JP2013018672A - Additive for concrete or mortar, and use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an additive having more excellent water reducing effect than a water reducing agent for concrete or mortar, which is a nontoxic and inexpensive additive for concrete or mortar obtained by solving a problem of a sulfonic acid-based water reducing agent of a condensation system having such anxiety that raw material formaldehyde may exert an influence on a human body or an environment, or a high cost problem of a polycarboxylic acid-based water reducing agent.SOLUTION: A cation exchange resin having a sulfonic acid group or the like or a waste cation exchange resin is oxidized and decomposed by an oxidizing agent under a proper condition, to thereby obtain a water-soluble ionic polymer. By using the water-soluble ionic polymer not having formaldehyde added thereto, and advantageous from the viewpoint of raw material cost, this additive for concrete or mortar capable of showing an excellent effect can be obtained.

Description

The present invention relates to additives such as concrete, mortar, cement and the like. In detail, water-soluble polymers can be obtained by recycling cation exchange resins, especially used waste cation exchange resins, and using them as raw materials for oxidative decomposition, and can be applied to additives such as concrete, mortar and cement. Is possible. As an additive, for example, a water reducing agent can be added to concrete, etc., so that the amount of water added can be reduced, so that fluidity can be maintained with a low amount of water, and high strength and high durability concrete can be obtained. .

Cement water reducing agents are used to improve the quality of cement compositions such as concrete and mortar. That is, in recent years, a cement water reducing agent has become an indispensable material for high-performance concrete such as high-strength concrete and high-fluidity concrete, and for unit water quantity countermeasures in areas where aggregate conditions are poor. This cement water reducing agent has sulfonic acid type and polycarboxylic acid type, and naphthalene sulfonic acid formalin water reducing agent, melamine sulfonic acid formalin condensate water reducing agent, lignin sulfonic acid type water reducing agent etc. are used in sulfonic acid type. Yes. Moreover, there exists an example of patent document 1 in a polycarboxylic acid type | system | group. However, sulfonic acid-based water reducing agents are often condensed and formaldehyde as a raw material has a concern for the human body and the environment. On the other hand, polycarboxylic acid-based cement water reducing agents are excellent in water reducing performance and fluidity retention ability, but are a copolymer of acrylic acid or methacrylic acid and monomers containing acrylamide or polyoxyethylene chains. Therefore, the cost is somewhat higher than the condensation system.

On the other hand, when considering the waste ion exchange resin to be discarded, the cation exchange resin that adsorbs the cation has a sulfonic acid group or a carboxyl group, but those whose performance is deteriorated are incineration or landfill disposal. However, it is a problem from the viewpoint of material reuse and carbon dioxide emission. There has been proposed a method of decomposing in supercritical water and recovering the oil, but the recovered oil is only reused as fuel, and is insufficient from the viewpoint of material reuse (see, for example, Patent Document 2) ). Needless to say, if the used ion exchange resin that has been discarded at present is processed and used as a new application, it is very advantageous in terms of raw material costs.

Japanese Patent Laid-Open No. 5-208855 Japanese Patent Laid-Open No. 11-049889

The subject of this invention exists in the following points. To solve the high cost of condensation-type sulfonic acid-based water reducing agents or polycarboxylic acid-based water reducing agents whose formaldehyde is a concern for human health and the environment, and develop non-toxic and low-cost additives for concrete or mortar That is.

A cation exchange resin having a sulfonic acid group or the like can be converted into a water-soluble ionic polymer by oxidative decomposition under an appropriate condition with an oxidizing agent, and these ionic polymers are excellent as additives for concrete or mortar. Demonstrate the effect.

The invention of claim 1 relates to an additive for concrete or mortar comprising a water-soluble ionic polymer obtained by oxidative decomposition of a cation exchange resin.

The invention according to claim 2 relates to the additive for concrete or mortar according to claim 1, wherein the cation exchange resin is a waste ion exchange resin.

