A quantitative evaluation method for mixing uniformity of fiber concrete
By calculating the mass error rate of fibers and slurries in fiber concrete and using the principle of probability statistics to quantify the fiber distribution, the problem of lack of scientific quantitative evaluation methods in the existing technology is solved, and the quantitative evaluation and intuitive results of the mixing uniformity of fiber concrete are achieved, and subjective and accidental errors are reduced.
Patent Information
- Application Number
- CN202210488002.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-05-06
- Publication Date
- 2025-03-28
- Estimated Expiration
- 2042-05-06
AI Technical Summary
The existing technology lacks scientific, quantitative and intuitive methods to evaluate the mixing uniformity of fiber concrete, resulting in large fluctuations in performance and dependent on the experience of professionals, and is susceptible to external factors.
By calculating the mass error rate of fibers and slurries in fiber concrete, the fiber distribution status is quantified using the principle of probability statistics to determine the stirring uniformity. Specific steps include calculating theoretical quality, obtaining and processing sample data, calculating error rate and making judgments.
The quantitative evaluation of the mixing uniformity of fiber concrete is achieved. The results are intuitive and visible, with a wide range of applications, avoiding subjectivity and accidental errors, and are simple to operate and do not require special professional requirements.
Smart Images
Figure CN114923805B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of composite material preparation, and in particular relates to a quantitative evaluation method for mixing uniformity of fiber concrete. Background Art
[0002] In actual engineering applications, the uniformity of concrete mixing has a great impact on its various performances. However, the state and performance of fresh concrete are mostly determined based on experience and mixing time, lacking scientific, quantitative, and intuitive technical characterization. This results in large fluctuations in the performance of fresh concrete, strong dependence on the professional quality of operators, and obvious influence of human subjective consciousness.
[0003] With the development of concrete, its types and components have been continuously enriched, especially the introduction of more difficult to disperse components such as fibers into the matrix, which makes concrete mixing more difficult. At present, there is no clear method for quantitative evaluation of fiber concrete mixing uniformity, and there is a lack of mature and efficient testing system.
[0004] By using the distribution state of the most difficult-to-disperse fibers in the matrix, the uniformity of fiber concrete mixing can be quantitatively characterized, breaking away from the current situation where the uniformity of fresh fiber concrete mixing is mostly based on observation and evaluation or the experience of professionals. Moreover, observation and evaluation or the experience of professionals are easily affected by external factors, have a great deal of randomness, and are not standardized, referenceable, and generally applicable. Summary of the invention
[0005] In view of the problems existing in the prior art, the present invention provides a quantitative evaluation method for the mixing uniformity of fiber concrete. The method of the present invention is economical and environmentally friendly, easy to operate, and provides accurate data. It realizes the quantitative evaluation of the mixing uniformity of concrete, the evaluation results are intuitively visible, and has a wide range of applications.
[0006] To achieve the above object, the present invention adopts the following technical solutions:
[0007] The present invention provides a quantitative evaluation method for mixing uniformity of fiber concrete, comprising the following steps:
[0008] Step 1: Calculate the theoretical mass m1 of fiber in each liter of freshly mixed fiber concrete and the theoretical mass m2 of slurry in each liter of freshly mixed fiber concrete according to the mix ratio of fiber concrete;
[0009] Step 2: Get fresh fiber concrete samples and pour them into glass test molds. The pouring amount of fiber concrete in each glass test mold is 1 liter. The total mass of the sample weighed with the mold is m 总 ;
[0010] Step 3: Pour out the fiber concrete in the glass test mold and wash it with water, pick out all the fibers and dry them, and then weigh the mass of the dried fibers m纤 And the test mold quality m 模 ;
[0011] Step 4: Calculate the fiber mass error rate ω and the paste mass error rate σ per liter of freshly mixed fiber concrete.
[0012] Step 5: Determine the uniformity of mixing of the freshly mixed fiber concrete by the measured fiber mass error rate ω and slurry mass error rate σ.
[0013] Furthermore, in the step 2, the freshly mixed fiber concrete needs to be directly obtained at the discharge port and cast into shape, with three samples being cast in each group.
[0014] Furthermore, in the step 2, a low-frequency vibration table is used, and the vibration is stopped immediately when there are no obvious bubbles on the wall of the glass test mold, and the vibration shall not exceed 20 seconds.
