Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/38—Concrete; Lime; Mortar; Gypsum; Bricks; Ceramics; Glass
  • G01N33/383—Concrete or cement
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
  • G01N29/02—Analysing fluids
  • G01N29/024—Analysing fluids by measuring propagation velocity or propagation time of acoustic waves
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N2291/00—Indexing codes associated with group G01N29/00
  • G01N2291/02—Indexing codes associated with the analysed material
  • G01N2291/024—Mixtures
  • G01N2291/02433—Gases in liquids, e.g. bubbles, foams
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N2291/00—Indexing codes associated with group G01N29/00
  • G01N2291/02—Indexing codes associated with the analysed material
  • G01N2291/025—Change of phase or condition
  • G01N2291/0251—Solidification, icing, curing composites, polymerisation

Definitions

• the present invention relates to a technique for bubble size determination in wet concrete; more particularly related to a technique for bubble size determination in wet concrete in order to control the amount of air in a mixture of concrete.
• gas is often required to achieve the optimum performance of the material.
• a primary example would be in the manufacture of concrete, where not only is a specific amount of air required in the product but also the bubble size of the gas component is critical.
• the assignee of the instant patent application has developed gas void fraction (GVF) measurement systems that perform well at determining the gas content however there are no readily available system for measurement of the bubble size.
• VVF gas void fraction
• the speed of sound of acoustic signals may be determined by injecting a signal into the concrete and measuring how long it takes for that acoustic signal to travel over a set distance.
• a piston may be used to cause a pressure fluctuation in the concrete and generate an acoustic signal.
• a pressure transducer arranged a set distance away is used to measure the arrival of the acoustic wave and then the speed of sound (SOS) in the concrete is determined.
• the GVF is then calculated using Wood's equation based on the SOS measurement.
• a number of techniques have been developed that rely on measuring the speed of sound through a material flowing through a pipe. These techniques include using a known SONAR-based GVF meter, density meter and potential mass fraction meter.
• a passive array-based sensor system is used to detect the presence and speed of acoustics traveling through the materials contained within a pipe. These materials can range from single phase homogeneous fluids to two or three phase mixtures of gases, liquids and solids. Since the measurements system is passive it relies on acoustics produced externally for the measurement. These acoustics can often times come from other equipment in or attached to the pipe such as pumps or valves.
• air is a very important component of many materials, such as viscous liquids, slurries or solids, and mixtures of concrete.
• air is a critical ingredient when making concrete because it greatly improves the cured product damage resistance to freeze/thaw cycles. Chemical admixtures are typically added during mixing to create, entrain and stabilize billions of small air bubbles within the concrete.
• the entrained air in concrete has the disadvantage of reducing strength so there is always a trade-off to determine the right amount of air for a particular application.
• it is important to control the entrained air present in the wet (pre-cured) concrete. Current methods for measuring the entrained air can sometimes be slow and cumbersome and additionally can be prone to errors.
• the durability of concrete may be enhanced by entraining air in the fresh mix. This is typically accomplished through the addition of chemical admixes. The amount of admix is usually determined through empirical data by which a "recipe" is determined. Too little entrained air reduces the durability of the concrete and too much entrained air decreases the strength. Typically the nominal range of entrained air is about 5-8% by volume, and can be between 4% and 6% entrained air by volume in many applications. After being mixed in the mixer box, the concrete is then released to the truck. The level of entrained air is then measured upon delivery of the mix to the site. The draw back of the current method is that the mix is committed to the truck without verification of that the air level in the mix is within specification.
• a measurement of the stiffness of the concrete or concrete mixture will be substantially directly proportional to the mean bubble size.
• a simple combination of a force probe connected to an acoustic piston and a displacement sensor may be used to provide a stiffness factor.
• Alternate sensor configurations can also be used to determine the stiffness such as a combination of a drive current sent to the piston, acceleration of the piston's motion, and the force imparted into the concrete mixture.
