Quantitative evaluation method for rapidly detecting lightweight aggregate concrete homogeneity based on ultrasonic waves

Abstract

The invention discloses a quantitative evaluation method for rapidly detecting the homogeneity of lightweight aggregate concrete based on ultrasonic waves, and belongs to the technical field of engineering material tests.The method comprises the steps that S1, transverse wave velocities and longitudinal wave velocities of a plurality of test points of a series of lightweight aggregate concrete reference test pieces are obtained; s2, calculating shear modulus and bulk modulus of each test point of each reference test piece; s3, calculating the elastic modulus of each test point of each reference test piece; s4, according to the elastic modulus obtained in the step S3, constructing a relational expression of the volume mixing amount, the transverse wave velocity and the longitudinal wave velocity of the lightweight aggregate; s5, acquiring the transverse wave velocity and longitudinal wave velocity of each test point of the to-be-tested piece, and calculating the volume mixing amount of the lightweight aggregate of each test point of the to-be-tested piece according to the relational expression; and S6, evaluating the homogeneity of the to-be-tested piece according to the lightweight aggregate volume mixing amount of each test point calculated in the step S5. The technical problem that the accuracy of the lightweight aggregate concrete homogeneity ultrasonic detection result is insufficient is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of engineering material testing, and in particular relates to a quantitative evaluation method for the homogeneity of lightweight aggregate concrete based on ultrasonic rapid detection. Background Art

[0002] Lightweight aggregate concrete, due to its lightweight, high strength, and excellent thermal insulation properties, has been widely used in engineering fields such as bridges and buildings. However, due to the significant density difference between lightweight aggregate and the cement matrix, a segregation phenomenon known as "aggregate floating and mortar sinking" is common during concrete construction. This phenomenon is primarily caused by the following factors: an excessively high water-cement ratio or low slurry viscosity, resulting in insufficient slurry encapsulation of the expanded clay; prolonged or excessive vibration force, exacerbating the separation of lightweight aggregate from the slurry; and excessively high pouring heights or rapid pouring speeds, further causing the lightweight aggregate to float. These issues can lead to reduced strength in the upper areas of the concrete structure where the lightweight aggregate is concentrated, while increasing shrinkage in the lower areas where the slurry is concentrated, severely impacting the mechanical and durability properties of the structure. Therefore, strict control of relevant parameters and enhanced structural testing are necessary to ensure the uniformity and overall performance of lightweight aggregate concrete.

[0003] Currently, the most common methods for testing the homogeneity of lightweight aggregate concrete are image analysis and density methods. However, these methods typically require concrete sampling and cutting, which can be time-consuming and destructive. CT scanning is also used to test lightweight aggregate concrete, but its testing costs are high, and it requires sample cutting and pretreatment, making it time-consuming and impractical for on-site implementation, limiting its applicability in engineering projects. In contrast, ultrasonic testing technology, due to its advantages of being non-destructive, rapid, portable, and highly accurate, has shown considerable application potential in the field of lightweight aggregate concrete. Homogeneity evaluation is primarily achieved through indirect methods, such as comparing ultrasonic velocity differences or evaluating differences in physical quantities such as compressive strength or elastic modulus derived indirectly from ultrasonic velocity. However, due to the large differences in raw materials and mix proportions of lightweight aggregate concrete, there is a lack of a unified and precise expression formula for the fitting relationship between ultrasonic waves and mechanical properties. This has certain limitations in practical applications, affecting the accuracy of ultrasonic testing results for the homogeneity of lightweight aggregate concrete. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a quantitative evaluation method for the homogeneity of lightweight aggregate concrete based on rapid ultrasonic detection, so as to solve the technical problem of insufficient accuracy of ultrasonic detection results of the homogeneity of lightweight aggregate concrete in the prior art.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is: a quantitative evaluation method for the homogeneity of lightweight aggregate concrete based on rapid ultrasonic detection, comprising the following steps: S1. Obtain the shear wave velocity at multiple test points of a series of lightweight aggregate concrete benchmark specimens and longitudinal wave velocity ; S2, according to the shear wave velocity obtained in step S1 and longitudinal wave velocity , calculate the shear modulus of each test point of each benchmark specimen separately and bulk modulus ; S3, according to the shear modulus calculated in step S2 and bulk modulus , calculate the elastic modulus of each test point of each benchmark specimen ; S4, according to the elastic modulus obtained in step S3 , construct the volumetric dosage of lightweight aggregate , shear wave velocity and longitudinal wave velocity The relationship between S5. Obtain the shear wave velocity at each test point of the test piece and longitudinal wave velocity , and calculate the volumetric dosage of lightweight aggregate at each test point of the test piece according to the relationship ; S6. The volumetric dosage of lightweight aggregate at each test point calculated in step S5 is , to evaluate the homogeneity of the test piece.

