Method for detecting hydration process of ardealite-based thermal insulation material

Abstract

The application discloses a method for detecting the hydration process of phosphogypsum-based thermal insulation material, and relates to the technical field of building materials. The method comprises the following steps: injecting the phosphogypsum-based thermal insulation material mixture into a mold provided with measuring heads at two ends, forming for 1-1.5 hours, and then demolding; the demolding time is relatively early, and after demolding, the friction of the phosphogypsum-based thermal insulation material test piece in the expansion process is reduced, and the expansion displacement of the phosphogypsum-based thermal insulation material test piece is more obviously detected; the phosphogypsum-based thermal insulation material test piece obtained after demolding is provided with measuring heads at two sections, the measuring heads are used for connecting expansion displacement detection equipment, the probability of slag deformation of the test piece is reduced in a point connection mode, and the expansion amount detection error is reduced; the expansion displacement and the detection time point are automatically recorded by detecting the expansion displacement of the test piece at different time points, and manual work is saved. The method is simple in operation process, sensitive in determination process, and accurate in determination result.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a method for detecting the hydration process of phosphogypsum-based thermal insulation materials. Background Technology

[0002] In the construction industry, hemihydrate phosphogypsum (CaSO4·0.5H2O) is commonly used as a binder in the preparation of phosphogypsum-based thermal insulation materials. During the preparation process, hemihydrate phosphogypsum reacts with added water to form dihydrate phosphogypsum (CaSO4·2H2O), a process known as hydration.

[0003] The hydration process is typically measured using either the heat of hydration method or the bound water method. The heat of hydration method detects the hydration process of phosphogypsum-based insulation materials by measuring the heat release rate at different times, since hemihydrate phosphogypsum generates heat during hydration. The bound water method detects the hydration process of phosphogypsum-based insulation materials by measuring the bound water content, as hemihydrate phosphogypsum gradually transforms into dihydrate phosphogypsum during hydration, leading to an increase in the bound water content.

[0004] However, both methods require sophisticated equipment, involve complex procedures, and are difficult to measure. Furthermore, the reaction time for ordinary gypsum is approximately half a day, while the reaction time for phosphogypsum-based insulation materials is much longer, typically requiring 2-4 days. This results in longer testing times and higher detection costs, making it difficult to use existing technologies to detect their 2-4 day hydration process. Summary of the Invention

[0005] The main objective of this invention is to propose a method for detecting the hydration process of phosphogypsum-based thermal insulation materials, aiming to solve the problems of high detection cost and low detection accuracy in existing technologies.

[0006] To achieve the above objectives, this invention proposes a method for detecting the hydration process of phosphogypsum-based thermal insulation materials, comprising the following steps:

[0007] S10. Mix hemihydrate phosphogypsum, thermal insulation material particles, water, and other ingredients to obtain a phosphogypsum-based thermal insulation material mixture.

[0008] S20. The phosphogypsum-based thermal insulation material mixture is injected into a mold with detection heads at both ends, and molded for 1 to 1.5 hours. The mold is then removed to obtain a phosphogypsum-based thermal insulation material specimen with detection heads at both ends.

[0009] S30. Detect the expansion displacement of the phosphogypsum-based thermal insulation material specimen during the hydration process, automatically record the expansion displacement of the phosphogypsum-based thermal insulation material specimen at different time points, and obtain the expansion displacement of multiple phosphogypsum-based thermal insulation material specimens and their corresponding detection times.

[0010] S40. Based on multiple test times and the expansion displacement of their corresponding phosphogypsum-based thermal insulation material specimens, plot a curve of expansion displacement versus test time.

[0011] S50. Determine the hydration stage of the phosphogypsum-based thermal insulation material specimen based on the trend of the curve.

[0012] Optionally, in step S10, the insulating material particles include at least one of vitrified microspheres and polystyrene particles.

