JPS5820897B2 - Non-air entraining cement admixture - Google Patents

Description

[Detailed description of the invention] The present invention relates to non-air entraining cement admixtures.

For further details, cement mortar is suitable for concrete pouring and molding of secondary concrete products, etc.; it is suitable for processing, improves workability, significantly reduces cement mixing water, and furthermore, cement after hardening. The present invention relates to a non-air-entraining cement admixture that has a large water-reducing effect and can significantly improve the strength of mortar or cement.

As is well known, hydraulic cement compositions, which are typified by various cement or concrete products including buildings, are obtained by kneading cement, sand, gravel, etc. with water and molding the mixture.

The properties of this coveted hydraulic cement mixture depend, of course, on the quality of the raw materials, but also on the compounding conditions.

It is well known that one of the most important mixing conditions in order to obtain a satisfactory hydraulic cement mixture is to mix the raw materials with as little unit water as possible. A product with excellent economic efficiency can be obtained by reducing the amount of cement.

This water reduction mechanism uses a cement dispersant that uniformly disperses the cement particles themselves as primary particles, improves the fluidity of the cement paste, and, as a result, reduces the amount of water required to obtain the same fluidity. There are also AE agents (air entraining agents) that entrain fine closed cells in mortar, concrete, etc., and give fluidity through the bearing effect of the cells, improving workability and reducing the amount of water. .

However, the water reduction effect of AE agents depends on the amount of air entrained;
In order to increase the water-reducing effect, the amount of entrained air must be increased, resulting in a significant decrease in strength, so there is a limit to the water-reducing effect of the AE agent.

Therefore, in order to obtain high-strength cement mortar and concrete products, there is a strong demand for admixtures (water-reducing agents) that have a high water-reducing effect and are non-air entraining.

Secondary concrete products include centrifugally molded concrete poles, piles or humid pipes, U-shaped grooves, blocks,
Poured products such as curbs or box culverts (
There is a vibrator (molded product).

Several water reducing agents have been put into practical use in the molding of these secondary products.

These include lignin sulfonate, melamine-formalin resin sulfonate, hydroxycarboxylate, alkylated neutral oil sulfonate, β-naphthalene sulfonic acid formalin condensate salt, and the like.

However, all of these have advantages and disadvantages, and they are not completely satisfied in all respects.

For example, lignin sulfonates and alkyl sulfonates of neutral oils have a weak water-reducing effect, and if they are added in large amounts to compensate for this, they are not only less economical, but also have a setting retardation effect, and moreover, the amount of entrained air increases. It causes a decrease in the strength of cement mortar and concrete.

Hydroxycarboxylic acid salts have a low air-entraining property, but have a weak water-reducing effect, and increasing the amount added causes a significant delay in setting, resulting in poor curing in some cases.

Similarly, melamine formalin resin sulfonate has a weak water-reducing effect, requires addition of a large amount, and is economically disadvantageous.

β-Naphthalenesulfonic acid formalin high condensate salt has excellent performance as a cement dispersant, is effective as a water reducing agent, has low setting retardation, and has low air entrainment properties, making it particularly suitable for secondary concrete products. It is reported that it is a concrete admixture (Special Publication No. 41-1173
7 and Special Publication No. 48-9564 However, β
- Naphthalene sulfonic acid formalin condensate salt actually has a large air entrainment amount and a large air bubble diameter. However, it is bad, resulting in pinholes or pockmarks that require repair after molding, which is disadvantageous in terms of workability and economy.

In view of these circumstances, the present invention aims to provide a cement admixture that is non-air-entraining and has a high water-reducing performance without the above-mentioned drawbacks.According to the present invention, the sulfonation rate is Non-containing alkali metal salts, alkaline earth metal salts, ammonium salts or organic amine salts of formaldehyde condensates of sulfonates of naphthalene or mixtures thereof containing up to 30 mol% of alkylnaphthalenes in the range of 105 to 135%. An air-entraining cement admixture is provided.

The salt of the formaldehyde condensate of sulfonic acid is naphthalene alone or has an alkylnaphthalene content of 30 mol%.
It can be produced by sulfonating the following mixture of naphthalene and alkylnaphthalene to a sulfonation rate of 105 to 135%, condensing the sulfonated product with formaldehyde, and then neutralizing it.

