JP2000319053A - Cement admixture composed of calcium saccharate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain calcium silicate at a relatively low temp. by reacting a silicate raw material with quick lime or lime in the presence of calcium saccharate obtained by the reaction of slaked lime or quick lime with saccharide. SOLUTION: The calcium silicate compound is easily obtained by utilizing a fact that the solubility of slaked lime or quick lime to water is remarkably increased when the saccharate is generated by the reaction of quick lime or slaked lime with saccharide and reacting with the silicate raw material at a low temp. of <=100 deg.C. As the saccharide, it is necessary to select a saccharide such as glucose, saccharose, molasses or the like having large degree of lime saturation and a high purity saccharide is not suitable. As the silicate raw material, a clay mineral such as diatom earth, siliceous earth, bentonite, or a natural silicate material such as silica stone, volcanic stone or an artificial silicate mineral such as incineration ash, blast furnace slag or the like is used. The quantity of the saccharide or calcium saccharate to be added is 0.02-10 pts.wt., preferably 0.1-5 pts.wt. per 100 pts.wt. lime expressed in terms of saccharide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement admixture comprising calcium saccharate which can be widely used in the field of civil engineering and construction materials, and a method for producing the same.

[0002]

2. Description of the Related Art It is known that, in the reaction between diatomaceous earth, clay, and volcanic ash, which are conventional silicate-containing substances, and quick lime, the reaction activity between the silicate-containing substance and quick lime greatly affects productivity. Have been. Therefore, special quicklime which controls hydration of quicklime is manufactured. However, since the initial strength is greatly affected by the composition of the CaO-SiO ₂ compound, productivity such as a cement product cannot be expected. This efficient synthesis only in CaO-SiO ₂ type compounds hydration control of the conventional methods quicklime is because were secondary. For this reason, a method of generating demolding strength by performing heat curing has been adopted.

[0003] In order to solve this problem, it is necessary not only to control the hydration of quicklime but also to find conditions for increasing the solubility of quicklime in water and resulting in supersaturation.

[0004] Furthermore, calcium chloride cannot be used due to the problem of rebar corrosion, and a cement quick-setting agent is required instead. Calcium nitrate, calcium sulfite, calcium thiosulfate, calcium formate, calcium acetate and the like are known as alternatives to calcium chloride, but at present there is no cement quick-setting agent having the performance of calcium chloride.

[0005] The problem of the cement quick setting agent is that a small amount is required, and after a certain period of time, a cured product having a high rise strength can be obtained. For this purpose, calcium aluminate such as C12A7 and C11A7CF2 is preferable, but it is expensive. is there.

[0006] A liquid quick-setting agent different from the above-mentioned calcium aluminate powder is also required. There is a need to search for new calcium salts that are not known substances. It is known that saccharides form calcium saccharate when added to cement, and when used in small amounts, act as a retarder, and when used in large amounts, rapidly set. In addition, it is not put to practical use because it causes a decrease in strength.

[0007] As for calcium saccharate, only sucrose is well known, and other saccharides are hardly known at present. Therefore, it has almost no use in addition to its physical properties.

Therefore, it is necessary to synthesize calcium saccharates of various saccharides, find their uses and new production methods, and provide them to the industry.

[0009]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, completed the present invention.

That is, the present invention relates to a cement admixture comprising calcium saccharate obtained by reacting slaked lime or quick lime with a saccharide and a method for producing the same, and a method for producing a silicic acid raw material and quick lime or lime in the presence of the calcium saccharate. It is intended to provide a method for producing calcium silicate characterized by reacting.

First, the case where the calcium saccharate of the present invention is used for producing a calcium silicate compound will be described.

[0012] The calcium silicate compound is used as a raw material for silicic acid, using clay minerals such as diatomaceous earth, clay, bentonite and the like, and natural silicate minerals such as silica powder and volcanic ash, or artificial silicate minerals such as incineration ash and blast furnace slag, and reacting with quick lime or lime. Product.

