JPH0818856B2 - Carbonation curing method of γ-type dicalcium silicate - Google Patents

Description

TECHNICAL FIELD The present invention relates to the production of concrete having a low alkali concentration useful as a building or civil engineering material, and more specifically to a carbonation curing method for γ-type dicalcium silicate. .

[Conventional technology]

Since concrete products that have been used in large quantities from the past are hydrates of Portland cement and mixed cement, the alkali concentration in the hardened product is significantly high. Deterioration is unavoidable, and it has the drawback that the strength of concrete is markedly reduced.

γ-type dicalcium silicate (hereinafter referred to as γ-C ₂ S) is γ-2Ca
It is a mineral represented by the chemical formula of O · SiO ₂ , and when carbonated in the presence of water, it reacts and hardens according to the following formula.

γ-2CaO ・ SiO ₂ ＋ 2CO ₂ ＋ 2H ₂ O → 2CaCO ₃ ＋ SiO ₂ ＋ 2H ₂ O ……
(1) This cured product of γ-C ₂ S has been noted as an industrial material for a long time without the above-mentioned drawbacks because its alkali concentration is significantly lower than that of conventional concrete, but its mass production technology has been established. Since it was not done, its applied research was hardly done.

However, the present applicant has previously established a technique for mass-producing γ-C ₂ S powder in a rotary kiln at low cost in a large amount by using an inexpensive raw material, and has proposed this as Japanese Patent Application No. 60-153154. Therefore, in the future, it is expected to develop a technique using γ-C ₂ S, which will be mass-produced by such a method.

[Problems to be solved by the invention]

The inventor has been further researching the applied technology with the fact that the applicant has established the technology for industrially mass-producing γ-C ₂ S powder as described above.
When producing a hardened body by carbonizing C ₂ S powder,
It is intended to provide a carbonation curing method for obtaining a cured product having high strength.

[Means for solving problems]

According to the present invention, gamma-type dicalcium silicate powder and sand and water,
Alternatively, when a mixture composed of an admixture or fibers is further molded and then a γ-type dicalcium silicate is carbonized to produce a cured product, an alkyl group or alkenyl group having 7 to 23 carbon atoms and a carboxyl group 1 or 2 0.03 to 2.0 wt% of a composition comprising 1 part by weight of at least one fatty acid, alkyl succinic acid or alkenyl succinic acid and 1 to 20 parts by weight of at least one alkylene oxide addition type nonionic surfactant. The above problems can be effectively solved by the carbonation curing method of γ-type dicalcium silicate, which is characterized in that the water suspension of (1) is used in place of the water, and in a preferred embodiment of the present invention, the fatty acid is stearin. Acid, oleic acid, linoleic acid, lauric acid, palmitic acid or stearic acid, and the alkylene oxide addition type nonionic surfactant is Le phenol, nonylphenol, lauryl alcohol, tridecyl alcohol, oleyl alcohol, myristyl alcohol or carbon atoms
It is obtained by adding 3 to 15 mol of ethylene oxide or 3 to 15 mol of ethylene oxide and 2 to 5 mol of propylene oxide to 1 mol of a secondary alcohol of 12 to 14, and a fatty acid, an alkylsuccinic acid or an alkenylsuccinic acid. , Salt neutralized with alkali is used.

 The present invention will be described in more detail below.

The present inventors have conducted various experiments, and when a mixture of special fatty acid, alkylsuccinic acid or alkenylsuccinic acid and a special nonionic surfactant is added to γ-C ₂ S powder and kneaded with water, γ- The inventors have completed the present invention by finding that the dispersibility of the C ₂ S powder is remarkably improved and the water content in the molded product can be reduced and that a cured product having a remarkably high strength can be obtained by curing with carbon dioxide gas thereafter.

A mixture of γ-C ₂ S powder and sand or an admixture,
In the present invention, 1 part by weight of a fatty acid having an alkyl or alkenyl group having 7 to 23 carbon atoms and one or two carboxyl groups, an alkylsuccinic acid, an alkenylsuccinic acid or a mixture thereof and an alkylene oxide addition type nonionic surfactant 1 ~ 20 parts by weight of the composition in a mixture with 0.03 to 2.0 wt% water.

In the present invention, a composition of 1 part by weight of a fatty acid, an alkylsuccinic acid, an alkenylsuccinic acid or a mixture thereof and 1 to 20 parts by weight of an alkylene oxide addition type nonionic surfactant (hereinafter abbreviated as a dispersant composition used in the present invention) .) Is preferably used. When used alone or when the composition ratio of the composition is out of this range, it is not preferable to use it because the dispersion effect of the γ-C ₂ S powder can hardly be expected. Further, the dispersant composition of the present invention is preferably used as a mixture with 0.03 to 2.0 wt% of water, when less than 0.03 wt%, the dispersion effect of the γ-C ₂ S powder is small, and carbonation curing is performed. Since the strength after the curing is small, and when it exceeds 2.0 wt%, the strength after the carbonation and curing is small, which is not preferable.