Examples of the alkylnaphthalene to be mixed with naphthalene include methylnaphthalene, ethylnaphthalene, butylnaphthalene, dimethylnaphthalene, and mixtures thereof.

These alkylnaphthalenes have a molar ratio of 0 to naphthalene.
．． They can be used in a mixed ratio of 3:0.7 or less.

If the mixing ratio of alkylnaphthalene increases more than this, the water reduction performance will decrease.

The sulfonation is carried out by a conventional method using concentrated sulfuric acid, fuming sulfuric acid, chlorosulfonic acid, etc. as a sulfonating agent.

In this case, it is essential for the cement admixture of the present invention that the sulfonation rate be in the range of 105 to 135%, preferably 110 to 130%.

When the sulfonation rate is less than 105%, a large amount of air is entrained, which not only deteriorates the hardness of cement mortar and concrete products and impairs their appearance, but also causes a decrease in strength and poor water reduction performance.

If the sulfonation rate is 135% or more, the amount of air entrained will decrease, but the fluidity of cement mortar and concrete will be extremely poor, making it unsuitable as a water reducing agent.

The sulfonation rate is based on the amount of sulfuric acid that is sufficient to convert the used naphthalene or a mixture of it and an alkylnaphthalene into monosulfonic acid, and is the amount actually consumed as determined by neutralization titration against this amount. It refers to the ratio of the amount of sulfuric acid added.

Therefore, disulfonic acid, disulfonated naphthylsulfone,
Naturally, by-products such as trisulfonic acid are produced.

Sulfonation can be achieved under the conditions for producing β-naphthylsulfonic acid, but it becomes necessary to increase the amount of sulfonating agent such as sulfuric acid in order to increase the sulfonation rate to the above range.

Next, for the condensation reaction with formaldehyde, the highly sulfonated product obtained in step (d) above is diluted with water, formaldehyde is added under acidic sulfuric acid, and condensation is carried out in a conventional manner.

The resulting condensate is neutralized with alkali hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide, ammonia, and amines such as alkanolamines to form the respective salts. be able to.

The cement admixture of the present invention significantly improves and improves the fluidity of cement mortar and concrete, and as a result, when obtaining the same fluidity, the unit water volume is significantly reduced, the amount of air entrained is extremely small, and the strength is significantly increased. let

Furthermore, the cement admixture of the present invention entrains much less air than the formalin high condensate salt of β-naphthalenesulfonic acid, which is conventionally known as a non-air-entraining water reducing agent, and even when the amount added is increased. without increasing air entrainment,
No decrease in strength was observed.

In addition, the cement admixture of the present invention does not retard the setting of cement mortar and concrete, does not cause accidents such as poor curing even if added in an excessive amount, and has a small amount of bleeding, which is different from conventional admixtures. It was confirmed that slump loss, which is a drawback, was also small.

A salt of a sulfonated formalin condensate of a mixture of naphthalene and methylnaphculene in a weight ratio of 80:20 to 20:80 is known as an air-entraining water reducing agent (Japanese Patent Publication No. 53
-14255).

However, as a result of advanced sulfonation, the admixture of the present invention has a more hydrophilic balance between hydrophobicity and hydrophilicity, has less surface activity, has less foaming properties, and is a non-air-entraining water-reducing agent. It was found that

Since the cement admixture of the present invention has an extremely large water-reducing effect, sufficient fluidity can be imparted to the cement by adding it in an amount of usually 0.1 to 3% by weight, preferably 0.3 to 1.2% by weight. be able to.

Further, if desired, it may be used in combination with a curing accelerator, retardant, anti-shrinkage material, expansion material, rust preventive agent, etc.

The admixture of the present invention is usually mixed with cement and aggregates such as sand or gravel and added when mixing water is added, but it may also be added by other methods, for example, after mixing mortar or concrete. Furthermore, it is also possible to adopt a method of dry powdering the mixing agent of the present invention and mixing it with cement in advance.

