JP2012025620A - Low-water ratio cement formed body, and method for forming low-water ratio cement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a cement formed body having a good compression resistive strength by a small amount of water.SOLUTION: The cement formed body is manufactured by kneading a cement, a microparticle having a particle diameter of ≤1 mm and water of 5 to 20% to the cement, and thereafter compression forming the kneaded material. Particularly, the microparticle is utilized which is prepared by water granulating municipal waste melt slag and sieving and sorting the granulated slag. Thus, a cement and a microparticle are compression formed, so that a cement formed body is well manufactured; water is added in a ratio of the water content necessary and enough to the cement of 5 to 20%, so that the use amount of water becomes smaller than in conventional cement forming and the curing time can e largely reduced and occurrence of slippage in compression is prevented to well carry out the forming; further, as the microparticles becoming aggregates, microparticles having a particle diameter of ≤1 mm are sieved and sorted and used, so that the compression-resistive strength can be increased.

Description

  The present invention relates to a low water cement molded body and a low water cement molding method.

  Conventionally, cement molded bodies using cement as a binder have been widely used as civil engineering / construction materials (see, for example, Patent Document 1).

  This conventional cement molded body contains a large amount of aggregates such as crushed stone and sand in order to obtain a desired compressive strength, kneaded after adding cement and a large amount of water to this, and then into a predetermined shape. In order to do this, it is poured into a mold, left to solidify for a long time, and then demolded.

JP 2007-291788 A

  However, in the conventional cement molded body, since the desired compressive strength is obtained by the aggregate, the aggregate itself is required to have hardness, strength, etc., and the aggregate material quality, size, etc. There were restrictions.

  On the other hand, in the field of civil engineering and construction, resources such as crushed stone and sand are depleted, and a large amount of fine powder is generated, such as sludge during crushed stone and noro during cleaning of ready-mixed concrete. Nevertheless, these fine powders have not been used as aggregates because they have a large surface area, increase the amount of cement required for solidification, and are weak in strength. .

  Therefore, the present inventor has developed a technique for producing a cement molded body having a good compressive strength by using a fine powder that has not been conventionally used as an aggregate.

  In the present invention according to claim 1, in the low water cement molding method, a cement molded body is manufactured by kneading cement, fine powder having a particle diameter of less than 1 mm, and water having a cement ratio of 5 to 20% and then compression molding. Decided to do.

  Further, in the present invention according to claim 2, in the present invention according to claim 1, the fine powder obtained by pulverizing municipal waste molten slag and then screening it is used.

  Moreover, in this invention which concerns on Claim 3, in this invention which concerns on the said Claim 1 or Claim 2, it decided to cure in alkaline water or normal water after mold removal.

  Moreover, in this invention which concerns on Claim 4, in this invention which concerns on the said Claim 3, the aging in alkaline water or normal water, and subsequent drying were repeatedly performed after demolding.

  Moreover, in this invention which concerns on Claim 5, in this invention which concerns on any one of the said Claims 1-4, it decided to knead | mix a fiber body.

  Further, in the present invention according to claim 6, the low water cement molded body is manufactured by kneading a cement, a fine powder having a particle size of less than 1 mm, and water having a cement ratio of 5 to 20% and then compression molding. I made it.

  Moreover, in this invention which concerns on Claim 7, in this invention which concerns on the said Claim 6, it decided to utilize what screened the municipal waste molten slag after granulating as the said fine powder.

  Moreover, in this invention which concerns on Claim 8, in this invention which concerns on the said Claim 6 or Claim 7, it decided to knead | mix a fiber body.

  In the present invention, a cement molded body using fine powder having good compression strength is manufactured by kneading cement, fine powder having a particle diameter of less than 1 mm, and water having a cement ratio of 5 to 20%, followed by compression molding. can do.

  In particular, when municipal waste molten slag is used as a fine powder, the municipal waste molten slag as waste can be effectively used.

  Moreover, when a fiber body is mixed, the bending strength of a low water cement molded object can be increased.

  Furthermore, when it is cured in water after demolding, sufficient reaction water necessary for solidification can be obtained.

In order to obtain a conventional compressive strength of 30 N / mm ² ,
Cement: 344Kg
Water: 165Kg
Aggregate: 733Kg
The mixture was kneaded, poured into a mold, demolded after a predetermined time, and cured after a demolding for a predetermined period.

  On the other hand, in the present invention, attention was paid to the use of fine powder as an aggregate in consideration of exhaustion of aggregate resources and processing of a large amount of fine powder.

  However, when fine powder is simply used as an aggregate, the amount of cement required for solidification increases due to the large surface area of the fine powder, and the amount of water used increases accordingly. In addition, there is a concern that the compressive strength is reduced by making the aggregate into fine powder.

