JPH0345539A - Cement additive - Google Patents

Abstract

PURPOSE:To obtain the title additive having small slump loss free from air entraining, etc., containing a modified lignin sulfonate concentrated by a specific method, sulfonated styrene-maleic acid copolymer and beta-naphthalenesulfonic acid aldehyde condensate (salt) as essential components. CONSTITUTION:A modified lignin sulfonate prepared by concentrating about 5wt.% solution of lignin sulfate to >=60vol.% using an ultrafilter having >=3,000 fractional molecular weight is prepared. A polysulfone and/or polyolefin must be used as the material of the ultrafilter. Then, a cement additive containing the modified lignin sulfonate, a saponified sulfonated styrene-maleic acid copolymer and a beta-naphthalenesulfonic acid aldehyde condensate (salt) as essential components is provided. The additive can improve and maintain workability irrespective of the amount of the additive added without reducing strength of cement blended material, essential function of additive.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a cement additive, and more specifically, the present invention relates to a cement additive, which is blended and added to cement compounds such as cement paste, mortar, and concrete, and which has little slump change over time and is free from air. The present invention relates to cement additives that do not carry entrainment or set retardation properties.

[Prior art] Fluidity and workability (
If the unit amount of water is increased in order to improve workability, the strength will decrease, making it impossible to obtain a cement mixture with the desired strength. On the other hand, if the unit amount of water in the cement mixture is reduced, the strength will not decrease and the desired strength will be achieved, but the workability will be significantly reduced.

Various cement additives are used to reduce the unit amount of water and improve workability while maintaining the desired strength. Typical examples include β-naphthalenesulfonic acid formaldehyde condensate or its salt, melamine sulfonic acid formaldehyde condensate or its salt,
Lignosulfonates and the like are known. The amount of these cement additives to be added is determined by considering their type and desired fluidity. Seed cement additives are used in considerable amounts. However, β-naphthalenesulfonic acid formaldehyde condensates or their salts, melaminesulfonic acid formaldehyde condensates or their salts have excellent dispersion effects, and can be used up to high loadings without adverse effects such as delayed condensation or air entrainment; It is known to create difficulties that make it extremely difficult to maintain over time. This decrease in fluidity over time is called slump loss, and is a major drawback of cement additives.

Various measures have been taken to solve this problem. For example, according to JP-A No. 54-139929, cement additives are powdered and the active ingredients are gradually dissolved to maintain their effect, and according to JP-A No. 51-15856, cement additives are repeatedly applied in small amounts. It is said that when added to cement mixtures, it is effective in preventing a decrease in slump.

Although the effectiveness of these measures has been well recognized, in the former case, cement additives are added in the form of powder, so local residuals are unavoidable, resulting in local bleeding. In addition, the latter method requires time and labor to be added repeatedly, and is not industrially desirable. Moreover, it has the drawback that the addition equipment is expensive.

Although lignin sulfonate is known as a cement additive with relatively low slump loss, it has the disadvantage that it cannot be added in large amounts due to negative effects such as low dispersibility, setting retardation, and air entrainment.

Therefore, in order to obtain lignin sulfonic acid with reduced air entrainment and setting retardation while increasing the amount of additives and suppressing slump loss, lignin sulfonate was modified using a special operation. It is being said. For example, according to JP-A No. 56-40106, lignin sulfonic acid containing 0.2 mol or more carboxyl group and 0.1 mol or more sulfonic group per phenylpropane unit obtained by air oxidation in alkaline Salt is said to be effective in preventing slump. Also, Unexamined Patent Publication 1987
According to No. 8656, a special lignin sulfonate containing 2.5 to 5.0% sugar in terms of pentose as a component of a cement dispersant is said to be effective in preventing slump loss. According to JP-A No. 58-176158, lignin sulfonic acid, in which the low molecular fraction passing through an ultrafiltration membrane with a molecular cutoff of 10,000 or more is 20% or less of the solid content, as well as naphthalene sulfonic acid and formaldehyde, It is said that a cement dispersant containing a copolymer can prevent a decrease in fluidity.

