Method for identifying cementing material by measuring DPI index of pressed sample

Abstract

The prior art still depends on special properties such as electrical resistivity or Blaine specific surface area, and special equipment such as a constant-temperature water bath, a temperature sensor and a data recorder is needed. In addition, a small enterprise is difficult to obtain a dust-free laboratory space and is difficult to bear the cost of professional experiment technicians. Besides, the test method consumes long time (1-91 days), and the long test period can generate adverse effects on the production process, which may cause production bottleneck, inventory cost increase and potential quality problems. Another problem is that the existing method only evaluates a very small amount of cementing materials and is difficult to reflect the real characteristics of a large batch of materials which are actually used in the industry. The invention provides a quality evaluation method, which can simply, quickly and accurately judge the similarity between different cementing materials. The method is based on the construction of a calibration curve which is used for representing the relationship between the particle density index (DPI) and the relative specific gravity of a series of given cementing materials.

Description

Technical Field

[0001] This invention relates to a method for identifying cementitious materials through compression molding. When such materials are used to assemble a product, this identification approach is an effective method for rapidly predicting material performance. Background Technology

[0002] Identifying the similarities between different types of cementitious materials or different batches of the same material is crucial, primarily because it relates to their applications in the construction and environmental sectors. Understanding the chemical and physical properties of cementitious materials helps in better material selection, improving their performance in concrete and mortar, and predicting their potential applications in other fields, such as wastewater treatment or soil remediation. Similar materials are expected to have similar performance in a given application, allowing for more accurate predictions of the material's strength, durability, and other properties. Essentially, identifying the similarities between cementitious materials helps in the more scientific and efficient use of these resources in the construction industry and environmental applications. Summary of the Invention

[0003] The purpose of this invention is to provide an economical and efficient method for evaluating cementitious materials, which can simply, economically and accurately predict the performance of unknown cementitious materials and identify the similarities between different cementitious materials.

[0004] The inventors conducted various experiments over decades and were surprised to discover a clear linear relationship between the DPI value introduced by this invention and the relative specific gravity of the pressed sample. The inventors confirmed that a given gelling material has a unique and repeatable DPI value, and that any gelling material with similar chemical properties will have the same DPI value, provided that the reference material, substitution ratio, water-to-powder ratio, curing process, and molding pressure are the same.

[0005] As described above, according to the present invention, using equipment readily available at production sites such as concrete plants and cement manufacturing plants, the similarities or differences between different types of cementitious materials or different batches of the same material can be easily and accurately identified within a short period of approximately 12 hours. The present invention provides users with a method to build their own proprietary database using commonly used materials and to predict the performance of newly purchased materials.

[0006] The advantages of this invention are: it can quickly and accurately predict the inherent properties of unknown cementitious materials and identify the similarities between materials within 12 hours, allowing users to predict substitution rates, usability, mechanical properties, and durability based on existing databases. This method requires only basic equipment typically found in factories, such as weighing equipment, mixers, steel molds, compressors, and steam chambers, making it significantly economical and practical. Attached Figure Description

[0007] Figure 1 This is an example of a steel mold that can be used to prepare samples; The mold is made of steel, and its internal space is a cylindrical steel cavity. The mold cavity is sealed by a cylindrical steel impact device, which can be used to compress the sample. In the figure, 1 is the cylindrical steel impact device, with a diameter of 50mm; 2 is the mold sidewall, with a height of 110mm; 3 is the mold cavity, with a diameter of 50mm and a height of 100mm; 4 is the bottom of the mold, with a diameter of 100mm.

[0008] Figure 2 It is a graph showing the boundary of the calibration curve as described in claim 1; The calibration curve is a function curve of particle density index (DPI) and relative specific gravity, exhibiting a linear relationship as represented by the equation y = mx + c, where y represents the DPI value and x represents the relative specific gravity. Here, the slope m is between 1.6 and 5.0, and the intercept c is between -0.2 and -4.2.

[0009] Figure 3 The calibration curve was obtained from Example 1; The calibration curve is generated from three points, corresponding to the DPI values ​​of two fly ash samples FA1 and FA2, and an independent sample, respectively. The horizontal axis represents the relative specific gravity. The DPI value and relative specific gravity show a linear relationship, with the equation being: Correlation coefficient The correlation coefficient is 0.98. It is a statistical indicator, also known as the coefficient of determination. The closer a value is to 1, the higher the reference value of the relevant equations; conversely, the closer a value is to 0, the lower the reference value.