[0015] Furthermore, in the step 2, before weighing with a mold, the surface of the sample should be scraped flat, and the outer surface of the glass test mold should be kept clean and dry.
[0016] Furthermore, in the step three, the surface of the washed and sorted fibers is clean and free of foreign matter, and is dried at a temperature of 80±5° C. to a constant weight, and the drying time shall not be less than 40 minutes.
[0017] Furthermore, in the step five, the fiber quality error rates ω corresponding to the three samples are recorded as ω1, ω2, and ω3 and sorted. If the absolute values of the differences between the maximum value, the minimum value and the middle value are all less than or equal to 40% of the middle value, and the difference between the maximum value and the minimum value is less than or equal to 50% of the middle value, then ω1, ω2, and ω3 are recorded as valid values; otherwise, the mixing uniformity of this batch of fiber concrete is directly judged to be unqualified.
[0018] Furthermore, when ω1, ω2, and ω3 are valid values, if the absolute values of the differences between the maximum value, the minimum value, and the intermediate value are all less than or equal to 15% of the intermediate value, the arithmetic mean of ω1, ω2, and ω3 is taken as the representative value of the fiber mass error rate per liter of fresh fiber concrete. If the absolute value of the difference between the maximum value and the minimum value and the middle value is greater than 15% of the middle value, the middle value of ω1, ω2, and ω3 is taken as the representative value of the fiber mass error rate per liter of fresh fiber concrete. If the absolute values of the differences between the maximum value and the minimum value and the middle value both exceed 15% of the middle value, it is directly determined that the mixing uniformity of the batch of fiber concrete is unqualified.
[0019] Furthermore, in the step five, the slurry quality error rates σ corresponding to the three samples are recorded as σ1, σ2, and σ3. If the absolute values of the differences between the maximum value, the minimum value and the middle value are all less than or equal to 40% of the middle value, and the difference between the maximum value and the minimum value is less than or equal to 50% of the middle value, then σ1, σ2, and σ3 are recorded as valid values; otherwise, the mixing uniformity of this batch of fiber concrete is directly judged to be unqualified.
[0020] Furthermore, when σ1, σ2, and σ3 are valid values, if the absolute values of the differences between the maximum value, the minimum value, and the middle value are all less than or equal to 15% of the middle value, the arithmetic mean of σ1, σ2, and σ3 is taken as the representative value of the paste mass error rate per liter of fresh fiber concrete. If the absolute value of the difference between the maximum value and the minimum value and the middle value is greater than 15% of the middle value, the middle value of σ1, σ2, and σ3 is taken as the representative value of the error rate of the paste mass per liter of fresh fiber concrete. If the absolute values of the differences between the maximum value and the minimum value and the middle value both exceed 15% of the middle value, it is directly determined that the mixing uniformity of the batch of fiber concrete is unqualified.
[0021] Furthermore, according to the formula When η>15%, the mixing uniformity of the batch of fiber concrete is directly judged to be unqualified; when η≤15%, if or The mixing uniformity of this batch of fiber concrete is judged to be unqualified; if or The mixing uniformity of this batch of fiber concrete is judged to be qualified; if or It is judged that the mixing uniformity of this batch of fiber concrete is average. It is judged that the mixing uniformity of this batch of fiber concrete is good.
[0022] Compared with the prior art, the present invention has the following technical effects:
[0023] (1) The present invention adopts the principle of probability statistics and takes the distribution of the most difficult-to-disperse fibers in concrete as a quantitative index. By comparing the mass error rate of the fibers in the concrete and the mass error rate of the slurry, the dispersion degree of the fibers in the freshly mixed concrete is quantified and the uniformity of the mixing is determined.
[0024] (2) The present invention is applicable to all kinds of fibers, with reasonable sampling, simple operation, accurate measurement and strong practicality. It avoids the subjectivity and experience of on-site sensory judgment and reduces accidental errors. Moreover, the method has no special professional requirements for operators, and the evaluation and characterization of the mixing uniformity of fiber concrete is more scientific and intuitive. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0026] Figure 1 The present invention is a flow chart of a quantitative evaluation method for mixing uniformity of fiber concrete.