• An alternative method to determine the concrete stiffness is to check the displacement of the piston when an impulsive force is applied. A measure of the displacement, force and subsequent dampening of the piston's motion will lead to an understanding of the stiffness of the concrete mixture.
• the pressure inside the air bubbles can be calculated, which in turn will give a measurement of the mean bubble size.
• the present application provides new techniques or ways of real time measurement of entrained air in wet concrete, consistent with, and further building on that set forth in, the aforementioned PCT/US 12/60822, filed 10 October 2012 (WFVA/CiDRA file nos. 712-2.365-1 /CCS-0075), as well as United States patent application serial no. 13/583,062, filed 12 September 2012 (WFVA/CiDRA file nos. 712-2.338-1 /CCS-0033, 35, 40, and 45-49).
• the present invention provides new measurement devices that may include, or take the form of, apparatus featuring: a signal processing module configured with at least one processor and at least one memory including computer program code, the at least one memory and computer program code configured, with the at least one processor, to cause the apparatus at least to:
• the present invention may include one or more of the following features:
• the signal processing module may be configured to provide corresponding signaling containing information about the average bubble size of gas contained in the concrete mixture.
• the signal processing module may be configured to determine the pressure inside air bubbles and determine an average air bubble size of the gas contained in the concrete mixture, based at least partly on the pressure determined inside the air bubbles.
• the apparatus may include a combination of a force probe connected to an acoustic piston and a displacement sensor that is configured to provide associated signaling containing information about the stiffness of the concrete mixture.
• the signal processing module may be configured to receive the associated signaling containing information about a force applied by the acoustic piston to the concrete mixture and sensed by the force probe, and information about a displacement of the acoustic piston in relation to the concrete mixture sensed by the displacement sensor, and configured to determine the stiffness factor of the concrete mixture, based at least partly the associated signaling received.
• the apparatus may include a combination configured with a piston to impart a force into the concrete mixture, a drive current sensor to sense a drive current sent to the piston, and a piston accelerometer to sense an acceleration of the piston's motion, and also configured to provide associated signaling containing information about the stiffness of the concrete mixture.
• the signal processing module may be configured to receive the associated signaling containing information about the drive current sent to the piston and sensed by the drive current sensor, about the acceleration of the piston's motion sensed by the piston accelerometer, and configured to determine the stiffness of the concrete mixture based at least partly on the associated signaling received.
• the apparatus may include a combination configured with a piston to apply an impulsive force to the concrete mixture and at least one sensor to sense or determine a displacement of the piston when the impulsive force is applied to the concrete mixture, the impulsive force applied to the concrete mixture and subsequent dampening of the piston's motion, and also configured to provide associated signaling containing information about the stiffness of the concrete mixture.
• the signal processing module may be configured to receive the associated signaling information about the displacement of the piston when the impulsive force is applied to the concrete mixture, the impulsive force applied to the concrete mixture, and subsequent dampening of the piston's motion, and configured to determine the stiffness of the concrete mixture based at least partly on the associated signaling received.
• the signal processing module may be configured to determine the average bubble size of the gas contained in the concrete mixture, based at least partly on a measurement of the stiffness of the concrete mixture being substantially directly proportional to the average bubble size.
• the apparatus may include a pressure transducer configured to sense at least one acoustic signal injected into the concrete mixture and provide associated signaling containing information about the information about the at least one acoustic signal sensed.
• the signal processing module may be configured to receive the associated signaling and to determine a gas volume fraction (GVF) of the concrete mixture, based at least partly on the associated signaling received.
• VVF gas volume fraction
• the signal processing module may be configured to receive in the signaling information about at least one acoustic signal injected into the concrete mixture, and to determine a gas volume fraction (GVF) of the concrete mixture, based at least partly on the signaling received.
• the signal processing module may be configured to determine the GVF of the concrete mixture, based at least partly on determining the speed of sound of the at least one acoustic signal injected in the concrete mixture, including by injecting the at least one acoustic signal into the concrete mixture and measuring how long the at least one acoustic signal takes to travel over a set distance.