The main goal of these methods for modifying lignin sulfonate is to keep the slump loss to a small level, and their effectiveness in this respect can be seen. However, since the improvement in air entrainment is insufficient, it has the disadvantage that the amount of air cannot be controlled, especially when sand or gravel that easily allows air to enter is used.

Next, according to JP-A-56-164051, the lignin sulfonic acid fraction obtained by fractional recovery, that is, the molecular weight 20
It is said that when the lignin sulfonic acid contains 25% by weight or less of 00 or less, and 40 or more parts of ligninsulfonic acid has a molecular weight of 10,000 or more, air entrainment is small and curing retardation can be prevented. This lignin sulfonic acid fraction can reduce air entrainment, and therefore can be used in areas where a large amount is added, but even if the amount added is increased, the effect of preventing slump loss may not be as great. Be looked at.

[Problem to be solved by the invention]

The problem to be solved by the present invention is to solve the drawbacks of this kind of conventional cement additives, namely, regardless of the amount added, the original function of the additive is to reduce the strength of the cement mixture. The objective is to develop a cement additive that can improve and sustain workability without causing any problems, that is, has a small slump loss and is free from air entrainment and setting retardation.

[Means to solve the problem]

As a result of intensive research to achieve the initial objective, the present inventors added a saponified product of a sulfonated styrene-maleic acid copolymer and a modified lignin sulfonate to a β-naphthalenesulfonic acid formaldehyde condensate or its salt. It has been found that the above object can be achieved by adding

That is, the present invention utilizes a special modified lignin sulfonate concentrated by ultrafiltration using polysulfone or/and polyolefin as a membrane material, a β-naphthalenesulfonic acid formaldehyde condensate or its salt, and a sulfonated styrene-maleic acid copolymer. The present invention relates to a cement additive characterized by containing a saponified product of a polymer as an essential component. Here, the modified lignin sulfonate is 5% by weight using an ultrafiltration membrane with a molecular weight cut-off of 3000 or more.
This is a solution obtained by concentrating a concentrated solution to a volume of 60% or less, and has never been used in this type of field.

[Function and structure of the invention]

Examples of the lignin sulfonate used in the present invention include lignin sulfonate obtained by purifying sulfite pulp waste liquid, which is usually produced as a by-product in pulp mills, and kraft pulp waste liquid.
Anything that has been used in this type of field can be used in a wide range of applications. One of its major features is that the lignin sulfonate is concentrated using an ultrafiltration membrane, and membrane materials include polysulfone, polyolefin, polyacrylonilolyl, cellulose acetate, polyimide, polyamide, polyvinylidene fluoride, and polyamide. Among various types such as imides and polyacrylonitrile copolymers, polysulfone and/or polyolefin must be used. In other words, when using other membrane materials, even if the molecular weight distribution is adjusted to be the same as the molecular weight distribution of the modified lignin sulfonate of the present invention, the air entrainment and setting retardation are still large. The dispersibility and slump loss prevention effect obtained when polysulfone and polyolefin membrane materials are used cannot be achieved.

If a membrane with a molecular weight cut-off of less than 3000 is used here, it will take too much time to concentrate and the improvement in air entrainment will be insufficient. Furthermore, if the volume of the lignin sulfonic acid solution in the concentrate is greater than 60% of the original volume, the improvement in air entrainment, that is, the reduction in air entrainment, will be insufficient.

As the β-naphthalenesulfonic acid formaldehyde condensate used in the present invention, any of those conventionally used in this type of field can be used in a wide range, and its salts can also be selected from alkali metals and alkaline earth metals. , ammonium salts, etc. can be used. The production method itself is not limited in any way, and any product produced by various methods can be used. For example, naphthalene is sulfonated with a sulfonating agent such as sulfuric acid, and then condensed with formalin, and the resulting reaction product is Can be obtained by liming soda. Specific examples of the salt include alkali metals or alkaline earth metals such as sodium, potassium, calcium, and ammonium, with sodium being particularly preferred.