[0006] The beneficial effects of the present invention are as follows: in this solution, ultrasonic signals at different test points of a specimen are obtained respectively by using ultrasonic waves; and the physical characteristics of the material at different test points are calculated based on the ultrasonic signals obtained at different test points; then a calculation formula is established between the volumetric content of lightweight aggregate and the physical characteristics of lightweight aggregate concrete, and the volumetric content of lightweight aggregate at each test point of the specimen is calculated based on the calculation formula, thereby calculating and evaluating the overall lightweight aggregate distribution in the lightweight aggregate concrete; and realizing non-destructive, rapid, and high-precision homogeneity evaluation of lightweight aggregate concrete.

[0007] Furthermore, in step S1, the step of acquiring ultrasonic signals at multiple test points includes: S101. For each reference specimen, do not use coupling agent to couple with the reference specimen test surface, and measure the shear wave velocity at each test point. :

[0008] in, For the i The shear wave velocity at each test point is For the iThe distance between the transmitting transducer and the receiving transducer at each test point or the actual sound path of the ultrasonic wave, For the i The time difference between the transmitting transducer and the receiving transducer at each test point; S102: For each reference specimen, couple the specimen to the test surface through the coupling agent and measure the longitudinal wave velocity at each test point. :

[0009] in, For the i The shear wave velocity at each test point is For the i The time difference between the transmitting transducer and the receiving transducer at each test point.

[0010] The beneficial effect of the above further solution is: by adjusting the shear wave velocity and longitudinal wave velocity Perform calculations to provide data support and preparation for subsequent analysis.

[0011] Furthermore, the shear wave velocity of each test point is obtained. and longitudinal wave velocity , respectively determine the shear wave velocity of the test point Is it less than the longitudinal wave velocity? If so, the shear wave velocity at the test point is obtained and longitudinal wave velocity Meet the standards, otherwise, re-measure.

[0012] The beneficial effect of the above further solution is: by adjusting the shear wave velocity and longitudinal wave velocity Comparison and verification are carried out to make the shear wave velocity detected and longitudinal wave velocity The numerical value can be more accurate, avoiding errors in the test results due to operations and other reasons during the test process, which will affect the accuracy of subsequent calculation and analysis results.

[0013] Furthermore, the step S2 is specifically as follows: S201, through shear wave velocity Calculate the shear modulus of each test point :

[0014]

[0015] Where, For the i The shear modulus of each test point, For thei The apparent density of lightweight aggregate concrete at each test point is: For the i The shear wave velocity at each test point is For the i The volume content of lightweight aggregate at each test point is is the apparent density of lightweight aggregate concrete mortar phase, is the apparent density of lightweight aggregate; S202, combined longitudinal wave velocity , shear wave velocity and apparent density Calculate the bulk modulus of lightweight aggregate concrete at each test point :

[0016] Where, For the i The bulk modulus of the test points, For the i The shear wave velocity at each test point is For the i The shear wave velocity at each test point.

[0017] The beneficial effect of the above further solution is: according to the detected shear wave velocity and longitudinal wave velocity The shear modulus and bulk modulus Calculation is carried out to facilitate the subsequent adjustment of the volumetric dosage of lightweight aggregate Perform calculations.

[0018] Furthermore, the elastic modulus in step S3 The expression is:

[0019] Where, For the i The elastic modulus of each test point, For the i The bulk modulus of the test points, For the i Shear modulus of each test point.