  Therefore, it is necessary to develop a technique that does not reduce the compressive strength as a cement molded body while using fine powder as an aggregate.

  Therefore, in order to maintain good compressive strength, first, cement and fine powder are compressed and molded inside the mold, not simply cured in the mold to produce a cement molded body. I made it.

When cement and fine powder are compressed and molded inside the mold, high-density cement moldings can be produced as the pressing force increases, but the density is naturally limited. in about 200Kgf / cm ² ~1000Kgf / cm ² or so), slippage occurs due to the frictional resistance of the fine mutual cement and fine powder, stepwise the density increases to not proportional and the pressure and density I understood.

  In order to perform the compression molding of the cement and the fine powder smoothly without causing any slip, it was considered to add a certain amount of water so as to reduce the frictional resistance of the fine powder.

  In the conventional cement molded body, since the cement is solidified by utilizing the hydration reaction between the cement and water, a lot of water is added in consideration of the water absorption of the aggregate itself. Since the cement and the fine powder are basically solidified by compression molding, it is sufficient to add a minimum amount of water. Therefore, when a cement molded body was produced by adjusting the amount of water, a moisture content of less than 5% in terms of the cement ratio could not obtain a compression resistance strength because the cement and fine powder could not be smoothly compression molded, It has been found that when the water content is 20% or more in terms of the cement ratio, the compression strength cannot be obtained due to excess water, and a long-term curing is required after molding.

Based on the above examination results, in the present invention, fine powder is used as an aggregate, and water having a cement-to-cement ratio of 5% or more and less than 20% is added thereto, and these are kneaded and then poured into the mold. Then, a predetermined pressure (about 320 kgf / cm ^{2 to} about 600 kgf / cm ² ) was applied inside the mold to perform compression molding.

  Furthermore, paying attention to the particle size of the fine powder, the influence of the particle size of the fine powder on the compressive strength of the cement molded body was examined.

That is,
Cement: 100Kg
Fine powder: 330Kg
Water: 15Kg
Then, the fine powder was sieved to produce a cement molded body having a different particle size of the fine powder, and its compressive strength was measured.

Then, it was found that when the particle size of the fine powder is 1.0 mm or more (less than 3.0 mm), the compressive strength is reduced to 17.46 N / mm ² compared to normal concrete.

On the other hand, when the particle size of the fine powder was less than 1.0 mm, it was found that the compressive strength was increased to 31.43 N / mm ² compared to ordinary concrete.

Furthermore, when the particle size of the fine powder is less than 0.5 mm, it becomes 32.97 N / mm ² , and when the particle size of the fine powder is less than 0.25 mm, it becomes 36.20 N / mm ² , which is more resistant than ordinary concrete. It was found that the compressive strength was increased.

Therefore, based on the above examination results, in the present invention, fine powder of less than 1.0 mm, preferably less than 0.5 mm, particularly less than 0.25 mm is used as aggregate, and in particular, when compressive strength is required, it is screened and used. cement and cement ratio more than 5% less than 20% of water is added, these poured inside the mold after the kneading, a predetermined pressure in the interior of the mold (about 320Kgf / cm ² ~600Kgf / cm ² or so) And decided to compress.

  Here, the fine powder is not limited to municipal waste molten slag, but sludge during crushed stone, noro during cleaning of ready-mixed concrete, foundry sand, metal powder, metal oxide powder, grinding stone powder, glass powder, fly ash and asbestos Various powdered substances such as asbestos decomposition products can be used, and in any case, a low water cement molded article with good compression strength can be obtained by screening and using the above particle size. .

  In particular, when municipal waste molten slag is finely powdered and then screened and then screened, it is possible to effectively use the municipal waste molten slag as waste.

  This municipal waste molten slag is usually discharged as sand particles dispersed in a size of 0.075 mm to 5 mm by water granulation. In addition, municipal waste molten slag has a number of microcracks, and has a disadvantage that its compressive strength is very low compared to ordinary stones and is easily cracked.

  For this reason, when municipal waste molten slag is used for purposes other than civil engineering, it is not suitable for use in the discharged state.

  On the other hand, municipal waste molten slag has a high hardness of about 5 Mohs hardness, a specific gravity of the same level as that of ordinary stone, a low water absorption of about 0.3%, and a small amount of foreign matter. .

  Therefore, in the present invention, the discharged municipal waste molten slag was crushed with a roll crusher, and then the crushed municipal waste molten slag was sieved using a 1 mm square mesh screen.

