JPS6050738B2 - High sulfate slag cement and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a slag cement and a method for producing the same, and more particularly to a high sulfate slag cement and a method for producing the same.

It has been known that blast furnace wood frame slag has a tendency to harden due to hydration. Taking advantage of this property, this slag is mixed with Portland cement clinker and ground, which is inexpensive and can be used for blast furnace cement or iron. Used as Portland cement.

However, even in this case, since wooden frame slag alone takes time to harden and does not have sufficient strength, slag has strong properties as an extender for Portland cement, and the slag content is around 30% at most. In addition to the above, high sulfate slag cement, typified by silitol cement, is also known, but in Japan it is difficult to obtain blast furnace wooden frame slag suitable for manufacturing this, and it takes a long time to set and harden. It has not been put to practical use because of this problem and other drawbacks such as the formation of brittle parts on the surface of the cured product.

The present invention provides an excellent high sulfate slag cement that sets and hardens quickly and does not produce any brittle parts on the surface, as well as a method for producing the same. As mentioned above, silitol cement, which is a representative of the known high sulfate slag cements, is not only unable to obtain granulated blast furnace slag suitable for its production in Japan, but also takes about 5 hours to start setting and about 1 hour to finish setting. It takes a long time and the surface of the cured product is difficult to cure and is brittle and easily crumbles.

The present inventor completed the present invention as a result of intensive studies on the development of a practical high sulfate slag cement.

The high sulfate slag cement of the present invention starts setting quickly in 1 to 3 hours and finishes setting in about 4 to 6 hours, and can be molded into acute angles without forming any brittle parts on the surface.

The high sulfate slag cement of the present invention has a CaO4O~50%
, Ae2O3l4-20%, SlO23O-35% and MgO 5-8% as essential constituents 80-85%, preferably 82-85%, CaSO
4l3-17%, Boatland cement 1.5-2.5
%, organic carboxylic acid or its alkali metal salt 0.1~
0.5%, water-soluble polymer compound 0.03-0.6% and sodium sulfate 0.6-2%, 4500-550
It is a fine powder mixture with a -plane specific surface area of 0 cT1/g.

The above cement is manufactured using granulated blast furnace slag or A
'203 and/or 80 to 85%, preferably 82 to 85%, of slag, which is made by adding CaO, uniformly mixing it, remelting it, and pulverizing it.
85%, CaSO4l3-17%, Boatland cement 1.5-2.5%, organic carboxylic acid or its alkali metal salt 0.1-0.5%, water-soluble polymer compound 0.0
3-0.6% and sodium sulfate 0.6-2%,
4500-55 by crushing or crushing and mixing
A fine powder mixture with a specific surface area of 00c shield/g is obtained. For the high sulfate slag cement of the present invention, the chemical composition of the slag used is important; it has a high basicity, CaO4O~50%, A'20314~20%, Si
It is necessary to use a slag containing ~35% O23O and 5-8% MgO.

However, the granulated blast furnace slag currently available in Japan generally contains ~43% CaO4O, ~16% Ae2O3l4, and S
lO23O~35%, MgO5~8%, TiO2O. 5
%, Sl. O%, FeOO. 2%, the quality of the granulated blast furnace slag available in Japan today is barely sufficient to satisfy the lower limit of the basicity of the slag used in the present invention. If the basicity is low, the curing time will be longer and the strength will be lower. Therefore, it is desirable to increase the basicity of granulated blast furnace slag. However, simply adding, mixing, and pulverizing Ae2O3 and CaO to increase the basicity is not suitable for the purpose of the present invention and gives worse results. The present inventor has discovered that a slag meeting the object of the present invention can be obtained by adding a desired amount of Ae2O3 and/or CaO to granulated blast furnace slag, mixing it, remelting it, and pulverizing it.

The steps of adding Ae2O3 and CaO, mixing, remelting, and granulation are performed so that the chemical composition of the raw material, granulated blast furnace slag, is below the basicity required by the present invention, in other words, it deviates from the above-mentioned essential constituent requirements. This is an essential process if
On the other hand, if the composition of the granulated slag used as the raw material is already within the above composition range, this is an optional step.

