Method for producing geopolymer cured body and curing chamber

Abstract

To provide a method for producing a geopolymer cured body capable of satisfying both compressive strength and bending strength without making a curing environment high temperature and high humidity and without being influenced by an outside air temperature.SOLUTION: A method for producing the geopolymer cured body according to the present invention includes: a step (P1) of preparing a plurality of materials including fly ash, slag, water glass, alkali metal hydroxide and water to form a geopolymer paste; and a step (P3) of curing the geopolymer paste filled into a formwork for a predetermined period of time in a curing chamber in which the room temperature is adjusted to be 30°C or higher and 50°C or lower.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a hardened geopolymer body and a curing chamber. [Background technology]

[0002] Geopolymer is one of the construction materials that contributes to reducing environmental impact. To achieve the desired compressive strength, it is recommended that geopolymer be cured in a high temperature and humidity environment (80°C, 95% RH).

[0003] On the other hand, as disclosed in Patent Publication No. 2021-178761 (Patent Document 1), a technology has also been proposed for setting the curing temperature of a geopolymer composition to 50°C or below by adjusting the concentration of alkali metal hydroxide contained in the geopolymer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-178761 Summary of the Invention [Problem to be solved by the invention]

[0005] To create a high-temperature, high-humidity curing environment for geopolymers, special steam-generating equipment is required, which poses the challenge of high initial investment costs in order to produce hardened geopolymers with sufficient strength and hardness.

[0006] Furthermore, although Patent Document 1 states that the curing temperature can be set to 50°C or below, it considers the curing temperature of the geopolymer composition based solely on the results of compressive strength tests. When using a hardened geopolymer as a decorative block to be installed in a residential garden, for example, it is necessary to consider not only compressive strength but also flexural strength. Therefore, even if the curing temperature is set to 50°C or below with the formulation described in Patent Document 1, satisfactory flexural strength may not be achieved.

[0007] Furthermore, in areas where there are large temperature differences depending on the season or time of day, curing geopolymer compositions in the air may not achieve a certain level of strength and hardness.

[0008] The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a method for producing a geopolymer hardened body that can satisfy both compressive strength and flexural strength without requiring a high temperature and humidity curing environment and without being affected by the outside temperature.

[0009] Another object is to provide a curing chamber to be used in the method for producing such a geopolymer hardened body. [Means for solving the problem]

[0010] A method for producing a hardened geopolymer body according to one aspect of the present invention includes the steps of: mixing a plurality of materials including fly ash, slag, water glass, alkali metal hydroxide, and water to produce a geopolymer paste; and curing the geopolymer paste filled into a formwork for a predetermined period of time in a curing chamber whose room temperature is adjusted to 30°C or higher and 50°C or lower.

[0011] The method for producing a cured polymer product preferably further comprises a step of curing the product in air after a predetermined time has elapsed.

[0012] Preferably, the relative humidity in the curing chamber is 20% or more and 85% or less.

[0013] A curing chamber according to another aspect of the present invention is a curing chamber for curing a geopolymer paste made from a mixture of multiple materials including fly ash, slag, water glass, alkali metal hydroxide, and water, and is provided with a temperature control means for adjusting the room temperature to 30 degrees or more and 50 degrees or less.

[0014] The curing chamber may be provided with a humidity adjusting means for adjusting the relative humidity to 20% or more and 85% or less. [Effects of the Invention]

[0015] According to the present invention, both compressive strength and flexural strength can be satisfied without requiring a high temperature and humidity curing environment. In addition, since the geopolymer paste is initially cured in a curing room with a controlled room temperature, it is possible to obtain a constant strength and hardness regardless of the outside temperature. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a flowchart showing a method for producing a hardened geopolymer body. [Figure 2] This is a graph showing the measurement results of the compressive strength and flexural strength of the hardened geopolymer body produced in the curing environment in Test 1. [Figure 3] This is a graph showing the measurement results of the compressive strength and flexural strength of the hardened geopolymer body produced in a curing environment in Test 2. [Figure 4] This is a graph showing the results of measuring the compressive strength and flexural strength of a hardened geopolymer body produced in a curing environment in an additional test. DETAILED DESCRIPTION OF THE INVENTION

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and description thereof will not be repeated.

[0018] <Method of manufacturing hardened geopolymer> The method for producing a hardened geopolymer will be described with reference to FIG.

[0019] The hardened geopolymer body is produced through the following steps in order: mixing process P1, molding process P2, initial curing process P3, air curing process P4, and demolding process P5.