[0010] Figure 4 This is an example of how to interpolate the DPI of an unknown sample; This figure illustrates the calibration curve obtained in Example 1 (e.g.) Figure 3 Next, how do we obtain the DPI of an unknown sample? First, measure and calculate the relative specific gravity of the unknown sample. Based on the relative specific gravity value of the unknown sample, draw a vertical line from the horizontal axis of the graph, and compare it to the calibration curve. Then, draw a horizontal line from the intersection point, and compare it to the vertical axis. This intersection point is the DPI value of the unknown sample. This method is called interpolation.

[0011] Figure 5 The calibration curve was obtained from Example 2; In Example 2, the relative specific gravity and DPI values ​​were calculated for independent samples, rice husk ash (RHA), glass powder (GLP), blast furnace slag (BFS), and silica fume (SIF), and a linear calibration curve was plotted based on five corresponding points. The graph shows a linear relationship between DPI value and relative specific gravity, with the equation being: Correlation coefficient It is 0.90.

[0012] Figure 6 The calibration curve was obtained from Comparative Example 1.

[0013] Comparative Example 1: The DPI values ​​of a new batch of fly ash samples FA1, FA2, and individual samples were measured and calculated. Three corresponding points were found in the relative specific gravity-DPI value coordinate system, and a calibration curve was plotted based on these three points. The graph shows that the DPI value and relative specific gravity have an approximately linear relationship, with the equation being: Correlation coefficient It is 0.83 Detailed Implementation

[0014] The following details the implementation of this invention. The identification of unknown cementitious material samples involves two stages: (I) construction of calibration curves, and (II) determination of the particle density index (DPI value) of the unknown sample (correlated sample). The entire process involves eight operations: (a) Preparation of independent samples (b) Preparation of associated samples (c) Determination of dry specific gravity (d) Determine compressive strength (e) Calculate the relative specific gravity of the independent samples (f) Calculate the relative specific gravity of the associated samples (g) Calculate the DPI value of independent samples (h) Calculate the DPI value of the associated samples For clarity, this embodiment uses Portland cement and fly ash as examples, but the present invention is not limited to these cementitious materials.

[0015] Preparation of independent samples Use a mixer to mix Portland cement with water. Then pour the mixture into a mold and seal it with an impact device. Next, apply pressure using a compressor to solidify the mixture into a solid form, after which the sample is removed. If necessary, the wet specific gravity of the sample can be measured immediately after removal. Allow the sample to dry and harden.

[0016] Preparation of associated samples Portland cement, a type of fly ash, and water are mixed using a mixer. The mixture is poured into a mold and sealed with an impact device. It is then pressurized by a compressor to solidify into a solid sample, which is then removed. If necessary, the wet specific gravity can be measured immediately after removal. The sample is then allowed to dry and harden. Other types of fly ash are prepared using the same procedure.

[0017] Determination of dry specific gravity Measure the weight of independent and related samples separately, and record their height and diameter to calculate specific gravity. For each sample, estimate the average of at least three samples.

[0018] Determination of compressive strength The compressive strength of independent and related samples was determined according to JIS A 1108 standard. For each sample, the average value of at least three samples was estimated.

[0019] Calculation of the relative specific gravity of independent samples The relative specific gravity of independent samples is calculated using the following equation, and the result is rounded to two decimal places. Equation (1) in, Relative specific gravity of independent samples Specific gravity of individual samples Calculation of relative specific gravity of associated samples The relative specific gravity of the associated samples is calculated using the following equation, and the result is rounded to two decimal places.

[0020] Equation (2) in, Relative specific gravity of associated samples Specific gravity of individual samples Specific gravity of associated samples Calculation of DPI values ​​for independent samples The DPI value of an independent sample is calculated using the following equation, and the result is rounded to two decimal places.

[0021] Equation (3) in, DPI values ​​of independent samples Compressive strength (MPa) of individual samples Calculation of DPI value of associated sample The DPI value of the associated sample is calculated using the following equation, and the result is rounded to two decimal places.