The amount of slag used is 80% of the total amount of high sulfate slag cement.
~85%, preferably 82-85%.

CasO4, ie, gypsum, used in the present invention may be anhydrous gypsum, calcined gypsum, or dihydrate gypsum. Usually flue gas desulfurization gypsum obtained from pollution control equipment is used. The amount of CasO4 used is calculated as anhydrous gypsum.
3 to 17%, which is about 16 to 22% when calculated as dihydrate gypsum. The amount of Boatland cement used is 1.5 to 2.5%, preferably 2 to 2.5%. Preferred examples of organic carboxylic acids or alkali metal salts thereof include tartaric acid, sodium tartrate, potassium tartrate, citric acid, sodium citrate, potassium citrate, and the like.

The amount used is 0.1-0.5%. This organic carboxylic acid or its alkali metal salt functions to promote coagulation and hardening. Preferred examples of the water-soluble polymer compound to be added include metal soaps such as methylcellulose and calcium stearate, and sodium laurylbenzenesulfonate.

The amount used is 0.03 to 0.6%, and in the case of methyl cellulose and metal soap, for example, 0.03% to 0.6% is used.
1 to 0.6%, preferably 0.03 to 0.06% in the case of sodium laurylbenzenesulfonate. Adding an excessive amount of sodium laurylbenzenesulfonate tends to reduce the rate of coagulation and curing, which is not very preferable, but on the other hand, the strength of the cured product is further improved, so the actual amount used should be determined depending on the purpose. It is. The above-mentioned organic carboxylic acid or its salt and water-soluble polymer compound can be used individually or in combination.

The amount of sodium sulfate used is 0.6-2%.

Potassium sulfate can be equally used, but it is expensive and provides no particular benefit. The high sulfate slag cement of the present invention preferably has a plain specific surface area of 4,500 to 5,500 c/g; the smaller the specific surface area, the longer the curing time;
On the other hand, even if it is pulverized to 5,500 cT1/g or more, there is no profit even though the work required for pulverization increases.

As can be easily understood from the above, the method for producing the high sulfate slag cement of the present invention is based on granulated blast furnace slag or granulated blast furnace slag. is A' for this
203 and/or CaO added, mixed, remelted, and pulverized slag is mixed with gypsum, Bortland cement, organic carboxylic acid or its alkali metal salt, water-soluble polymer compound, and sodium sulfate in the above proportions. Finely pulverize until a predetermined plain specific surface area is obtained, or finely pulverize each of the above components individually or in combination, and then mix them uniformly in a predetermined ratio to obtain a mixture having a predetermined specific surface area. There are things.

The reason why the high sulfate slag cement of the present invention exhibits significantly superior rapid setting and hardening compared to conventionally known silitol cement, and the detailed explanation of the invention have not yet been fully explained, but the present invention Although the present invention is not limited to the following explanation, the inventor believes as follows.

That is, when an appropriate amount of water is added to the high sulfate slag cement of the present invention and kneaded, Na2O, . The CaO. ．． The elution of Ae2O3 and the increase in the concentration of the gypsum solution increase the probability of collisions between molecules in the liquid phase and accelerate the reaction, resulting in water-impermeable dense SiO2-containing silicic acid salting out. Gel formation is suppressed, and the resulting silicic acid gel has a rough porous structure that allows water to easily penetrate, promoting the formation of ettringite, promoting the formation of calcium silicate-based hydrates, and as the reaction progresses. CaO-A'203 in the liquid phase without
, the concentration of CaO-SO4 decreases, and alumina hydrate (A
The formation of gel structure of e2O3-3H20) progresses, and SiO
2. Along with the gel, crystalline particles are formed on the surface of the slag particles.
Furthermore, a network structure is formed by ionic reaction, filling the voids of ettringite and solidifying it. This series of reactions is accelerated by the rapid decomposition of the solute due to the action of the solvent accompanying the hydrolysis of the additive, which prevents the saturation of the liquid phase.
Therefore, it is believed that the time required for the initiation and completion of coagulation is shortened. On the other hand, added water-soluble polymers such as metal soap, methyl cellulose, and sodium laurylbenzenesulfonate dissolve and form a film on the surface of the cured product, blocking air and preventing the formation of fragile parts. It increases the density and strength of the hardened material in order to promote the dispersion of cement particles and provide a water-reducing effect.

