Device and method for evaluating uniformity of foam concrete

Abstract

The invention relates to a device and method for evaluating the uniformity of foam concrete, and belongs to the technical field of concrete.The method comprises the steps that a concrete test piece is formed through a cubic mold; uniformly dividing the upper surface of the concrete test piece into a plurality of sections, placing an ultrasonic scanning unit on each section of the concrete test piece for ultrasonic detection in sequence, recording the sound velocity of each measuring line, and calculating to obtain the average sound velocity Vk of each section; calculating a homogeneity coefficient lambda; and when the uniformity coefficient lambda is smaller than a uniformity coefficient threshold value specified by the corresponding density, determining that the uniformity of the concrete is qualified, otherwise, determining that the concrete is unqualified. According to the method, pores in the concrete are rapidly positioned by using an ultrasonic detection technology, the uniformity of the foam concrete is judged through discreteness of the acoustic velocity, and the method has the advantages of reliable detection result, simplicity and convenience in operation and the like.

Description

TECHNICAL FIELD

[0001] The application relates to a device and a method for evaluating the uniformity of foamed concrete, and belongs to the technical field of concrete. BACKGROUND

[0002] Foamed concrete is a kind of lightweight porous material, which has a large number of pores inside. Since the thermal conductivity of air is much lower than that of the cement matrix, compared with ordinary concrete, foamed concrete has good heat preservation and insulation performance. In recent years, with the extensive research on foamed concrete, its application range has gradually expanded from roadbed filling, house warming to airport runway shock absorption, large structure heat preservation and even application to the heat preservation and protection of the surface of concrete dams in cold regions.

[0003] As a kind of heat preservation and insulation material, the heat preservation and insulation performance of foamed concrete comes from its complex pore structure. The size and distribution of the pores have a great influence on the thermal conductivity of foamed concrete. Therefore, it is necessary to evaluate the uniformity of the pores of foamed concrete in the actual process.

[0004] However, the existing method usually uses image method to evaluate the uniformity of the concrete, which is not only time-consuming but also low in precision. At present, there is still a lack of fast and effective uniformity evaluation method. SUMMARY

[0005] In view of the above problems, the application provides a device and a method for evaluating the uniformity of foamed concrete. The ultrasonic detection technology is used to quickly locate the pores inside the concrete, and the uniformity of the foamed concrete is judged by the discreteness of the sound velocity. The method has the advantages of reliable detection result and simple operation.

[0006] The technical scheme of the application is as follows:

[0007] A device for evaluating the uniformity of foamed concrete comprises an ultrasonic scanning unit and a statistical calculation unit. The ultrasonic scanning unit is composed of 10 transceiving probes and is used for ultrasonic scanning of a section of a concrete test piece. The statistical calculation unit is used for statistical calculation of the sound velocity of each section and calculation of the uniformity coefficient of the sound velocity of each section, so as to evaluate the uniformity through the uniformity coefficient.

[0008] A method for evaluating the uniformity of foamed concrete based on the above device comprises the following steps:

[0009] (1) A cubic mold is used to form a concrete test piece, and a layer of coupling agent is applied on the surface of the concrete test piece before ultrasonic detection, so as to avoid the influence of small air gaps on the detection result;

[0010] (2) evenly divide multiple sections on the upper surface of the concrete test piece, place the ultrasonic scanning unit on each section of the concrete test piece to sequentially perform ultrasonic detection, and record the sound velocity of each measuring line to calculate the average sound velocity V of each section k , k represents the kth section;

[0011] (3) calculate the uniformity coefficient λ:

[0012] The average sound velocity of the 10 sections is calculated wherein V k represents the average sound velocity of the kth section; the uniformity of the entire test piece is judged by the dispersion of V k of the 10 sections;

[0013]

[0014]

[0015] λ = max{λ1, λ2}

[0016] (4) when the uniformity coefficient λ is less than the uniformity coefficient threshold value corresponding to the density, the concrete uniformity is qualified, otherwise, it is unqualified.

[0017] Preferably, in step (1), the concrete test piece is a 100*100*100mm cubic concrete test piece.

