Systems and methods for a conductive concrete slab having protection against one or more of surface current, ground fault current, and current leakage. A method includes, but is not limited to, introducing an electrical insulation base layer to a ground surface; introducing a plurality of electrodes to the electrical insulation base layer; and casting conductive concrete over the plurality of electrodes and the electrical insulation base layer. An electrical insulation top layer can also be applied to mitigate one or more of surface current and ground fault current.
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1. A method for providing a conductive concrete slab, comprising:
introducing an electrical insulation base layer to a ground surface,
wherein the ground surface comprises at least one of soil or an aggregate base;
introducing a plurality of electrodes to the electrical insulation base layer;
casting conductive concrete over the plurality of electrodes and the electrical insulation base layer; and
applying a current to the conductive concrete,
wherein the conductive concrete has a conductivity ranging from 5 millisiemens per meter to 5 siemens per meter.
10. A system, comprising:
a concrete slab comprising:
an electrical insulation base layer disposed over at least one of soil or an aggregate base;
a plurality of electrodes positioned over a surface of the electrical insulation base layer, the plurality of electrodes arranged in a parallel configuration; and
a conductive concrete structure positioned over the plurality of electrodes and the electrical insulation base layer,
wherein the concrete slab has a conductivity ranging from 5 millisiemens per meter to 5 siemens per meter; and
a power source configured to apply alternating current to the concrete slab.
6. A method comprising:
positioning an electrical insulation base layer over a ground surface comprising at least one of soil or an aggregate base;
positioning a plurality of electrodes over a surface of the electrical insulation base layer, the plurality of electrodes arranged in a parallel configuration;
casting conductive concrete over the plurality of electrodes and the electrical insulation base layer; and
positioning an electrical insulation top layer to a top surface of the conductive concrete; and
heating the conductive concrete,
wherein the conductive concrete has a conductivity ranging from 5 millisiemens per meter to 5 siemens per meter.
2. The method of
a polyester sheet,
a polystyrene layer,
a geotextile containing substantially no carbon black,
a tile comprising at least one of marble, granite, ceramics, wood, or linoleum, or
a grounded wire mesh embedded in a layer of non-conductive concrete.
3. The method of
electrically connecting the plurality of electrodes to a power source via an electrical connection.
4. The method of
introducing an electrical insulation top layer to a top surface of the conductive concrete.
5. The method of
an epoxy layer,
a layer of non-conductive concrete,
a tile comprising at least one of marble, granite, ceramics, wood, or linoleum, or
a grounded wire mesh embedded in a layer of non-conductive concrete.
7. The method of
a polyester sheet,
a polystyrene layer,
a geotextile containing substantially no carbon black,
a tile comprising at least one of marble, granite, ceramics, wood, or linoleum, or
a grounded wire mesh embedded in a layer of non-conductive concrete.
8. The method of
an epoxy layer,
a layer of non-conductive concrete,
a tile comprising at least one of marble, granite, ceramics, wood, or linoleum, or
a grounded wire mesh embedded in a layer of non-conductive concrete.
9. The method of
electrically connecting the plurality of electrodes to a power source via an electrical connection.
11. The system of
a polyester sheet,
a polystyrene layer,
a geotextile containing substantially no carbon black, or
a grounded wire mesh embedded in a layer of non-conductive concrete.
12. The system of
13. The system of
an epoxy layer,
a layer of non-conductive concrete, or
a grounded wire mesh embedded in a layer of non-conductive concrete.
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This application is a National Stage of International Application No. PCT/US17/26415 filed Apr. 6, 2017, which is a PCT International Application of U.S. Provisional Patent Application No. 62/319,038 filed Apr. 6, 2016. The entire disclosure of the provisional application referenced above is incorporated by reference.