[0022] Equation (4) in, DPI value of associated samples Compressive strength (MPa) of individual samples Compressive strength (MPa) of the associated sample Example 1 Construction of calibration curves (a) Preparation of independent samples 1100 grams of Portland cement and 198 grams of water were mixed in a paddle mixer for 4 minutes. 200 grams of the mixture was then poured into a cylindrical steel mold cavity with a diameter of 50 mm and a height of 100 mm, and sealed using a steel cylindrical impact device. Subsequently, a pressure of 10 MPa was applied using a compressor to mold the mixture into a cylinder. The wet specific gravity of the sample was immediately measured using a laser volume analyzer after removal. A total of 6 samples were prepared in this batch. The samples were first moisture-cured at 20°C and 100% relative humidity for 4 hours, and then cured in a steam chamber at 80°C and 100% relative humidity for 8 hours.

[0023] (b) Preparation of associated samples Two fly ashes with significantly different chemical properties (hereinafter referred to as FA1 and FA2) were selected, and their chemical compositions are shown in Table 1.

[0024] [Table 1] ; 660 g of Portland cement, 440 g of FA1, and 198 g of water were mixed in a paddle mixer for 4 minutes. 200 g of the mixture was then poured into a cylindrical steel mold cavity with a diameter of 50 mm and a height of 100 mm, and sealed using a steel cylindrical impact device. A compressor was then used to apply a pressure of 10 MPa to mold the mixture into a cylinder. The wet specific gravity of the sample was immediately measured using a laser volume analyzer after removal. A total of 6 samples were prepared in this batch. The samples were first moisture-cured at 20°C and 100% relative humidity for 4 hours, and then cured in a steam chamber at 80°C and 100% relative humidity for 8 hours. 660 g of Portland cement, 440 g of FA2, and 198 g of water were mixed in a paddle mixer for 4 minutes. 200 g of the mixture was then poured into a cylindrical steel mold cavity with a diameter of 50 mm and a height of 100 mm, and sealed using a steel cylinder impact device. A compressor was then used to apply a pressure of 10 MPa to mold the mixture into a cylinder. The wet specific gravity of the sample was immediately measured using a laser volume analyzer after removal. A total of 6 samples were prepared in this batch. The samples were first moisture-cured at 20°C and 100% relative humidity for 4 hours, and then cured in a steam chamber at 80°C and 100% relative humidity for 8 hours.

[0025] (c) Determination of dry specific gravity Use a balance to measure the weight of independent and related samples, and use vernier calipers to determine the sample height and diameter and calculate the specific gravity. Estimate the average value of the six samples.

[0026] (d) Determination of compressive strength The compressive strength of independent and related samples was determined according to JIS A 1108 standard. The average value of the six samples was estimated.

[0027] (e) Calculate the relative specific gravity of independent samples The relative specific gravity of the independent samples was calculated using formula (1), and the calculation results were rounded to two decimal places.

[0028] (f) Calculate the relative specific gravity of the associated samples The relative proportions of the associated samples were calculated using formula (2), and the results were rounded to two decimal places.

[0029] (g) Calculate the DPI value of independent samples The DPI value of the independent sample was calculated using formula (3), and the calculation result was rounded to two decimal places.

[0030] (h) Calculate the DPI value of the associated sample The DPI value of the associated sample was calculated using formula (4), and the calculation result was rounded to two decimal places.

[0031] (i) Experimental Results The experimental results of steps (a) to (e) above are shown in Table 2.

[0032] [Table 2] ; (j) Plotting the calibration curve Based on the data in columns four and five of Table 2, draw a graph showing the correspondence between DPI values ​​and relative weights. For example... Figure 3 As shown in the figure, the DPI value and the relative weight have a linear relationship, and the equation of the line is:

[0033] The slope m of the line is between 1.6 and 5.0, and the intercept c is between... 0.2 to The values ​​are between 4.2 and 4.2. These data satisfy the necessary conditions described in the claims of this invention. The correlation coefficient is 0.98, which is higher than 0.90, indicating a strong correlation, and can be used as a valid calibration curve.