[0018] Preferably, in step (2), the upper surface of the concrete test piece is evenly divided into 10 sections.

[0019] Preferably, the ultrasonic detection process of the ultrasonic scanning unit on each section of the concrete test piece is the same, for each section, 10 transceiving probes are sequentially and evenly arranged on the section and sequentially numbered as A-J, and the distance between adjacent transceiving probes is 10mm.

[0020] The ultrasonic scanning unit is used for scanning the pore system of the section of the foam concrete test piece to be detected, and the transceiving probe is used for transmitting and receiving signals. The scanning method of the present application is single transmission and multiple reception. During ultrasonic detection, the transceiving probe A first transmits ultrasonic waves, the ultrasonic waves are reflected at the bottom of the concrete test piece, the transceiving probe B receives the reflected ultrasonic waves, and the distance and time of the measuring line are recorded to calculate the sound velocity of the measuring line; the transceiving probe A changes the transmission angle to transmit ultrasonic waves, the ultrasonic waves are reflected at the bottom of the concrete test piece, so that the transceiving probe B receives the reflected ultrasonic waves, and the distance and time of the measuring line are recorded to calculate the sound velocity of the measuring line; according to this process, the transmission angle of the transceiving probe A is sequentially changed, so that the transceiving probes C-J after it sequentially receive the reflected ultrasonic waves, and the distance and time of the measuring line are recorded to calculate the sound velocity V 1jWhere i represents the transceiver probe number, ranging from 1 to 10, j represents the j-th ultrasonic wave emitted by the ultrasonic probe, ranging from 0 to 9, and V 1j This indicates that the first transceiver probe emits an ultrasonic wave for the jth time; transceiver probe A emits a total of 9 ultrasonic waves.

[0021] Then, transceiver probe B emits ultrasonic waves, which are reflected at the bottom of the concrete specimen. Transceiver probe C receives the reflected ultrasonic waves and records the distance and time along the measurement line, calculating the sound velocity along the line. Afterward, transceiver probe B sequentially changes its emission angle, causing subsequent transceiver probes C through J to receive the reflected ultrasonic waves in turn, recording the distance and time along the measurement line, and calculating the sound velocity V along the line. 2j The transceiver probe B emitted a total of 8 ultrasonic waves.

[0022] Transceiver probes C through I all follow the transmission method of transceiver probe B, ensuring that subsequent transceiver probes can receive one reflected ultrasonic wave. Transceiver probe C transmits a total of 7 ultrasonic waves, transceiver probe D transmits a total of 6 ultrasonic waves, transceiver probe E transmits a total of 5 ultrasonic waves, transceiver probe F transmits a total of 4 ultrasonic waves, transceiver probe G transmits a total of 3 ultrasonic waves, transceiver probe H transmits a total of 2 ultrasonic waves, and transceiver probe I transmits a total of 1 ultrasonic wave. V is calculated for each. ij , where i represents the transceiver probe number, with a value ranging from 1 to 10.

[0023] In this invention, when transceiver probe A acts as the transmitter, subsequent transceiver probe BJ acts as the receiver. Transceiver probe B acts as the transmitter, and subsequent transceiver probe CJ acts as the receiver to receive the ultrasonic signal emitted by B. This continues until transceiver J acts as the transmitter, completing the scan. J becomes the last transceiver probe, and no subsequent probe can receive the ultrasonic signal emitted by J. Typically, J is the default receiver. Since the emission angle of each transceiver probe is determined based on the distance between the probes, it ensures that the remaining transceiver probes can receive the emitted signal.

[0024] Preferably, the transmission angle of the transceiver probe h is the height of the concrete specimen, in mm. Inputting this height into the statistical calculation unit will automatically calculate θ and adjust the transmission angle automatically. x is half the distance between the transmitting and receiving probes, in mm. In this invention, the test specimen h is 100 mm. Taking transceiver probe A as an example, x is 5, 10, 15, 20, 25, 30, 35, 40, and 45 mm respectively, therefore the transmission angles are 87°, 84°, 82°, 79°, 76°, 73°, 71°, 68°, and 66°.