[0027] Figure 2 It is a structural schematic diagram of the glass test mold of the present invention. DETAILED DESCRIPTION
[0028] In the description of the present invention, it is necessary to understand that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.
[0029] This embodiment provides a quantitative evaluation method for mixing uniformity of fiber concrete, comprising the following steps:
[0030] Step 1: According to the fiber concrete mix ratio, calculate the theoretical mass m1 of fiber per liter of freshly mixed fiber concrete (accurate to 0.1 g) and the theoretical mass m2 of slurry per liter of freshly mixed fiber concrete (excluding fiber, accurate to 0.1 g).
[0031] Step 2: Get a freshly mixed fiber concrete sample and pour it into a glass test mold with a capacity of 1 liter. Vibrate until there are no obvious bubbles on the mold wall and stop immediately. Scrape off the excess concrete on the surface and clean the outer surface of the glass test mold. Weigh the total mass of the sample with the mold. 总 .
[0032] Fresh fiber concrete samples should be directly obtained and cast at the discharge port to avoid secondary stirring of the samples due to sampling. Three samples should be cast in one group. A low-frequency vibration table should be used. When there are no obvious bubbles on the test mold wall, stop immediately and the vibration time should not exceed 20s.
[0033] Step 3: Pour out the fiber concrete, wash it with water, pick out all the fibers and dry them, and then weigh the clean and dried fiber mass m 纤 And the test mold quality m 模The surface of the washed and sorted fibers should be clean and free of foreign matter, and dried at 80±5℃ to constant weight. The drying time should not be less than 40 minutes.
[0034] Step 4: Calculate the fiber mass error rate ω and the paste mass error rate σ per liter of freshly mixed fiber concrete (both retain 1 decimal place):
[0035]
[0036] Among them, m 纤 —The mass of clean and dry fiber in each sample (accurate to 0.1g);
[0037] m1—theoretical mass of fiber per liter of freshly mixed fiber concrete (accurate to 0.1g).
[0038]
[0039] Among them, m 总 —Total mass of each test mold and test specimen (accurate to 0.1g);
[0040] m 模 —The mass of each test mold (accurate to 0.1g);
[0041] m 纤 —The mass of clean and dry fiber in each sample (accurate to 0.1g);
[0042] m2—theoretical mass of freshly mixed fiber concrete paste per liter (accurate to 0.1g).
[0043] Step 5: Determine the uniformity of mixing of the freshly mixed fiber concrete by the measured fiber mass error rate ω and slurry mass error rate σ.
[0044] Using formula When the error rates ω1, ω2, and ω3 of the calculated fiber mass per liter of fresh fiber concrete have a difference of neither the maximum nor the minimum value from the middle value exceeding 40% (R1≤40%) of the middle value, and the difference between the maximum and minimum values does not exceed 50% (R1'≤50%) of the middle value, the error rates (ω1, ω2, ω3) are a set of valid values. Otherwise, the mixing uniformity of this batch of fiber concrete is directly judged to be unqualified.
[0045] Using formula When the calculated error rates σ1, σ2, and σ3 of the paste mass per liter of freshly mixed fiber concrete have a maximum or minimum value whose difference from the middle value does not exceed 40% (R2≤40%), and the difference between the maximum and minimum values does not exceed 50% (R'2≤50%) of the middle value, the error rates (σ1, σ2, σ3) are a set of valid values. Otherwise, the mixing uniformity of this batch of fiber concrete is directly judged to be unqualified.
[0046] When the fiber mass error rates ω1, ω2, and ω3 are valid, and none of the maximum or minimum values differs from the middle value by more than 15% of the middle value, the arithmetic mean of the three values is taken as the representative value of the fiber mass error rate per liter of fresh fiber concrete. If the difference between the maximum value or the minimum value and the middle value exceeds 15% of the middle value, the middle value is taken as the representative value of the fiber quality error rate per liter of freshly mixed fiber concrete; if the difference between the maximum value and the minimum value and the middle value both exceeds 15% of the middle value, it is directly judged that the mixing uniformity of this batch of fiber concrete is unqualified.