[0013] Optionally, step S10 includes: mixing hemihydrate phosphogypsum, thermal insulation material particles, water and ingredients to obtain a phosphogypsum-based thermal insulation material mixture;

[0014] The ingredients include at least two of hydroxypropyl methylcellulose, plant protein retarder, and hydroxypropyl starch ether.

[0015] Optionally, in step S20, demolding includes demolding assistance.

[0016] Optionally, the demolding aid includes covering the mold with a plastic film before injection molding.

[0017] Optionally, in step S30, the automatic recording time interval is 0 to 1 minute.

[0018] Optionally, in step S50, the four hydration stages include the pre-hydration induction stage, the hydration induction stage, the hydration acceleration stage, and the hydration deceleration stage.

[0019] This invention proposes a method for detecting the hydration process of phosphogypsum-based thermal insulation materials. The phosphogypsum-based thermal insulation material mixture is injected into a mold with probes at both ends and molded for 1-1.5 hours before demolding. Early demolding reduces friction on the phosphogypsum-based thermal insulation material specimen during expansion, allowing for more obvious detection of expansion displacement. The resulting phosphogypsum-based thermal insulation material specimen has probes at both ends, which are used to connect to expansion displacement detection equipment. This point connection reduces the probability of specimen deformation and flaking, thus reducing errors in expansion measurement. By detecting the expansion displacement of the specimen at different time points, the method automatically records the expansion displacement and the detection time, saving manual labor. This method is simple to operate, highly sensitive, and provides accurate results. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0021] Figure 1 This is a diagram of the complete detection device provided in Embodiment 1 of the present invention;

[0022] Figure 2A This is the logarithmic diagram of expansion displacement-detection time provided in Embodiment 1 of the present invention;

[0023] Figure 2B This is a logarithmic diagram of expansion displacement-detection time provided in Embodiment 2 of the present invention.

[0024] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially. Furthermore, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, or solution B, or a solution where both A and B are satisfied simultaneously. In addition, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] In the construction industry, hemihydrate phosphogypsum (CaSO4·0.5H2O) is commonly used as a binder in the preparation of phosphogypsum-based insulation materials. During preparation, hemihydrate phosphogypsum reacts with added water to form dihydrate phosphogypsum (CaSO4·2H2O), a process known as hydration. The hydration process is typically measured using either the hydration heat method or the bound water method. The hydration heat method detects the hydration progress by measuring the heat release rate of the phosphogypsum-based insulation material at different times, as hemihydrate phosphogypsum gradually transforms into dihydrate phosphogypsum during hydration, leading to an increase in the bound water content. Therefore, the bound water method detects the hydration process by measuring the bound water content in the material. However, both methods require sophisticated equipment, are complex to operate, and are not easily measured. Furthermore, the reaction time of ordinary gypsum is about half a day, while the reaction time of phosphogypsum-based insulation materials is much longer, usually requiring 2 to 4 days. This results in a longer testing time and higher detection costs, making it difficult to use existing technologies to detect their 2 to 4-day hydration process. Therefore, this invention provides a method for detecting the hydration process of phosphogypsum-based insulation materials, aiming to solve the problems of high detection costs and low accuracy in existing technologies.

[0027] Currently, phosphogypsum thermal insulation mortar is a newer, more environmentally friendly, and more economical interior wall leveling product that can replace cement mortar. It has the strength of cement, but is healthier, more environmentally friendly, more durable, has strong adhesion, is not easy to powder, does not crack, does not hollow, and does not shed powder. It is easy to use and saves costs.

[0028] Unlike ordinary gypsum and phosphogypsum materials, phosphogypsum-based thermal insulation mortar uses hemihydrate phosphogypsum as the base material, polymers as the cementing material, and lightweight insulating materials as the insulating agent, thus possessing thermal insulation functions. Furthermore, the reaction time for ordinary gypsum and phosphogypsum materials is completed in about half a day during preparation, while phosphogypsum-based thermal insulation materials typically require 2-3 days to react.