[0020] Furthermore, the step S4 is specifically as follows: S401, Constructing the volumetric dosage of lightweight aggregate and elastic modulus The relationship:

[0021] Where, For thei The volume content of lightweight aggregate at each test point is For the i The elastic modulus of each test point, a Volume content of lightweight aggregate The quadratic coefficient of is the elastic modulus of the mortar phase, is the elastic modulus of lightweight aggregate, b Volume content of lightweight aggregate The linear coefficient of ; S402, according to the volume of lightweight aggregate and elastic modulus The relationship between the volumetric dosage of lightweight aggregate is constructed by , shear wave velocity and longitudinal wave velocity The relationship:

[0022]

[0023] Where, is the density of lightweight aggregate, is the apparent density of lightweight aggregate concrete mortar phase, is a polynomial related to the speed of sound, For the i The shear wave velocity at each test point is For the i Shear wave velocity at each test point; S403, fitting the quadratic coefficient based on the lightweight aggregate concrete benchmark specimen data a and the linear coefficient b .

[0024] The beneficial effect of the above further solution is: according to the volumetric dosage of lightweight aggregate and elastic modulus The relationship between ultrasonic velocity and lightweight aggregate volume content is The relationship between is constructed as a two-variable linear equation, so that when the volume of lightweight aggregate is added When performing calculations, the volumetric dosage of lightweight aggregate can be quickly determined based on the discriminant of the binary linear equation according to the detected ultrasonic velocity and other information. Is there a unique numerical solution that makes the volumetric dosage of lightweight aggregate The calculation and judgment efficiency can be greatly improved.

[0025] Furthermore, the step S6 is specifically as follows: according to the volumetric dosage of lightweight aggregate at each test point calculated in step S5, , calculate the volumetric dosage of lightweight aggregate The coefficient of variationCV , according to the coefficient of variation CV Evaluation of the homogeneity of lightweight aggregate concrete specimens:

[0026] Where, is the standard deviation of lightweight aggregate volume content, is the average volume content of lightweight aggregate, For the i The volume content of lightweight aggregate at each test point is is the total number of test points.

[0027] The beneficial effect of the above further solution is: by adjusting the volume of lightweight aggregate The coefficient of variation CV The calculation is performed to facilitate the evaluation of the homogeneity of lightweight aggregate concrete specimens in the subsequent steps.

[0028] Furthermore, the coefficient of variation CV Evaluate the homogeneity of lightweight aggregate concrete specimens, specifically: determine the coefficient of variation CV Is the value of less than or equal to the coefficient of variation threshold? If so, the lightweight aggregate is evenly distributed; otherwise, the lightweight aggregate is unevenly distributed.

[0029] The beneficial effect of the above further solution is that when distributing the homogeneity of the entire lightweight aggregate concrete specimen, the coefficient of variation of the lightweight aggregate at each test point in the specimen can be quickly determined. CV Make judgments to ensure the convenience of evaluating the homogeneity of lightweight aggregate concrete. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a flow chart of a quantitative evaluation method for rapid ultrasonic detection of lightweight aggregate concrete homogeneity in an embodiment of the present invention; Figure 2 This is a distribution diagram of ultrasonic detection points in an embodiment of the present invention; Figure 3 Schematic diagram of the ultrasonic detection structure in an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The figure marks in the drawings of the specification include: lightweight aggregate concrete 1, test point 2, sound range 3, shear wave transmitting transducer 4, shear wave receiving transducer 5, shear wave collector 6, longitudinal wave transmitting transducer 7, longitudinal wave receiving transducer 8, and longitudinal wave collector 9.

[0032] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the concepts of the present invention are protected.