[0034] Determine the DPI value of an unknown sample (a) Preparation of independent samples 1100 g of silicate cement and 198 g of water were mixed in a paddle mixer for four minutes. Then, 200 g of the mixture was filled into a cylindrical steel mold cavity with a diameter of 50 mm and a height of 100 mm, and sealed with a steel cylindrical impact device. The mixture was then compressed into a cylindrical shape using a compressor at a pressure of 10 MPa, and the sample was removed. The wet specific gravity of the sample was measured immediately after removal using a laser volume analyzer. A total of six samples were prepared in this batch. After moisture curing at 20°C and 100% relative humidity for 4 hours, the samples were cured in a steam chamber at 80°C and 100% relative humidity for 8 hours.

[0035] (b) Preparation of unknown fly ash samples 660 g of silicate cement, 440 g of fly ash, and 198 g of water were mixed in a paddle mixer for four minutes. Then, 200 g of the mixture was filled into a cylindrical steel mold cavity with a diameter of 50 mm and a height of 100 mm, and sealed with a steel cylindrical impact device. The mixture was then pressed into a cylindrical shape using a compressor at a pressure of 10 MPa, and the sample was removed. The wet specific gravity of the sample was measured immediately after removal using a laser volume analyzer. A total of six samples were prepared in this batch. After moisture curing at 20°C and 100% relative humidity for 4 hours, the samples were cured in a steam chamber at 80°C and 100% relative humidity for 8 hours.

[0036] (c) Measure the dry specific gravity Measure the weight of each individual sample using a balance. Measure the height and diameter of each sample using vernier calipers and calculate the specific gravity. Estimate the average value of the six samples.

[0037] The weight of the sample containing the unknown fly ash was measured using a balance. The height and diameter of the sample were measured using vernier calipers, and the specific gravity was calculated. The average value of the six samples was estimated.

[0038] (d) Calculate the relative specific gravity of the independent samples. The relative specific gravity of the independent samples is calculated using formula (1) and rounded to two decimal places.

[0039] (e) Calculate the relative specific gravity of the unknown fly ash sample The relative specific gravity of the unknown fly ash sample is calculated using the following equation and rounded to two decimal places.

[0040] (Equation 5) Relative specific gravity of unknown sample Specific gravity of individual samples Specific gravity of unknown sample (f) Results The experimental results for steps (a) to (e) above are shown in Table 3.

[0041] [Table 3] (a) ; (g) DPI value interpolation As shown in Figure 4, the DPI value is interpolated by drawing a vertical line at a relative specific gravity of 0.90. The intersection of this vertical line and the calibration curve represents the DPI value, which is 0.70 in this case. Therefore, the DPI value of the unknown sample is 0.70. Example 2 Construction of calibration curves (a) Preparation of independent samples 1100 g of silicate cement and 198 g of water were mixed in a paddle mixer for four minutes. Then, 200 g of the mixture was filled into a cylindrical steel mold cavity with a diameter of 50 mm and a height of 100 mm, and sealed with a steel cylindrical impact device. The mixture was then pressed into a cylindrical shape using a compressor at a pressure of 10 MPa, and the sample was removed. The wet specific gravity of the sample was measured immediately after removal using a laser volumetric meter. A total of six samples were prepared in this batch. After moisture curing at 20°C and 100% relative humidity for 4 hours, the samples were cured in a steam chamber at 80°C and 100% relative humidity for 8 hours.

[0043] (b) Preparation of relevant specimens Four types of associated samples were prepared using four different types of supplementary cementitious materials. Their mixing ratios are shown in Table 4.

[0044] [Table 4] ; Each mixture was blended in a paddle mixer for four minutes. Then, 200 grams of the mixture were filled into a cylindrical steel mold cavity with a diameter of 50 mm and a height of 100 mm, and sealed with a steel cylindrical impact device. The mixture was then pressed into a cylindrical shape using a compressor at a pressure of 10 MPa, and the sample was removed. The wet specific gravity of the sample was measured immediately after removal using a laser volumetric meter. A total of six samples were prepared in this batch. After moisture curing at 20°C and 100% relative humidity for 4 hours, the samples were cured in a steam chamber at 80°C and 100% relative humidity for 8 hours.

[0045] (c) Measure dry specific gravity Use a balance to measure the weight of individual and related samples. Use vernier calipers to measure the height and diameter of the samples and calculate their specific gravity. Take the average of 6 samples for each type.