Paved surfaces, such as asphalt and concrete, can accumulate snow and ice in winter weather conditions. Accumulation of snow or ice on paved surfaces can pose hazards for vehicles, pedestrians, and animals. Removal of such accumulation can include mechanical methods, such as plowing, shoveling, auger-based removal (e.g., “snow-blowing”), or the like, and/or chemical methods, such as distributing salts (e.g., sodium chloride (NaCl), calcium chloride (CaCl2), etc.) or other deicing chemicals over the paved surface. However, such methods can involve significant physical or mechanical exertion, pavement deterioration, environmental hazards, or the like.
Systems and methods for providing a conductive concrete slab having protection from one or more of surface current, ground fault current, and/or current leakage are described. A method embodiment includes, but is not limited to, introducing an electrical insulation base layer to a ground surface; introducing a plurality of electrodes to the electrical insulation base layer; and casting conductive concrete over the plurality of electrodes and the electrical insulation base layer. An electrical insulation top layer can also be applied to mitigate one or more of surface current and ground fault current.
A concrete structure embodiment includes, but is not limited to, an electrical insulation base layer. The concrete structure also includes electrodes positioned over a surface of the electrical insulation base layer. The conductive concrete structure also includes a conductive concrete structure positioned over the electrodes and the electrical insulation base layer.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
The Detailed Description is described with reference to the accompanying figures. The use of the same reference numbers in different instances in the description and the figures may indicate similar or identical items.
Overview
Conventional concrete is not electrically conductive for practical purposes. For instance, the electrical resistivity of normal weight concrete ranges between 6.54 and 11 kΩ-m. A hydrated concrete consists of pore solution and solids, including aggregates, hydrates and unhydrated cement. The electrical resistivity of the pore solution in cement paste is about 0.25-0.35 Ω-m. Most aggregates (e.g., limestone) used in concrete, with electrical resistivity ranges between 3×102 and 1.5×103 Ω-m, are essentially not conductive. Conductive concrete may be defined as a cement-based admixture, which contains a certain amount of electrically conductive components to attain a stable and relatively high electrical conductivity. Due to the electrical resistance in the conductive concrete mixture, heat is generated when connected to a power source. Some applications currently incorporating conductive concrete include electromagnetic shielding, often required in the design and construction of facilities and equipment to protect electrical systems or electronic components; radiation shielding in the nuclear industry; anti-static flooring in the electronic instrumentation industry and hospitals; and cathodic protection of steel reinforcement in concrete structures. In these applications, conductive concrete is not required to be connected to a power source.
Conductive concrete can also provide deicing properties, such as when the conductive concrete mixture is formed into a slab or other configuration. For instance, the deicing properties can be attributed to the heat generated through electrical resistance of the conductive concrete mixture when power is supplied. Electrodes connected to the power source can be employed within the conductive concrete to facilitate transfer of electricity throughout the slab. Since concrete slabs can be formed on a ground surface, such as on compacted soil or aggregate material, conductive concrete slabs have a natural ground in the ground material or the earth, which can contribute to electrical losses.
For instance, referring to
The surface current relates to a current between two points on a surface of the conductive concrete slab 100. The ground fault current relates to a current between a point on a surface of the conductive concrete slab 100 and a point on a top surface of the ground or material on which the conductive concrete slab 100 is positioned, which may result in system inefficiencies (e.g., reduce the amount of electrical power available to heat the slab). The leakage current relates to a current from the conductive concrete slab (e.g., a bottom portion) to the ground (e.g., back to the power source), where such current leakage can result in system inefficiencies and/or in difficulties in maintaining functionality of the conductive concrete electrical system, particularly where a ground fault current interrupter (GFCI) is utilized (e.g., where an isolation transformer is unfeasible, such as through installation codes, cost, or the like).
Accordingly, the present disclosure is directed to systems and methods for providing a conductive concrete slab 100 having protection against one or more of the surface current, ground fault current, and leakage current. In implementations, the conductive concrete slab 100 includes an electrical insulation base layer 108 positioned on a bottom surface 110 of the conductive concrete slab 100 to mitigate current leakage. For example, the electrical insulation base layer 108 can include, but is not limited to, one or more of a polyester sheet, a polystyrene layer, a geotextile containing substantially no carbon black (e.g., a carbon black content sufficient to avoid a conductive geotextile, such that the geotextile is less conductive than the conductive concrete slab; a substantially clear plastic sheet), a grounded wire mesh (e.g., a layer of non-conductive concrete having an embedded wire mesh which is grounded).