[0033] In one embodiment of the present invention, a quantitative evaluation method for the homogeneity of lightweight aggregate concrete based on rapid ultrasonic detection is provided. Figure 1 As shown, the following steps are included: S1. Prepare a series of lightweight aggregate concrete benchmark specimens and test specimens, and obtain the shear wave velocity at multiple test points on each lightweight aggregate concrete benchmark specimen and each test specimen. and longitudinal wave velocity ; In this embodiment, in this step, the lightweight aggregate concrete 1 specimen is a cube, and the size of the cube is selected as length × thickness × height = d 1× d 2× h , d 1≥10cm, 40cm≥ d 2 ≥ 10 cm, h ≥10cm; the test point of the test surface is thickness = d Two parallel surfaces in 2 directions, the measured thickness is ≤40cm, and the age of the concrete is ≥7 days.

[0034] Specifically, in this embodiment, the lightweight aggregate selected is fly ash composite ceramsite (wherein the ceramsite particle size is about 6mm, the cylinder pressure strength is 7MPa, and the ceramsite apparent density is 1409kg / m 3 , saturated mass water absorption rate is about 8.2%), the concrete specimen is a cube specimen of 150mm×150mm×150mm.

[0035] In this example, five test mixes were designed for comparative analysis. Sample number C1 is the baseline, with a ceramsite content of 0%. Sample numbers LC2-LC5 are the test pieces, with sample numbers LC2 and LC3 containing 30% ceramsite, and sample numbers LC4 and LC5 containing 50% ceramsite. The apparent density of the LC2 and LC3 samples is 2213 kg / m³, while that of the LC4 and LC5 samples is 2048 kg / m³. The mix ratios for each lightweight aggregate concrete sample are shown in Table 1. Table 1 Mix ratio of lightweight aggregate concrete 1

[0036] For the specimens, LC2 and LC4 were vibrated for 5 seconds after casting, and LC3 and LC5 were vibrated for 20 seconds. All specimens were placed under standard curing conditions (temperature 20±2°C, relative humidity ≥95%) for 28 days before performance testing.

[0037] In the arrangement of test points 2 of lightweight aggregate concrete 1 specimen, multiple test points 2 are distributed in multiple layers on the lightweight aggregate concrete 1 specimen, wherein the interval between multiple test points 2 in each layer is ≥2cm, the horizontal interval is ≥2cm, and the number of test points in each layer is the same and ≥3; as shown in the attached Figure 2 As shown, in this embodiment, the side surface of the specimen is evenly divided into five measurement areas along the height direction (inter-layer height h1 = 30 mm), and three measuring points are arranged at equal intervals in each layer. The ultrasonic pair measurement method is used to obtain the ultrasonic parameter characteristics at different measuring points, thereby obtaining the aggregate distribution data of each measuring point to evaluate the effect of vibration time on homogeneity.

[0038] In step S1, when ultrasonic testing is performed on the specimen, Figure 3 As shown, the radiation surfaces of the longitudinal wave transmitting transducer 7 and the longitudinal wave receiving transducer 8 use a coupling agent to enable them to be well coupled with the test surface of the specimen, and the radiation surfaces of the shear wave transmitting transducer 4 and the shear wave receiving transducer 5 do not use a coupling agent. The specific content of the coupling agent is the existing technology and will not be described in detail here. When the shear wave collector 6 and the longitudinal wave collector 9 are used to collect the first wave sounds of the ultrasonic shear wave and the longitudinal wave in sequence, the geometric center coincidence error of the transmitting end surface and the receiving end surface of the two transducers is ≤1mm, realizing the spatial homology of the wave type excitation and reception, and ensuring the consistency of the ultrasonic propagation path in the lightweight aggregate concrete 1. Specifically, when acquiring the ultrasonic signal on the lightweight aggregate concrete 1 specimen, a plurality of test points i ( i =1~ n ), and then the shear wave velocity of each test point 2 is and longitudinal wave velocity Take measurements.

[0039] In step S1, when ultrasonic testing is performed on each test point 2, each test point 2 is measured three times continuously, the acoustic time measurement is accurate to 0.lus, the size measurement is accurate to 1mm, the ultrasonic velocity is accurate to 0.01km / s, and the representative value of the ultrasonic velocity is the average acoustic velocity value of the three measured values ​​at the test point.

