality and concurring health problems due to the rapid growth of bacteria and mold.  
           [0004]    In selective problem areas, the usual approach to the treatment of water intrusion problems is to ‘trench and drain’. In other words, to excavate and expose the wall area and the base of the foundation, to replace waterproofing on the wall surface, and to install a drain tile system around the building or affected area. Other areas, such as floors, are untreatable using conventional methods.  
           [0005]    Electro-osmosis has origins in 1809, when F. F. Reuss originally described an experiment that showed that water could be forced to flow through a clay-water system when an external electric field was applied to the soil. Research since then has shown that flow is initiated by the movement of cations present in the pore fluid of clay, or similar porous medium such as concrete, brick, and cementitious construction materials; and the water surrounding the cations moves with them. The basic physics and chemistry of electro-osmosis can be found in several textbooks and treatises. Glasstone, S.,  Textbook of Physical Chemistry,  2d ed., D. Van Nostrand Company, Inc., Princeton, N.J., 1946. Tikhomolova, K. P.,  Electro - Osmosis,  Ellis Horwood Limited, Chichester, West Sussex, England, 1993.  
           [0006]    Electro-osmosis is typically used to solve the problem of groundwater intrusion, which can cause serious damage to a building&#39;s foundation and interiors. As noted above, basement dampness, can ruin expensive electrical and mechanical equipment, which is often located in basement space; can increase maintenance requirements through frequent repainting or cleaning to combat mold growth; and can make affected areas uninhabitable or even unusable due to poor air quality. Electro-Osmotic Pulse (EOP) technology typically offers an alternative that can mitigate some water-related problems from the interior of affected areas without the cost of excavation. Examples of such systems are described below.  
           [0007]    In one system, humidity is removed from a damp structure by positioning electrodes within the structure and applying a D.C. voltage across them. U.S. Pat. No. 3,856,646,  Methods and Electrodes for the Drying of Damp Buildings,  to Morarau, Dec. 24, 1974.  
           [0008]    In another system, chloride ions are removed from concrete by embedding an anode in an electrolyte and establishing an electric current between the anode and the concrete structure in order to avoid corrosion of the concrete&#39;s reinforcing means, typically steel rebar. U.S. Pat. No. 5,296,120,  Apparatus for the Removal of Chloride from Reinforced Concrete Structures,  to Bennett et al., Mar. 22, 1994.  
           [0009]    Another system discloses a process for changing the bond strength between concrete and its steel reinforcement by passing DC current through the concrete. U.S. Pat. No. 5,312,526,  Method for Increasing or Decreasing Bond Strength Between Concrete and Embedded Steel, and for Sealing the Concrete - to - Steel Interface,  to Miller, May 17, 1994.  
           [0010]    Still another method used to eliminate humidity from concrete uses electro-osmosis to pass current pulses in a predetermined pattern through the concrete. U.S. Pat. No. 5,368,709,  Method and Apparatus for Controlling the Relative Humidity in Concrete and Masonry Structures,  to Utklev, Nov. 29, 1994.  
           [0011]    A method that claims improvement over existing methods by choice of a narrow range of relationships among the three pulse durations of the pulse train provides longer anode life while optimizing the process of dehydration. U.S. Pat. No. 5,755,945,  Method for Dehydrating Capillary Materials,  to Kristiansen, May 26, 1998.  
           [0012]    An improvement over previous methods claims to increase anode life while optimizing dehydration and the time to effect it. It uses a specific pulse train in which the positive pulse width is much greater than the negative pulse width that is, in turn, greater than the off period. U.S. Pat. No. 6,117,295,  Method for Dehydrating a Porous Material,  to Bjerke, Sep. 12, 2000.  
           [0013]    A method that claims to be an improvement over the &#39;709 patent provides a control unit to control the pulse width of individual pulses by monitoring characteristics of the energizing source. U.S. Pat. No. 6,126,802,  Method and Device for Regulating and Optimizing Transport of Humidity by Means of Electroosmosis,  to Utklev, Oct. 3, 2000.  