[0020] (Mixing process) In the mixing step P1, multiple materials including fly ash, slag (blast furnace slag), water glass, alkali metal hydroxide, fine aggregate, and water are mixed to produce a geopolymer paste. Note that the materials for the geopolymer paste only need to contain fly ash, slag, water glass, alkali metal hydroxide, and water (for example, they do not need to contain fine aggregate).

[0021] At this time, the various materials are mixed so that the "volume ratio of unit water volume to active filler (W / P)," "molar ratio of alkali to water (A / W)," and "molar ratio of silicon to alkali (Si / A)" are the values ​​shown below. W / P:1±0.05 A / W:0.1±0.01 Si / A: 0.7±0.01 The mixing of a plurality of materials is carried out, for example, in the following manner. i) Weigh out each ingredient. ii) Add the powder and fine aggregate to the mixer and mix at low speed for 3 minutes, then mix thoroughly by hand using a scoop. iii) Mix the water glass, caustic soda and hydrated water for 1 minute, then add to a mixer and mix at low speed for 5 minutes. iv) Stir at high speed for 1 minute.

[0022] (Molding process) In the molding process P2, the geopolymer paste produced in the mixing process is poured into a formwork.

[0023] (Initial curing process) The initial curing step P3 is carried out immediately after the molding step P2. In this step P3, the geopolymer paste filled in the formwork is cured in a curing chamber for a predetermined time. The predetermined time may be 6 hours or more. The initial curing environment in the curing chamber will be described later.

[0024] (Air curing process) The air curing step P4 is performed following the initial curing step P3. In this step P4, curing is performed in air for a predetermined period of time. The predetermined period is, for example, about four weeks.

[0025] (Demolding process) The demolding process P5 is carried out after the air curing process P4, and the hardened geopolymer paste, i.e., the hardened geopolymer body, is demolded.

[0026] <Initial curing environment test> Using the same geopolymer test materials and manufacturing procedures for the hardened geopolymer, tests were conducted to determine the optimal temperature and humidity environment for initial curing. In the tests, compressive strength and flexural strength were measured. Note that compressive strength and flexural strength can be measured using test methods specified in JIS standards (JIS R 5201 or JIS A 1106).

[0027] (Test materials) The geopolymer test materials used were fly ash (FA), blast furnace slag (BFS), water glass (WG), sodium hydroxide (NaOH), fine aggregate, and water. The amounts of each material are shown in Table 1.

[0028] [Table 1]

[0029] When the above amounts are used, the "volume ratio of unit water amount to active filler (W / P)," "molar ratio of alkali to water (A / W)," and "molar ratio of silicon to alkali (Si / A)" are as shown in Table 2.

[0030] [Table 2]

[0031] (Test 1) In Test 1, the humidity in the curing chamber was not adjusted, and the temperature was adjusted to 40°C, 60°C, and 80°C for initial curing. The strength of the hardened geopolymer material produced in Test 1 after 4 weeks was confirmed. The measurement results of compressive strength and flexural strength for each pattern are shown in Figure 2.

[0032] In addition, Figure 2 also shows, as comparative examples, the measurement results when the material was air-cured in the summer (Comparative Example 1) and the measurement results when the material was initially cured in a high-temperature, high-humidity (80°C, 85% RH) environment (Comparative Example 2).

[0033] As shown in Figure 2(A) and (B), when the temperature was set to 60°C or 80°C, the compressive strength was the recommended value (18 N / mm 2 ) and target value (30N / mm 2 ), but the bending strength is still below the target value (3N / mm 2 ) significantly lower than the standard. In this case, it is difficult to use it as a decorative block.

[0034] On the other hand, when the temperature was set at 40 degrees, both the compressive strength and bending strength exceeded the target values.

[0035] The results of Test 1 showed that in summer, when initial curing was done in air, the compressive strength and bending strength were slightly higher than when the room temperature of the curing room was adjusted to 40°C. The outdoor environment in summer was about 30°C and 80% RH. From this, it was predicted that the target values ​​for use as decorative blocks could be achieved if the room temperature of the curing room was set in the medium temperature range of 40°C ± 10°C.

[0036] (Test 2) In Test 2, the temperature of the curing room was adjusted to the medium temperature range of 30°C and 40°C, and initial curing was carried out at each temperature under low and high humidity environments (20%RH and 85%RH), and the strength after four weeks was confirmed. The measurement results of compressive strength and flexural strength for each pattern are shown in Figure 3.