[0040] The shear wave velocity at each test point 2 in step S1 The calculation formula is , longitudinal wave velocity at each test point 2 The calculation formula is ,in, Indicates the distance between the transmitting transducer and the receiving transducer or the actual sound path of the ultrasonic wave3. Indicates the time difference between the transmitting transducer and the receiving transducer. In this embodiment, the ultrasonic velocity measurement results of each reference specimen and the object to be tested are shown in Table 2: Table 2 Ultrasonic velocity measurement results

[0041] The ultrasonic test results in Table 2 show that lightweight aggregate concrete specimens containing different ceramsite volumetric content exhibit significant differences in acoustic properties. Specifically, the ultrasonic propagation velocities for specimens containing 30% ceramsite ranged from 2.66 to 2.77 km / s for shear waves and 4.54 to 4.79 km / s for longitudinal waves. For specimens containing 60% ceramsite, the corresponding parameters were 2.41 to 2.58 km / s for shear waves and 4.28 to 4.48 km / s for longitudinal waves. This difference in acoustic velocity is primarily due to changes in the material's internal structure caused by the varying ceramsite content. A gradient of ultrasonic velocity was observed in different locations within the same specimen, with the bottom layer generally having higher velocities than the upper layer. This phenomenon may be related to aggregate settlement and uneven porosity distribution during the forming process. Ultrasonic waves are highly sensitive to changes in the internal microstructure of a material and can effectively monitor the distribution of lightweight aggregate within the concrete matrix.

[0042] Step S1 also includes S11, the shear wave velocity and longitudinal wave velocity To verify, when the shear wave velocity and longitudinal wave velocity When the verification result does not verify the comparison conditions, specifically in the shear wave velocity and longitudinal wave velocity When verifying, compare the shear wave velocity Is it less than the longitudinal wave velocity? ,like Less than The accuracy of the measurement is verified and the shear wave velocity is and longitudinal wave velocity Remeasure.

[0043] S2, according to the shear wave velocity obtained in step S1 and longitudinal wave velocity , calculate the shear modulus of each test point of the benchmark specimen and bulk modulus Specific examples include: S201 According to the wave theory in solid elastic media, the shear wave velocity Determine the shear modulus of each test point 2 ; Shear modulus of each test point 2 of the benchmark specimen The calculation formula is:

[0044] Where, For the i The shear modulus of each test point, For the i The apparent density of lightweight aggregate concrete at each test point is: For the i The shear wave velocity at each test point.

[0045] S202, combined longitudinal wave velocity , shear wave velocity and apparent density Calculate the bulk modulus of each test point 2 The bulk modulus of each test point 2 is The calculation formula is:

[0046] Where, For the i The apparent density of lightweight aggregate concrete 1 at each test point is: For the i The bulk modulus of the test points, For the i The shear wave velocity at each test point is For the i The shear wave velocity at each test point.

[0047] S3, according to the shear modulus calculated in step S2 and bulk modulus , calculate the elastic modulus of each test point of the benchmark specimen Specifically, in step S3, the bulk modulus of each test point 2 of the reference specimen calculated in step S2 can be and shear modulus , through the generalized Hooke's law" E - K - G” Expression for the elastic modulus of lightweight aggregate concrete 1 Determine the elastic modulus of lightweight aggregate concrete 1 at test point 2 The calculation formula is:

[0048] Where, For the i The elastic modulus of each test point, For the i The bulk modulus of the test points, For the i Shear modulus of each test point.

[0049] S4, according to the elastic modulus obtained in step S3 , construct the volumetric dosage of lightweight aggregate , shear wave velocity and longitudinal wave velocity The relationship between the two is: Constructing lightweight aggregate volumetric dosage and elastic modulus The relationship:

[0050] Where, For the i The volume content of lightweight aggregate at each test point is For the i The elastic modulus of each test point, is the elastic modulus of the mortar phase, is the elastic modulus of lightweight aggregate, is the density of lightweight aggregate, a Volume content of lightweight aggregate The quadratic coefficient of b Volume content of lightweight aggregate The linear coefficient of .