• the apparatus may include a combination having a piston and an actuator configured to cause a pressure fluctuation in the concrete mixture and generate the at least one acoustic signal; a pressure transducer configured the set distance away from the piston, configured to sense the at least one acoustic signal, and to provide associated signaling containing information about the arrival of the at least one acoustic wave; and the signal processing module being configured to receive the associated signaling and to determine a speed of sound (SOS) in the concrete mixture and the GVF of the concrete mixture, including by using a Wood's equation based on a SOS measurement.
• SOS speed of sound
• the stiffness of the concrete mixture may be based on, or may be understood to include, or may take the form of, or may be understood to be, the rigidity of the concrete mixture as an object, including the extent to which the concrete mixture resists deformation in response to an applied force.
• the present invention may take the form of a method that may include, or take the form of, steps for receiving in a signal processor module signaling containing information about the stiffness and a gas volume fraction (GVF) of a concrete mixture; and determining in the signal processor module an average bubble size of gas contained in the concrete mixture, based at least partly on the signaling received.
• a signal processor module signaling containing information about the stiffness and a gas volume fraction (GVF) of a concrete mixture
• VVF gas volume fraction
• This method may also include some combination of the aforementioned features set forth herein.
• the present invention makes important contributions to this current state of the art for bubble size determination in wet concrete, as well as techniques to control the amount of air in a mixture of concrete.
• Figure 1 a is a diagram of an arrangement known in the art for determining the entrained air in concrete or a concrete mixture, including a SONAR-based
• Figure 2a shows a diagram of apparatus, e.g., including a signal processing module, according to some embodiments of the present invention.
• Figure 2b shows a diagram of apparatus, e.g., including a combination of a signal processing module, an actuator, a piston and a transducer, according to some embodiments of the present invention.
• Figures 2a and 2b show, by way of example, the present invention that may include, or take the form of, apparatus 1 0 featuring: a signal processing module 10a configured with at least one processor or signal processor and at least one memory including computer program code, the at least one memory and computer program code configured, with the at least one processor or signal processor, to cause the apparatus at least to:
• a signal processing module 10a configured with at least one processor or signal processor and at least one memory including computer program code, the at least one memory and computer program code configured, with the at least one processor or signal processor, to cause the apparatus at least to:
• the signaling may including first signaling Si , e.g., provided by a combination 12 having an actuator 12a and a piston 12b, and may also include second signaling S 2 , e.g., provided by a pressure transducer 14, consistent with that shown in Figure 2b.
• the signal processing module 10a may be configured to provide
• the corresponding signaling S 3 may be further processed, e.g., to display the average bubble size in the concrete or concrete mixture C, or to control the manufacturing process of the concrete or concrete mixture C, such as by dosing the concrete mixture with some agent to adjust the average bubble size in the concrete or concrete mixture.
• the signal processing module 10a may be configured to determine the pressure inside air bubbles and determine an average air bubble size of the gas contained in the concrete or concrete mixture C, based at least partly on the pressure determined inside the air bubbles. This determination process may be used in relation to other types of kinds of gases other than air.
• the apparatus 1 0 may include a force probe connected or coupled to the acoustic piston 12b and a displacement sensor that is configured to provide associated signaling containing information about the stiffness of the concrete mixture.
• the force probe and displacement sensor may forms part of the actuator 1 2a, or alternatively be separate stand alone elements, all within the spirit of the present invention.
• the signal processing module 10a may be configured to receive the associated signaling containing information about a force applied, e.g., by the acoustic piston 12b to the concrete or concrete mixture C and sensed by the force probe, and information about a displacement of the acoustic piston 12b in relation to the concrete or concrete mixture C sensed by the displacement sensor, and to determine the stiffness factor of the concrete or concrete mixture C, based at least partly the associated signaling received.