[0025] Preferably, the distance to a certain survey line is The speed of sound on a certain measuring line was calculated. Among them, t ijThis represents the time taken from the transmission to the reception of the ultrasonic wave emitted by the i-th transceiver probe j-th time. The ultrasonic scanning unit has a built-in timer that can record t in real time. ij ;

[0026] Finally, calculate the average sound velocity of all survey lines for each cross section.

[0027] Preferably, during the preparation of foamed concrete, due to the mix proportions, the proportion of cement paste encapsulating the foam is relatively small, resulting in thinner cement walls. Alternatively, foam aggregation or defoaming may occur during mixing. These factors all contribute to uneven pore size distribution and poor uniformity in the prepared foamed concrete samples. Because the pore size within foamed concrete is small, the average pore size differs depending on the density of the foamed concrete. Low-density samples have fewer pores and a larger average pore size, while high-density samples have smaller pores and a larger number of pores. This invention establishes different uniformity coefficient thresholds based on different densities:

[0028] When the concrete density is <450, the uniformity coefficient threshold is 30%; when the concrete density is in the range of [450-600), the uniformity coefficient threshold is 25%; when the concrete density is in the range of [600-750), the uniformity coefficient threshold is 20%; when the concrete density is in the range of [750-900), the uniformity coefficient threshold is 15%; and when the concrete density is ≥900, the uniformity coefficient threshold is 10%.

[0029] Preferably, there are two sets of ultrasonic scanning units, which can realize simultaneous detection of two cross sections, that is, using 10×2=20 transceiver probes. They are compact and portable, and can also be combined for scanning according to different user needs, which is efficient and low cost.

[0030] For any details not covered in this invention, please refer to the prior art.

[0031] The beneficial effects of this invention are as follows:

[0032] This invention provides a simple and practical method for predicting and evaluating the uniformity of foamed concrete. By testing foamed concrete specimens with ultrasound, the operation is simple and can evaluate the uniformity of the pore system of foamed concrete in a short time.

[0033] The high line density in this invention makes the specimen testing more accurate and the results more reliable.

[0034] This invention can not only provide a basis for optimizing the mix proportion of foamed concrete, but also evaluate the excellent structure of the mixing process, making it a widely applicable technology. Attached Figure Description

[0035] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application.

[0036] Figure 1 This is a schematic diagram of the apparatus for evaluating the uniformity of foamed concrete according to the present invention;

[0037] Figure 2 This is a schematic diagram for inspecting a certain cross section;

[0038] Figure 3 Schematic diagram of a cubic concrete specimen;

[0039] In the diagram, 1-control switch, 2-handle, 3-transmit / receive probe, 4-computer. Detailed Implementation

[0040] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. However, this is not the only description; all aspects not described in detail herein are based on conventional techniques in the field.

[0041] Example 1

[0042] An apparatus for assessing the homogeneity of foamed concrete, such as Figure 1 As shown, it includes an ultrasonic scanning unit and a statistical calculation unit. The ultrasonic scanning unit consists of 10 transceiver probes 3, which are used to perform ultrasonic scanning on a certain section of the concrete specimen. The statistical calculation unit is implemented by a computer 4, which is used to calculate the sound velocity of each section and calculate the sound velocity uniformity coefficient of each section, and then evaluate the uniformity through the uniformity coefficient.

[0043] The device also includes a control switch 1 and a handle 2.

[0044] Example 2

[0045] A method for assessing the homogeneity of foamed concrete includes the following steps:

[0046] (1) Concrete specimens were formed using a cubic mold. The concrete specimens were 100×100×100mm cubic concrete specimens. Before ultrasonic testing, a layer of coupling agent was applied to the surface of the concrete specimens to avoid the influence of tiny air gaps on the test results.

