JP5185754B2 - Humidity conditioning material and method for producing the same - Google Patents

Description

  The present invention relates to a humidity control material having a function of adjusting humidity in a building or a space such as a storage box, that is, moisture absorption / release properties, and a manufacturing method thereof, and in particular, a cement-based humidity control material using cement as a raw material and the manufacture thereof. Regarding the method.

  Lightweight cellular concrete (ALC) is well known as a cement-type humidity control material. This is produced by mixing and molding siliceous raw material powder with calcareous raw material powder and cement etc., and then autoclaving and steam curing at high temperature and high pressure. Tobermorite obtained by autoclave reaction is produced. It is used.

  Regarding the humidity control material using this lightweight cellular concrete, in Patent Documents 1 and 2, the moisture conditioning property can be improved by carbonizing the lightweight cellular concrete powder mainly composed of tobermorite in the presence of water. Proposed. In addition, in Patent Document 3, as the lightweight cellular concrete material to be used, the material cost can be suppressed by using a defective product generated in the lightweight cellular concrete manufacturing process or a milled end material generated during construction. Proposed.

  However, in such a humidity control material using lightweight aerated concrete, since autoclave is used when producing lightweight aerated concrete as a raw material, there is a problem that the equipment cost and the operating cost become very high and the cost becomes high. is there.

  On the other hand, Patent Document 4 proposes a method for producing a humidity control material by mixing a cement-based hardened granular material other than lightweight aerated concrete with water, pressure molding, and carbon dioxide curing. However, this method increases the width of the material used and reduces the material cost. On the other hand, a cemented hardened product is used as a powder, and after mixing with water, it is pressure-molded and cured with carbon dioxide gas. A device, a pressure molding device, a carbon dioxide gas curing device, etc. are required, and there is a problem that the equipment cost becomes expensive and entry is difficult unless the facility has already been introduced.

JP 10-33979 A JP 2001-353418 A JP-A-6-99063 JP-A-7-284628

  The problem to be solved by the present invention is to provide a cement-based humidity control material that can be manufactured at room temperature and normal pressure without using an expensive device, and a method for manufacturing the same.

The present invention, water-cement ratio is a ratio of water to cement to give a 5 or more of the cement slurry, the cement slurry is held water-cement ratio is 5 or more states 4 hours or more, after its processes carbonation Thus, a cement-based humidity control material is obtained.

  In cement-based humidity control materials obtained by carbonation treatment, it is the crystal structure of calcium carbonate in the humidity control material that greatly affects the humidity control function. It is said that the greater the amount, the greater the surface area and the higher the humidity control capacity.

  In the present invention, this fine crystal structure of the vaterite-type calcium carbonate is efficiently generated by increasing the water cement ratio (water / cement) to 5 or more.

The present invention will be explained in detail. First, tricalcium silicate, which is a main component of cement, is in contact with water, half of which is calcium silicate hydrate and the other half is calcium hydroxide. The hydration reaction of tricalcium silicate progressed remarkably between 6 and 24 hours after hydration, and initially the amount of calcium silicate hydrate is high, but the amount of calcium hydroxide increases with time. It has been reported. Here, calcium hydroxide is greatly affected by changing the water cement ratio, but the calcium hydroxide crystal structure changes depending on the water cement ratio. That is, when the water cement ratio is small, the calcium hydroxide develops in a columnar shape, and the crystal becomes larger as the water cement ratio is smaller. Conversely, when the water cement ratio is large, the calcium hydroxide is the most beautiful figure. And the size is reduced. (For example, Kashima Publishing Co., Ltd. Easy-to-understand knowledge of cement and concrete P64-65)

  The present invention utilizes the difference in the crystal structure of calcium hydroxide depending on the size of the water cement ratio. By increasing the water cement ratio to 5 or more, the crystal structure of calcium hydroxide is made fine. By subjecting calcium hydroxide to carbonation treatment, vaterite-type calcium carbonate having a fine crystal structure is obtained. In addition, in the concrete mix at the time of concrete product production, in order to increase the strength of the concrete, the water cement ratio is reduced in a range that does not affect the slump, etc., the water cement ratio is usually about 0.5, The water cement ratio is not increased to 5 or more as in the present invention.