Conventionally, in order to obtain these calcium silicate compounds, a mixture of a silicic acid raw material and quicklime or lime is kneaded with water, and the mixture is produced by an autoclave curing by a hydrothermal reaction. This is because the reaction between silica and lime is the best condition in the conventional method at around 150 ° C, and the reaction cannot be completed at a temperature of 100 ° C or less.

In the present invention, when quicklime or slaked lime reacts with saccharides to form calcium saccharate, it takes advantage of the fact that its solubility in water is very large, and it is possible to use the silicate material as a raw material.
We succeeded in easily obtaining calcium silicate compound at low temperature below ℃.

In this reaction, the saccharide forms a supersaturated aqueous solution with quicklime or slaked lime, and the solid and liquid of silicic acid and calcium saccharate react with each other. When the reaction is completed, the saccharide dissociates to form quicklime or lime and calcium saccharate again. The reaction is based on the principle that saccharides react to form a kind of catalytic action to produce calcium silicate.

Therefore, the amount of saccharide added to the reaction has a great influence on the formation of calcium silicate. That is, there is a difference in reactivity depending on the degree of lime supersaturation of the sugar, which affects the reaction as a quantitative difference. Therefore, it is necessary to select a saccharide having as high a degree of lime supersaturation as possible.

[0017] Sugars suitable for this purpose are glucose, sucrose and molasses, and saccharides with a high degree of purification are not suitable.

In the present invention, the reaction equivalent of quicklime or lime and various silicic acid raw materials depends on the respective purity, but is generally 100 parts by weight of diatomaceous earth with respect to 65 parts by weight of quicklime for Bordeaux. This reaction equivalent is almost a stoichiometric amount, and even if other raw materials are used, the objective can be achieved by a stoichiometric amount in terms of purity. If necessary, quicklime may be used by partially replacing it with slaked lime.

Although quick lime is not particularly specified in the present invention, hard-burned quick lime is mainly used in the conventional method, while lightly burnt quick lime can be used in the present invention.

The method for synthesizing a calcium silicate compound using the calcium saccharate of the present invention includes a method in which a saccharide is directly dissolved in kneading water and use, a method in which a calcium saccharate is previously synthesized and used as an aqueous solution, or a method in which a powdered calcium saccharate is used. Any method, such as a method of using as a rate, may be used.

These calcium saccharate addition methods have some differences in the initial reaction of calcium silicate, but do not affect the final product.

In the present invention, the amount added as saccharide or calcium saccharate is 0.02 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of lime in terms of saccharide.

In the present invention, cement, alumina, sodium silicate, gypsum, alkali metal salts, and chelating agents can be used as reaction aids.

The present invention does not deny the conventional method, and is also a means by which the present invention and the conventional method can be used together to further rationalize the production of calcium silicate.

In the present invention, the synthesis of calcium silicate is promoted by using calcium saccharate as a reaction catalyst. Therefore, if the added amount of the saccharide is not within the above range, the cured product has reduced water resistance and cannot obtain good physical properties.
The nature of the hydrated product of calcium silicate containing saccharides was that the initial hydrate generated a large amount of CSH diels, and CSH and topamolite, which were not seen in the conventional method, were formed at room temperature.

Ca (OH) accompanying hydration of CaO by addition of saccharides
_This is the reason why the above reaction is promoted at room temperature because the solubility of water in ₂ becomes large and increases with the amount of added sugar.

By utilizing this reaction, not only calcium silicate products conventionally produced but also Portland cement can be used, and on-site construction can be performed. In addition, it is possible to harden clay or the like which is hard to cure with Portland cement. In addition, it is widely used because of its low cost. For example, not only can ALC and silica plate be supplied at low cost, but also most concrete products for civil engineering and construction can be manufactured. Waste soil at the site can also be used as a soil stabilizer.

For example, when a mixture of quicklime containing calcium saccharate and slaked lime of slaked lime is consolidated by using construction waste soil of Kanto Loam, an early-strength hardened product can be obtained.