[0047] When the paste mass error rates σ1, σ2, and σ3 are valid, and none of the maximum or minimum values differs from the middle value by more than 15% of the middle value, the arithmetic mean of the three measured values is taken as the representative value of the paste mass error rate per liter of fresh fiber concrete. If the difference between the maximum value or the minimum value and the middle value exceeds 15% of the middle value, the middle value is taken as the representative value of the paste quality error rate per liter of fresh fiber concrete; if the difference between the maximum value and the minimum value and the middle value both exceeds 15% of the middle value, the mixing uniformity of this batch of fiber concrete is directly judged to be unqualified.
[0048] According to the formula When η>15%, the mixing uniformity of the batch of fiber concrete is directly judged to be unqualified; when η≤15%, refer to the table below to judge the mixing uniformity of the fresh fiber concrete.
[0049]
[0050] In order to enable technical personnel to better understand this evaluation method, this embodiment also provides an application scenario of a quantitative evaluation method for mixing uniformity of fiber concrete. Taking the evaluation of mixing uniformity of ultra-high performance concrete (UHPC) as an example, the steps are as follows:
[0051] Step 1: According to the fiber concrete mix ratio (see the table below), calculate the theoretical mass of fiber per liter of freshly mixed fiber concrete m1 = 100.0 g and the theoretical mass of slurry per liter of freshly mixed fiber concrete m2 = 2370.0 g.
[0052]
[0053] Step 2: Get about 5L of freshly mixed UHPC sample directly from the mixer outlet and pour it into three glass test molds respectively. Put it into a low-frequency vibration table and vibrate it until there are no obvious bubbles on the test mold wall. Stop immediately, and the vibration should not exceed 20s. After scraping off the excess concrete on the surface and cleaning the outer surface of the glass test mold, weigh the total mass of the sample with the mold m 总1 、m 总2 、m 总3 They are 3701.3g, 3901.8g, and 3827.1g respectively;
[0054] Step 3: Pour out the fiber concrete in the test mold, wash it with water, pick out all the fibers, and dry it in a constant temperature box at 80±5℃ to constant weight, and obtain the fiber mass m after drying. 纤1 、m 纤2 、m 纤3 They are 89.3g, 119.5g, and 104.7g respectively; after cleaning and drying the test mold, its mass m is obtained. 模1 、m 模2 、m 模3 They are 1458.9g, 1460.7g, and 1461.2g respectively;
[0055] Step 4: According to the formula The fiber quality error rates ω1, ω2, and ω3 per liter of freshly mixed fiber concrete are calculated to be 89.3%, 119.5%, and 104.7%, respectively. None of the maximum or minimum values differ from the middle value by more than 40% (R1≤40%), and the difference between the maximum and minimum values does not exceed 50% (R1'≤50%) of the middle value. The fiber quality error rates ω1, ω2, and ω3 are a set of valid values. It is further determined that none of the maximum or minimum values differ from the middle value by more than 15% of the middle value. The arithmetic mean of the three measured values is taken as the representative value of the actual proportion of fiber in each liter of freshly mixed fiber concrete, that is,
[0056] According to the formula The calculated error rates σ1, σ2, and σ3 of the paste mass per liter of fresh fiber concrete are 90.8 g, 98.0 g, and 95.4 g, respectively. None of the maximum or minimum values differ from the middle value by more than 40% (R2≤40%), and the difference between the maximum and minimum values does not exceed 50% (R'2≤50%) of the middle value. The paste error rates σ1, σ2, and σ3 are a set of valid values. It is further determined that none of the maximum or minimum values differ from the middle value by more than 15% of the middle value. The arithmetic mean of the three measured values is taken as the representative value of the actual proportion of fiber in each liter of fresh fiber concrete, that is,
[0057] Step 5: According to the formula Determine η≤15% (η=9.8%) and refer to the table below to determine whether the mixing uniformity of the freshly mixed fiber concrete is good.
[0058]
[0059] Although the above embodiments have been described in detail for the present invention, it should be understood by those skilled in the art that modifications or improvements may be made based on the contents disclosed in the present invention without departing from the spirit and scope of the present invention, and such modifications and improvements are within the spirit and scope of the present invention.