[0046] (d) Measuring compressive strength The compressive strength of both independent and associated samples was measured according to JIS A 1108 standard. The average value of six samples in each type was calculated.

[0047] (e) Calculate the relative specific gravity of the independent samples The relative specific gravity of the independent samples is calculated using equation (1) and rounded to two decimal places.

[0048] (f) Calculate the relative specific gravity of the associated samples The relative specific gravity of the associated samples is calculated using equation (2) and rounded to two decimal places.

[0049] (g) Calculate the DPI value of independent samples The DPI value of the independent sample is calculated using equation (3) and rounded to two decimal places.

[0050] (h) Calculate the DPI value of the associated samples. The DPI value of the associated sample is calculated using equation (4) and rounded to two decimal places.

[0051] (i) Results The results of the operations described in (a) to (h) are shown in Table 5.

[0052] [Table 5] ; (j) Plot the calibration curve Using the data shown in columns four and five of Table 5, a graph depicting the relationship between DPI values ​​and relative weight is plotted, as shown in Figure 5. This graph shows a linear relationship between DPI values ​​and relative weight; the analytical equation for this line is:

[0053] The slope m of this straight line is between 1.6 and 5.0, and the intercept c is between -0.2 and -4.2. Therefore, these values ​​meet the basic requirements claimed in this invention. The correlation coefficient is 0.90, so it is strongly correlated and can be used as a calibration curve.

[0054] Comparative Example 1 Construction of calibration curves (a) Preparation of independent samples 1100 g of limestone powder and 132 g of water were mixed in a paddle mixer for four minutes. Then, 200 g of this mixture was filled into a cylindrical steel mold cavity with a diameter of 50 mm and a height of 100 mm, and sealed with a steel cylindrical impact device. The mixture was then pressed into a cylindrical shape using a compressor at a pressure of 10 MPa, after which the sample was removed. Immediately after removal, the wet specific gravity of the sample was measured using a laser volume analyzer. A total of six samples were prepared in this batch. After moisture curing at 20°C and 100% relative humidity for 4 hours, the samples were placed in a steam chamber and cured at 80°C and 100% relative humidity for 8 hours.

[0055] (b) Preparation of associated samples Select two fly ash samples with significantly different chemical properties listed in Table 1 (hereinafter referred to as FA1 and FA2).

[0056] Preparation of FA1 samples: 660 g of limestone powder, 440 g of FA1, and 132 g of water were mixed in a paddle mixer for four minutes. Then, 200 g of this mixture was filled into a cylindrical steel mold cavity with a diameter of 50 mm and a height of 100 mm, and sealed with a steel cylindrical impact device. The mixture was then pressed into a cylindrical shape using a compressor at a pressure of 10 MPa, after which the sample was removed. Immediately after removal, the wet specific gravity of the sample was measured using a laser volume analyzer. A total of 6 samples were prepared in this batch. After moisture curing at 20°C and 100% relative humidity for 4 hours, the samples were placed in a steam chamber and cured at 80°C and 100% relative humidity for 8 hours.

[0057] Preparation of FA2 samples: 660 g of limestone powder, 440 g of FA2, and 132 g of water were mixed in a paddle mixer for four minutes. Then, 200 g of this mixture was filled into a cylindrical steel mold cavity with a diameter of 50 mm and a height of 100 mm, and sealed with a steel cylindrical impact device. The mixture was then pressed into a cylindrical shape using a compressor at a pressure of 10 MPa, after which the sample was removed. Immediately after removal, the wet specific gravity of the sample was measured using a laser volume analyzer. A total of 6 samples were prepared in this batch. After moisture curing at 20°C and 100% relative humidity for 4 hours, the samples were placed in a steam chamber and cured at 80°C and 100% relative humidity for 8 hours.

[0058] (c) Measurement of dry specific gravity Measure the weight of individual and related samples using a balance. Measure the height and diameter of the samples using vernier calipers. Calculate the dry specific gravity. Take the average of the six samples.

[0059] (d) Measurement of compressive strength The compressive strength of independent and related samples was measured according to JIS A1108 standard. The average value of 6 samples was taken.

[0060] (e) Calculate the relative specific gravity of independent samples The relative specific gravity of the independent samples was calculated using equation (1), and the result was rounded to two decimal places.