As the age of the material progresses, the composition of the hydrates settles and fuses, giving a stable hardened material that maintains waterproofing ability.

EXAMPLES The present invention will be explained in more detail with reference to Examples below, but these are not merely for the purpose of illustration. ”
In this specification, % is by weight unless otherwise specified.

Example 1 CaO4l. obtained at Nippon Steel's Hirohata Plant. 8%, Af
2O3l4%, SlO234%, MgO7%, MnOO
．． 5%, 7T1021.0%, Sl. O%, FeOO.
Granulated blast furnace slag with a chemical composition of 2%, loss on ignition 0.5%, and basicity 1.85 was processed into a stainless steel vibratory pulverizer (carbon steel rods and holes) manufactured by Chuo Kakoki Co., Ltd. in Toyota City, Aichi Prefecture. 83% of the powder was finely crushed to 5,000 c1t/g, and 32.3 to 33
%, SO344.8-45.5%, H2O2O. 7-2
0.9%, Fe2O3O. O5-0.12%, SO. O
5-0.92%, CO2O. 4l~0.82%, C'0
．． 03-0.05%, H2SO4O. O7%, water-soluble alkali 0.07-0.23%, MgOO. Ol%, A'
Flue gas desulfurization gypsum 18% (anhydrous gypsum equivalent: 13.8
%) and Bortland cement 2%, citric acid 0.2%
, 0.3% of metallic soap, 0.6% of sodium sulfate, and 0.1% of methyl cellulose were mixed and mixed to form a milky mass to produce a high sulfate slag cement.

Water was added to this cement at a w/c ratio of 28%, and the mixture was kneaded to form mortar and cast.

At a temperature of 10 to 20° C. and a humidity of 78%, 3 powders were set in the first 1 hour and 3 powders were set in the final 4 hours. A film was formed on the surface of the cast product and it became devitrified.

After 24 hours, the mold was demolded and the formation of brittle parts was observed, the surface was milky white and the bottom surface was blue-green.

A 28-day-old cured material cured in water for 27 days had high strength and no swelling or contraction was observed, with a Tl of 4. Compressive strength test results Example 2 83% of the slag used in Example 1, 1% of dihydrate gypsum
Calcium stearate 0.45%, methyl cellulose 0.8%, Bortland cement 2% mixed sample.
1%, sodium tartrate 0.21%, sodium sulfate 0
．． 6%, tripotassium citrate (K3C6H5O7・H2
O) 0.2% was added and applied to the milk.

Water was added to this at a w/c ratio of 28%, kneaded to prepare a mortar, and the mortar was cast at a temperature of 10 to 20°C and a humidity of 78%. It took 2 hours to start condensing and 5 hours to finish condensation. A film was formed on the surface and devitrified. After 24 hours, the mold was removed and the bottom surface was green and the surface was also blue-green.

After 14 days of curing in water, the blue color on the surface increased, and the entire cured product turned blue, and the surface became glossy. The strength was high, and no expansion or contraction was observed, which remained unchanged even after air-drying. Example 3 The slag, gypsum dihydrate and cement mixture of Example 1 contains 0.3% calcium stearate and 0 methylcellulose.
．． 3%, potassium citrate 0.21%, and sodium sulfate 0.6% were added, and water was added to the limestone at a w/c ratio of 26%, kneaded, and cast. %.