As the saponified product of the sulfonated styrene-maleic acid copolymer used in the present invention, any of the products that have been used in this field can be used in a wide range. Earth metals, ammonium salts, etc. can be used. The manufacturing method itself is not limited in any way, and any product manufactured by various methods can be used. For example, a reaction product obtained by resulfonating a styrene-maleic anhydride copolymer by a conventional method may be used. Ng・
It can be obtained by soaping. Specific examples of the salt include not only alkali metals or alkaline earth metals such as sodium, potassium, and calcium, but also ammonium, with sodium being particularly preferred.

In the additive of the present invention, the ratio of the β-naphthalenesulfonic acid formaldehyde condensate or its salt to the saponified product of the modified lignin sulfonate and the sulfonated styrene-maleic acid copolymer is usually 9575 to 9575 in solid weight ratio. 20/
80, preferably 90/10 to 40,760, and the ratio of the modified lignin sulfonate to the saponified product of the sulfonated styrene-maleic acid copolymer is 9,515 to 5/95, preferably 90 /10~20/80
It is. And 0.05 in terms of solid content relative to cement
~1.5% by weight, preferably 0.08~0.8% by weight is suitable. If the amount added to the cement is less than the overlapping portion of O and OS, the fluidity of the cement cannot be expected. On the other hand, if it exceeds 1.5% by weight, it not only causes aggregate separation but also extremely slows down the setting.

The cement additive of the present invention can be added to a cement mixture by adding a modified lignin sulfonate, a saponified sulfonated styrene-maleic acid copolymer, a β-naphthalene sulfonic acid formaldehyde condensate, or a salt thereof simultaneously or separately. It can be added in the form of an aqueous solution or powder. Further, it can be added at once or in portions during or after kneading the cement mixture. In addition to the cement additive of the present invention, various conventionally used cement additives such as water reducing agents,
Air entraining agents, set retarders, accelerators, etc. may also be added.

〔Effect of the invention〕

According to the present invention, compared to conventional additives of this kind, it is possible to significantly suppress the decrease in fluidity over time, that is, slump loss, and even if the usage rate is significantly increased, air entrainment and condensation It has no retardation properties and does not reduce the strength of cement mixtures, which is the original function of additives.
Workability can be improved and sustained.

Therefore, regardless of the proportion of its use, it is extremely effective industrially.

〔Example〕

The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 (+) Concrete mix and materials used: Cement (C)
: Ordinary Portland cement fine aggregate (S) : Sand produced for Kuzuryu (specific gravity 2.57) Coarse aggregate (G) : Produced land-grown ball crusher for Kuzuryu (specific gravity 2.64) Water (W) : Tap water aggregate amount (A): Set aggregate + coarse aggregate (by volume) (2) Mixing method of concrete Mix the cement additives obtained under the conditions in Table 2 below in advance, dissolve in water, and tilt at 20°C. The concrete shown in Table 1 was obtained by mixing 3ON with a type mixer. Further, the kneading was carried out at rotational speeds of 3r, p, and m for a predetermined period of time, and the slump and air amount changes over time were measured. Note that a natural resin acid-based AE agent (air entrainment agent) was used to adjust the amount of air. Here, slump, air volume, compressive strength, and setting test are each determined by JIS A-110.
1. JIS A-1128, JIS A1108, JI
It was conducted in accordance with SA-6204. The results are shown in Table 3.