[0061] (f) Calculate the relative specific gravity of the associated samples The relative specific gravity of the associated samples is calculated using equation (2), and the result is rounded to two decimal places.

[0062] (g) Calculate the DPI value of independent samples The DPI (particle densification index) value of the independent sample was calculated using equation (3), and the result was rounded to two decimal places.

[0063] (h) Calculate the DPI value of the associated sample The DPI (particle densification index) value of the associated sample was calculated using equation (4), and the result was rounded to two decimal places.

[0064] (i) Results The results of the tests described in items (a) to (h) above are shown in Table 6.

[0065] [Table 6] ; (j) Plot the calibration curve like Figure 6 As shown, a graph depicting the relationship between DPI values ​​and relative weight was plotted using the data in columns four and five of Table 6. The graph shows an approximate linear relationship between DPI values ​​and relative weight. The equation of this straight line is:

[0066] The slope m of the straight line is not between 1.6 and 5.0, and the intercept c is not between -0.2 and -4.2, therefore it does not meet the basic requirements of this invention. Furthermore, the correlation coefficient of the straight line is 0.83, which is less than 0.90, therefore it cannot be considered a strong correlation and is unsuitable for use as a calibration curve. The reason for the correlation coefficient being lower than 0.90 is that the reference (independent) sample used is a non-cementing material—limestone powder, which does not meet the basic requirements described in claim 9.

[0067] Comparative Example 2 Construction of calibration curves (a) Preparation of independent samples 1100 g of ordinary Portland cement and 198 g of water were mixed in a paddle mixer for 4 minutes. Then, 200 g of this mixture was filled into a cylindrical steel mold cavity with a diameter of 50 mm and a height of 100 mm, and sealed with a steel cylindrical impact device. A pressure of 0.2 MPa was applied by a compressor to mold the mixture into a cylinder, which was then demolded. The sample collapsed, making it impossible to prepare individual samples. The collapse was caused by a molding pressure below 0.25 MPa, which did not meet the basic conditions required by this invention. Attempts to construct calibration curves failed.

Claims

1. A method for identifying cementitious materials, comprising: Press molding at least one mixture consisting of a cementitious material and water; measure the wet or dry specific gravity of the molded sample made using the above mixture; The particle densification index (DPI) is calculated by interpolation using a calibration curve represented by the equation y = mx + c. Here, the slope m is between 1.6 and 5.0, and the intercept c is between -0.2 and -4.2, where y represents the DPI value and x represents the relative specific gravity.

2. The method of claim 1, wherein the cementing material is at least one of the group consisting of hydraulic cement and supplementary cementitious materials (SCMs).

3. The hydraulic cement of claim 2, wherein the hydraulic cement is at least one of the group consisting of silicate cement, mixed cement, calcium aluminate cement, calcium sulfoaluminate cement and calcium hydroxide.

4. The supplementary cementitious material of claim 2, wherein the supplementary cementitious material is at least one of the group consisting of fly ash, silica fume, metakaolin, rice husk ash, slag, natural volcanic ash, calcined clay, glass powder and palm oil fuel ash.

5. The method of claim 1, wherein the compression molding is performed in a cylindrical mold. A pressure of 0.25 MPa or higher is applied to the sample.

6. The method of claim 1, wherein the wet specific gravity is a specific gravity measured immediately after molding, prior to room temperature moisture curing, heat curing, steam curing, or high-pressure steam curing.

7. The method of claim 1, wherein the dry specific gravity is the specific gravity measured after the sample has undergone room temperature moisture curing, heat curing, steam curing, or high pressure steam curing.

8. The method of claim 1, wherein the wet or dry specific gravity of the molded sample is measured by manual intervention or automatically using specialized equipment. The specialized equipment, such as a laser volume analyzer, acoustic volume analyzer, or 3D scanner, measures the volume and weight of the object without manual intervention.

9. The method of claim 1, wherein the relative specific gravity of the molded specimen is calculated by dividing the wet or dry specific gravity of a dependent specimen made using one or more cementing materials by the wet or dry specific gravity of an independent specimen made using a single cementing material.

10. The calibration curve in claim 1 shall have a correlation coefficient of at least 0.9.

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