This composition contains 70 parts by weight of quicklime and 30 parts of slaked lime.
20 parts by weight of the mixture, 120 parts by weight of a 3% aqueous glucose solution and waste soil 20
0 parts by weight were mixed and consolidated. The setting time is 23 minutes,
Specimen increases strength temporarily at room temperature, compressive strength 18kg / cm in one week
^TwoCompressive strength 64kg / cm in 4 weeks ^TwoMet.

When the present invention is used as a grouting agent, it must satisfy conditions such as particle size, viscosity, thixotropy, permeability, gel time, gel strength, water resistance and safety of the raw material used. The grouting agent is used for various purposes, and different performances such as water-stop grout, back grout, and soil stable grout are required. Therefore, the grouting agent of the present invention has a particle size of 5 μm or more, so that the range of use is naturally restricted. However, it is suitable for back grout and soil stable grout requiring a gel time of about 10 minutes.

For example, 100 parts by weight of bentonite, quicklime,
60 parts by weight of slaked lime mixture (of which calcium saccharate 20
In the formulation of 200 parts by weight of water and 200 parts by weight of water, the liquid properties of LW method are similar to 100 parts by weight of No. 3 sodium silicate + 100 parts by weight of water, 100 parts by weight of Portland cement + 100 parts by weight of water. However, the grout of the present invention is superior in permeability to standard sand. To accelerate the gel time, it is effective to add caustic soda, sodium silicate, or the like to the grout formulation of the present invention to increase the reaction activity.

The calcium silicate compound obtained in the present invention is used in substantially the same manner as Portland cement, and the difference is in the heat generated during mixing. However, as in Portland cement, aggregates or various admixtures are used. Moldings can be manufactured.

Next, the case where the calcium saccharate of the present invention is used as a cement admixture will be described.

The calcium saccharate of the present invention is added to Portland cement (hereinafter referred to as cement) in an amount of 2 to 10%.
When the weight% is added, the viscosity of the cement slurry increases and at the same time, the cement becomes quick setting.

[0035] Sugars are conventionally known to retard the setting of cement and reduce the strength and to erode concrete. However, this is for use as a sugar, and the one obtained by completely reacting the OH group of the sugar with calcium and crushing it like the calcium saccharate of the present invention is completely harmless to concrete. That is, even if the concrete specimen is immersed in a 20% by weight aqueous solution of calcium saccharate for one month, the strength of the concrete specimen does not decrease at all.

The neutralized concrete specimen is applied with a 20% by weight aqueous solution of calcium saccharate to re-alkalize, which is effective for increasing the strength.

The saccharides used in the cement admixture include polysaccharides in addition to sucrose and starch sugar.

[0038] Preferably, a saccharide having high solubility of calcium which is inexpensive and does not affect the cement strength is required.
Such saccharides include glucose, sucrose, fructose, maltose, xylose, lactose, sorbose, sugar alcohols and invert sugars or sugar derivatives thereof.

To produce the cement admixture of the present invention,
The OH groups of the saccharide must be reacted until they are completely saturated with calcium. Therefore, it is necessary to use a little excess quicklime or add slaked lime so that there is no unreacted state. However, there must be no unreacted quicklime.

The reaction ratio of the above saccharide to quicklime or slaked lime is 20 to 40 parts by weight of lime to 100 parts by weight of saccharide. However, this depends on the type of sugar, and sucrose has 20 to 30 parts by weight of lime per 100 parts by weight. Depending on the application, the cement admixture is provided in powder or aqueous solution. Further, another cement admixture may be used in common.

This cement admixture has almost the same quick-setting properties as calcium chloride, and has higher strength than calcium nitrate, calcium formate, calcium thiosulfite and the like.