[0051] When constructing the calculation formula between ultrasonic velocity and lightweight aggregate volumetric dosage, the lightweight aggregate volumetric dosage can be calculated based on the wave theory. and elastic modulus Specifically, the bulk modulus in step S2 is and shear modulus The calculation formula of the elastic modulus in step S3 Substitute the calculation formula into the volumetric dosage of lightweight aggregate and elastic modulus The relationship can be obtained:

[0052] The apparent density It is related to the volume content of lightweight aggregate, among which the apparent density The calculation formula is:

[0053] Where, is the volumetric content of lightweight aggregate at test point 2 of lightweight aggregate concrete 1, is the apparent density of the mortar phase of lightweight aggregate concrete 1, is the apparent density of lightweight aggregate.

[0054] Therefore, the apparent density Substitute the calculation formula into the volumetric dosage of lightweight aggregate and elastic modulus The relationship can be obtained by simplifying it:

[0055] Where, is the density of lightweight aggregate, is the apparent density of lightweight aggregate concrete mortar phase, For the i The shear wave velocity at each test point is For the i Shear wave velocity at each test point; represents a polynomial related to the speed of sound, .

[0056] The quadratic coefficient is obtained by fitting the data of lightweight aggregate concrete benchmark specimens a and the linear coefficient b , preferably in this embodiment, by fitting a The value is 0.272, b The value is 0.042, a and b The specific fitting process is prior art and will not be described in detail here.

[0057] S5. Obtain the shear wave velocity at each test point of the test piece and longitudinal wave velocity , and calculate the shear wave velocity according to the relationship and longitudinal wave velocity Volumetric dosage of lightweight aggregate ; In the volumetric dosage of lightweight aggregate When performing the calculation, specifically: Solve the simplified lightweight aggregate volume dosage in step S4 and elastic modulus Volumetric dosage of lightweight aggregate in the relationship And the quadratic coefficient obtained after fitting a and the linear coefficient b , according to the solution formula of the quadratic equation, the volumetric dosage of lightweight aggregate can be obtained The solution formula in the relationship is:

[0058] in The discriminant for solving a quadratic equation, specifically The calculation formula is:

[0059] According to the definition of solving the quadratic equation, we can know that when the volume of lightweight aggregate is When solving, you can The value of When it is equal to 0, the dosage There is only one solution; when When it is greater than 0, there are two solutions. Remove the results with values ​​less than 0 and greater than 1, and the result is the only solution.

[0060] In the above formula, the elastic modulus of the mortar phase is The measurement was obtained using a mortar test block with a consistent mix ratio with the mortar in lightweight aggregate concrete 1. The specific content of the mortar test block measurement is prior art and will not be repeated here.

[0061] When calculating the above calculation formula, the various data tested in step S1 can be entered into the relevant program through a computer program to calculate and obtain the volumetric dosage of lightweight aggregate at each test point 2. , wherein the specific content of calculating the numerical value by computer program is the existing technology and will not be described in detail here.

[0062] S6. The volumetric dosage of lightweight aggregate at each test point calculated in step S5 is , evaluate the homogeneity of the test piece. Specifically, the volumetric dosage of lightweight aggregate at each test point 2 calculated for each test piece is The coefficient of variation CV Calculate the coefficient of variation CV The calculation formula is:

[0063] Where, is the standard deviation of lightweight aggregate volume content, where The calculation formula is:

[0064] is the average volume content of lightweight aggregate, The calculation formula is:

[0065] Where n is the total number of test points, For the i Volumetric dosage of lightweight aggregate at each test point When evaluating the homogeneity of lightweight aggregate concrete test pieces, determine the coefficient of variation of each test piece. CV Is the value of less than or equal to the coefficient of variation threshold? CVWhen the value of is less than or equal to the coefficient of variation threshold, the lightweight aggregate is evenly distributed. CV When the coefficient of variation is greater than the threshold value, the lightweight aggregate is unevenly distributed. Preferably, in this embodiment, the coefficient of variation threshold is 10%, that is, when evaluating the homogeneity of the lightweight aggregate concrete specimen 1, when Coefficient of variation CV When ≤10%, the lightweight aggregate is evenly distributed. CV When it is greater than 10%, the lightweight aggregate is unevenly distributed.