[0047] (2) Divide the upper surface of the concrete specimen into 10 sections evenly. Place the ultrasonic scanning unit on each section of the concrete specimen and perform ultrasonic testing in sequence. Record the sound velocity along each test line and calculate the average sound velocity V of each section. k , k represents the k-th cross section;

[0048] The ultrasonic scanning unit performs the same ultrasonic testing process on each cross section of the concrete specimen. For each cross section, 10 transceiver probes are arranged evenly on the cross section and numbered sequentially from A to J. The distance between adjacent transceiver probes is 10 mm.

[0049] The ultrasonic scanning unit is used to scan the pore system of the cross-section of the foamed concrete specimen to be tested. Transceiver probes are used to transmit and receive signals. This invention adopts a single-transmitter, multi-receiver scanning method. During ultrasonic testing, transceiver probe A first transmits ultrasonic waves, which are reflected at the bottom of the concrete specimen. Transceiver probe B receives the reflected ultrasonic waves and records the distance and time of the measurement line, calculating the sound velocity of the measurement line. Transceiver probe A then changes its transmission angle to transmit ultrasonic waves, which are reflected at the bottom of the concrete specimen, allowing transceiver probe B to receive the reflected ultrasonic waves and record the distance and time of the measurement line, calculating the sound velocity of the measurement line. Following this process, the transmission angle of transceiver probe A is changed sequentially, allowing subsequent transceiver probes C through J to sequentially receive the reflected ultrasonic waves, recording the distance and time of the measurement line, and calculating the sound velocity V of the measurement line. 1j Where i represents the transceiver probe number, ranging from 1 to 10, j represents the j-th ultrasonic wave emitted by the ultrasonic probe, ranging from 0 to 9, and V 1j This indicates that the first transceiver probe emits an ultrasonic wave for the jth time; transceiver probe A emits a total of 9 ultrasonic waves.

[0050] Then, transceiver probe B emits ultrasonic waves, which are reflected at the bottom of the concrete specimen. Transceiver probe C receives the reflected ultrasonic waves and records the distance and time along the measurement line, calculating the sound velocity along the line. Afterward, transceiver probe B sequentially changes its emission angle, causing subsequent transceiver probes C through J to receive the reflected ultrasonic waves in turn, recording the distance and time along the measurement line, and calculating the sound velocity V along the line. 2j The transceiver probe B emitted a total of 8 ultrasonic waves.

[0051] Transceiver probes C through I all follow the transmission method of transceiver probe B, ensuring that subsequent transceiver probes can receive one reflected ultrasonic wave. Transceiver probe C transmits a total of 7 ultrasonic waves, transceiver probe D transmits a total of 6 ultrasonic waves, transceiver probe E transmits a total of 5 ultrasonic waves, transceiver probe F transmits a total of 4 ultrasonic waves, transceiver probe G transmits a total of 3 ultrasonic waves, transceiver probe H transmits a total of 2 ultrasonic waves, and transceiver probe I transmits a total of 1 ultrasonic wave. V is calculated for each. ij , where i represents the transceiver probe number, with a value ranging from 1 to 10.

[0052] In this invention, when transceiver probe A acts as the transmitter, subsequent transceiver probe BJ acts as the receiver. Transceiver probe B acts as the transmitter, and subsequent transceiver probe CJ acts as the receiver to receive the ultrasonic signal emitted by B. This continues until transceiver J acts as the transmitter, completing the scan. J becomes the last transceiver probe, and no subsequent probe can receive the ultrasonic signal emitted by J. Typically, J is the default receiver. Since the emission angle of each transceiver probe is determined based on the distance between the probes, it ensures that the remaining transceiver probes can receive the emitted signal.

[0053] Furthermore, the transmission angle of the transceiver probe. h is the height of the concrete specimen, in mm. Inputting this height into the statistical calculation unit will automatically calculate θ and adjust the transmission angle automatically. x is half the distance between the transmitting and receiving probes, in mm. In this invention, the test specimen h is 100 mm. Taking transceiver probe A as an example, x is 5, 10, 15, 20, 25, 30, 35, 40, and 45 mm respectively, therefore the transmission angles are 87°, 84°, 82°, 79°, 76°, 73°, 71°, 68°, and 66°.