The invention according to claim 3 is characterized in that the ion equivalent value of the water-soluble ionic polymer is 2.0 to 5.0 meq / g. The additive for concrete or mortar according to claim 1 or 2 About.

The invention of claim 4 relates to a method for using a water-soluble ionic polymer, characterized in that a water-soluble ionic polymer obtained by oxidative decomposition of a cation exchange resin is added to ready-mixed concrete or mortar.

According to the present invention, it is possible to keep raw material costs very low, and as a result, it is possible to produce a water reducing agent for concrete that is price competitive. Moreover, since a water-soluble ionic polymer can be obtained in high yield from waste cation exchange resin that has hardly been reused in the past, the environmental impact can be reduced.

As a cation exchange resin used in the present invention, it is natural that a new ion exchange resin before use can be used, but it is particularly preferable to use a waste ion exchange resin from the viewpoint of recycling. The cation exchange resin is a resin for exchanging cations, and has an anionic group in the molecule. The anionic group is a sulfonic acid group or a carboxyl group, and more preferably a sulfonic acid group. The reason for this is that cation exchange resins that are generally used are mostly sulfonic acid groups and few carboxyl groups, but the carboxyl groups are weakly acidic groups, The sulfonic acid group is a strongly acidic group and can be stably dissociated to exhibit a certain performance.

The waste ion exchange resin referred to in the present invention is as follows. While the ion exchange resin is repeatedly regenerated and used, organic contaminants are adsorbed on the surface of the resin particles, and it is difficult to desorb during the regeneration, thereby reducing the ion exchange capacity. Alternatively, if the recycling is repeated, the crosslinking point is cut and the crosslinking degree is lowered, the particles are swollen, the raw water is difficult to pass through the column, the processing amount is lowered, and this is a practical problem. Further, the resin particles are broken by collision and become finer and the processing amount is also reduced. The ion exchange resin deteriorated due to such various factors is constantly disposed of in practice and becomes a waste ion exchange resin. In the method for producing the water-soluble ionic polymer of the present invention, either a waste ion exchange resin or a new ion exchange resin can be used as a raw material. However, considering the growing awareness of environmental issues, it is very important to use waste ion exchange resin as a raw material, convert it as a water-soluble ionic polymer, and apply it to new industrial applications. . In particular, the present invention relates to converting a waste cation exchange resin into a water-soluble ionic polymer and using it as a water reducing agent for concrete.

The present invention is described in detail below. Since the waste ion exchange resin may have various contaminants adsorbed on the resin surface, it may have to be pretreated before the oxidation reaction is performed. If necessary, after performing the treatment, 0.1 to 5 times as much water as the mass of the water-containing waste ion exchange resin is added and mixed. If necessary, an iron ion source, a copper ion source such as iron sulfate (divalent), iron chloride (trivalent), copper sulfate (divalent), and the like are added and dissolved as a catalyst. The added amount of iron ions and copper ions is 0.0002 to 0.02 times, preferably 0.0005 to 0.01 times the amount of waste ion exchange resin dry mass. When the amount of the catalyst is less than this, the decomposition rate is lowered. When the amount of the catalyst is larger than this, it is difficult to control the reaction, and the amount obtained as the water-soluble ionic polymer is remarkably reduced. To this, 35% hydrogen peroxide solution is added as hydrogen peroxide in an amount of 0.03 to 3 times, more preferably 0.06 to 2 times. If the amount of hydrogen peroxide is less than this, the decomposition rate becomes low. If the amount of hydrogen peroxide is larger than this, it is difficult to control the reaction, and the amount obtained as a water-soluble ionic polymer is significantly reduced.