Furthermore, the method of applying mortar or concrete containing the admixture of the present invention and the method of molding the secondary product may be the same as conventional methods, and may include painting by troweling, spraying, filling into formwork, etc. can.

The curing method may be the same as the conventional method, and air dry curing, underwater curing, steam curing, autoclave curing, and combinations thereof can be used.

Next, the present invention will be explained in detail with reference to Examples.

Examples and percentages are by weight.

Example 1 98% sulfuric acid was added to 1 mole of naphthalene at 1.4 mole (composition I of the present invention), 1.5 mole (composition ■), 1.6 mole (composition ■), and 1.7 mole ( Composition ■), 1.8 mol (
Sulfonation was carried out in a conventional manner using 1.9 mol of composition (1) and 1.9 mol (composition (2)).

As comparative examples, 98% sulfuric acid was similarly added at 1.1 mol (composition A), 1.3 mol (composition B), and 2 mol (composition C).
) was used for sulfonation.

Next, water is added to the obtained sulfonated product, and then 0.82 mol of 37% formalin is added dropwise under acidic sulfuric acid, and a condensation reaction is carried out by a conventional method.

The condensation products were neutralized with calcium hydroxide and cooled to remove by-product limestone to zero to obtain compositions with a solid content of 45%. However, Comparative Example Composition C had a significantly thicker viscosity, so the solid content was lower. 3
It was set at 8%.

Table 1 shows the sulfonation rate of the resulting composition, the air content of the mortar, and the mortar consistency (J-Rotow).

Note 11 Mortar mix pore volume ('') (J funnel value) Compressive strength Asano ordinary pot'' 520 glooo g land cement Toyoura standard sand 1040 g 1100 g Water (+ admixture) 338 ru 1400 m12, mortar kneading ASTM C-305 -65.

3. Measuring the amount of air According to ASTM C-185-59.

4. J funnel value Using a J funnel (discharge opening diameter 100 mm) specified by the Japan Society of Civil Engineers, the flow time (seconds) of the mortar is measured immediately after kneading and after 30 minutes.

5. Compressive strength According to JIS R5201.

As is clear from Table 1, the admixtures I to II of the present invention have an extremely small amount of air compared to Comparative Examples A and B, which correspond to ordinary salts of β-naphthalenesulfonic acid formalin condensates, and have a sufficient amount of air. It provides excellent fluidity, and there is little decline in fluidity over time.

The compressive strength is about 20 to 30% higher for the 7th caliber and 5 to 25% higher for the 28th caliber.

Although Comparative Example C had a low air content and no problem in compressive strength, it had no fluidity at all and was confirmed to be unsuitable as a mortar admixture (water reducing agent).

Example 2 For 1 mole of naphthalene, 1.52 moles of 98% sulfuric acid (
Composition (■) of the present invention, 1.65 mol (composition (■)) and 1.
．． Sulfonation was carried out according to Example 1 using 83 mol (composition ①).

As a comparative example, sulfonation was carried out in the same manner using 1.28 mol (comparative example composition D) and 2.2 mol (composition E) of 98% sulfuric acid, and after cooling the obtained sulfonated product, sulfonation was performed using sulfuric acid. Then, 0.98 mol of 37% formalin was added dropwise to carry out a condensation reaction.

The condensation products were neutralized with 48% caustic soda and cooled to remove any by-product sodium sulfate, yielding compositions each having a solid content of 43%.

However, Comparative Example Composition E had a significantly high viscosity and poor workability, so the solid content was set at 30%.

The sulfonation rate of the obtained composition is shown in Table 2, and the concrete formulation and test results are shown in Table 3, as well as the results of comparison with commercially available admixtures (water reducers).

remarks 1. Measuring air volume According to JIS A L128.

2. Measuring slump According to JISAIIOI.

3. The compressive strength specimen was prepared in accordance with JIS A 1132, and the test method was in accordance with JIS A 1108.

As is clear from Table 3, the admixture of the present invention ■.

■ and ■ have less air volume and compression than the comparative example.

It can be seen that the strength has also improved.

Comparative Example E has the same amount of air as the admixture of the present invention, but
It is clear that the slump is extremely small and the water reducing properties are greatly inferior.