One raw material of the dispersant composition used in the present invention,
As a fatty acid having an alkyl or alkenyl group having 7 to 23 carbon atoms and one or two carboxyl groups, as alkylsuccinic acid or alkenylsuccinic acid, capric acid, lauric acid, stearic acid, oleic acid, linoleic acid, myristic acid, palmitin Acids, coconut fatty acids, beef tallow fatty acids, rapeseed fatty acids, and other fatty acids obtained by decomposing natural fats and oils, isostearic acid obtained by synthesis, n-alkylsuccinic acid having 8 to 22 carbon atoms, isoalkylsuccinic acid, n-alkenylsuccinic acid, Isoalkenyl succinic acid and the like can be mentioned, but from the viewpoint of performance and handling, a liquid at room temperature is preferable, and stearic acid, oleic acid, linoleic acid, lauric acid, palmitic acid, or isostearic acid or a carbon number of 14 to Using 18 (n or iso) alkenyl succinic acid It is preferable to. These usually exhibit the dispersing effect of γ-C ₂ S powder when used in the acid state, but they should be neutralized with an alkali such as caustic soda, caustic potash, ammonia, and mono (di, tri) ethanolamine before use. Can be done. At this time, the solubility of carbon dioxide gas in the aqueous solution is increased, and as a result, the carbonation reaction is promoted, which is preferable.

Another raw material of the dispersant composition used in the present invention, an alkylene oxide addition type nonionic surfactant is decyl alcohol, lauryl alcohol, stearyl alcohol, cetyl alcohol, oleyl alcohol, myristyl alcohol, tridecyl alcohol, oxo. Synthetic alcohols having 11 to 15 carbon atoms, higher alcohols such as secondary alcohols having 12 to 14 carbon atoms by the method, octylphenol, nonylphenol, dinolylphenol,
1 mol of ethylene oxide and / or propylene oxide per 1 mol of alkylphenol such as dodecylphenol
It is obtained by adding ~ 50 mol, but from the viewpoint of performance, octylphenol, nonylphenol, lauryl alcohol, tridecyl alcohol, oleyl alcohol, myristyl alcohol or 1 to 15 mol of a secondary alcohol having 12 to 14 carbon atoms is added with 3 to 15 parts of ethylene oxide. It is preferable to use 3 to 15 moles of ethylene oxide and 2 to 5 moles of propylene oxide added.

The fineness of the γ-C ₂ S powder used in the present invention is preferably in the range of Blaine specific surface area of 3000 to 10000 cm ² / g, more preferably 5500 to 10000 c when the strength is taken into consideration.
Use m ² / g stuff. Because when less than 3000 cm ² / g has a small strength after carbonation curing, and 10000 cm ² / exceeds undesirable finer for increasing the ground even strength is small economically disadvantageous when.

As the admixture materials such as sand or slag powder, fly ash, and fine powder substances used in the present invention, those conventionally used can be used. Further, in the case of producing fiber reinforced concrete, conventionally used glass fiber, carbon fiber, natural inorganic fiber (eg asbestos), synthetic inorganic fiber, organic fiber and the like can be used.

The dispersant of the present invention may be used alone, but it is usually preferable to add it after mixing it with water to a predetermined concentration.

In the present invention, the kneading and molding of the γ-C ₂ S powder, sand, admixtures and the like used with the dispersant used in the present invention and water can be carried out by ordinary methods.

When the fiber-reinforced concrete is produced by the present invention, any of a premix method, a spray suction method, a direct spray method or a papermaking method can be adopted.

In the present invention, it is preferable to adjust the water content of the molded product so that the water saturation is 0.4 to 0.8 according to the following formula, and then carry out carbonation curing.

When the amount is out of this range, the strength after carbonization curing is small, or the time for carbonation curing becomes long, which is not preferable.

In the case of an instant demolding product, the water content can be adjusted by adjusting the amount of added water, but in the case of casting or the like, the water content can be adjusted by drying, vacuum suction, pressing or a combination thereof.

In the present invention, the water content may be adjusted in a CO ₂ -containing gas and the water content adjustment and the carbonation curing may be simultaneously performed.

In the present invention, carbonation curing is performed in a CO ₂ -containing gas,
At this time, the higher the CO ₂ concentration, the better, but usually 20 Vol%
The above is preferable.

 Hereinafter, the present invention will be described in more detail with reference to examples.

Example-1 0.5 wt of various dispersants was added to 50 g of γ-C ₂ S powder shown in Table 1.
% Add 25 ml of a mixture with water and knead for 3 minutes, then fill the metal mold with an inner diameter of 28 mm and a height of 50 mm placed on a glass plate with the slurry, and after 2 minutes, gently pull up the mold to leave only the slurry. The spread of the slurry in contact with the glass plate was measured after 1 minute, and the results shown in Table 2 were obtained.