  Here, as described above, the hydration reaction of tricalcium silicate (formation of calcium hydroxide) proceeds rapidly when about 6 hours or more have passed after adding water to the cement, and gradually declines after about 24 hours. Therefore, in order to sufficiently produce fine calcium hydroxide, a cement slurry in which water is added to cement to have a water cement ratio of 5 or more is used for at least 4 hours or more, preferably 6 in a state where the water cement ratio is 5 or more. Hold for more than an hour. However, since the formation of calcium hydroxide does not increase much even if it is maintained for more than 24 hours, the retention time of the cement slurry is preferably 6 hours or more and 24 hours or less after adding water to the cement.

  Since the cement slurry contains hexavalent chromium, the hexavalent chromium is reduced as needed while the cement slurry is held for the predetermined time.

  In the carbonation treatment carried out after holding the cement slurry for the predetermined time described above, carbon dioxide is absorbed by calcium hydroxide produced by a hydration reaction such as tricalcium silicate, and the vaterite-type calcium carbonate having a fine crystal structure is absorbed. Reform. This carbonation treatment is preferably carried out using an apparatus that is cured under a carbon dioxide atmosphere from the viewpoint of efficiency. However, the use of combustion exhaust gas or air drying that absorbs carbon dioxide in the atmosphere and performs carbonation may be used. . In air drying, the speed of carbonation changes depending on temperature, humidity, etc., and the humidity control ability of the resulting humidity control material will also be affected. If carbonation is advanced over a period of about one week, charcoal and zeolite A humidity control material having a certain level of humidity control capability can be obtained. This air drying is preferable from the viewpoint of cost because no special apparatus is required for the carbonation treatment.

  As described above, the humidity control material obtained by the present invention has a humidity control capability equivalent to that of commercially available charcoal and zeolite, and can be used as a material for a humidity control material for a floor or a humidity control building material. In particular, when used as a humidity control material for underfloor, the calcium hydroxide in the material reacts with water to form a strong alkaline aqueous solution having a pH value of about 11 to 12, so that it also has an insect repellent function that suppresses the generation of mold and white ants. Demonstrate. Moreover, since this humidity control material has a deodorizing capability in addition to the humidity control capability, it can also be used as a material for a deodorizing material.

  In addition, the humidity control material obtained according to the present invention is passed through a crushing device and a sieve, further carbonized, and dropped to a weak alkali having a pH value of about 9 (8.5 to 9.5). come. For example, it can be used for livestock materials used instead of bedding as a mastitis prevention measure for dairy cows. Since this carbonation requires a certain period of time, a carbonator or the like may be used. As a low-cost means, humidity control material passed through a 5 mm sieve is spread to a thickness of 2 to 10 cm or less, and by repeating watering and air drying, it can be lowered to a predetermined pH value in 1 to 2 months. .

  As the cement used for the production of the humidity control material in the present invention, Portland cement, blast furnace cement, silica cement, fly ash cement, and mixtures thereof such as early strong, very early strong, moderate heat, low heat, and white are used. can do. A new cement slurry may be prepared by blending these cements with water, but in the present invention, concrete sludge generated in the concrete production process can be used as the cement slurry. Concrete sludge is obtained by washing concrete adhering to a manufacturing apparatus or the like with water during the concrete manufacturing process, and its water-cement ratio is always greater than 5 without any particular adjustment. It can be used as a cement slurry as a raw material.

  Concrete sludge belongs to the category of sludge under the Waste Management Law, and when it is finally disposed, it is obliged to bring it to a managed landfill unless intermediate treatment is performed. As an effective method of using this concrete sludge, it can be used for roadbed materials, etc., but the main component calcium hydroxide reacts with water to form a strong alkaline aqueous solution having a pH of about 11 to 12, and there is concern about the impact on the environment, etc. For the reasons mentioned above, most of the landfill is disposed at the final disposal site. Thus, in the present invention, the concrete sludge that has been disposed of in the past can be effectively used as a raw material for the humidity control material, and the humidity control material can be manufactured at a low cost and the disposal cost of the concrete sludge can be reduced. it can. In addition, it can extend the life of final disposal sites and contribute to global environmental conservation.