The reaction temperature is room temperature to 90 ° C, preferably 40 to 70 ° C. The reaction time is about 5 to 600 minutes, although the disappearance of the ion exchange resin solids is a guideline and depends on the amount of oxidant and the amount of catalyst. Further, for example, when hydrochloric acid or the like is added at the time of decomposition to make it acidic, the decomposition is accelerated, and a water-soluble ionic polymer can be obtained with a smaller amount of hydrogen peroxide. After mixing the cation exchange resin, the metal ions as the catalyst, and hydrogen peroxide to form a uniform dispersed liquid, stirring can be stopped and the reaction can proceed without stirring. This method is a particularly effective process when carrying out the oxidation reaction at a high concentration. Therefore, considering that the reaction is performed without stirring, the concentration of the oxidation reaction is 10 to 50% by mass, preferably 15 to 40% by mass.

The ion equivalent value is an ion equivalent value with respect to 1 g of the water-soluble ionic polymer in the decomposition solution produced by decomposing 1 g of the waste ion exchange resin dry mass, and is a value obtained by colloid titration. For colloidal titration, an automatic potentiometric titrator AT-510 (manufactured by Kyoto Electronics) incorporating a streaming potential detector PCD-500 (manufactured by Kyoto Electronics) was used. At the time of titration, an aqueous polyvinyl sulfonate solution was used for titration of the cationic water-soluble polymer, and an aqueous polydiallyldimethylammonium chloride solution was used for titration of the anionic water-soluble polymer.

The water-soluble anionic polymer returned by being decomposed by the oxidizing agent of the waste cation exchange resin of the present invention usually produces a water-soluble ionic polymer having a weight average molecular weight of several thousand to several hundred thousand. On the other hand, the usual water reducing agent produced by polymerizing a vinyl monomer has a weight average molecular weight in the range of 10,000 to 1,000,000. The weight average molecular weight of naphthalene sulfonic acid formalin water reducing agent, melamine sulfonic acid formalin condensate water reducing agent, and lignin sulfonic acid water reducing agent is about several thousand to several tens of thousands because it is manufactured using a polycondensation reaction. Presumed to be. Therefore, the water-soluble anionic polymer obtained by the oxidative decomposition method of the waste cation exchange resin used in the present invention exhibits its function sufficiently when used as a water reducing agent, and can withstand practical use. Those having a weight average molecular weight of less than several thousand are not preferable for use since the water reducing effect is lowered. And if you try to make something higher than hundreds of thousands,
This is possible by reducing the amount of oxidant used, but the reaction is slow and is not very practical. Therefore, the range of the weight average molecular weight is several thousand to several hundred thousand.

The ion equivalent value of the water-soluble ionic polymer is preferably 2.0 to 5.0 meq / g. If it is lower than 2.0 meq / g, for example, the water-reducing effect will be reduced, and if it is higher than 5.0 meq / g, it will be susceptible to sulfate ions and the effect may be reduced. Or, it is not preferable because it is affected. Therefore, the ion equivalent value is preferably 2.0 to 5.0 meq / g.

There is no particular limitation on the cement used in combination with the water-soluble ionic polymer concrete or mortar additive of the present invention. For example, Portland cement (ordinary, early strength, very early strength, moderate heat, sulfate resistance and low alkali type of each), various mixed cements (blast furnace cement, silica cement, fly ash cement), white Portland cement, alumina cement, Super fast cement (1 clinker fast cement, 2 clinker fast cement, magnesium phosphate cement), grout cement, oil well cement, low exothermic cement (low exothermic blast furnace cement, fly ash mixed low exothermic blast furnace cement, belite High-concentration cement), ultra-high-strength cement, cement-based solidified material, eco-cement (city waste incineration ash, sewage sludge incineration ash as a raw material), and blast furnace slag, fly ash , Cinder ash, clinker ash Husk ash, silica fume, silica powder, a fine powder and gypsum limestone powder may be added. In addition to gravel, crushed stone, granulated slag, recycled aggregate, etc., as aggregate, siliceous, clay, zircon, high alumina, silicon carbide, graphite, chromium, chromic, magnesia, etc. The refractory aggregate can be used.