[0066] Specifically in this embodiment, the calculation results of the dosage of each lightweight aggregate concrete 1 to be tested and the homogeneity evaluation content are shown in Table 3: Table 3 Calculation and evaluation results of the dosage of each test piece

[0067] Table 3 shows that the vertical distribution of the ceramsite volume content in specimens LC3 and LC5 exhibits significant non-uniformity, with large coefficients of variation. This phenomenon can be attributed to the upward migration of lightweight aggregate due to its low density during the long-term vibration of fresh concrete, resulting in a gradient distribution of ceramsite within the specimens, which intensifies the material's non-uniformity. This result further validates the sensitivity of ultrasonic testing technology to changes in the internal structure of lightweight aggregate concrete 1. It also demonstrates that the vibration process has a significant impact on the uniformity of lightweight aggregate distribution. In practical projects, it is necessary to optimize the construction process to improve the stability of material properties.

[0068] Compared with the existing technology, this solution adopts the ultrasonic pair measurement method to obtain ultrasonic signals at different measuring points of the specimen; calculates the physical characteristics of the materials at different test points based on the wave theory in solid elastic media; and then establishes a calculation formula between the volume content of lightweight aggregate and the physical characteristics of lightweight aggregate concrete; can obtain multi-dimensional data such as ultrasonic velocity, bulk modulus, shear modulus and lightweight aggregate content in the local range of different test points of the component, which can realize the homogeneity evaluation of the entire cross-section of the lightweight aggregate concrete component and realize non-destructive, rapid and high-precision homogeneity evaluation of lightweight aggregate concrete.

[0069] In this solution, ultrasonic technology allows testing to be completed simply by placing measurement points on the specimen surface, fully maintaining component integrity and ensuring high repeatability. During the testing process, a portable ultrasonic detector is all that is needed for rapid on-site testing. This lightweight, easy-to-use device significantly reduces testing costs and eliminates the need for a dedicated testing environment. Testing can be completed by placing measurement points on the component surface, avoiding the tedious process of sample transportation and preparation and improving the adaptability of the testing method to different testing environments.

[0070] This solution also constructs a precise calculation model for lightweight aggregate volumetric content and ultrasonic parameters through multi-parameter fusion, significantly improving test accuracy compared to traditional non-destructive testing methods. This model enables direct quantitative conversion of ultrasonic parameters to lightweight aggregate volumetric content, accurately characterizing lightweight aggregate content, a key performance indicator. This effectively overcomes the limitations of existing indirect evaluation methods and provides a more accurate technical solution for testing the homogeneity of lightweight aggregate concrete.

Claims

1. A quantitative evaluation method for the homogeneity of lightweight aggregate concrete based on rapid ultrasonic detection, characterized in that: The following steps are involved: S1. Obtain the shear wave velocity at multiple test points of a series of lightweight aggregate concrete benchmark specimens and longitudinal wave velocity ; S2, according to the shear wave velocity obtained in step S1 and longitudinal wave velocity , calculate the shear modulus of each test point of each benchmark specimen separately and bulk modulus ; S3, according to the shear modulus calculated in step S2 and bulk modulus , calculate the elastic modulus of each test point of each benchmark specimen ; S4, according to the elastic modulus obtained in step S3 , construct the volumetric dosage of lightweight aggregate , shear wave velocity and longitudinal wave velocity The relationship between S5. Obtain the shear wave velocity at each test point of the test piece and longitudinal wave velocity , and calculate the volumetric dosage of lightweight aggregate at each test point of the test piece according to the relationship ; S6. The volumetric dosage of lightweight aggregate at each test point calculated in step S5 is , to evaluate the homogeneity of the test piece.