The initial setting time was 1 hour and 5 hours, and the final setting time was 5 hours, a film was formed on the surface, there was no precipitated water, and the surface was devitrified. 2? When the mold was demolded after that time, the surface was milky white, no brittle parts were observed, and the bottom surface had a spotted blue color.

The results of underwater curing were the same as in Example 2. Example 4 0.3% methyl cellulose and 0 calcium stearate in the mixture of slag, gypsum dihydrate and cement of Example 1
．． 2%, sodium sulfate 0.7%, potassium tartrate 0.
1% and sodium laurylbenzenesulfonate 0.0
1% added, 10-200C, humidity 78%,
Water was added at a w/c ratio of 25%, kneaded to form a morphthal, and cast.

The initial setting was 4 particles in 2 hours, and the final setting was 2 particles in 5 hours. A film was formed on the surface, and a slight amount of bridging water was observed.
The mold was demolded after 2ff, but there were no brittle parts, the corners were sharp, the surface was white, and the bottom was pale blue.

After step 7, only air-drying was performed, and observation showed that the pale blue color had disappeared, but the curing was good. After 7 days of air drying, water curing for 28 days.
In the case of the cured product, no swelling, shrinkage, cracking, or crumbling phenomena were observed, and the corners were at acute angles. Similarly to Examples 1 to 4, the other seven tests on cement having the composition of the present invention gave almost similar results.

In another example in which the amount of sodium laurylbenzenesulfonate added was too large and the amount of water added was also large, it took a long time to cure, but the strength of the cured product was high. Example 5 In order to increase the basicity of granulated blast furnace slag, CaO and Af2O3 were added to the slag used in Example 1, and the slag was remelted and granulated to obtain CaO45. Ol%, Af2O3l8.28%, SlO
229.87%, MgO6. lO%, MnOO. 25%
, TlO2O. 4%, SO. 7%, Fe2O3O. l%
A granulated slag with a basicity of 2.32 and a chemical composition whose loss on ignition has not been measured was obtained.

This slag 83%, Bortland cement 2%, dihydrate gypsum 19% (CasO4 equivalent 14.6%), methyl cellulose 0.15%, calcium stearate 0.2%,
Sodium sulfate 0.6%, sodium tartrate 0.05%
, and 0.1% potassium tartrate were mixed and pulverized in a stainless steel drum to a specific surface area of 5000 cr1/g, mixed with an appropriate amount of water, and cast as a mortar. It was cured at 10-20°C and 72% humidity.

The mold was demolded after 24 hours, but brittle parts were observed.The cured product had a dark blue color, and after 27 days of underwater curing and 28 days of age, no cracks, expansion, shrinkage, or deformation were observed, and there was no crumbling part.

Claims (1)

[Claims] 1 CaO 40-50%, Al_2O_314-20%
, SiO_2 30-35% and MgO 5-8% as essential constituents 80-85%, Ca
SO_413~17%, Portland cement 1.5~
2.5%, organic carboxylic acid or its alkali metal salt 0
．． 1-0.5%, water-soluble polymer compound 0.03-0.6
% and sodium sulfate 0.6-2%, 4500
High sulfate slag cement with Blaine specific surface area of ~5500 cm^2/g. 2. The cement according to claim 1, wherein the amount of granulated slag is 82 to 85% and the amount of Portland cement is 2 to 2.5%. 3 CaO40-50%, Al_2O_314-20%
, SiO_2 30-35% and MgO 5-8% as essential constituents 80-85%, Ca
SO_413~17%, Portland cement 1.5~
2.5%, organic carboxylic acid or its alkali metal salt 0
．． 1-0.5%, water-soluble polymer compound 0.03-0.6
A method for producing a high sulfate slag cement, which comprises mixing, crushing or pulverizing and mixing 0.6 to 2% of sodium sulfate to obtain a fine powder mixture having a Blaine specific surface area of 4500 to 5500 cm^2/g. 4 Al_2O_3 and/or CaO in granulated blast furnace slag
The manufacturing method according to claim 3, wherein the granulated slag is manufactured by adding, mixing, remelting, and pulverizing.