[0029] Because the composition of phosphogypsum-based thermal insulation mortar is relatively complex, when using the traditional hydration heat method and the bound water method to measure it, the hydration heat method is inaccurate because it contains thermal insulation material particles, and the bound water method is also inaccurate because the thermal insulation material particles can also absorb water. Therefore, it is difficult to accurately measure and distinguish each stage of the hydration process, and thus it is difficult to judge the degree of preparation in the implementation process.

[0030] In this invention, the method for detecting the hydration process of phosphogypsum-based thermal insulation materials includes the following steps:

[0031] S10. Mix hemihydrate phosphogypsum, thermal insulation material particles and water to obtain a phosphogypsum-based thermal insulation material mixture;

[0032] S20. The phosphogypsum-based thermal insulation material mixture is injected into a mold with movable detection heads at both ends, and molded for 1 to 1.5 hours. The mold is then removed to obtain a phosphogypsum-based thermal insulation material specimen with detection heads at both ends.

[0033] S30. Detect the expansion displacement of the phosphogypsum-based thermal insulation material specimen during the hydration process, automatically record the expansion displacement of the phosphogypsum-based thermal insulation material specimen at different time points, and obtain the expansion displacement of multiple phosphogypsum-based thermal insulation material specimens and their corresponding detection times.

[0034] S40. Based on multiple test times and the expansion displacement of their corresponding phosphogypsum-based thermal insulation material specimens, plot a curve of expansion displacement versus test time.

[0035] S50. Determine the hydration stage of the phosphogypsum-based thermal insulation material specimen based on the trend of the curve.

[0036] Understanding the hydration process is essential for the application of phosphogypsum-based insulation materials. Referring to the analysis of cement hydration, after hemihydrate phosphogypsum (CaSO4·0.5H2O) is mixed with water, in the first stage, the surface of the hemihydrate phosphogypsum particles reacts with water to form dihydrate phosphogypsum. This exothermic chemical reaction causes the phosphogypsum-based insulation material to expand in volume, gradually increasing its height; this process is called the induction phase. Once the surface of the hemihydrate phosphogypsum particles is completely coated with the formed dihydrate phosphogypsum, the rate of water diffusion from the outside to the inside of the particles slows down. At this point, the chemical reaction rate gradually decreases due to water shortage, and the released heat also decreases. The heat accumulated in the phosphogypsum-based insulation material gradually dissipates. During this heat dissipation process, the volume of the material shrinks due to thermal expansion and contraction, gradually decreasing its height; this process is called the induction phase. The process is divided into four stages: the induction stage and the deceleration stage. In the third stage, the water that diffuses into the hemihydrate phosphogypsum particles reacts with the internal hemihydrate phosphogypsum, forming dihydrate phosphogypsum which expands. This causes cracks in the surface layer of dihydrate phosphogypsum, allowing external water to diffuse more quickly into the interior. This further accelerates the chemical reaction, which is exothermic and causes the specimen to expand in volume, increasing its height again. This process is called the acceleration stage. In the fourth stage, after all the effective components in the hemihydrate phosphogypsum particles have reacted, the reaction rate gradually decreases, and the released heat also decreases. The heat accumulated in the phosphogypsum-based insulation material gradually dissipates. During this heat dissipation, the material shrinks due to thermal expansion and contraction, reducing its height again. This process is called the deceleration stage. The molding time for the phosphogypsum-based insulation material specimen is 1–1.5 hours, specifically 1 hour, 1.2 hours, or 1.5 hours. This molding time range ensures good hardness of the specimen, facilitates demolding, and allows for the measurement of the four stages of hydration.