Furthermore, carbonation of concrete sludge is performed by air drying in the production of humidity conditioning materials, and if used as a humidity conditioning material, CO ₂ in the atmosphere can be fixed. For example, calcium hydroxide contained in concrete sludge When the amount is 30% by mass, the fixed amount of CO ₂ by carbonation is about 0.2 tons per ton of concrete sludge, which can also contribute to global environmental conservation. That is, conventionally, concrete sludge has been landfilled at the final disposal site and has only fixed CO ₂ only on the surface in contact with the atmosphere, and has not been effectively used as a CO ₂ fixing means. By enlarging the value, enormous CO ₂ fixation can be realized. Even if the raw material for new concrete and water-cement slurry humidity material blended can be fixed CO _2.

  In the present invention, when concrete sludge is used as a raw material for humidity control material, the concrete sludge contains crushed stone and sand of the concrete raw material, so the crushed stone and sand are removed with a sieve etc. from the quality control aspect, and only the sludge is separated. You should do it. This removal treatment may be performed after holding the concrete sludge for the above-mentioned predetermined time. However, if the water-cement ratio does not become less than 5 by this treatment, it may be performed during the above-mentioned holding for the predetermined time. Further, in the carbonation treatment, it is preferable to perform a dehydration treatment in advance in order to secure a contact surface with carbon dioxide. In this dehydration treatment, it is preferable that the water content of the sludge is about 1 to 1.5 from the viewpoint of workability. The same applies to the case where a cement slurry having a water-cement ratio of 5 or more is used by newly blending cement and water.

  According to the present invention, a cement-based humidity control material can be obtained at room temperature and normal pressure without using an expensive device such as an autoclave as in the prior art. Therefore, it can be manufactured by existing facilities of small-scale commercial concrete companies and concrete product companies.

  Further, in the present invention, by performing the carbonation treatment after setting the water-cement ratio of the cement slurry to 5 or more and holding it for 4 hours or more, calcium carbonate containing a large amount of the crystal structure of vaterite can be efficiently generated. Since the humidity function can be improved, a humidity control material having a humidity control capability equivalent to that of commercially available charcoal or zeolite can be obtained at a low cost.

  Furthermore, in the present invention, by using concrete sludge generated in the concrete manufacturing process as cement slurry as a raw material of the humidity control material, it is possible to effectively use the concrete sludge that has been disposed of in the past, The disposal cost can be reduced. Moreover, since the raw material cost of the humidity control material becomes substantially zero, the cost of the humidity control material can be reduced.

In addition, in the present invention, if the carbonation treatment of the cement slurry (concrete sludge) is performed by air drying in the production of the humidity control material, a special carbonation treatment apparatus is not required, and CO _{2 in} the atmosphere is eliminated. Can be fixed and contribute to global environmental conservation.

  In addition, the animal husbandry material whose humidity-controlling material has a pH value of about 9 is used in place of bedding as a mastitis prevention measure for dairy cows. It has very high water absorption and water retention and is weakly alkaline. In addition to the sterilization effect by, it has a deodorizing effect, thus providing a sanitary fattening environment. Furthermore, from the porous nature of the humidity control material, it can be expected to promote fermentation by cow manure composting.

  Embodiments of the present invention will be described below based on examples.

  In this example, the influence of the water-cement ratio of the cement slurry on the humidity control ability of the obtained humidity control material was investigated.

  In this example, 13 parts by weight (water cement ratio: 0.65), 40 parts by weight (water cement ratio: 2), 100 parts by weight with respect to 20 parts by weight of ordinary Portland cement and 80 parts by weight of silica sand. A cement slurry was prepared by mixing (water cement ratio: 5), 200 parts by weight (water cement ratio: 10), 400 parts by weight (water cement ratio: 20), and 800 parts by weight (water cement ratio: 40). Then, these cement slurries were kept at a temperature of 25 ° C. for one day and night, and those with a lot of water were discarded from the supernatant water and air-dried for about one week to obtain a humidity control material.

The obtained humidity control material was passed through a 3 mm sieve, filled in a petri dish with an inner diameter of 86 mm, and placed in a constant temperature and humidity chamber with substantially the same surface area, and a moisture absorption / release test was conducted. The moisture absorption / release test is based on JIS
It implemented based on A6909 (finishing coating material for construction) 7.32 moisture absorption / release property, and calculated moisture absorption / release amount (g / m ² ). FIG. 1 shows the relationship between the water cement ratio and the amount of moisture absorbed and released. From FIG. 1, it can be confirmed that the moisture absorption and desorption amount of the humidity control material increases when the water cement ratio is increased. In the present invention, the water-cement ratio of the cement slurry is set to 5 or more from the test results and the like. The water cement ratio is preferably 10 or more, and more preferably about 40 (40 to 50).

