JPH0216260B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel admixture for hydraulic cement that has excellent performance as a dispersant, water reducer, fluidizer, etc. More specifically, the active ingredient is an amide of an α,β-unsaturated monocarboxylic acid and a sulfonic acid containing a primary or secondary amino group, and an addition copolymer of an α,β-unsaturated monocarboxylic acid or a salt thereof. This invention relates to a new admixture for hydraulic cement. Generally, when producing concrete, mortar, paste, etc. using cement, admixtures called dispersants, water reducers, or fluidizers are used. This admixture is expected to have the following effects. (1) Increase the workability of unhardened cement mixtures. Also, with the same workability, the amount of water used can be reduced. (2) Since the amount of water used can be reduced, as a result, if the strength after construction is maintained, the amount of cement used can be reduced. (3) Increase watertightness. etc. Conventionally, such admixtures include, for example, those mainly composed of lignin sulfonate, those mainly composed of salts of gluconic acid, glucoheptanoic acid, etc.
Known materials include those based on a formalin condensate of β-naphthalenesulfonate, those based on a formalin high condensate of melamine having a sulfonic acid residue, and those based on a polysaccharide. However, each of these has its advantages and disadvantages, and no admixture has been found to exhibit good performance in terms of dispersion fluidity, slump retention, and hardening properties of cement. Therefore, the present inventors have made extensive studies to overcome these drawbacks, and have found that if a hydraulic cement admixture containing a specific copolymer or its salt as a main component is added to a cement mixture, A cement compound with good dispersion fluidity and good workability with significantly suppressed slump reduction can be obtained, and the amount of air entrainment can be kept low regardless of changes in the amount added, resulting in a cured product with high strength. The present inventors have discovered that the following can be obtained, and have completed the present invention. Thus, according to the present invention, (a) 95 to 5 mol % of an amide of an α,β-unsaturated monocarboxylic acid and a sulfonic acid containing a primary or secondary amino group; and (b) an α,β-unsaturated monocarboxylic acid. A hydraulic cement admixture is provided which contains as an active ingredient an addition copolymer containing 5 to 95 mol% of an acid or a salt thereof. The above copolymers used in the present invention are conventionally known substances. For example, U.S. Pat.
No. 3806367 and No. 3898037 disclose that such a copolymer, together with a homopolymer of 2-acrylamide-2-methylpropanesulfonic acid (hereinafter referred to as AMPS), is effective as a dispersant for iron, calcium, manganese, aluminum, etc. It is stated that. However, in the present invention, it is essential that the copolymer is composed of the above-mentioned components (a) and (b). It is inferior in terms of dispersion fluidity, water reduction property, slump retention, etc., and cannot achieve the object of the present invention. In addition, the composition of component (a) and component (b) is appropriately selected depending on the required performance, but the composition of component (a) is 5 to 95 mol%, component (b) is
95 to 5 mol%, preferably component (a) 10 to 90 mol%, component (b) 90 to 10 mol%, more preferably (a)
20 to 60 mol% of component, and 80 to 40 mol% of component (b). Specific examples of component (b) used in the present invention include:
Examples include acrylic acid, methacrylic acid, and crotonic acid, with acrylic acid and methacrylic acid being preferred because of their ease of availability and ease of reaction. On the other hand, component (a) is an amide of the above α,β-unsaturated monocarboxylic acid and a sulfonic acid containing a primary or secondary amino group. Here, the sulfonic acids containing primary and secondary amino groups refer to sulfonic acid groups (-
In addition to the narrowly defined sulfonic acid having SO ₃ H), it also includes sulfonic acid esters having a sulfonic acid ester residue (-OSO ₃ H), and specific examples thereof include aminomethane sulfonic acid, aminomethane sulfonic acid,
Aminoethanesulfonic acid, amino-2-methylpropanesulfonic acid, aminobutanesulfonic acid, aniline monosulfonic acid, aniline disulfonic acid,
Aminotoluenesulfonic acid, naphthylamine monosulfonic acid, naphthylamine disulfonic acid, naphthylamine trisulfonic acid, N-methylaminomethanesulfonic acid, N-ethylaminoethanesulfonic acid, N-methylaniline monosulfonic acid, N-
Primary and secondary compounds containing 1 to 3 sulfonic acid groups such as methylnaphthylamine disulfonic acid, amidosulfuric acid, monoaminoethyl sulfate, monoaminopropyl sulfate, monoaminobutyl sulfate, monoaminohexyl sulfate, monoaminooctyl sulfate, etc. Examples include amino group-containing sulfonic acids, especially aliphatic or aromatic primary and secondary acids having 1 to 10 carbon atoms.
Sulfonic acids containing amino groups are preferred. Both components (a) and (b) constituting the copolymer do not necessarily have to be used alone, and two or more components may coexist as appropriate. Further, other copolymerizable components may be included as necessary within a range that does not essentially impair the effects of the present invention. Specific examples include acrylamide, methacrylamide, acrylic ester, methacrylamide, acid ester, maleate ester, acrylonitrile, vinyl acetate,