The conductive concrete slab 100 can be formed over at least a portion of the electrical insulation base layer 102, such that the conductive concrete slab 100 is cast on the electrical insulation base layer 108 with a plurality of parallel electrodes. In implementations, a conductive concrete slab 100 includes an electrical insulation top layer 112 positioned on a top surface 114 of the conductive concrete slab 100 to mitigate one or more of the surface current and the ground fault current. For example, the electrical insulation top layer 112 can include, but is not limited to, one or more of an epoxy layer, a layer of non-conductive concrete, one or more tiles that comprise marble, granite, ceramics, wood, linoleum, or the like, and/or a grounded wire mesh (e.g., a layer of non-conductive concrete having an embedded wire mesh which is grounded).
Example implementations directed to a conductive concrete slab 100 having protection against one or more of surface current, ground fault current, and current leakage is now provided. In one or more implementations of the present disclosure, the conductive concrete slab 100 may have a conductive characteristic (for example, a measured conductivity) ranging from about five millisiemens per meter (5 mS/m) to about five siemens per meter (5 S/m).
Referring to
For example,
Referring to
The systems and methods for providing a conductive concrete slab having protection from one or more of surface current, ground fault current, and leakage current can be utilized to provide a variety of support surfaces including, but not limited to, walkways, driveways, tile flooring (e.g., conductive concrete tiles having thin metal electrodes disposed therein).
Referring to
The measured ground fault was 690 mA under 120 VAC, with a test geotextile layer present as an electrical insulation base layer. Since the geotextile layer and the concrete base are approximately in series, the total resistance of the two layers would be 120 V/690 mA=174Ω. The resistance of the geotextile layer=174−123=51Ω. This value suggests that the test geotextile is relatively conductive, possibly containing carbon black which is an additive for a polymer matrix used during production to stabilize dimensions of the geotextile (e.g., stabilize the dimensions of the polymers). This finding suggests that a geotextile containing carbon black may not provide a suitable level of electrical insulation for use as an electrical insulation base layer or an electrical insulation top layer.
If the ground fault current is limited to 5 mA under 120 V (e.g., per NEC guidelines), the minimum resistance needed would be 120 V/5 mA=24 kΩ. So, the minimum volume resistivity required would be 24 kΩ×3.726 m2/0.000254 m=352 MΩ-m, with a 10 mil (10 thousandths of an inch) thick plastic sheet for an electrical insulation base layer. (The resistance of the plastic sheet=electric resistivity×thickness/surface area.) Given their relatively high electric volume resistivity values, polyester sheeting and polystyrene (e.g., Styrofoam) can be used as the electrical insulation base layer.
TABLE 1
Electrical
Typical
Properties
Properties
Value
Units
Test Method
Dielectric Strength
AC, 20° C., .000092″
7,000
volts/mil
ASTM-D149-64
Dielectric Constant
25° C., 1 kHz
3.2
n/a
ASTM-D150-81
Dissipation Factor
25° C., 1 kHz
0.005
n/a
ASTM-D150-65
Volume Resistivity
25° C.
1.00E+199
ohm-cm
ASTM-D257-78
Corona Threshold
V-AC
V-AC
ASTM-D2275-80
The potential ground fault from the hot electrode through the 8-in. wide and 6.25-in. deep curb is calculated as follows. The resistance would be 6,000 Ω-m×8-in./(76 in.×6.25-in.)=6,000 Ω-m×0.2 m/0.31 m2=3,870Ω. The ground fault current would be 120 V/3,870Ω=30 mA. Therefore, in implementations, it may be necessary to insulate side portions of a conductive concrete form (e.g., side portions of a curb) with electrical insulation, such as the polyester sheet.