The amount of the concrete or mortar additive comprising the water-soluble ionic polymer of the present invention added to the cement is preferably 0.01 to 3.0%, more preferably 0.1 to 1.0%. If the addition rate is less than 0.01%, a sufficient cement dispersion effect does not appear, and even if the addition rate exceeds 3.0%, the effect becomes unacceptable in terms of quality and is not preferable from the viewpoint of cost. When this is added to concrete or mortar, it is generally about 0.2%.

The ionic polymer water-solubilized by the above method is dried, pulverized, salted out, coagulation sedimentation, freeze-drying, coagulation crushing, spray drying, belt dryer, etc., preferably in the form of dry powder or slurry. You may use as a kind of concrete admixture.

When used in the state of a dry powder or slurry, it is appropriate to form a particle size of usually 1 to 10,000 μm, preferably 10 to 1,000 μm. When the particle size is less than 1 μm, the bulk of the powder becomes large and easily scattered in the atmosphere, which makes handling difficult. Moreover, since the viscosity of the slurry itself becomes too high and becomes close to a gel state even in the slurry state, handling becomes difficult. When the particle diameter exceeds 10,000 μm, it does not dissolve quickly, so it takes a long time to obtain sufficient viscosity and separation resistance. As a result, the productivity of the concrete decreases, and fine adjustment of the fluidity depending on the amount added becomes considerably difficult.

The additive for concrete or mortar comprising the water-soluble ionic polymer of the present invention is used in the state of paste, mortar or concrete depending on the intended use and purpose. When used in the state of mortar or concrete, fine and coarse aggregates usually used in mortar and concrete production, ie river sand, mountain sand, sea sand, crushed sand, river gravel, mountain gravel, sea gravel , Crushed stone, etc. can be used. Moreover, conventionally well-known cement admixtures, such as an air entraining agent, an antifoamer, a shrinkage reducing agent, and a thickener, can be added as needed within the range which does not have trouble. Conventional methods can also be applied to mortar and concrete manufacturing methods. In addition, it is preferable to perform the so-called post-addition method in which the concrete or mortar additive of the present invention is added in a divided manner, or to perform double mixing, for example, in order to more effectively exhibit water reduction performance.

Furthermore, the concrete or mortar additive according to the present invention may further contain at least one of conventionally known various cement additives, if necessary. Examples of such concrete additives include air entraining agents, cement wetting agents, swelling agents, waterproofing agents, retarding agents, quick setting agents, flocculants, drying shrinkage reducing agents, strength enhancers, curing accelerators, fillers, In addition to antifoaming agents, foaming agents, colorants, flame retardants, preservatives, water resistance agents, anti-aging agents, stabilizers, vulcanization accelerators, antistatic agents, etc., blast furnace slag, Pozzolans, fly ash, silica fume, limestone, expansion materials mainly composed of minerals such as CaO and C ₃ A ₃ CaSO ₄ may also be used. These concrete admixtures are not particularly limited with respect to the timing and form of their addition, and may be added as appropriate in the same manner as in the past. It may be within the range that can be expressed, and may be as usual.

The above-described concrete additive of the present invention is not limited to ordinary general mortar and concrete, but also high-fluidity concrete, underwater non-separable concrete, sprayed concrete, upside-down concrete, ground injection (improving) method, concrete molding It can be used for cement, mortar, concrete, etc.

The water reduction test was performed in the following procedure using a mortar flow test apparatus (manufactured by Maruhishi Kagaku Seisakusho).
1) Place the flow cone correctly in the center of the top plate of the flow table.
2) Pack the kneaded mortar to half the depth of the flow cone and poke it 15 times over the entire surface so that the tip of the stab stick is about half the depth of the layer.
3) After filling the first layer, fill the flow cone with the same amount of mortar, and after poking, supplement the mortar to fill the top of the flow cone and smooth the surface.
4) Immediately remove the flow cone vertically and rotate the handle of the flow table to give the mortar on the table 15 drops in 15 seconds.
The length of the part where the mortar is most spread and the spread of the mortar in the part perpendicular to this direction are measured.