*l: Polysulfone (Nitto Denko rNTU) as membrane material
3508 J) and 10% ligninsulfonic acid (I
Modified lignin sulfonic acid *2: styrene-maleic anhydride copolymer (Arc.

rsMA100OJ manufactured by Cheraica1) 100
After reacting 140 g of fuming sulfuric acid (25 g) and 50 h l of dichloroethane at 40"C for 1 hour and removing the dichloroethane by fractionation, liming soap -
A saponified product of styrene-maleic acid copolymer obtained by

*3: While heating 50 g of 2-naphthalenesulfonic acid, 35 g of water, and 8.8 g of 98% sulfuric acid to 85°C,
A salt of a β-naphthalenesulfonic acid formaldehyde condensate obtained by dropping 20.6 g of formalin, reacting for 105° cxts, and then performing liming soap John.

*4: Setting time is expressed as time delayed from brane concrete Comparing the present invention and comparative examples, it is clear that the additive of the present invention is excellent in preventing slump loss. That is, cement additives containing component (c) alone or containing component (c) and either component (a) or (b) are insufficient in preventing slump loss.

Example 2 Concrete was obtained in the same manner as in Example 1 except that the cement additives shown in Table 4 were used, and slump, air content, compressive strength, and setting time were measured. The results are shown in Table 5.

Table 4 Comparing the present invention and comparative examples, it is clear that the additives of the present invention are excellent in preventing slump loss, and of course have low air connectivity and setting retardation.

That is, cement additives containing only each of (a) and (b), or only both, still have a large setting retardation property.

Example 3 Concrete was obtained in the same manner as in Example 1 except that the cement additive was obtained under the conditions shown in Table 6, and the slump and air content were measured. The results are shown in Table 7.

*10 Two-modified ligninsulfonic acid However, in Comparative Example 7, a ligninsulfonic acid salt manufactured by rTT Corporation of America was used.

Comparing the present invention and comparative examples, the additive of the present invention not only has the advantage of low air entrainment and the ability to freely adjust the amount of air by adding an AE agent, but also has an excellent slump loss prevention effect. is obvious.

Example 4 Concrete was obtained in the same manner as in Example 1 except that the cement additive was obtained under the conditions shown in Table 8, and the slump and air content were measured. The results are shown in Table 9.

Table 9 Comparing the present invention and comparative examples, it is clear that the additive of the present invention has the advantage of low air entrainment and the ability to freely adjust the airscape by adding an AE agent. It also has an excellent slump loss prevention effect.

(Above) Procedural author's letter (spontaneous) April 3, 1990 Patent Application No. 180012, 1999 2. Title of invention: Cement additive 3. Relationship with the person making the amendment: Patent applicant's address: Fukui 96-11 Asahi, Kanazu-cho, Sakai-gun, Prefecture Name Fukui Chemical Industry Co., Ltd. Representative Takeuchi Part 4, Agent 〒530 255゜6゜7゜1-1 Minamimorimachi, Kita-ku, Osaka-shi Specification subject to amendment Detailed explanation of the invention Contents of amendments List of attached documents (1) Contents of amendments Contents of amendments 1, in Table 1 on page 13 of the specification, replace r S/a J with rs/AJ I am corrected.

2. Line 11 from just below No. 13 of the specification “Aggregate fit (A)
: Coarse aggregate + coarse aggregate" should be corrected to "fine aggregate ratio (A): fine aggregate + coarse aggregate."

(that's all)

Claims (3)

[Claims] (1) (a) a modified lignin sulfonate concentrated by ultrafiltration using polysulfone or (and) polyolefin as a membrane material; (b) a saponified product of a sulfonated styrene-maleic acid copolymer; (c) a β-naphthalenesulfonic acid formaldehyde condensate or (and) a salt thereof; A cement additive characterized by containing as an essential component. (2) Use a modified lignin sulfonate obtained by concentrating a lignin sulfonate solution with a concentration of 5% by weight or more to 60% or less by volume using an ultrafiltration membrane with a molecular weight cut-off of 3000 or more. The cement additive according to claim (1). (3) The ratio of component (c) to component (a) and component (b) is 95/5 to 20 in solid weight ratio.
/80, and the ratio of component (a) to component (b) is 95/5 to 5/95 in terms of solid content weight ratio (1
) or the cement additive according to claim (2).