• the apparatus 1 0 may include a combination, e.g., configured with a piston like element 12b to impart a force into the concrete or concrete mixture C, a drive current sensor to sense a drive current sent to the piston 12b, and a piston accelerometer to sense an acceleration of the piston's motion, and also configured to provide associated signaling containing information about the stiffness of the concrete mixture.
• the signal processing module may be configured to receive the associated signaling containing information about the drive current sent to the piston 12b and sensed by the drive current sensor, about the acceleration of the piston's motion sensed by the piston accelerometer, and to determine the stiffness of the concrete mixture based at least partly on the associated signaling received.
• the drive current sensor and the piston accelerometer may form part of the actuator 12a, or alternatively be separate stand alone elements, all within the spirit of the present invention.
• the apparatus 1 0 may include a combination, e.g., configured with a piston like element 12b to apply an impulsive force to the concrete or concrete mixture C and at least one sensor to sense or determine a displacement of the piston 12b when the impulsive force is applied to the concrete or concrete mixture C, the impulsive force applied to the concrete or concrete mixture C and subsequent dampening of the piston's motion.
• a combination may also be configured to provide associated signaling containing information about the stiffness of the concrete or concrete mixture C.
• the at least one sensor may form part of the actuator 1 2a, or alternatively be a separate stand alone element, all within the spirit of the present invention.
• the signal processing module 10a may be configured to receive the associated signaling information about the displacement of the piston when the impulsive force is applied to the concrete mixture, the impulsive force applied to the concrete mixture, and subsequent dampening of the piston's motion, and to determine the stiffness of the concrete or concrete mixture C based at least partly on the associated signaling received.
• the signal processing module 10a may be configured to determine the average bubble size of the gas contained in the concrete mixture C, based at least partly on a measurement of the stiffness of the concrete or concrete mixture C being substantially directly proportional to the average bubble size.
• the apparatus 1 0 may include the pressure transducer 14 configured to sense at least one acoustic signal injected into the concrete mixture and provide associated signaling containing information about the at least one acoustic signal sensed.
• the signal processing module 10a may be configured to receive the associated signaling and to determine a gas volume fraction (GVF) of the concrete or concrete mixture C, based at least partly on the associated signaling received.
• VVF gas volume fraction
• the signal processing module 10a may be configured to receive in the signaling information about at least one acoustic signal injected into the concrete or concrete mixture, and to determine a gas volume fraction (GVF) of the concrete mixture, based at least partly on the signaling received.
• the signal processing module 10a may be configured to determine the GVF of the concrete or concrete mixture C, based at least partly on determining the speed of sound of the at least one acoustic signal injected in the concrete or concrete mixture C, including by injecting the at least one acoustic signal into the concrete or concrete mixture C and measuring how long the at least one acoustic signal takes to travel over a set distance.
• the apparatus 10 may include a combination 12 having the actuator 12a and the piston 12b configured to cause a pressure fluctuation in the concrete or concrete mixture C and generate the at least one acoustic signal; the pressure transducer 14 configured the set distance away from the piston 1 2b configured to sense the at least one acoustic signal, and to provide associated signaling containing information about the arrival of the at least one acoustic wave.
• the signal processing module 10a may be configured to receive the associated signaling and to determine the SOS in the concrete or concrete mixture C and the GVF of the concrete or concrete mixture C, including by using a Wood's equation based on a SOS measurement.
• the functionality of the signal processing or signal processing module 10a may be implemented using hardware, software, firmware, or a combination thereof, although the scope of the invention is not intended to be limited to any particular embodiment thereof.
• the signal processor would be one or more microprocessor-based architectures having a microprocessor, a random access memory (RAM), a read only memory (ROM), input/output devices and control, data and address buses connecting the same.
• a person skilled in the art would be able to program such a microprocessor-based implementation to perform the functionality set forth in the signal processing block 10a, such as determining the gas volume fraction of the aerated fluid based at least partly on the speed of sound measurement of the acoustic signal that travels through the aerated fluid in the container, as well as other functionality described herein without undue
• the apparatus 10 may include one or more other modules, components, circuits, or circuitry 10b for implementing other functionality associated with the apparatus that does not form part of the underlying invention, and thus is not described in detail herein.