[0054] Furthermore, for a certain survey line, the distance is... The speed of sound on a certain measuring line was calculated. Among them, t ij This represents the time taken from the transmission to the reception of the ultrasonic wave emitted by the i-th transceiver probe j-th time. The ultrasonic scanning unit has a built-in timer that can record t in real time. ij ;

[0055] Finally, calculate the average sound velocity of all survey lines for each cross section.

[0056] (3) Calculate the uniformity coefficient λ:

[0057] The average sound velocity of the 10 cross sections was calculated. Where V k This represents the average sound velocity at the k-th cross section; using V from 10 cross sections k The discreteness of the sample determines its uniformity.

[0058]

[0059]

[0060] λ = max{λ1, λ2}

[0061] (4) During the preparation of foamed concrete, due to the mix proportions, the proportion of cement paste encapsulating the foam is relatively small, resulting in thinner cement walls. Furthermore, phenomena such as foam coalescence and defoaming may occur during mixing. These factors all contribute to uneven pore size distribution and poor uniformity in the prepared foamed concrete samples. Because the pore size within foamed concrete is small, the average pore size varies depending on the density of the foamed concrete. Low-density samples have fewer pores and a larger average pore size, while high-density samples have smaller pores and a larger number of pores. This invention establishes different uniformity coefficient thresholds based on different densities:

[0062] When the uniformity coefficient λ is less than the specified uniformity coefficient threshold for the corresponding density, the concrete is considered to be of acceptable uniformity; otherwise, it is considered unacceptable.

[0063] As shown in Table 1, the uniformity coefficient threshold is 30% when the concrete density is <450; 25% when the concrete density is in the range of [450-600); 20% when the concrete density is in the range of [600-750); 15% when the concrete density is in the range of [750-900); and 10% when the concrete density is ≥900.

[0064] Table 1: Uniformity coefficient thresholds for different densities

[0065] Density (kg / m 3 )]]> Uniformity coefficient threshold ＜450 30％ [450-600) 25％ [600-750) 20％ [750-900) 15％ ≥900 10％

[0066] Example 3

[0067] A method for evaluating the uniformity of foamed concrete, as described in Example 2, except that two sets of ultrasonic scanning units are preferably used, enabling simultaneous detection of two cross-sections. Figure 3 The two ultrasonic scanning tracks shown represent a 2-fold increase in detection efficiency when using 10×2=20 transceiver probes.

[0068] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An apparatus for assessing the uniformity of foamed concrete, characterised in that, The application relates to a concrete uniformity evaluation method, which comprises an ultrasonic scanning unit and a statistical calculation unit, wherein the ultrasonic scanning unit is composed of 10 transceiving probes and is used for ultrasonic scanning of a certain section of a concrete sample; the statistical calculation unit is used for statistically calculating the sound velocity of each section and calculating the uniformity coefficient of the sound velocity of each section, and then evaluating the uniformity through the uniformity coefficient.

2. A method based on the device for evaluating the homogeneity of foamed concrete according to claim 1, characterized in that, The method comprises the following steps: (1) forming a concrete sample by using a cubic mold, and smearing a layer of coupling agent on the surface of the concrete sample; (2) evenly divide multiple sections on the upper surface of the concrete test piece, place the ultrasonic scanning unit on each section of the concrete test piece in turn to perform ultrasonic detection, and record the sound velocity of each measuring line to calculate the average sound velocity V of each section k , k represents the kth section; (3) calculating the uniformity coefficient lambda: The average sound velocity of 10 sections is calculated where V k represents the average sound velocity of the kth section; Lambda = max {lambda1, lambda2} (4) when the uniformity coefficient lambda is smaller than the uniformity coefficient threshold value corresponding to the density, the concrete uniformity is qualified, otherwise, the concrete uniformity is unqualified.

3. A method of assessing the uniformity of foamed concrete according to claim 2, characterised in that, In step (1), the concrete sample is a cubic concrete sample with the size of 100*100*100mm.

4. The method of assessing the uniformity of foamed concrete according to claim 2, wherein, In step (2), the upper surface of the concrete sample is evenly divided into 10 sections.