           [0014]    A more recent patent proposes a solution to overcome the disadvantage of the &#39;709 patent when used to dehumidify steel-reinforce structures. It specifically prevents the deterioration of the reinforcing steel by providing a second voltage to the reinforcement steel in addition to the typical electro-osmosis configuration of the &#39;709 patent and its predecessors. U.S. Pat. No. 6,370,643 B1,  Method for Effecting Fluid Flow in Porous Materials,  to Finnebraaten, Aug. 7, 2001.  
           [0015]    An Electro-Osmotic Pulse (EOP) system is realized by installing anodes (positive electrodes) in the interior wall, floor or ceiling of the structure and cathodes (negative electrodes) in the soil exterior to the structure. Due to the extreme electrochemical environment surrounding the anode, special material and geometry requirements may be placed on an anode intended to be used for other than “trickle current” loads or extended periods, or both.  
           [0016]    Durable, dimensionally stable anodes are a recent development in anode technology. They have excellent characteristics to include: low resistivity, very low dissolution rates, long life, durability, and corrosion resistance. Durable, dimensionally stable anodes are also referred to as semiconductive anodes. Durable anodes that are classified as dimensionally stable generally consist of a valve metal substrate such as niobium, tantalum, titanium or alloys thereof, with a catalytic coating consisting of precious metal(s), most often from the platinum metal group, and often in oxide form in combination with valve metal oxides as a mixed metal oxide.  
           [0017]    Although conventionally used for “humidity control,” a rather unconventional use for EOP systems in porous structures lies in taking water (moisture) removal to extremes, i.e., removing sufficient water to weaken the structure in that a minimum amount of moisture is needed to hold together the porous structure. For example, concrete deteriorates rapidly when significant moisture is removed.  
           [0018]    Conventionally, several methods are used to demolish concrete or other masonry structures. Some require a mechanical device or explosives to remove the concrete or masonry material or to dismantle the structure. Most if not all of these processes are noisy, dusty and potentially dangerous to the workers involved.  
           [0019]    In a preferred embodiment of the present invention, an objective heretofore undesired in prior patents is attained, i.e., concrete or masonry is treated by electro-osmosis until the concrete or masonry and the structure it is supporting is weakened.  
         SUMMARY  
         [0020]    Provided is a method for controlling the amount of water (moisture) in porous (capillary) materials via incorporation of a durable, dimensionally stable anode in an Electro-Osmotic Pulse (EOP) system. Employing such a system yields water transport that is both more efficient and more reliable than conventional methods. Additionally, flexibility of design is inherent in the use of the durable, dimensionally stable anodes that may be shaped easily to meet specific requirements, thus also facilitating their installation. These anodes may also handle higher current levels than similarly sized non-durable anodes which means that they are able to be used in a broader range of applications.  
           [0021]    Alternative designs may be employed by using semiconductive coatings applied to valve metal substrates to produce a durable, dimensionally stable composite anode. Anode coatings may be one or more precious metals, precious metal oxides, valve metal oxides, or any combination of these. The resulting durable, dimensionally stable anode may include metallic, cermet or ceramic coated anodes that are chemically and electrochemically stable. The use of durable, dimensionally stable anode composites has three advantages:  
           [0022]    the anode does not change shape overtime;  
           [0023]    the anode may be manufactured easily and inexpensively in any shape, such as wire, a cylinder, an elongated cylinder, or a torus; and  
           [0024]    the chemically inert, typically iridium based, anodes are impervious to degradation.  
           [0025]    These three advantages allow durable, dimensionally stable anodes to be placed where conventional anodes fail. Conventional EOP systems use “ionic” or “massive” anodes that are consumed over time, thereby separating from the surrounding material while exhibiting decreasing current transfer, eventually reduced to zero. Since the dimensionally stable anode does not change shape, this allows a wider variety of placement options and a practically unlimited lifetime in this application. The wide range of available shapes greatly increases design flexibility. Since iridium and its metal oxide are two of the most chemically inert materials, they are the materials most often chosen for use in the manufacturing of dimensionally stable anodes. Unlike materials conventionally used for EOP anodes, it will not degrade if solvents and many other chemicals are spilled on the floor or wall in which the anodes have been installed. Specifically, iridium based anodes may be employed in both chlorine and oxygen rich environments.  
