Patent Application
20130075942
This application relates to an apparatus and method for controlling the quality of concrete and, more particularly, to an apparatus and method of controlling concrete vibration.
Concrete structures, such as nuclear facilities, often use thick and/or large sections of concrete to form the appropriate structure. These types of structures require that the concrete forming the structures be of a high quality, resulting in quality control challenges. Two such challenges are the quality of concrete vibration and the placement of the concrete.
Poor quality control of concrete vibration and placement can result in low concrete quality which compromises the durability of the structures and creates delays and cost overruns in construction. One of the problems during the construction of concrete structures is degradation of the concrete due to aging. In nuclear constructions, these problems are described in NUREG 4652 (existing fleet) and NRC IN 2008-17 (new plants in other countries).
The acceptance criterions for new construction are mainly based on visual inspection performed by an inspector on site. Quality Control is performed visually by an inspector on site that has the task of ensuring that the proper vibration procedures are followed, resulting in excessive responsibility for the inspectors. Common imperfections resulting from under-vibration are honeycombing, excessive amounts of entrapped air voids, and layer lines. When hidden in the concrete, mass flaws like these are hardly detectable and when detected later, as the structure ages, become the responsibility of the owner.
Correct placement of concrete requires consolidation generally achieved by internal vibrators for normal weight concrete. Vibration ensures that the entrapped air contained in unconsolidated concrete is released leading to a volume change of about 5% to 20%. Under-vibration is a frequent cause of poor consolidation. It is commonly accepted that under-vibration is far more common than over-vibration. Under-vibration may be caused by the following: (1) use of an undersized, underpowered, or poorly maintained vibrator; (2) excessive or haphazard spacing of vibrator insertions; (3) inadequate vibration during each insertion; (4) failure of the vibrator to penetrate into the preceding layer; and/or (5) vibrator in the wrong position relative to the form. Currently, there are no available concrete vibrators that include quality control and that can track the location and duration of the vibration process.
Accordingly, there is a need for an apparatus and method that includes quality control and has the ability to track the location and duration of the vibration process.
According to one aspect of the invention, an apparatus for ensuring proper concrete consolidation includes a global positioning sensor adapted to provide a location of a vibrator relative to a concrete structure, a recording device adapted to record data during vibration of the concrete, and a data transmission device adapted to transmit the data to a processor for analysis of the data to determine if the vibration is in compliance. The vibrator is adapted to vibrate the concrete to remove air contained therein and promote concrete consolidation.
According to another aspect of the invention, an apparatus for ensuring proper concrete consolidation includes a vibrator for vibrating concrete to promote proper concrete consolidation and a quality control unit connected to the vibrator. The quality control unit includes a global positioning sensor adapted to provide a location of the vibrator relative to a concrete structure to be vibrated, a recording device adapted to record data during vibration of the concrete, and a transmission device adapted to transmit the data to a processor for analysis. The global positioning sensor allows an operator to determine where the concrete structure has been vibrated.
According to another aspect of the invention, a method of ensuring proper vibration of concrete to remove air therein and promote concrete consolidation includes the steps of providing an apparatus for ensuring proper concrete consolidation. The apparatus includes a global positioning sensor, a recording device, and a transmission device. The method further includes the steps of vibrating the concrete with a vibrator, using the recording device to record data from the vibrating step, using the transmission device to transmit the data to a processor for analysis and determining whether the vibrating step is in compliance, and providing a compliance report to a user.
The subject matter that is regarded as the invention may be best understood by reference to the following description taken in conjunction with the accompanying drawing figures in which:
Referring to the drawings, an exemplary apparatus according to an embodiment of the invention is illustrated in
The present invention pertains to concrete vibrated with internal vibrators. Internal vibrators do not currently have capabilities for quality control. For instance, there is no track record of where, when, and for how long the concrete vibrated; and there is no way of recording/documenting quality control during this process.
The apparatus 10 may be in the form of a stand alone apparatus attached to a vibrator for quality control of vibration during concrete placement or in the form of a vibrator having built-in quality control. The apparatus 10 records the exact location, timing and duration of the vibration, resulting in a quality control of the vibration process embedded in the vibrator. The apparatus 10 includes a Global Positioning Sensor (GPS) 11; a recording device (data logger) 12 to track time, position, and duration of vibration; a transmission device 13 for wired or wireless capabilities for data transmission to analysis hardware, such as a processor or computer 14 equipped with data analysis software.
Referring to
The data recorded by apparatuses 10 and 20 may be processed in one of two ways. The first option ensures a real-time follow-up of vibration but only provides a post-analysis of performed vibration. The second option ensures a real-time follow-up of vibration and real time warnings to ensure a proper consolidation of the fresh concrete. Both options may lead to further inspection (NDE, core drilling) to be eventually taken by the owner prior to the reception of the structure.
A more detailed description of both options follows below.
1. Set-up criteria for minimal vibration duration and minimal distance between two vibration spots in compliance with the construction codes and local specifities (reinforcement rate);
2. Record vibration;
3. Transfer data to computer;
4. Analyze data and locate non-compliances; and
5. Provide an automatic report.
1. Set-up criteria for minimal vibration duration and minimal distance between two vibration spots in compliance with the construction codes and local specifities (reinforcement rate);
2. Record vibration;
3. Real-time transfer to computer, real-time analysis. If non-compliances detected (duration, distance) send signal to vibrating operator for correction;
4. After finishing vibration of the concrete element or a set of elements, analyze data and locate remaining non-compliances; and
5. Provide an automatic report.
The foregoing has described an apparatus and method for controlling the quality of concrete. While specific embodiments of the present invention have been described, it will be apparent to those skilled in the art that various modifications thereto can be made without departing from the spirit and scope of the invention. Accordingly, the foregoing description of the preferred embodiment of the invention and the best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation.
| Number | Date | Country | |
|---|---|---|---|
| 61540199 | Sep 2011 | US |