Claims
1. A quantitative evaluation method for mixing uniformity of fiber concrete, characterized in that: The following steps are involved: Step 1: Calculate the theoretical mass m1 of fiber in each liter of freshly mixed fiber concrete and the theoretical mass m2 of slurry in each liter of freshly mixed fiber concrete according to the mix ratio of fiber concrete; Step 2: Get fresh fiber concrete samples and pour them into glass test molds. The pouring amount of fiber concrete in each glass test mold is 1 liter. The total mass of the sample weighed with the mold is m 总 ,The freshly mixed fiber concrete needs to be directly obtained and cast at the discharge port, and three specimens are cast in each group; Step 3: Pour out the fiber concrete in the glass test mold and wash it with water, pick out all the fibers and dry them, and then weigh the mass of the dried fibers m 纤 And the test mold quality m 模 ; Step 4: Calculate the fiber mass error rate ω and the paste mass error rate σ per liter of freshly mixed fiber concrete. Step 5. Determine the uniformity of mixing of freshly mixed fiber concrete by the measured fiber mass error rate ω and paste mass error rate σ. The fiber mass error rates ω corresponding to the three samples are recorded as ω1, ω2, and ω3 and sorted. If the absolute values of the differences between the maximum value, the minimum value, and the middle value are all less than or equal to 40% of the middle value, and the difference between the maximum value and the minimum value is less than or equal to 50% of the middle value, then ω1, ω2, and ω3 are recorded as valid values; otherwise, the mixing uniformity of this batch of fiber concrete is directly determined to be unqualified; when ω1, ω2, and ω3 are valid values, if the absolute values of the differences between the maximum value, the minimum value, and the middle value are all less than or equal to 15% of the middle value, take the arithmetic mean of ω1, ω2, and ω3 as the representative value of the fiber mass error rate per liter of freshly mixed fiber concrete. If the absolute value of the difference between the maximum value and the minimum value and the middle value is greater than 15% of the middle value, the middle value of ω1, ω2, and ω3 is taken as the representative value of the fiber mass error rate per liter of fresh fiber concrete. If the absolute value of the difference between the maximum value and the minimum value and the middle value exceeds 15% of the middle value, it is directly judged that the mixing uniformity of the batch of fiber concrete is unqualified; The paste quality error rates σ corresponding to the three samples are recorded as σ1, σ2, and σ3. If the absolute values of the differences between the maximum value, the minimum value and the middle value are all less than or equal to 40% of the middle value, and the difference between the maximum value and the minimum value is less than or equal to 50% of the middle value, then σ1, σ2, and σ3 are recorded as valid values; otherwise, the mixing uniformity of this batch of fiber concrete is directly judged to be unqualified; when σ1, σ2, and σ3 are valid values, if the absolute values of the differences between the maximum value, the minimum value and the middle value are all less than or equal to 15% of the middle value, the arithmetic mean of σ1, σ2, and σ3 is taken as the representative value of the paste quality error rate in each liter of freshly mixed fiber concrete. If the absolute value of the difference between the maximum value and the minimum value and the middle value is greater than 15% of the middle value, the middle value of σ1, σ2, and σ3 is taken as the representative value of the error rate of the paste mass per liter of fresh fiber concrete. If the absolute value of the difference between the maximum value and the minimum value and the middle value exceeds 15% of the middle value, the batch of fiber concrete mixing uniformity is directly judged to be unqualified. According to the formula When η>15%, the mixing uniformity of the batch of fiber concrete is directly judged to be unqualified; when η≤15%, if or The mixing uniformity of this batch of fiber concrete is judged to be unqualified; if or The mixing uniformity of this batch of fiber concrete is judged to be qualified; if or It is judged that the mixing uniformity of this batch of fiber concrete is average. It is judged that the mixing uniformity of this batch of fiber concrete is good.
2. A quantitative evaluation method for mixing uniformity of fiber concrete according to claim 1, characterized in that: In the step 2, a low-frequency vibration table is used, and the vibration is stopped immediately until there are no obvious bubbles on the wall of the glass test mold, and the vibration shall not exceed 20 seconds.
3. A quantitative evaluation method for mixing uniformity of fiber concrete according to claim 1, characterized in that: In the step 2, before weighing with a mold, the surface of the sample should be scraped flat and the outer surface of the glass test mold should be kept clean and dry.
4. A quantitative evaluation method for mixing uniformity of fiber concrete according to claim 1, characterized in that: In the step 3, the surface of the washed and sorted fibers is clean and free of foreign matter, and the fibers are dried at a temperature of 80±5° C. to a constant weight, and the drying time shall not be less than 40 minutes.