           [0026]    Further, a durable, dimensionally stable anode increases the efficiency of an EOP system, enabling higher current densities for the same anode geometry or reduction in the size of the anode for a given current density.  
           [0027]    The employment of conductive grouts function with a durable, dimensionally stable anode increases the anode&#39;s effective surface area, permitting more current to be transferred while reducing any impedance mismatch effects due to high current densities at the anode-media interface. In a conventional humidity control task, employing durable, dimensionally stable anodes and conductive grouts allows the interior surface moisture to be reduced and maintained for the long term below 55% relative humidity (RH). At this level of RH, growth of mold and bacteria is reduced substantially, leading to improved indoor air quality.  
           [0028]    A preferred embodiment of the present invention provides a method of controlling the movement of water (moisture) through porous (capillary) materials by electro-osmosis. It specifically includes inserting a durable, dimensionally stable anode in porous material containing moisture. The durable, dimensionally stable anode comprises a valve metal substrate with a semiconductive coating of a precious metal, cermet or ceramic material. Also provided is a cathode located in an area outside of the porous material. A voltage is applied across the durable, dimensionally stable anode and cathode thereby creating an electromagnetic field in the porous material that causes cations and associated water molecules to move from the durable, dimensionally stable anode to the cathode.  
           [0029]    In a specific embodiment of the present invention, an electro-osmotic system employing durable, dimensionally stable anodes inserts an electric field in select parts of a structure composed of porous material in a pre-specified pattern and over a pre-specified cycle for the purpose of weakening it to facilitate its demolition. The electric field establishes an osmotic outward flow of moisture from within the structure to which it is applied.  
           [0030]    The system operates with pre-specified parameters including, but not limited to, a pre-specified pulse train of energy at a pre-specified amplitude level in a pre-specified cycle for a pre-specified time. The pre-specified parameters are determined by relating measurements, e.g., resistivity, taken from the structure and its surrounding environs to known data. In its normal mode of operation, the system is operated at a level that eliminates the possibility of damaging electrical shock to workers installing and operating it.  
           [0031]    The pre-specified pulse train comprises a first positive DC voltage pulse of a first pre-specified duration, a second negative DC voltage pulse of a second pre-specified duration, and a zero DC voltage period of a third pre-specified duration. To attain its goal of reducing the level of shock hazard to workers in its normal mode of operation, the system operates at a nominal voltage of 40 V DC or less with pulse widths in the 1-60 second range. In a preferred embodiment, the first pulse is a positive pulse with a greater pulse width than the second negative pulse. The off period, or zero-voltage pulse, normally is of a longer duration than the negative pulse. This pulse train is continued until the porous material is determined to be sufficiently dehydrated to weaken the structure for demolition.  
           [0032]    The system, in its most basic configuration comprises durable, dimensionally stable anodes in electrical communication with the structure, cathodes that complete a circuit between the anode and the power supply and a pathway between each anode and its corresponding cathode to carry energy from an external source to create the electric field that establishes an electro-osmotic flow of moisture from the structure. To optimize the life of anodes selected for the process, it is advantageous to employ durable dimensionally stable anodes, e.g., any of those built using a process detailed in U.S. Pat. No. 5,055,169,  Method of Making Mixed Metal Oxide Coated Substrates,  to Hock et al., Oct. 8, 1991, incorporated herein by reference. The system is operated within pre-specified parameters including but not limited to: a pre-specified pattern of disposition of the anodes and cathodes within the structure, energy in the form of a pulsed DC voltage at a pre-specified voltage level with a pre-specified cycle of pulses, i.e., a repeating pulse train having a pre-specified number of pulses of a pre-specified type and pre-specified pulse duration.  