[0037] In the technical solution of this invention, the phosphogypsum-based thermal insulation material mixture is injected into a mold with probes at both ends and molded for 1-1.5 hours before demolding. Early demolding reduces friction on the phosphogypsum-based thermal insulation material specimen during expansion, allowing for more obvious detection of expansion displacement. The resulting phosphogypsum-based thermal insulation material specimen has probes at both ends, which are used to connect to expansion displacement detection equipment. This point connection reduces the probability of specimen deformation and flaking, thus reducing errors in expansion detection. By detecting the expansion displacement of the specimen at different time points, the expansion displacement and detection time points are automatically recorded, saving labor. This method is simple to operate, highly sensitive, and accurate. This method can accurately determine the four stages of hydration of phosphogypsum-based thermal insulation materials on a macroscopic scale.

[0038] Further, in step S10, the mass ratio of the hemihydrate phosphogypsum, the insulation material particles, and the water is (11-12):(0.5-1.5):(8-9). Maintaining this mass ratio ensures that the prepared phosphogypsum-based insulation material specimens have good strength. During implementation, phosphogypsum-based insulation material specimens may have different sizes and thicknesses; the hydration process can be measured using the method of this invention.

[0039] Further, in step S10, the thermal insulation material particles include at least one of vitrified microspheres and polystyrene particles. That is, the thermal insulation material particles may contain either vitrified microspheres or polystyrene particles, or may contain both, all of which fall within the scope of protection of this invention. Both the vitrified microspheres and polystyrene particles are lightweight thermal insulation materials that play a role in thermal insulation in phosphogypsum-based insulation materials.

[0040] Further, step S10 includes: mixing hemihydrate phosphogypsum, thermal insulation material particles, water, and other ingredients to obtain a phosphogypsum-based thermal insulation material mixture; wherein the ingredients include at least two of hydroxypropyl methylcellulose, plant protein retarder, and hydroxypropyl starch ether. That is, the ingredients can be any two of hydroxypropyl methylcellulose, methylcellulose, and hydroxypropyl starch ether, or can contain all of these, all within the scope of this invention. The hydroxypropyl methylcellulose, methylcellulose, and hydroxypropyl starch ether are all humectants; their high water retention allows for complete hydration of the phosphogypsum and increases its bonding strength.

[0041] Further, in step S20, demolding includes a demolding aid. The demolding aid involves covering the mold with a plastic film before injection molding. Using a demolding aid facilitates easy separation between the mold and the phosphogypsum-based insulation material specimen, thereby avoiding frictional interference between the mold and the specimen during testing. Using a plastic film reduces adhesion between the plastic film and the phosphogypsum-based insulation material specimen.

[0042] Furthermore, in step S30, the automatic recording time interval is 0–1 min. The automatic recording time interval can be 0.2 min, 0.6 min, or 1 min. Within this range, the automatic recording time ensures more accurate differentiation of the four stages of the hydration process of the phosphogypsum-based insulation material. If the automatic recording time is too long, the data differences will be too large, and the logarithmic graph of expansion displacement and detection time will show a significant step-like gap, resulting in inaccurate measurement results. Figure 1 As shown, the terminal represents an automatic data logger. When the instrument for detecting expansion is a length comparator, the detection head at one end of the specimen is fixed to the bottom of the length comparator, and the detection head at the other end is connected to a micrometer in the length comparator. The micrometer is connected to the automatic data logger, which can be a computer, mobile phone, etc. Since the micrometer is fixed in a fixed state, the specimen is in a fixed state within the length comparator. During the hydration process of 3–5 days, when the set automatic recording interval is 0.5 min, the terminal automatically records the specimen's expansion displacement at the detection time points of 0 min, 0.5 min, 1 min, 1.5 min, ... The expansion displacement is the micrometer reading.

[0043] Further, in step S50, the four hydration stages include the pre-hydration induction stage, the hydration induction period, the hydration acceleration period, and the hydration deceleration period. The resulting curve of expansion displacement versus the logarithm of detection time shows an upward, downward, upward, and downward trend from left to right, corresponding to the four hydration stages: the pre-hydration induction stage, the hydration induction period, the hydration acceleration period, and the hydration deceleration period. This correspondence is unique, thus accurately distinguishing the stages of the phosphogypsum-based insulation material during the hydration process. The four stages of the hydration process of this phosphogypsum-based insulation material are divided and defined using the cement particle hydration process.