• the one or more other modules, components, circuits, or circuitry 10b may include random access memory, read only memory, input/output circuitry and data and address buses for use in relation to implementing the signal processing functionality of the signal processor 10a, or devices or components related to mixing or pouring concrete in a ready-mix concrete truck or adding chemical additives, etc.
• the Dual Frequency Techniques for Determining Entrained Air may include, by way of example, using dual frequency techniques to determine the entrained air in the concrete or concrete mixture C, according to some embodiments of the present invention.
• a signal processor 10a may be configured to receive signaling containing information about an acoustic signal injected into a mixture of concrete; and determine a measurement of air percentage in the mixture of concrete based at least partly on a dual frequency technique that depends on a relationship between the acoustic signal injected and the signaling received.
• the scope of the invention may include using other techniques to determine the entrained air in the concrete or concrete mixture C, according to some embodiments of the present invention.
• another approach for the measurement of air percentage in concrete e.g., is to measure the speed of sound (SOS) in the mixture and then through the use of the Wood's equation to calculate the amount of gas present.
• SOS speed of sound
• Various acoustic speed of sound measurements used in relation to SONAR-based technology as well as other sound receiving technology are set forth below with numerous patents disclosing this technology.
• This measurement of air percentage in concrete can be very difficult in materials like concrete where acoustic waves will quickly die out in strength due to the material's constituents along with other factors. This can be overcome by injecting a strong acoustic signal into the mixture at one point and then timing the signal propagation through a representative section of the material.
• this approach requires significant amounts of energy to produce a large compression wave in the concrete.
• a variation of this approach may be implemented that would require a modest acoustic signal to be injected but a very sensitive detection technique that can pull the injected signal out of the other acoustic "noise" that is present in the system.
• a detection technique that is well suited for this is a phase sensitive lock-in approach.
• a reference signal may be injected into the mixture and that same signal may be mixed with a resultant detected signal from the mixture. After a low pass filter is used to get the DC component of the result, a value may be obtained that is proportional to the amplitude and phase of the detected signal at the reference frequency.
• the phase and amplitude components can be separately determined. If one takes Gref as the reference phase, Gdet as the detected phase, Adet as the detected signal amplitude at the frequency of interest, then the signal amplitude and the signal phase difference may be determined using the following set of equations:
• the signal phase difference calculated along with the frequency can then be used to determine the time of propagation of the signal in the material and then the SOS.
• an ambiguity exists once the detected signal has gone though a propagation time equal to 2 * pi of the injected signal (or any multiple). This can be somewhat prevented by assuring that the frequency used for injection is low enough that the time delay can not introduce the ambiguity, however this will severely restrict the operational range of the measurement. Variations in the air content along with the attenuation characteristic of the materials may force the system to operate in a region where the ambiguity will exist. This can be prevented by injecting two slightly different frequencies into the material and then detecting each to determine the relative phase between the two injected signals, e.g., using the acoustic probe that include two dynamic transducers. An ambiguity can still exist but it will be a function of the difference of the two injected signals rather than just the single injected frequency.
• the SONAR-based entrained air meter may take the form of SONAR-based meter and metering technology disclosed, e.g., in whole or in part, in United States Patent Nos. 7,165,464; 7,134,320; 7,363,800; 7,367,240; and 7,343,820, all of which are incorporated by reference in their entirety.
• the known SONAR-based technology includes a gas volume fraction meter (known in the industry as a GVF-100 meter) that directly measures the low- frequency sonic speed (SOS) of the liquid or slurry flowing through a pipe.
• the SONAR-based entrained air meter may take the form of SONAR-based meter and metering technology disclosed, e.g., in whole or in part, in United States Patent Nos. 7,1 65,464; 7,134,320; 7,363,800; 7,367,240; and 7,343,820, all of which are incorporated by reference in their entirety.