  As a result, the crushed municipal waste molten slag was separated into municipal waste molten slag with a particle size of 1 mm or more remaining on the screen by sieve sorting and municipal waste molten slag with a particle size of less than 1 mm that passed through the screen by sieve sorting. .

  Here, the size of municipal waste molten slag is selected in relation to the required compressive strength, since the compressive strength improves as the size of the slag becomes finer. The following is preferable, desirably 0.25 mm or less.

  Then, municipal waste molten slag having a particle diameter of 1 mm or more was recovered, supplied as shot blasting material, and repeatedly used as blasting material 5-6 times.

  This municipal waste molten slag with a particle size of 1 mm or more has characteristics such as high hardness and low water absorption, so even if it is used as a blasting material, the roughness of the blasting surface, the sedimentation speed, hardness, durability, etc. There is no problem in fluidity due to moisture absorption, it can be used as an excellent blasting material, and it costs about a fraction of the cost of a conventional grit material. It was confirmed that

  Moreover, the municipal waste molten slag supplied as the blast material was collected after being repeatedly used as the blast material 5 to 6 times. The recovered blast material (city waste molten slag) is repeatedly used as a blast material, so that it is crushed and worn, and is smaller in size than at the time of supply. When collecting, powdery metal generated in shot blasting, rust, coating agent, and the like were also collected.

  This recovered blast material (city waste molten slag) was used as aggregate. At that time, the recovered blast material may be screened and only the blast material having a particle size of less than 1 mm may be used as the aggregate. However, the aggregate is mixed with the municipal waste molten slag of less than 1 mm separated in the screen screening. I decided to use it as

  In this way, municipal waste molten slag less than a predetermined size (here, particle size of 1 mm) by sieving and municipal waste molten slag repeatedly used as blasting material is compared with the municipal waste molten slag discharged at the beginning. Atomized. This is because the initial municipal waste molten slag is unsuitable as an aggregate because of its low compressive strength, but the compressive strength increases due to atomization and can be mixed in large quantities as an aggregate of a solidifying agent. Because it becomes.

  As described above, in the present invention, a low water cement molded body is manufactured by compression molding after kneading cement, fine powder having a particle size of less than 1 mm, and water with a cement ratio of 5 to 20%. ing.

  Thus, by compressing and molding cement and fine powder, a cement molded body can be produced satisfactorily, and by adding water of 5 to 20% to the cement ratio as necessary and sufficient water, The amount of water used is significantly less than cement molding, and the curing time can be greatly shortened, and it can be molded well by preventing the occurrence of slipping during compression. Compressive strength can be increased by screening and using particles having a particle size of less than 1 mm.

  Moreover, since it is a low water cement with a low moisture content, it can be removed immediately after compression molding, the curing period in the mold can be omitted, and the production in a short period is possible. .

  Further, after demolding, sufficient reaction water required for solidification may be obtained by immersing in alkaline water (alkaline water) or normal water (neutralized water) for about 10 hours, for example. This curing in alkaline water or normal water and subsequent drying (for example, natural standing for 3 days) may be repeated a plurality of times. In addition, you may make it cure in the air which is not restricted to water but a water | moisture content is supersaturated.

  Moreover, when kneading cement, fine powder and water, it is not limited to the case where water with a weight ratio of cement of 5 to 20% is added. Water having a ratio of 20% or more may be added so that the amount of water remaining after dewatering from the mold is 5 to 20% in terms of the weight ratio of cement.

  Furthermore, a fibrous body such as cellulose may be mixed for reinforcement. When a fiber body is mixed, since it does not contain coarse particles and has good fluidity, the fiber body is aligned and solidified in a direction perpendicular to the compression direction during compression molding. The bending strength of the low water cement molded product can be increased.

Claims (8)

  A low water cement molding method comprising producing a cement molded body by kneading cement, fine powder having a particle diameter of less than 1 mm, and water having a cement ratio of 5 to 20%, followed by compression molding.   The low water cement molding method according to claim 1, wherein the fine powder is obtained by granulating municipal waste molten slag and then screening.   The low water cement molding method according to claim 1 or 2, wherein the molding is performed in alkaline water or normal water after demolding.   4. The low water cement molding method according to claim 3, wherein after demolding, curing in alkaline water or normal water and subsequent drying are repeated.   The low water cement molding method according to any one of claims 1 to 4, wherein the fiber body is kneaded.   A low water cement molded article produced by compression molding after kneading cement, fine powder having a particle size of less than 1 mm and water having a cement ratio of 5 to 20%.   The low water cement molded article according to claim 6, wherein a municipal waste molten slag which has been subjected to water granulation and then screened is used as the fine powder.   The low water cement molded article according to claim 6 or 7, wherein a fibrous body is kneaded.