Calcium chloride was used in an amount of 1.0 to 3.0 parts by weight per 100 parts by weight of cement. It was used in. However, it was discontinued due to rebar corrosion, and a new quick-setting agent was required instead. The calcium saccharate of the present invention has the same quick setting property and freezing point lowering action as calcium chloride.Conventionally, when calcium chloride is added to cement, some heat is generated, but this heat is very effective for setting of cement. is there. The calcium saccharate of the present invention also generates more heat than calcium chloride. 5.3 for a water ratio of 0.5 on a 200 g cement scale
A temperature increase of ° C. was observed.

Further, when synthesizing C12A7 and C11A7CF2, conventionally, a method of melting alumina, calcium carbonate as a main raw material in an electric furnace, pulverizing and hydrating, re-melting and re-milling has been performed. Was. This is because the reactivity during melting is low. Therefore, in the present invention, aluminum dross, aluminum hydroxide, and alumina are used as the alumina source, and slaked lime or quicklime is used as the calcium source to reduce the saccharides to 1 to 1.
When kneaded with 50% by weight aqueous solution and melted, C12A7,
C11A7CF2 could be synthesized.

This is because, when the powder used as the alumina source and the powder used as the calcium source simply use water, they react on the surface of these particles to easily generate an unreacted calcium source. This is because it is difficult to form a lump by reacting in a solution state. As a result, the reaction efficiency increased, and free lime was 0.7% in one melting. Also, when baked at 800 ° C. which is not a melting method, it was 0.9% free lime.

Calcium aluminate synthesized in this manner is mixed with a small amount of hydroxycarboxylate and added in an amount of 5 to 10% by weight of the cement to provide a high-performance cement quick setting agent.

The calcium saccharate of the present invention as described above can be obtained by using quick lime, slaked lime or dolomite plaster as limes and reacting with various sugars.

The calcium saccharate of the present invention has a production method in which the type of saccharide and the content of calcium saccharate in quicklime and slaked lime are varied depending on the use. A method for obtaining a pure calcium saccharate is a method in which a saccharide and a lime such as quicklime, slaked lime or dolomite plaster are reacted as an aqueous solution, and recrystallized from the reaction solution to obtain a pure product. In this method, a general method is to filter the reaction solution, concentrate the filtrate, and cool to precipitate crystals of calcium saccharate. However, in the case of a highly deliquescent calcium saccharate, the water in the concentrate is replaced with a water-soluble solvent to precipitate calcium saccharate crystals. The crystals are filtered, vacuum dried and packaged without exposure to air. The calcium saccharate crystals thus obtained are in the form of white plates or needles, and depending on the type of sugar, some calcium saccharates have a low melting point, and some are easily liquefied at room temperature and exist as crystals only in the concentrated solution. .

The higher the sugar purity, the easier it is to obtain calcium saccharate crystals, and the lower the purity, the worse the crystallinity.

In the method for producing a calcium saccharate of the present invention, the reaction equivalent of CaO or Ca (OH) _{2 to} a saccharide is proportional to one molecule of a monosaccharide, which is a sugar composition, regardless of the kind of the saccharide. This is the weight ratio of monosaccharide 4.

[0050]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 Activated sludge incineration ash 100 parts by weight, lightly burnt lime powder 65 parts by weight,
Five parts by weight of the upper sucrose were mixed, and 135 parts by weight of water was added, followed by rapid kneading. This slurry was poured into a mold of 40 × 40 × 160 mm, and when it was allowed to stand, coagulation started after about 10 minutes, and heat was generated at 43 ° C., and finally hardened 4 minutes after the start. The specimen was cured in the air, and the strength for 4 weeks was 36 kg / cm ² in bending, 367 kg / cm ^{2 in} compression, and 0.92 in specific gravity.

Comparative Example 1 100 parts by weight of activated sludge incineration ash and 65 parts by weight of lightly burnt lime powder were mixed, and 135 parts by weight of water were added, followed by rapid kneading. Although this was poured into a mold, it rapidly generated heat and expanded, and a molded product could not be obtained.