[0044] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0045] Examples 1-4 are identical except for the specimen size, raw material ratio, molding time, and automatic recording time interval.

[0046] Example 1

[0047] A method for detecting the hydration process of phosphogypsum-based thermal insulation materials includes the following steps:

[0048] S10. Mix hemihydrate phosphogypsum, vitrified microspheres, water, and plant protein retarder to obtain a phosphogypsum-based thermal insulation material mixture; the mass ratio of hemihydrate phosphogypsum, vitrified microspheres, and water is 11.6:1:8.14:0.03.

[0049] S20. First, lay a plastic film in a mold with dimensions of 25mm×12.5mm×280mm, then inject the phosphogypsum-based thermal insulation material mixture into the mold with detection heads at both ends. After one hour, the mixture will harden slightly and be demolded to obtain a phosphogypsum-based thermal insulation material specimen with dimensions of 25mm×12.5mm×280mm and detection heads at both ends.

[0050] S30. Detect the expansion displacement of the phosphogypsum-based thermal insulation material specimen during the hydration process, automatically record the expansion displacement of the phosphogypsum-based thermal insulation material specimen at different time points, and obtain the expansion displacement of multiple phosphogypsum-based thermal insulation material specimens and their corresponding detection times; the automatic recording time interval is 1 minute.

[0051] S40. Based on multiple test times and the expansion displacement of their corresponding phosphogypsum-based thermal insulation material specimens, plot a curve of expansion displacement versus test time.

[0052] S50. Determine the hydration stage of the phosphogypsum-based thermal insulation material specimen based on the trend of the curve.

[0053] Example 2

[0054] The mass ratio of hemihydrate phosphogypsum, vitrified microspheres, water and plant protein retarder was 11.6:1:8.14:0.03. The mold size was 25mm×25mm×280mm. The molding time was 1 hour, and the automatic recording time interval was 1 minute.

[0055] Example 3

[0056] The mass ratio of hemihydrate phosphogypsum, vitrified microspheres, and water is 11:1.5:9. The mold size is 25mm×12.5mm×280mm. The molding time is 1.2h. The automatic recording time interval is 0.01min.

[0057] Example 4

[0058] The mass ratio of hemihydrate phosphogypsum, vitrified microspheres, and water is 12:0.5:8. The mold size is 25mm×12.5mm×280mm. The molding time is 1.5h. The automatic recording time interval is 0.5min.

[0059] Comparative Example 1

[0060] Compared with Example 1, Comparative Example 1 is the same as Example 1 except that it is molded for 2 hours.

[0061] Since Comparative Example 1 was molded for 2 hours, the method for detecting the hydration process of the phosphogypsum-based thermal insulation material in Comparative Example 1 could not accurately distinguish the four hydration stages, resulting in poor accuracy of the measurement results.

[0062] Performance testing

[0063] The hydration process of the two groups of phosphogypsum-based thermal insulation material specimens prepared in Examples 1 and 2 was detected, and the results are shown in Figure 2.

[0064] Figure 2A This refers to the phosphogypsum-based thermal insulation material specimen prepared in Example 1. Figure 2B The figures show the phosphogypsum-based thermal insulation material specimens prepared in Example 2. As shown in the logarithmic expansion-displacement-detection-time graph in Figure 2, the curves for both specimens A and B exhibit an overall upward, downward, upward, and downward trend, corresponding to the pre-induction, induction, acceleration, and deceleration phases experienced by the specimens during the hydration process, respectively. The comparison between A and B in Figure 2 clearly illustrates the hydration process of the phosphogypsum-based thermal insulation materials at different thicknesses. In both figures, I represents the pre-induction hydration phase, II represents the induction hydration phase, III represents the acceleration hydration phase, and IV represents the deceleration hydration phase. Comparing the curves of A and B, it was found that the deceleration phase of specimen A began around 2 days, while that of specimen B began around 3 days. This is because the volume of specimen A is half that of specimen B; a change in volume results in a significant change in the corresponding hydration curve. This indicates that the method of the present invention has high sensitivity and can effectively distinguish between different specimens. In the curve graph of specimen A, during the early stage of hydration induction, the surface moisture easily evaporates due to the thinness of the specimen, which is the stage indicated by "Water Loss" in the graph, resulting in slight shrinkage in the initial part. Furthermore, in actual construction, some phosphogypsum-based insulation materials are relatively thick, while others are relatively thin. The method of this invention can effectively detect the hydration process of phosphogypsum-based insulation materials of different thicknesses under different working conditions.