• the volume percent of any gas bubbles or the gas void fraction (GVF) is determined from the measured SOS.
• the Wood's equation requires several other inputs in addition to the measured SOS of liquid/gas mixture.
• One of the additional inputs in particular, the static pressure of the liquid/gas mixture can be very important for an accurate calculation of the GVF.
• the static pressure used for the GVF calculation differs from the actual static pressure of the liquid/gas mixture, then the calculated GVF may typically differ from the actual GVF by 1 % as well.
• Static Pressure used for GVF calculation 20 psia
• the static pressure of the liquid/gas mixture is available through existing process plant instrumentation.
• the measured static pressure can be input directly to the GVF calculation through, e.g., an analog 4-20 mA input in the SONAR-based gas volume fraction transmitter (e.g. GVF-100 meter).
• a correction to the calculated GVF can be made in the customer DCS for any variation from the fixed pressure that was used to originally calculate the GVF.
• a static pressure transmitter can be added to the process plant specifically to measure the static pressure used for the GVF calculation.
• the measured pressure can either be input to the SONAR-based gas volume fraction transmitter (e.g., GVF-1200) or correction made in the DCS as described above.
• a the SONAR-based gas volume fraction meter (e.g., GVF-100) may be installed at a location in the process that does not already have a static pressure gauge installed and it is impractical to add one. This could be a location where there is no existing penetration of the pipe to sense the pressure and it would be difficult or expensive to add one.
• a traditional pressure gauge is not available and it is desirable to have a static pressure measurement the following description of a non-intrusive (clamp on) static pressure measurement could be used.
• a non-intrusive static pressure measurement may be sensed using traditional strain gauges integrated into the sensor band of the SONAR-based gas volume fraction sensing technology (e.g. the known GVF-100 meter).
• the static strain on the outside of the pipe changes.
• the radius, wall thickness and modulus is generally known, or at least constant and so if the tangential strain is measured the internal static pressure can be determined.
• strain gauges could be arranged on the sensor band of the SONAR-based gas volume fraction sensing technology (e.g. the known GVF-100 meter) in a
• the sensitivity assuming a strain gauge factor of 2, the sensitivity is approximately 1 3 ⁇ / ⁇ , where V is volts. Assuming a 4-inch schedule 40 carbon steel pipe, a one psi change in pressure would cause a 4 ⁇ change in Wheatstone bridge output. This sensitivity would increase for larger diameter pipes which generally have a smaller t/R.
• the integrated pressure gauge could be calibrated in-situ for best accuracy, but it may be sufficient to normalize the pressure output to a certain know state then use the tangential strain formula above with know pipe parameters to calculate the pressure from the measured strain.
• the SONAR-based entrained air meter and metering technology are known in the art and may take the form of a SONAR-based meter disclosed, e.g., in whole or in part in United States Patent Nos. 7,165,464; 7, 134,320; 7,363,800; 7,367,240; and 7,343,820, all of which are incorporated by reference in their entirety.
• the SONAR- based entrained air meter and metering technology is capable of providing a variety of information, including the pure phase density and pure phase liquid sound speed is known, such that the GVF can be determined by measuring the speed of sound and then applying the Woods Equation.
• Determining the GVF by measuring the speed of sound can provide fast an accurate data. Also the SOS measurement system can be very flexible and can easily be configured to work with different concrete containers and sample particular volumes.
• the SONAR-based entrained air meter and metering technology are known in the art and may take the form of a SONAR- based meter disclosed, e.g., in whole or in part in United States Patent Nos.
• the pistons, acoustic transmitters, actuators, the acoustic receiver or receiver probes, pressure transducers, and/or transponders are devices that are known in the art, and the scope of the invention is not intended to be limited to any particular type or kind either now known or later developed in the future.
• the Scope of the Invention is not intended to be limited to any particular type or kind either now known or later developed in the future.

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