Example 2 100 parts by weight of diatomaceous earth and 60 parts by weight of light burnt lime powder were mixed, and an aqueous solution in which 5 parts by weight of glucose was dissolved in 130 parts by weight of water was added and kneaded rapidly. This slurry was poured into a mold of 40 × 40 × 160 mm, and when it was allowed to stand, setting started after about 10 minutes and hardened after 5 minutes while gradually generating heat. The test specimen was cured in the air, and the strength for 4 weeks was bending 26 kg / cm ² , compression 107 kg / cm ² and specific gravity 0.86.

Comparative Example 2 100 parts by weight of diatomaceous earth and 60 parts by weight of light burnt lime powder were mixed, and 130 parts by weight of water were added, followed by rapid kneading. In about 1 minute, heat was generated rapidly, and the product expanded and no molded product was obtained.

Example 3 100 parts by weight of fly ash and 60 parts by weight of light burnt lime powder were mixed with 10 parts by weight of calcium saccharate (a reaction product consisting of 2 parts by weight of lightly burnt lime powder and 8 parts by weight of crystalline glucose) and mixed. Then, 100 parts by weight of water was added and kneaded rapidly. This slurry was poured into a mold of 40 × 40 × 160 mm, and when it was allowed to stand, setting started after about 30 minutes and hardened after 5 minutes while gradually generating heat. This test specimen was cured in the air and the strength was bent for 4 weeks.
kg / cm ² , compression 117 kg / cm ² , specific gravity 0.96. The above slurry has very good fluidity and is suitable for grouting agents.

Example 4 Silica powder (200 mesh under) 100 parts by weight, light burnt lime powder
60 parts by weight of powder and 5 parts by weight of white sugar are mixed, and 80 parts by weight of water are mixed.
In addition, it was kneaded rapidly. This slurry is 40 × 40 × 160 mm
Pour into the formwork and allow to set after about 10 minutes
It generated heat at 62 ° C. and was finally cured 4 minutes after the start. This test
Curing the body in the air and bending for 4 weeks with a strength of 32kg / cm ^Two, Compression 467kg
/cm^Two, Specific gravity was 1.92.

A surfactant (Lipon F) was added to the slurry.
When 0 parts by weight and 60 parts by weight of water were added and kneaded rapidly, it foamed and cured in 36 minutes. This foam has a specific gravity of 0.38 and compressive strength
It was 69 g / cm ² . This foam is suitable for ALC replacement.

Comparative Example 3 100 parts by weight of silica powder (under 200 mesh), 60 parts by weight of calcined lime powder and 80 parts by weight of ice water were added and kneaded rapidly. The slurry was poured into a mold of 40 × 40 × 160 mm and cured at 90 ° C. for 5 hours.
The compression strength was 12 kg / cm ² and the compression was 93 kg / cm ² .

Example 5 100 parts by weight of Siegrite (pH 3.6), 60 parts by weight of lightly burnt lime powder, and 5 parts by weight of white sucrose were mixed, and 80 parts by weight of water was added, followed by rapid kneading. This slurry was poured into a mold of 40 × 40 × 160 mm, and when it was allowed to stand, it started to coagulate after about 10 minutes and generated heat at 52 ° C., and finally hardened 4 minutes after the start. The specimen was cured in the air, and the strength was 38 kg / cm ^{2 for} bending for 4 weeks and the compression was 537 kg / c.
m ² and specific gravity 2.2. This cured product has high whiteness,
Suitable for artificial stone.

Example 6 100 parts by weight of Akadama clay (dried at 250 ° C. for 6 hours), lightly burnt lime powder
Mix 60 parts by weight and 5 parts by weight of white sugar, and add 140 parts by weight of water
In addition, it was kneaded rapidly. This slurry is 40 × 40 × 160 mm
Pour into the formwork and allow to set after about 10 minutes
It generated heat at 51 ° C. and was finally cured 4 minutes after the start. This test
Curing the body in the air, 4 weeks strength bending 18kg / cm ^Two, Compression 47kg /
cm^TwoThe specific gravity was 1.2. This cured product is backfill grout
Suitable for.