[0065] The duration of the first hydration stage varies under different conditions, ranging from 1.2 hours to 4 hours. When the molding time exceeds 1.5 hours, as in Comparative Example 1, although the early stage of hydration induction can be detected, the four hydration stages cannot be accurately distinguished by the naked eye, resulting in poor accuracy in actual use.

[0066] In summary, the method for detecting the hydration process of phosphogypsum-based thermal insulation materials provided by this invention is simple to operate, reduces manpower, has high sensitivity, and can effectively distinguish the four stages of the hydration process of phosphogypsum-based thermal insulation materials.

[0067] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the patent protection scope of the present invention.

Claims

1. A method for detecting the hydration process of phosphogypsum-based thermal insulation materials, characterized in that, Includes the following steps: S10. Mix hemihydrate phosphogypsum, thermal insulation material particles and water to obtain a phosphogypsum-based thermal insulation material mixture; S20. The phosphogypsum-based thermal insulation material mixture is injected into a mold with movable detection heads at both ends, and molded for 1 to 1.5 hours. The mold is then removed to obtain a phosphogypsum-based thermal insulation material specimen with detection heads at both ends. S30. Detect the expansion displacement of the phosphogypsum-based thermal insulation material specimen during the hydration process, automatically record the expansion displacement of the phosphogypsum-based thermal insulation material specimen at different time points, and obtain the expansion displacement of multiple phosphogypsum-based thermal insulation material specimens and their corresponding detection times. S40. Based on multiple test times and the expansion displacement of their corresponding phosphogypsum-based thermal insulation material specimens, plot a curve of expansion displacement versus logarithm of test time with the logarithm of test time as the abscissa and expansion displacement as the ordinate. S50. Determine the hydration stage of the phosphogypsum-based thermal insulation material specimen based on the trend of the curve.

2. The method for detecting the hydration process of phosphogypsum-based thermal insulation materials as described in claim 1, characterized in that, In step S10, the heat insulation material particles are at least one of vitrified microspheres and polystyrene particles.

3. The method for detecting the hydration process of phosphogypsum-based thermal insulation materials as described in claim 1, characterized in that, Step S10 includes: mixing hemihydrate phosphogypsum, thermal insulation material particles, water and other ingredients to obtain a phosphogypsum-based thermal insulation material mixture; The ingredients are at least two of hydroxypropyl methylcellulose, plant protein retarder, and hydroxypropyl starch ether.

4. The method for detecting the hydration process of phosphogypsum-based thermal insulation materials as described in claim 1, characterized in that, In step S20, demolding includes demolding assistance.

5. The method for detecting the hydration process of phosphogypsum-based thermal insulation materials as described in claim 4, characterized in that, The demolding aid includes covering the mold with a plastic film before injection molding.

6. The method for detecting the hydration process of phosphogypsum-based thermal insulation materials as described in claim 1, characterized in that, In step S30, the automatic recording time interval is 0 to 1 minute.

7. The method for detecting the hydration process of phosphogypsum-based thermal insulation materials as described in claim 1, characterized in that, In step S50, the hydration stage includes the pre-hydration induction period, the hydration induction period, the hydration acceleration period, and the hydration deceleration period.

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