Examples include styrene. The addition copolymer used in the present invention is not particularly limited as long as it functions as a cement admixture, but it has a number average molecular weight of 500 to 50,000, preferably 1,000 to 40,000, and if the molecular weight is larger than this, it will disperse. The performance deteriorates, and conversely, if the molecular weight is too small, the dispersion performance becomes insufficient. The carboxyl groups and/or sulfonic acid groups present in the copolymer may be in the acid form, but if necessary, some of them may be converted into salts with monovalent or polyvalent cations to improve water solubility. It is also possible to increase Specific examples of such salts include salts of alkali metals or alkaline earth metals such as sodium, potassium, magnesium, calcium, barium, etc., ammonium salts, amine salts such as trimethylamine, triethylamine, triethanolamine, etc. Among these, alkali metal salts are prized for their economic efficiency, safety, and dispersibility. Further, a part of the carboxyl group may be esterified or amidated before use, as long as the effects of the present invention are not essentially impaired. The copolymer or salt thereof used in the present invention may be produced by any method as long as it has the properties described above. A specific example of its production method includes the radical polymerization of an N-substituted α,β-unsaturated monocarboxylic acid amide containing a sulfonic acid group, such as AMPS, and an α,β-unsaturated monocarboxylic acid (for example, the method described in U.S. Pat. 3806367, etc.), a copolymer of α,β-unsaturated monocarboxylic acid amide such as acrylamide and α,β-unsaturated monocarboxylic acid is reacted with formaldehyde and bisulfite to sulfomethylate the amino group. Examples include a method in which a polymer of α,β-unsaturated monocarboxylic acid and an amino group-containing sulfonic acid are reacted at high temperature in an aqueous medium to form an amidation. Further, the form in which it is used is not particularly limited, and it can be used either in the form of an aqueous solution or in a solid form such as powder, and can be used alone or in combination with other cement admixtures. Cement admixtures that can be used in combination include conventional cement dispersants, air entraining agents, cement wetting and dispersing agents, swelling agents, waterproofing agents, strength enhancers, hardening accelerators,
Examples include setting accelerators and setting retarders. The cement admixture of the present invention is generally used in a proportion of 0.01 to 5% by weight, preferably 0.05 to 3% by weight, based on the solid content of cement. As the amount used decreases, the effect of improving workability decreases, and on the other hand, if it increases excessively, it may adversely affect the hardening of cement. Further, the timing of addition to the cement mixture can be appropriately selected depending on the intended use. Specific methods include, for example, mixing it with cement in advance, adding it at the same time when mixing cement mixtures such as concrete, adding it after adding water or other admixtures and starting stirring, and adding it in advance. An example is a method in which the additive is added at appropriate intervals after the product is kneaded. The types of cement to which the hydraulic cement admixture of the present invention can be applied are not particularly limited, and specific examples thereof include ordinary Portland cement, early-strength Portland cement, moderate heat Portland cement, alumina cement, fly-ash cement, blast-furnace cement, Examples include silica cement, slag cement, and various mixed cements. Thus, according to the present invention, it is possible to obtain a cement composition that has good dispersion fluidity of cement and has good workability in which slump reduction is significantly suppressed, and it is also possible to obtain a cured product with high strength. The present invention will be explained in more detail with reference to Examples below. Note that parts and percentages in the examples are based on weight unless otherwise specified. Example 1 Sodium salt of acrylic acid (AA)-2-acrylamide-2-methylpropanesulfonic acid (AMPS) copolymer with various molar ratios as shown in Table 1 obtained by radical polymerization as a hydraulic cement admixture The performance of the mortar was evaluated according to the following mortar test conditions. The results are shown in Table 2. [Mortar test] Prepare cement mortar with the following composition, and
A mortar test was conducted according to R-5201 (the amount of admixture added was adjusted so that the target flow was 230 mm ± 5 mm). The amount of air entrainment was measured according to JIS-A-1116. The mortar temperature is 20℃±2℃, and the temperature during underwater curing for compressive strength measurement is 20℃±2.
℃. Cement: Asano Ordinary Portland Cement Sand: Cement with river sand from the Oigawa River: 600 parts Sand: 1200 parts Water: 210 parts (Total amount including water in the admixture below) Cement admixture: As shown in Table 2 Cement/sand ratio = 1/2 cement/water ratio = 1/0.35