[0037] As shown in Figure 3(A) and (B), the compressive strength was 30 N / mm under all conditions. 2 Over 3N / mm bending strength 2 These results show that by setting the temperature in the curing chamber to the medium temperature range, good compressive strength and bending strength can be obtained even in a low-humidity environment.

[0038] (Test 3) Based on the results of Test 2, it is believed that if the temperature in the curing room is kept in the medium temperature range (30 to 40 degrees), the desired compressive strength and flexural strength can be achieved without adjusting the humidity. To prove this, additional tests were conducted.

[0039] Figure 4 is a graph showing the measurement results of the additional test together with the test results of Tests 1 and 2. In addition, the additional test also shows, as a comparison, the measurement results when the room temperature in the curing room was set to 20°C and the relative humidity was set to 50% (Comparative Example 3).

[0040] As shown in Figures 4(A) and (B), when the humidity in the curing room was not adjusted and the room temperature was adjusted to 30°C and 40°C, the compressive strength was 30 N / mm 2 Over 3N / mm bending strength 2 Furthermore, in this medium temperature range, slightly better results were obtained with no adjustment or low humidity than with adjustment to high humidity (85%).

[0041] Furthermore, in Comparative Example 3, where the room temperature in the curing room was 20°C and the relative humidity was 50%, both the compressive strength and flexural strength were significantly lower than the measured values ​​when the room temperature in the curing room was 60°C. Therefore, it was concluded that the room temperature in the curing room should be at least 30 to 50°C, and preferably 30 to 40°C.

[0042] From the above, it was found that sufficient compressive strength and bending strength can be obtained even without installing a humidity control means, as long as the curing chamber is equipped with a temperature control means to adjust the room temperature to 30 to 40 degrees (or 30 to 50 degrees).

[0043] Furthermore, under such a temperature environment, sufficient strength and hardening were observed even with an initial curing time of 6 hours, indicating that an initial curing time of 6 hours or more is sufficient.

[0044] <Curing room> Based on the above test results, the curing chamber for initial curing of the geopolymer paste in the initial curing step P3 only needs to be equipped with a temperature control device that adjusts the room temperature to between 30°C and 50°C. In other words, the curing chamber does not need to be equipped with a humidity control device. The relative humidity of a curing chamber without a humidity control device is expected to be around 20% to 85%.

[0045] In another embodiment, the curing chamber may be equipped with a humidity adjusting means for adjusting the relative humidity of the curing chamber to 20% or more and 85% or less.

[0046] As explained above, the method for manufacturing a hardened geopolymer body according to the present embodiment does not require special equipment for creating a high-temperature, high-humidity curing environment, making it possible to manufacture a hardened geopolymer body at low cost and easily. Furthermore, because the geopolymer paste is initially cured in a curing room with a regulated room temperature, it is possible to obtain a consistent strength and hardness regardless of the outside temperature.

[0047] Furthermore, while it is recommended that the curing time be 12 hours or more when the curing environment is high temperature and humidity, the manufacturing method of the geopolymer hardened body according to the present embodiment allows the initial curing time to be 6 hours, thereby shortening the manufacturing time of the geopolymer hardened body.

[0048] In addition, since the temperature range of the curing chamber can be set to a medium temperature range, it is possible to use a space simply partitioned off by walls in a section of a factory as a curing chamber. Such a curing chamber can be realized, for example, by a room surrounded by walls that has an entrance through which workers can enter and exit.

[0049] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

Claims

1. A process of mixing a plurality of materials including fly ash, slag, water glass, alkali metal hydroxide, and water to produce a geopolymer paste; A method for producing a geopolymer hardened body, comprising a step of curing the geopolymer paste filled in the formwork for a predetermined time in a curing chamber whose room temperature is adjusted to 30 degrees or higher and 50 degrees or lower.

2. The method for producing a hardened geopolymer body according to claim 1, further comprising a step of curing in air after the predetermined time has elapsed.

3. The method for producing a hardened geopolymer body according to claim 1 or 2, wherein the relative humidity in the curing chamber is 20% or more and 85% or less.

4. A curing chamber for curing a geopolymer paste prepared by mixing a plurality of materials including fly ash, slag, water glass, alkali metal hydroxide, and water, The curing chamber is provided with a temperature control means for adjusting the room temperature to 30 degrees or more and 50 degrees or less.

5. 5. The curing chamber according to claim 4, further comprising a humidity adjusting means for adjusting the relative humidity to 20% or more and 85% or less.

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