Example 7 100 parts by weight of Akadama clay (dried at 250 ° C. for 6 hours), lightly burnt lime powder
50 parts by weight, 10 parts by weight of slaked lime, and 5 parts by weight of white sucrose were mixed, and 80 parts by weight of water was added, followed by rapid kneading. The slurry set in 5 minutes and finished in 8 minutes.

The physical properties of this cured product showed a flexural strength of 13 days at an age of 7 days.
kg / cm ² and compressive strength 113 kg / cm ² , suitable for gypsum replacement.

Example 8 100 parts by weight of Akadama clay (dried at 250 ° C. for 6 hours), lightly burnt lime powder
45 parts by weight, 15 parts by weight of slaked lime, 5 parts by weight of white sugar and 2 parts by weight of sodium sesquisilicate were mixed, and 70 parts by weight of water was added, followed by rapid kneading. The slurry set in 17 minutes and ended in 28 minutes.

The physical properties of the cured product are as follows: specific gravity 1.36, 80 ° C., 4 hours
Bending strength 23kg / cm in 7 days ^Two, Compressive strength 280 kg
/cm^TwoIn the field of civil engineering construction materials and civil engineering methods
Can be widely used.

Example 9 100 parts by weight of ordinary Portland cement, 5 parts by weight of calcium saccharate (4 parts by weight of white sucrose, 1 part by weight of light burnt lime powder) were mixed, and 300 parts by weight of silica sand were mixed. 80 parts by weight of water was added and kneaded. The setting time of this mortar was 46 minutes at the beginning and 74 minutes at the end. With the same formulation as above, but with 10 parts by weight of calcium saccharate, the first 16 minutes and the last 22 minutes. In addition, calcium saccharate 5 and
The same result was obtained when 10 parts by weight were dissolved and used in 80 parts by weight of water.

Comparative Example 4 The setting time of the blank mortar of Example 9 was 175 minutes,
The end is 216 minutes. 1 week strength bending 6.4 kg / cm ² compression 67 kg / cm ² 4 week strength bending 37 kg / cm ² compression 382 kg / cm ² Example 10 100 parts by weight of amidrode, 50 parts by weight of lightly burnt lime powder, 5 white sugar When 100 parts by weight of water were added and kneaded, and the mixture was kneaded, heat was generated to cure the mixture, but further kneading resulted in hard sludge. This was agglomerated, dried and calcined at 800 ° C. for 4 hours in an electric furnace. It was cooled and pulverized to 300 mesh under.

10 parts by weight of this was added to 100 parts by weight of Portland cement and mixed, and 300 parts by weight of silica sand and 80 parts by weight of water were added and kneaded to prepare a mortar bar specimen. The setting time of this mortar was the first 17 minutes and the last 21 minutes.

When 0.1 part by weight of sodium citrate was added to the above mixture, the setting time was 32 minutes at the beginning and 48 minutes at the end. X-ray analysis confirmed C12A7, with a free lime content of 1.2%.

Comparative Example 5 When 100 parts by weight of alumidroth and 50 parts by weight of lightly burnt lime powder were mixed and added with 100 parts by weight of water and kneaded, the mixture was heated and hardened, but when further kneaded, it became granular. This was fired and pulverized in the same manner as described above and added to ordinary Portland cement, but the setting was poor and the strength was low. X-ray analysis confirmed C12A7, but unreacted free lime was 5.2%.

Claims (4)

[Claims] 1. A cement admixture comprising calcium saccharate obtained by reacting slaked lime or quicklime with saccharides. 2. The method for producing a cement admixture according to claim 1, wherein the saccharide and quicklime or slaked lime are reacted as an aqueous solution, and crystals are precipitated from the reaction solution. 3. The method for producing a cement admixture according to claim 1, wherein the saccharide and quicklime or slaked lime are ground and mixed. 4. A method for producing calcium silicate, comprising reacting a raw silicate material with quick lime or lime in the presence of calcium saccharate obtained by reacting slaked lime or quick lime with a saccharide.