Commercially available products (1) and (2) are all inferior to the admixture of the present invention in terms of water-reducing properties and strength.

Example 3 The admixtures (1) and (2) of the present invention obtained in Example 2 and the comparative example were tested for the amount added, the amount of air, and the change in slump over time.

The results are shown in Table 4.

As is clear from Table 4, the admixture (■) of the present invention.

It is clear that in case (2), there is less variation in the amount of air depending on the amount added than in Comparative Example, and there is less slump loss.

Example 4 To a mixture of 0.8 mol of naphthalene and 0.2 mol of methylnaphthalene, 98% sulfuric acid was added in amounts of 1.45 mol (invention composition X), 1.53 mol (composition M), and 1.6 mol. As a comparative example, 98% sulfuric acid was used as a comparative example. 15 mol (Comparative Example F
), 1.3 mol (Comparative Example G), and 2 mol (Comparative Example H) were sulfonated in the same manner as in Example 1.

After adding water to the obtained sulfonated product, 0.86 mol of 37% formalin was added dropwise under acidic sulfuric acid, followed by a condensation reaction, neutralized with calcium hydroxide, cooled, and the by-product gypsum was passed through the mouth. and removed to obtain compositions each having a solid content of 40%.

However, since Comparative Example Composition H has a high viscosity, the solid content is 34%.
And so.

*G Table 5 shows the sulfonation rate, mortar air content, and mortar consistency (J-Roth value) of the resulting composition.

The conditions are the same as in Example 1.

As is clear from Table 5, the admixtures X to W of the present invention have an extremely small amount of air compared to Comparative Examples F and G, which correspond to salts of ordinary β-naphthalenesulfonic acid formalin condensates, and have a sufficient amount of air. It provides excellent fluidity, and there is little decline in fluidity over time.

Compressive strength is about 20 to 30% of 7 caliber, 15 after 28 days
or 25% higher.

Comparative Example H has a low air content and no problem with compressive strength, but its fluidity is poor.

Example 5: 0.7 mol of naphthalene, 0.24 mol of methylnaphthalene, 1.55 mol of 98% sulfuric acid (composition of the present invention)
, 1.65-E# (composition XvIN), Oyohi 1.85
Sulfonation was carried out according to Example 4 using Mol (composition E[).

As a comparative example, 1.28 mol of 98% sulfuric acid (Comparative Example T),
Sulfonation was carried out in the same manner using 2.2 mol (Comparative Example J), and 0.96 mol of 37% formalin was added dropwise to the obtained sulfonated product under acidic sulfuric acid to perform a condensation reaction.

The condensation products were neutralized with 48% caustic soda, cooled, and the by-produced sodium sulfate was removed by filtration, resulting in a solid content of 43% each.
% composition was obtained.

However, Comparative Example J had a high viscosity and poor workability, so the solid content was set at 30%.

Table 6 shows the sulfonation rate of the obtained composition.

Table 7 shows the concrete preparation and test results conducted in the same manner as in Example 2, and also shows the results of comparison with conventional commercially available admixtures (water reducers).

As is clear from Table 7, it can be seen that the admixtures XVI to XVI of the present invention have a smaller air content and improved compressive strength than Comparative Example Composition (2).

Comparative Example J has the same amount of air as the admixture of the present invention, but
The slump is extremely small and the water reduction properties are greatly inferior.

Commercial products (1) and (2) are both inferior in water-reducing properties and strength to the non-exploited *bright admixture.

Example 6 Regarding the admixtures XVI and XVI of the present invention obtained in Example 5 and Comparative Example ■, the addition amount and air amount,
We also tested the change in slump over time.

The results are shown in Table 8. As is clear from Table 8,
Inventive admixture XVI.

It is clear that in comparison with Comparative Example (3), there is less variation in the amount of air depending on the amount added, and there is less slump loss.

Claims (1)

[Claims] 1. Alkali metal salts, alkaline earth metal salts, ammonium salts or formaldehyde condensates of sulfonated naphthazine or mixtures thereof containing 30 mol% or less of alkylnaphculene, with a sulfonation rate in the range of 105 to 135%. A non-air-entraining cement admixture characterized by containing an organic amine salt.