5. A method of assessing the uniformity of foamed concrete according to claim 4, characterised in that, The ultrasonic scanning unit has the same ultrasonic detection process on each section of the concrete sample, for each section, 10 transceiving probes are evenly arranged on the section in sequence and are numbered in sequence as A-J, the distance between adjacent transceiving probes is 10mm; When the ultrasonic detection is performed, the transmitting-receiving probe A first transmits ultrasonic waves, the ultrasonic waves are reflected at the bottom of the concrete test piece, the transmitting-receiving probe B receives the reflected ultrasonic waves, and the distance and time of the measuring line are recorded to calculate the sound velocity of the measuring line; the transmitting-receiving probe A changes the transmission angle to transmit ultrasonic waves, the ultrasonic waves are reflected at the bottom of the concrete test piece, so that the transmitting-receiving probe B receives the reflected ultrasonic waves, and the distance and time of the measuring line are recorded to calculate the sound velocity of the measuring line; according to the process, the transmission angle of the transmitting-receiving probe A is changed in turn, and the transmitting-receiving probes C to J behind the transmitting-receiving probe A receive the reflected ultrasonic waves in turn, and the distance and time of the measuring line are recorded to calculate the sound velocity V of the measuring line 1j wherein i represents the number of the transmitting-receiving probe, and the value is 1 to 10, j represents the jth transmission of ultrasonic waves by the ultrasonic probe, and the value is 0 to 9, V 1j represents the jth transmission of ultrasonic waves by the first transmitting-receiving probe; the transmitting-receiving probe A transmits ultrasonic waves for 9 times; Then, the transceiving probe B transmits ultrasonic waves, the ultrasonic waves are reflected at the bottom of the concrete test piece, the transceiving probe C receives the reflected ultrasonic waves, and the distance and time of the measuring line are recorded, and the sound velocity of the measuring line is calculated; then, the transceiving probe B changes the transmission angle in turn, and the transceiving probes C-J behind it receive the reflected ultrasonic waves in turn, and the distance and time of the measuring line are recorded, and the sound velocity V of the measuring line is calculated 2j ; the transceiving probe B transmits ultrasonic waves for 8 times; The transmitting and receiving probes C-I all transmit according to the transmitting mode of the transmitting and receiving probe B, so that the following transmitting and receiving probes can receive the once-reflected ultrasonic waves. The transmitting and receiving probe C transmits 7 times, the transmitting and receiving probe D transmits 6 times, the transmitting and receiving probe E transmits 5 times, the transmitting and receiving probe F transmits 4 times, the transmitting and receiving probe G transmits 3 times, the transmitting and receiving probe H transmits 2 times, and the transmitting and receiving probe I transmits 1 time. The V ij wherein i represents the number of the transmitting and receiving probe, and the value is 1-10.

6. A method of assessing the uniformity of foamed concrete according to claim 5, characterised in that, Firing angle of the transducer h is the height of the concrete specimen, mm; x is half the distance between the transmitting and receiving transducers, mm.

7. A method of assessing the uniformity of foamed concrete according to claim 6, characterised in that, The distance of a certain measuring line is The sound velocity of a certain measuring line is calculated Where, t ij represents the time used for the ultrasonic wave emitted by the ith transceiving probe for the jth time from emission to reception; Finally, the average sound velocity of all measuring lines of each section is calculated.

8. The method of assessing the uniformity of foamed concrete according to claim 2, wherein, In step (4), when the concrete density is <450, the uniformity coefficient threshold value is 30%; when the concrete density belongs to [450-600), the uniformity coefficient threshold value is 25%; when the concrete density belongs to [600-750), the uniformity coefficient threshold value is 20%; when the concrete density belongs to [750-900), the uniformity coefficient threshold value is 15%; and when the concrete density is >=900, the uniformity coefficient threshold value is 10%.

9. The method of assessing the uniformity of foamed concrete according to claim 2, wherein, The ultrasonic scanning unit is preferably two sets, which can realize the simultaneous detection of two sections.

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