  In this example, the influence of the condition of carbonation treatment in the present invention on the humidity control ability of the obtained humidity control material was investigated.

  In this embodiment, concrete sludge (water cement ratio 10 to 13) generated in the concrete manufacturing process is used as a cement slurry, and this concrete sludge is passed through a sieve to remove crushed stones and sand, followed by a filter press for dehydration treatment. A sludge cake was obtained. The moisture content of this sludge cake was 1.3 to 1.4. It took 6 to 20 hours from the generation of concrete sludge to immediately before the dehydration treatment, and 6 to 20 hours until the completion of the dehydration treatment.

The obtained sludge cake was carbonized under the following five conditions.
Condition 1: Drying in an air atmosphere for about 3 hours Drying condition 2: Air-drying condition for 1 week 3: Air-drying for 1 week Once in the middle Water injection condition 4: Air-drying for 1 week: 1 day every 2 days Water injection condition 5: Drying to about pH 9 by air drying

  Each humidity control material obtained by carbonation treatment under these conditions was passed through a 3 mm sieve, filled into a petri dish with an inner diameter of 86 mm, placed in a constant temperature and humidity chamber with substantially the same surface area, and the same as in Example 1. The moisture absorption / release amount was calculated by the test procedure. The results are shown in FIG.

  As shown in FIG. 2, the carbonation treatment by air drying requires sufficient time to absorb carbon dioxide in the atmosphere, and in the carbonation treatment, calcium hydroxide, which is the main component in the sludge cake, is calcium carbonate. It can be seen that the reforming reaction is accelerated in the presence of water.

Carbonation treatment by air drying is affected by temperature and humidity. When drying the sludge cake to a moisture content of about 40-50%, it takes 1 day in the summer, 2 to 3 days in the winter, and the rainy season. A period of about one week is required. Usually, in order to make the moisture absorption / release amount of the humidity control material obtained from the sludge cake as in this example equivalent to that of a commercially available humidity control material such as zeolite (about 200 g / m ² ), a period of about one week It is sufficient to dry slowly while sprinkling water so as not to dry too much.

  In the present invention, the humidity control material carbonized by air drying has a pH value of about 10 to 12, and is not completely carbonized. By using it as a humidity control material, it absorbs carbon dioxide in the atmosphere and neutralizes over a long period of time. This process is the one in which the pH value was reduced to 9 or less under Condition 5. is there. According to the test conducted by the present inventor, the moisture absorption / release amount tends to increase / stabilize as the pH value decreases, and can be used for a long time.

  This example shows an example of the manufacturing process of the humidity control material of the present invention. FIG. 3 shows the manufacturing process.

  Sludge water generated in the concrete product manufacturing process is collected in the raw water pit 1. The concrete sludge collected in the raw water pit 1 is passed through a rotary sieve 2 to remove crushed stone and sand. Thereafter, the concrete sludge is sent to the stirring tank 3 and sufficiently stirred, and then sent to the settling tank 4. In the sedimentation tank 4, the supernatant water is removed and the concrete sludge is concentrated (water cement ratio 10 to 15). Next, the concentrated concrete sludge is sent to the filter press 5 for dehydration. Thereby, a sludge cake is obtained. The moisture content of this sludge cake was 1.3 to 1.4. It took 6 to 20 hours from the generation of concrete sludge to immediately before the dehydration treatment, and 6 to 20 hours until the completion of the dehydration treatment.

  Next, the obtained sludge cake is air-dried in the sludge drying station 6. In the sludge drying place 6, the sludge cake is loosened and dried to a water content of about 40 to 50%. In this drying, since the carbonization treatment of the sludge cake is performed at the same time, the carbonation period is a point. In order to loosen the sludge cake and dry it to a moisture content of about 40-50%, as explained in Example 2, it takes 1 day in summer, 2 to 3 days in winter, and about 1 week in the rainy season. Specifically, the air drying period is preferably about one week. Moreover, since moderate water is required for carbonation, it is necessary to spray the water so that it does not dry too rapidly.