【table】

Table 2 shows that compared to conventional dispersants, the product of the present invention provides good workability over a long period of time even when added in a small amount, and also has a small amount of air entrainment. It can also be seen that good results are obtained in terms of compressive strength development performance after curing. Example 2 Acrylic acid (AA)-2-acrylamido-2-methylpropanesulfonic acid (AMPS) copolymers (molar ratio = 50/50) with different molecular weights were synthesized by radical polymerization, and the hydraulic properties of their sodium salts were Performance as an admixture was evaluated in the same manner as in Example 1. The results are shown in Table 3.

[Table] Example 3 Regarding the sodium salts of various acrylic acid (AA)-2-acrylamidomethanesulfonic acid (AMS) copolymers with a molecular weight of approximately 5000 obtained by radical polymerization,
The performance as a cement admixture was evaluated in the same manner as in Example 1. The results are shown in Table 4.

[Concrete test]

After mixing cement, water, aggregate, and hydraulic cement admixture according to the following formula, knead for 90 seconds with a forced mixing mixer, measure slump and air content, and then measure the slump and air content after 30 and 60 minutes, respectively. Kneading, slump, and air volume were measured. A sample for compressive strength measurement was taken after 60 minutes. The amount of admixture added was adjusted so that the target slump immediately after kneading was a slump of 20±1 cm. The measurement method was JIS A1101 for slump, JIS A1116 for air content, and JIS A1108 for compressive strength. The concrete temperature is 20℃±2℃, and the sample for compressive strength measurement is 20℃.
It was cured in water at ±2°C. Concrete mix (with admixture added) Cement: 450Kg/m ² Asano Ordinary Portland Cement Coarse aggregate: 1006〃 Ome crushed stone (maximum particle size 25mm) Fine aggregate: 747〃 Oigawa sand water: 162〃 (with admixture total amount) Hydraulic cement admixture: As shown in Table 4, water/cement ratio = 36% Fine aggregate ratio = 43%

[Table] *1 Same as Example 1 The product of the present invention exhibits the same water-reducing properties as commercially available products with a smaller amount added, and also has good slump retention, which was desired to be improved over conventional commercially available products. I understand that. Example 5 Regarding the copolymers (), () used in Example 4 and the acrylic acid-acrylamide methanesulfonic acid (70:30) copolymer sodium salt used in Example 3, the following concrete formulation was used for general concrete. We conducted an evaluation regarding the formulation. The results are shown in Table 6. Concrete blended cement: 300Kg/m ² Asano ordinary Portland cement Coarse aggregate: 1012〃 Ome crushed stone (maximum particle size 25mm) Fine aggregate: 815〃 Oigawa sand water: 166.0〃 (Total amount with admixture) Hydraulic cement Admixture: As shown in Table 6. Water/cement ratio = 55.3% Fine aggregate ratio = 44.6% Target slump: 10 ± 1 cm Target air volume: 4.5 ± 0.5% (air volume adjustment Vinsol: Yamaso Kagakusha)

[Table] From Table 6, it can be seen that even in concrete formulations for general use, good performance is achieved with a lower additive amount compared to conventional products, and the strength of the cured product is also good.

Claims (1)

[Scope of Claims] 1 (a) Amide 95 of α,β-unsaturated monocarboxylic acid and sulfonic acid containing a primary or secondary amino group
5 mol% and (b) α,β-unsaturated monocarboxylic acid 5 to 95 mol%
An admixture for hydraulic cement containing an addition copolymer or a salt thereof as an active ingredient.