As is clear from Table 2, it is understood that the dispersant used in the present invention significantly fluidizes the slurry of γ-C ₂ S powder.

It is understood that the fluidizing agent conventionally used as a dispersant for cement has a very small effect as a fluidizing agent for γ-C ₂ S powder.

It is also understood that the use of the fatty acid or nonionic surfactant constituting the dispersant used in the present invention alone has a very small fluidizing effect.

Adjust EXAMPLE -2 Example isostearic acid with secondary higher alcohols used in the -1 (C ₁₂ ~ ₁₄₎ ethylene oxide 5 mol adduct was mixed mixing ratio is different for various compositions, followed Water A 0.5 wt% mixed solution was prepared by mixing. Then, 30 g of γ-C ₂ S powder used in Example-1 and Toyoura standard sand 30
15 ml of the previously prepared mixed solution was added to the mixture of g and kneaded for 3 minutes, and then the spread of the rally was measured in the same manner as in Example-1 to obtain the results shown in FIG. As is apparent from FIG. 1, the composition of the dispersant used in the present invention is preferably 1 to 20 parts by weight of the nonionic surfactant with respect to 1 part by weight of the fatty acid, alkylsuccinic acid or alkenylsuccinic acid. . Outside this range, the fluidizing action of the γ-C ₂ S powder slurry cannot be expected, which is not preferable.

Example-3 100 g of γ-C ₂ S powder used in Example-1 and Toyoura standard sand 1
To a mixture of 200 g, mixed solution of water with various concentrations of a mixture of 1 part by weight of isostearic acid and secondary higher alcohols (C ₁₂ ~ ₁₄₎ ethylene oxide 5 mole adduct 3 parts by weight used in Example -1 Was added and kneaded to form a slurry. Then, this was sucked under reduced pressure and formed into a flat plate of 10 cm × 10 cm × 1 cm.

Then, put this molded body in a closed dryer at 30 ° C,
It was aged for 24 hours while flowing carbon dioxide with a concentration of 99% or more.

Separately, a molded body molded in the same manner is dried at 110 ° C,
Immediately after molding, the water content of the molded body was measured and the results shown in Table 3 were obtained.

 The water content was calculated by the following formula.

For samples after carbon dioxide curing, 2.5 cm × 9 cm ×
A 1 cm test piece was prepared, and the 3-point bending strength (span 7 cm) was measured for this to obtain the results shown in Table 3.

The sample whose flexural strength was measured was crushed to a particle size of 1 mm or less, 50 gr of which was put in 70 ml of distilled water and stirred, and the pH value of the supernatant after 24 hours was measured to obtain the results shown in Table 3.

Further, in the same manner as in Example-2, the spread of the slurry when the dispersant concentration was changed was measured, and the results shown in Table 3 were obtained.

As is clear from Table 3, the concentration of the dispersant used in the present invention is preferably 0.03 to 2.0 wt%. Concentration
When it is lower than 0.03wt%, the effect of reducing water content is small and the strength after carbonization is small, and when it is higher than 2.0wt%,
It is not preferable because the strength after carbonization curing becomes small.
It is also understood that the larger the spread of the slurry is, the smaller the water content of the molded product is, and that the pH value of the cured product of the present invention is remarkably low at 10.2 to 10.3.

Example-4 A mixture of 1 part by weight of isostearic acid used in Example-1 and 3 parts by weight of secondary higher alcohol and ethylene oxide 5 mol adduct was neutralized with an aqueous solution of potassium caustic, ammonia and monoethanolamine (pH). While adjusting the value to 10), a mixed solution with 0.5 wt% of water was prepared. Then, the mixed solution was added, kneaded, and sucked in the same manner as in Example-3.
It was molded into a flat plate of 10 cm x 10 cm x 1 cm. 40 compacts
The mixture was placed in an airtight dryer at ℃ for 16 hours for carbonation and curing while flowing a carbon dioxide gas having a concentration of 99% or more, and then a sample was prepared in the same manner as in Example-3, and the three-point bending strength was measured to obtain a fourth value. The results in the table were obtained.

Separately, the water content of the molded product molded in the same manner was measured in the same manner as in Example-3, and the results shown in Table 4 were obtained.

The spread of the slurry when the neutralized dispersant was used was measured in the same manner as in Example-2, and the results shown in Table 4 were obtained.

It can be seen from Table 4 that the water content of the molded article can be further reduced by neutralizing the dispersant used in the present invention with an alkali and then using it. This is because bubbles introduced into the mortar during kneading increase.