2. The quantitative evaluation method for homogeneity of lightweight aggregate concrete based on rapid ultrasonic detection according to claim 1 is characterized in that: The step S1 is specifically as follows: S101. For each reference specimen, do not use coupling agent to couple with the reference specimen test surface, and measure the shear wave velocity at each test point. : in, For the i The shear wave velocity at each test point is For the i The distance between the transmitting transducer and the receiving transducer at each test point or the actual sound path of the ultrasonic wave, For the i The time difference between the transmitting transducer and the receiving transducer at each test point; S102: For each reference specimen, couple the specimen to the test surface through the coupling agent and measure the longitudinal wave velocity at each test point. : in, For the i The shear wave velocity at each test point is For the i The time difference between the transmitting transducer and the receiving transducer at each test point.

3. The quantitative evaluation method for homogeneity of lightweight aggregate concrete based on rapid ultrasonic detection according to claim 2, characterized in that: The shear wave velocity of each test point is obtained and longitudinal wave velocity , respectively determine the shear wave velocity of the test point Is it less than the longitudinal wave velocity? If so, the shear wave velocity at the test point is obtained and longitudinal wave velocity Meet the standards, otherwise, re-measure.

4. The quantitative evaluation method for homogeneity of lightweight aggregate concrete based on rapid ultrasonic detection according to claim 1, characterized in that: The step S2 is specifically as follows: S201, through shear wave velocity Calculate the shear modulus of each test point : Where, For the i The shear modulus of each test point, For the i The apparent density of lightweight aggregate concrete at each test point is: For the i The shear wave velocity at each test point is For the i The volume content of lightweight aggregate at each test point is is the apparent density of lightweight aggregate concrete mortar phase, is the apparent density of lightweight aggregate; S202, combined longitudinal wave velocity , shear wave velocity and apparent density Calculate the bulk modulus of each test point : ； Where, For the i The bulk modulus of the test points, For the i The shear wave velocity at each test point is For the i The shear wave velocity at each test point.

5. The quantitative evaluation method for homogeneity of lightweight aggregate concrete based on rapid ultrasonic detection according to claim 1, characterized in that: The elastic modulus in step S3 The expression is: Where, For the i The elastic modulus of each test point, For the i The bulk modulus of the test points, For the i Shear modulus of each test point.

6. The quantitative evaluation method for homogeneity of lightweight aggregate concrete based on rapid ultrasonic detection according to claim 1, characterized in that: The step S4 is specifically as follows: S401, Constructing the volumetric dosage of lightweight aggregate and elastic modulus The relationship: Where, For the i The volume content of lightweight aggregate at each test point is For the i The elastic modulus of each test point, a Volume content of lightweight aggregate The quadratic coefficient of is the elastic modulus of the mortar phase, is the elastic modulus of lightweight aggregate, b Volume content of lightweight aggregate The linear coefficient of ; S402, according to the volume of lightweight aggregate and elastic modulus The relationship between the volumetric dosage of lightweight aggregate is constructed by , shear wave velocity and longitudinal wave velocity The relationship: Where, is the density of lightweight aggregate, is the apparent density of lightweight aggregate concrete mortar phase, is a polynomial related to the speed of sound, For the i The shear wave velocity at each test point is For the i Shear wave velocity at each test point; S403, fitting the quadratic coefficient based on the lightweight aggregate concrete benchmark specimen data a and the linear coefficient b .

7. The quantitative evaluation method for homogeneity of lightweight aggregate concrete based on rapid ultrasonic detection according to claim 1, characterized in that: The step S6 specifically comprises: according to the volumetric dosage of lightweight aggregate at each test point calculated in step S5, , calculate the volumetric dosage of lightweight aggregate The coefficient of variation CV , according to the coefficient of variation CV Evaluation of the homogeneity of lightweight aggregate concrete specimens: Where, is the standard deviation of lightweight aggregate volume content, is the average volume content of lightweight aggregate, For the i The volume content of lightweight aggregate at each test point is is the total number of test points.

8. The quantitative evaluation method for homogeneity of lightweight aggregate concrete based on rapid ultrasonic detection according to claim 7, characterized in that: The coefficient of variation CV Evaluate the homogeneity of lightweight aggregate concrete specimens, specifically: determine the coefficient of variation CV Is the value of less than or equal to the coefficient of variation threshold? If so, the lightweight aggregate is evenly distributed; otherwise, the lightweight aggregate is unevenly distributed.

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