           [0033]    The most common type of porous material targeted for weakening is concrete, including concrete reinforced with steel, although other types of durable porous material, such as brick, concrete block, and composite masonry material, may also be targeted. In one embodiment, the cathode is a rod in electrical communication with the earth and the anode is an electrically conducting wire embedded in the structure. The anode may be electrically connected to the structure via an electrically conducting coating on the surface of the structure.  
           [0034]    In an alternate mode, the system may be operated to provide a current of at least 400 mA/ft 2  of surface area of the anode to induce the formation of acid, or acids, in the porous material. Also provided is a method of implementing the system.  
           [0035]    The method of an embodiment of the present invention for weakening a structure using an electro-osmotic system operated at a voltage level that insures worker safety, comprises:  
           [0036]    measuring selected parameters of the structure and it&#39;s surrounds; comparing the selected parameters to known data;  
           [0037]    establishing operating parameters of the electro-osmotic system;  
           [0038]    connecting the electro-osmotic system to porous material in the structure in accordance with the established operating parameters; and  
           [0039]    establishing an osmotic flow of moisture from within the porous material using the established operating parameters to operate the electro-osmotic system.  
           [0040]    An alternative method involves applying a significantly higher voltage to the porous material to enable formation of an acid or acids within the porous material. The acids, in turn, degrade the material from within, thereby degrading the structure.  
           [0041]    Advantages of a specific embodiment of the present invention employed to facilitate demolition include:  
           [0042]    less energy applied to effect demolition;  
           [0043]    less dust and debris presented to the atmosphere;  
           [0044]    lower overall cost;  
           [0045]    less danger to the employees and passersby;  
           [0046]    noiseless; and  
           [0047]    requires workers that are easily trained and who do not need specialized skills. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0048]    [0048]FIG. 1 is a schematic diagram of elements used in a preferred embodiment of the present invention.  
         [0049]    [0049]FIG. 2 is a schematic diagram showing the installation of the cathode through a concrete wall.  
         [0050]    [0050]FIG. 3 is a schematic diagram showing the installation of the cathode through a concrete floor.  
         [0051]    [0051]FIG. 4A is a schematic diagram showing the installation of a durable, dimensionally stable wire anode into a concrete wall or floor.  
         [0052]    [0052]FIG. 4B is an enlarged perspective view of the durable, dimensionally stable anode shown in FIG. 4A.  
         [0053]    [0053]FIG. 5 is a diagram of the voltage waveform used in a preferred embodiment of the present invention.  
         [0054]    [0054]FIG. 6 illustrates a typical electro-osmotic pulse (EOP) installation of the present invention in a cut away view.  
         [0055]    [0055]FIG. 7 illustrates an EOP system of one embodiment of the present invention utilizing reinforcing steel as the cathode.  
         [0056]    [0056]FIG. 8 schematically illustrates an alternate embodiment of the present invention with a durable, dimensionally stable anode and generated acids.  
         [0057]    [0057]FIG. 9 depicts a perspective view of an arrangement of cathodes or durable, dimensionally stable anodes in a preferred embodiment of the present invention for an EOP demolition of a concrete slab.  
         [0058]    [0058]FIG. 10 shows three separate arrangements of electrodes as used in a preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0059]    Refer to FIG. 1. In a specific embodiment, the present invention facilitates electro-osmosis by inserting durable, dimensionally stable anode wires  5 , such as the durable dimensionally stable anode wires that may be produced via the process detailed in the &#39;169 patent noted above, into the concrete  3  that may be part of a structure comprising porous material, for example, a concrete structure to be demolished, and places cathode rods  7  in the soil I directly outside of that structure. The durable, dimensionally stable anode wire  5  is embedded in the concrete  3 , e.g., using mortar, and the cathode rod  7 , typically a copper-clad steel ground rod, is embedded into the soil  1 . As depicted, the cathode rod  7  may be placed a short distance, e.g., 2 meters, from the concrete  3 . Hard wires  9 ,  11  are used to form the circuit containing the durable, dimensionally stable anode wire  5 , the cathode rod  7  and a DC power supply  13  in turn fed by an electrical power source  12 . The number of durable, dimensionally stable anode wires  5  and cathode rods  7 , and placement thereof, are determined from an initial resistivity test of the concrete  3  and soil  1 . The objective is to achieve a pre-specified current density to create an electric field strength in the concrete  3  sufficient to overcome the force exerted by the hydraulic gradient on the water molecules  17  enclosed therein. When the system is energized, the cations  15  (e.g., Ca++) and water molecules  17  in the concrete flow in the direction of the arrows  18  towards the cathode rod  7 , thus “de-watering” the concrete in the structure.  