In order to eliminate ground fault current, the concrete panel should avoid direct contact with the ground. The stray current can follow a conductive path, even through a small contact area. In implementations, the ground surface can include a regular concrete base (e.g., non-conductive concrete) with an electrical insulation base layer 108 positioned between the regular concrete base and the conductive concrete.
Electrical safety tests were performed to measure surface current, ground fault current, and leakage current (e.g., as shown in
Although the subject matter has been described in language specific to structural features and/or process operations, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.
Tuan, Christopher, Nguyen, Lim
Patent | Priority | Assignee | Title |
11078116, | Jun 15 2018 | HOLCIM TECHNOLOGY LTD | Method for encasing underground electrical cables |
11753346, | Dec 18 2020 | HOLCIM TECHNOLOGY LTD | Method for the construction of a data center |
Patent | Priority | Assignee | Title |
2334355, | |||
2726339, | |||
2868659, | |||
3207705, | |||
3309196, | |||
3377462, | |||
3475304, | |||
3721058, | |||
4174912, | Jul 31 1978 | Electroosmosis Inc. | System for heave reduction in highways due to frost or moisture in expansive clay or shale materials |
4656313, | Dec 19 1983 | GSEG LLC | EMI/EMP electrical cable penetration seal |
4811770, | Mar 25 1986 | Structural element for a building | |
4855024, | Sep 16 1986 | Raychem Corporation | Mesh electrodes and clips for use in preparing them |
5312526, | Mar 23 1993 | Norwegian Concrete Technologies AS | Method for increasing or decreasing bond strength between concrete and embedded steel, and for sealing the concrete-to-steel interface |
5346547, | May 08 1992 | The United States of America as represented by the Secretary of the Army | Method of making concrete electrically conductive for electromagnetic shielding purposes |
5392580, | May 06 1992 | Modular reinforcement cages for ductile concrete frame members and method of fabricating and erecting the same | |
5422174, | Aug 18 1992 | Sekisui Chemical Co. Ltd. | Electromagnetic wave shielding building material |
6214454, | Sep 25 1996 | NIPPON PAINT CO , LTD ; CHIOYODA UTE CO , LTD | Electromagnetic wave absorbing material |
6461424, | Feb 21 2001 | Wisconsin Electric Power Company | Electrically conductive concrete and controlled low-strength materials |
6503318, | Mar 29 2000 | National Research Council of Canada | Conductive concrete composition |
6821336, | Aug 15 2003 | Wisconsin Electric Power Company | Electrically conductive concrete and controlled low strength materials having carbon fibers |
6825444, | Jan 29 1999 | Board of Regents of University of Nebraska | Heated bridge deck system and materials and method for constructing the same |
7578881, | Apr 12 2006 | Wisconsin Electric Power Company | Electrically conductive concrete and controlled low strength materials having spent carbon sorbent |
8067084, | May 16 2001 | Bridgestone Corporation | Electromagnetic-wave shielding and light transmitting plate, manufacturing method thereof, and display panel |
8617309, | Feb 08 2013 | SUPERIOR GRAPHITE CO | Cement compositions including resilient graphitic carbon fraction |
8968461, | May 16 2011 | NUtech Ventures | Concrete mix for electromagnetic wave/pulse shielding |
9278887, | May 16 2011 | NUtech Ventures | Concrete mix for electromagnetic wave/pulse shielding |
9681592, | May 16 2011 | NUtech Ventures | Structural concrete mix for construction for electromagnetic wave/pulse shielding |
20020017466, | |||
20020162484, | |||
20070039277, | |||
20070186824, | |||
20070246857, | |||
20120227630, | |||
20120324811, | |||
20150361625, | |||
20160234977, | |||
CN101030454, | |||
CN101339818, | |||
CN101891419, | |||
CN102219447, | |||
CN102444070, | |||
CN102674881, | |||
CN102869132, | |||
CN102875090, | |||
CN1552657, | |||
JP6240843, | |||
JP7157356, | |||
WO240799, | |||
WO2010059169, | |||
WO2013096990, | |||
WO2014184146, | |||
WO2014210007, |
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