Further, from Table 4, when the dispersant used in the present invention is neutralized with an alkali and then used, the strength after carbonation curing becomes large. It is considered that this is because the kneading solution was alkaline, so that the solubility of CO ₂ was high, and as a result, the carbonation reaction was promoted.

The samples whose flexural strengths were measured were ground to 1 mm or less and the pH values were measured in the same manner as in Example-3. As a result, the pH values of all the samples were 10.5 or less.

Example-5 A mixed solution of the dispersant of the present invention prepared in Example-1 and 0.5 wt% of water (No. 8, Table 10, No. 8, No. 11, No. 12 and No. 13 in Table 2).
55 ml was added and kneaded to a mixture of 100 g of γ-C ₂ S powder used in Example-1 and 100 g of Toyoura standard sand, and then molded into a flat plate of 10 cm × 10 cm × 1 cm in the same manner as in Example-3. The molded product is then dried in a dryer at 50 ° C until the water content of the molded product reaches a water saturation value of 0.5 to 0.6, and then at room temperature while flowing carbon dioxide gas with a concentration of 99% or more in an airtight container. Carbonated for an hour.

For carbonation-cured samples, 2.5 cm × 9 cm × 1 cm specimens were prepared, and the 3-point bending strength (span 7c
m) was measured and the results shown in Table 5 were obtained. Separately, a molded product immediately after molding, which was molded in the same manner, was measured for water content in the same manner as in Example-3, and the results shown in Table 5 were obtained. For comparison, the same test was performed when kneading and molding was performed using only water.

As is clear from Table 5, the use of the dispersant of the present invention makes it possible to significantly reduce the water content of the molded product, and to obtain a cured product having high strength after a short period of carbonation and curing. .

Example-6 In a mixture of 1 part by weight of γ-C ₂ S powder used in Example-1 and 1 part by weight of river sand having a diameter of 2 mm or less, water having a concentration of 0.5 wt% of the oxidizing agent of the present invention used in Example 3 was used. A mortar was prepared by adding and kneading 0.55 parts by weight of a mixed solution of and. Using the spray suction method, cut the roving of E glass prepared separately with this mortar into 25 mm chopped strands.
Two 0 × 450 × 10 mm flat plates were formed.

After that, one molded body (designated as A) was placed in an airtight dryer at 30 ° C., and carbon dioxide gas having a concentration of 99% or more was flowed to cure it for 20 hours.

The other remaining molded body (denoted as B) was dried in a dryer at 50 ° C until the water content of the molded body reached 0.55 at the water saturation level, and then placed in an airtight thermostat box to remove carbonic acid with a concentration of 99% or more. Carbonation was carried out at room temperature for 4 hours while flowing gas.

For each of the cured products after curing, a test piece of 25 × 5 × 1 cm was prepared, and the three-point bending strength (span: 20 cm) was measured, and the following results were obtained.

 The fiber content was 5 wt%.

Bending strength: A: 315 kg / cm ² , B: 284 kg / cm ² [Effect of the invention] As described in detail above, according to the present invention, a concrete product having a high strength and a significantly low alkali content by curing for a short time is provided. Easy to manufacture.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the spread of the slurry of Example-2 and the amount of the dispersant added.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C04B 16:06) Z (72) Inventor Takeshi Kuroda 1-7 Hoshu, Koto-ku, Tokyo (56) Reference JP-A-62-241856 (JP, A) JP-A-59-223261 (JP, A) JP-A-51-28816 (JP, A) JP-A-52 -15516 (JP, A) JP-A-59-137358 (JP, A)

Claims (3)

[Claims] 1. A mixture of γ-type dicalcium silicate powder and sand and water, or a further admixture or fiber is molded,
Then, when γ-type dicalcium silicate is carbonated to produce a cured product, at least 1 of an alkyl group or an alkenyl group having 7 to 23 carbon atoms and 1 or 2 carboxyl groups, an alkylsuccinic acid or an alkenylsuccinic acid. 0.1 parts by weight of a composition and 1 to 20 parts by weight of at least one alkylene oxide addition type nonionic surfactant.
A method for γ-type dicalcium silicate carbonation curing, characterized in that a water suspension of 03 to 2.0 wt% is used in place of the water. 2. The fatty acid is stearic acid, oleic acid, linoleic acid, lauric acid, palmitic acid or isostearic acid, and the alkylene oxide addition type nonionic surfactant is octylphenol, nonylphenol, lauryl alcohol, tridecyl alcohol, oleyl. Alcohol, myristyl alcohol or 12 carbons
Claim 1 characterized in that 3 to 15 moles of ethylene oxide or 3 to 15 moles of ethylene oxide and 2 to 5 moles of propylene oxide are added to 1 mole of the secondary alcohol of -14. the method of. 3. The method according to claim 1 or 2, wherein the fatty acid, alkyl succinic acid or alkenyl succinic acid is a salt neutralized with an alkali.