         [0060]    Refer to Table 1 below for practical limits on operating current over time for the durable, dimensionally stable anode. It is expressed in current per area of contact, such as Amps (A) or milliamps (mA) current per square meter (m 2 ) or square feet (ft 2 ) of anode in contact with the porous material, i.e., electrode (anode) current density, A/m 2.  or mA/ft 2 . Note that the anode current density may achieve a destructive objective on the porous material around the anode if maximum current density or time of application, or both, is exceeded. This is discussed below in relation to the formation of acids in the porous material.  
                             TABLE 1                           Anode Operating Parameters                Current Density   Current 1.6 mm dia.       Operating   on Anode   wire mA/m       Duration   A/m 2  (mA/ft 2 )   (mA/lineal ft)               two weeks   4.4 (400)   21.3 (6.5)        six months   0.44 (40)   2.1 (0.65)        projected life   0.22 (20)   1.07 (0.33)                  
 
         [0061]    The required current density depends on the initial moisture content in the porous material. Assuming the application of anode current density as provided in Table 1, a practical maximum current density for a typical concrete structure is provided in Table 2. The values in Table 2 are derived by dividing the values of Table 1, i.e., current density capacity of the 1.6 mm ({fraction (1/16)}″) diameter wire current density limit per lineal meter (or lineal feet) by an assumed maximum area that one meter (or one foot) of the anode wire is able to treat. For treating high moisture content concrete (&gt;30% water), empirical measurements indicate 0.92 m 2  (3.0 ft 2 ) of concrete may be addressed by a lineal meter (foot) of anode wire and 1.8 m 2  (6.0 ft 2 ) may be addressed by a lineal meter (foot) for low moisture concrete (&lt;30% water). Moisture measurements may be taken with a PROTI-METER.  
                                 TABLE 2                           Current Density to Achieve Effective Treatment of Concrete            Initial Moisture Content   Two Weeks   Six Months   Expected life       of Concrete surveyed at   mA/m 2     mA/m 2     20 yrs+       2.5 cm &amp; 7.6 cm depth   (mA/ft 2 )   (mA/ft 2 )   mA/m 2  (mA/ft 2 )               &gt;30%   23.7 (2.2)   2.4 (0.22)   1.2 (0.11)       &lt;30%   11.9 (1.1)   1.2 (0.11)   0.6 (0.06)                  
 
         [0062]    Refer to FIG. 2. Because a good earth ground is not always readily accessible, a borehole  20  may be drilled through the wall  19  of the structure to be demolished. The cathode rod  7  which may be a copper clad steel rod, or rebar, typically of one-inch diameter is inserted in the borehole  20 , together with a cathode wire  23  suitably attached to the free end of the cathode rod  7  and encapsulated with epoxy  25  as insulation from the concrete. The cathode rod  7  may extend from and through the surrounding existing soil  1  to the wall  19  that will be demolished. Not shown in FIG. 2, but understood, is the cathode wire  23  extending from the wall  19  to where it is joined to the external DC power supply  13 . Encapsulating the wall  19  abutting the borehole, the inserted portion of the cathode rod  7  and the insulating compound  25  is epoxy  27  used to bond and seal the borehole  20  in the concrete wall  19 .  
         [0063]    Refer also to FIG. 3, providing a view similar to FIG. 2 but for a concrete floor poured above a suitable base of gravel and soil  1 .  