  The dried sludge cake is passed through the crushing device 7, further passed through a vibration sieve 8, and stored in the stock yard 9 after being classified to 15 mm or less. The product classified into 15 mm or less is defined as a product (humidity control material).

The humidity control material of the present invention thus manufactured was compared with a humidity control material (zeolite, charcoal) commercially available. Each humidity control material was filled into a container having a length of 180 mm, a width of 180 mm, and a depth of 15 mm, and placed in a thermo-hygrostat and a moisture absorption / release test was conducted. The moisture absorption / release test was carried out in the same procedure as in Example 1, and the moisture absorption / release amount (g / m ² ) was calculated. FIG. 4 shows the measurement result by the humidity response method, and it can be seen that it has sufficient humidity control ability even when compared with a commercially available product.

  Moreover, the deodorizing ability evaluation test was done about the humidity control material of this invention. In this test, 10 g of the test material was dried in a constant temperature and humidity chamber with a humidity of about 30% for one week or more, and the test material was placed in a tetra bag and evacuated, and then air was adjusted to a specified concentration. And a test gas were added, and the gas concentration was measured with a detector tube after a specified elapsed time.

  The result is shown in FIG. It can be seen that the humidity control material of the present invention also has a deodorizing ability and can be used as a material for the deodorizing material.

[ Reference example ]
This reference example investigates the effect on the composting of cattle manure and the effect of the resulting fertilizer on the plant when the pH value of the humidity conditioning material is reduced to about 9 (hereinafter referred to as sludge) It is a thing.

  Since the amount of experimental compost is small, four types of compost with sludge content adjusted to 0%, 10%, 20%, and 30% were produced using a stirring fermentation system. In each case (100 L), 7 kg of raw manure, 3 kg of rice bran, and 20 kg of primary fermented cow dung were added, and further, 0 kg, 3 kg, 6 kg, and 9 kg of livestock materials were added according to the test section and stirred well. The manure was made by the method of measuring and recording the temperature at five arbitrary places before stirring the next day with stirring. FIG. 6 shows the transition of the compost fermentation temperature. As shown in the figure, the effect of accelerating fermentation can be confirmed from the fact that all of the added zones exceeded the temperature of the non-added zone on the third day of the test, and the 10,20% added zone clearly exceeded the non-added zone at the integrated temperature. It was.

  The fertilization effect test was done using the experimental compost that was made. In the germination survey, the test fertilizer plots showed the same results for germination and germination rate in all test plots, and the weight of the livestock was the same as the sludge content increased when evaluated based on the 0% sludge test plot (compost 100%) Or better. From this, there was no abnormal symptom of plant growth that was considered to be the effect of sludge formulation. FIG. 7 is a photograph of the growth situation 21 days after sowing.

The influence which the water cement ratio of a cement slurry has on the humidity control ability of the obtained humidity control material is shown. The influence which the conditions of a carbonation process have on the humidity control ability of the obtained humidity control material is shown. The manufacturing process example of the humidity control material of this invention is shown. The humidity control capability of the humidity control material of this invention is shown. The deodorizing ability of the humidity control material of this invention is shown. The fermentation promotion effect in the cow manure composting by the livestock material of this invention is shown. The fertilization effect test result using the cow manure compost by the livestock material of this invention is shown.

1 Raw water pit 2 Rotary sieve 3 Stirring tank 4 Sedimentation tank 5 Filter press (dehydration processing equipment)
6 Sludge drying area 7 Crushing device 8 Vibrating sieve 9 Stockyard

Claims (3)

Water-cement ratio is a ratio of water to cement to give a 5 or more cement slurry, the cement slurry is held water-cement ratio is 5 or more states 4 hours or more, Later, obtained by treating carbonated Humidity conditioning material. A method for producing a humidity control material, wherein a cement slurry having a water cement ratio of 5 or more, which is a ratio of water to cement, is obtained, and the cement slurry is held for 4 hours or more in a state where the water cement ratio is 5 or more, and then carbonized. . 2. The humidity control material according to claim 1, wherein the cement slurry is Portland cement, blast furnace cement, silica cement, fly ash cement and their components, a mixture and water are kneaded, and sand is further added and kneaded. Humidity control material characterized by being