         [0064]    A durable, dimensionally stable anode wire  5  is shown in perspective detail in FIG. 4B. Refer to FIG. 4A in which the durable, dimensionally stable anode wire  5  of FIG. 4A is depicted in use. Non-shrink grout  33  extends around the durable, dimensionally stable anode wire  5  located within a previously formed groove  8  in the concrete floor  29 . The durable, dimensionally stable anode wire  5  consists of a base material  6 , typically titanium, and an electrically conducting oxide layer such as a conductive ceramic coating  37 . The electrically conductive ceramic coating  37  may consist of a dual phase mixture of iridium, tantalum and titanium oxides. Although the exact composition for this ceramic coating  37  may vary, it may generally comprise a mixed metal oxide film incorporating a dual phase mixture of TiO 2  (rutile) and RuO 2  or IrO 2 , or both. It is highly desirable that this current conducting ceramic coating  37  have a resistivity less than 0.002 ohm-centimeter (Ω-cm) and bond strength greater than 50 Megapascals (MPa). This ceramic-coated durable, dimensionally stable anode wire  5  is desired to be chemically inert and the electrically conductive ceramic coating  37  dimensionally stable. The durable, dimensionally stable ceramic anode wire  5  should be able to sustain a current density of 100 ampere/meter (A/m) in an oxygen-generating electrolyte at 65° C. (150° F.) for 20 years as described in the &#39;169 patent, to maintain necessary current carrying capacity in use. Other types of durable, dimensionally stable anodes, including those having different conductive coatings, may be used. One such coating, described in the &#39;169 patent, is an electrically conducting coating that is able to sustain a current density of approximately 150 A/m 2  of exposed coating surface in fresh water electrolyte for at least 75 hours without a significant increase in a voltage level required to maintain that current density.  
         [0065]    Refer to FIG. 5. The operating cycle of the DC power supply  13  is represented by a positive pulse, a negative pulse, and an off period having time durations of T 1 , T 2 , and T 3 , respectively. T is the total elapsed time for one operating cycle. As a result of the application of this energy in this manner, the pore fluid in the concrete moves in the direction of the cathode rod  7 . Typically, the positive voltage pulse has the longest pulse width of T 1  and the negative voltage pulse&#39;s width of T 2  is even shorter than the off period, T 3 . In some applications, the pulse width, T 1 , of the positive pulse might equal T, representing the degenerative case of a constant direct-current voltage of amplitude V being applied. The amplitude, V, and pulse durations of the pulse train are application dependent. Generally, assuming significant moisture within the concrete, the rate of moisture removal is directly proportional to the voltage, the greater the voltage the greater the rate of moisture removal and drying.  
         [0066]    Refer to FIG. 6. A concrete wall  19  and concrete floor  29  each have the cathode rod  7  inserted as depicted in FIG. 3 and the durable, dimensionally stable anode wire  5  as depicted in FIG. 4A. The durable, dimensionally stable anode wire  5  is in a groove at the junction of the wall  19  and floor  29 . As shown, the durable, dimensionally stable anode wire  5 , surrounded by grout  33 , is placed at a depth of about 38 mm (½″) into the floor  29 . Preferably, grout  33  forms a channel of a width of about 13 mm (½″).  
         [0067]    In addition, a conventional concrete footing  37  is located below ground level under the wall  19 . By installing the durable, dimensionally stable anode wire  5  in the juncture between the wall  19  and floor  29 , both the wall  19  and floor  29  may be energized by one durable, dimensionally stable anode wire  5 . The cathode  7 , preferably having a length of about 60-120 cm, is inserted through the concrete floor  29 , having suitable insulating epoxy encapsulating it for the length of its insertion in the floor  29 , and is spaced about 60 cm from the durable, dimensionally stable anode wire  5 .  
         [0068]    Refer to FIG. 7 depicting an EOP system utilizing reinforcing steel as the cathode rod  7  in a concrete column  39  installed above a concrete footing  37 . This footing  37  provides a base support for the column  39 , as would be used in a structure, e.g., a building or bridge. The durable, dimensionally stable anode wire  5  is placed at the intersection of the column  39  and footing  37  as is also shown in FIG. 6.  
         [0069]    Refer to FIG. 8 depicting what occurs when, using an alternative embodiment, a high-energy pulse that may be considerably longer in duration than typical is applied. This high-energy pulse generates the formation of acid  82  that attacks the concrete in the area  81  immediately around the durable, dimensionally stable anode wire  5 . When the operation of the electro-osmotic system is at a high current density, i.e., greater than 4.4 A/m 2  (400 mA/ft 2 ) of anode surface area, i.e., 0.2 mA/cm (6.5 mA/ft) for a 0.8 mm (0.032″) diameter durable, dimensionally stable anode wire  5 , oxidation of hydroxyl ions, OH − , occurs, producing two molecules of water (i.e., four for each four hydroxyls produced), one oxygen molecule and four electrons that are transferred via the system&#39;s established conductive (metallic) path to the cathode rod  7 . The reaction may be represented by:  
         4OH − →2H 2 O+O 2 +4e −   (1)  
         6H 2 O+E→4( + H 3 O)+O 2    (2)  
         [0070]    where E is the energy supplied from electrolysis at the durable, dimensionally stable anode wire  5 .  
         [0071]    With the process depicted in FIG. 8, hydroxyls and water molecules are employed in the vicinity of the durable, dimensionally stable anode wire  5 , increasing concentration of hydrogen ions and reducing pH upon formation of acid  82  that eventually degrades the concrete structure. In principle, the configuration of the durable, dimensionally stable anode wires  5 , cathode rods  7  and DC power supply  13  is similar to previously described embodiments. However, spacing and sizing of the respective elements, i.e., durable, dimensionally stable anode wires  5 , cathode rods  7 , and DC power supply  13 , is adjusted to achieve the higher current densities required to achieve the oxidation of the hydroxyl ions and electrolysis of water molecules  17 . Likewise, the voltage levels used and the pulse widths are appropriately adjusted, i.e., the voltage may be increased as well as the pulse width of the energizing pulses with the off-cycle duration approaching zero to quickly oxidize the generated hydroxyl ions.  
         [0072]    Refer to FIG. 9 in which a DC power source  13  is connected to durable, dimensionally stable anode wires  5  and cathode rods  7  (not shown in boreholes accessing a soil ground, but implied) in a concrete slab  45 . This configuration facilitates pre-specified sequential demolition of structural elements. Although not shown, the durable, dimensionally stable anode wires  5  and cathode rods  7  may be placed on opposite surface sides of selected areas of the slab  45  to allow for weakening in place without inducing weakening in adjacent structural elements. The area  47  represents an electrically conductive coating that may be applied to the slab  45  to facilitate conduction. Using this coating as a durable, dimensionally stable anode or cathode may be accomplished by placing a wire from the DC power source  13  to one side of the coating  49  and a wire to another terminal  51  on the surface of the concrete slab  45  opposite that with the coating  49 .  
         [0073]    Refer to FIG. 10. The three methods of connecting to a concrete structure described above are illustrated side by side. The first method, as illustrated in slab A, involves connecting durable, dimensionally stable hard anode wires  5  and rods  7  by embedding them in the concrete or providing an electrically conductive surface coating  49 . Note that in any of the three examples, each side of the concrete slab may be configured differently, so that side  1  may be configured as shown in FIG. 10A and side  2  may be configured as shown in FIG. 10B where only durable, dimensionally stable hard anode wires  5  and rods  7  are used. Finally, all connections to the slab may be via a conductive coating  49  as shown in FIG. 10C.  
         [0074]    Although specific types of electro-osmotic configurations are discussed, other similar configurations or methods, including those that may have only some of the constituents or steps used in the above examples, may be suitable for dehydrating a structure or weakening a structure for demolition and thus fall within the ambit of a preferred embodiment of the present invention as provided in the claims herein.