Example 1
0.2 g of ferrous sulfate heptahydrate was dissolved in 30 g of demineralized water, and 10 g of dried cation exchange resin SK104 (manufactured by Mitsubishi Chemical Corporation) was added and dispersed therein. At 60 ° C., 5 g of 35% hydrogen peroxide was added and held for 1.5 hours. The cation exchange resin was completely dissolved. Demineralized water was added to the resulting solution to prepare a 50 g water-soluble ionic polymer aqueous solution. A part was sampled from here, and the ion equivalent value was determined by colloid titration. The obtained water-soluble ionic polymer had an ion equivalent value of 3.8 meq / g (Sample-1). The results are shown in Table 1.

(Example 2)
0.2 g of ferrous sulfate heptahydrate was dissolved in 28.5 g of demineralized water, 1.46 g of 35% hydrochloric acid was added, and 10 g of dried cation exchange resin SK1B (manufactured by Mitsubishi Chemical Corporation) was added and dispersed. . At 60 ° C., 9.0 g of 35% hydrogen peroxide was added and held for 2 hours. The cation exchange resin was completely dissolved. Demineralized water was added to the resulting solution to prepare a 50 g water-soluble ionic polymer aqueous solution. A part was sampled from here, and the ion equivalent value was determined by colloid titration. The obtained water-soluble ionic polymer had an ion equivalent value of 4.0 meq / g (Sample-2). The results are shown in Table 1.

Using the cation exchange resin SK104, Sample-3 to Sample-5 were synthesized by the same operation. The physical properties of the product are shown in Table 1.

(Example 3)
The water-soluble ionic polymer solution obtained in Example 1 was adjusted to pH 6.8 using an aqueous sodium hydroxide solution. The final water-soluble ionic polymer concentration was 9%. This was used to conduct a mortar fluidity test. 215 g of water was added to and mixed with 2000 g of mortar (trade name Homecon, manufactured by Kashima Concrete Mortar Division). From this, 1000 g was collected, and 15 g of a water-soluble ionic polymer solution was added and mixed. A mortar flow test was performed, and the spread of the mortar was measured by measuring the length of the most spread portion and the length in the direction perpendicular thereto, and the average value was taken as the spread value. The spread value was 22.6 cm. The spread value of the mortar when only the same amount of water was added was 11.5 cm. In this case, the amount added to the mortar is 0.15% by mass. The results are shown in Table 1.

Example 4
Sodium hydroxide aqueous solution was added to the water-soluble ionic polymer solution obtained in Example 2 to adjust the pH to 6.7. The final water-soluble ionic polymer concentration was 9%. Using this, a mortar fluidity test was conducted in the same manner as in Example 1. The spread value of the mortar was 21.1 cm. The physical properties and results of the samples are shown in Table 1.

The test of Example 4-Example 6 was done by the same operation. The results are shown in Table 1.

(Comparative Example 1)
A mortar fluidity test was carried out in the same manner as in Example 1 using Carribon L-400 (manufactured by Sanyo Chemical Co., Ltd., polycarboxylic acid type, comparative product-1). The spread value of the mortar was 14.0 cm. The physical properties and results of the samples are shown in Table 1.

(Comparative Example 2)
A mortar fluidity test was conducted in the same manner as in Example 1 using Mighty 150 (manufactured by Kao, naphthalenesulfonic acid type, comparative product-2). The spread value of the mortar was 17.8 cm. The physical properties and results of the samples are shown in Table 1.

(Table 1)
Molecular weight: weight average (unit: 10,000), ion equivalent value: meq / g, addition amount: mass% with respect to mortar, spread value: cm.

Claims (4)

An additive for concrete or mortar comprising a water-soluble ionic polymer obtained by oxidative decomposition of a cation exchange resin. The additive for concrete or mortar according to claim 1, wherein the cation exchange resin is a waste ion exchange resin. The additive for concrete or mortar according to claim 1 or 2, wherein an ion equivalent value of the water-soluble ionic polymer is 2.0 to 5.0 meq / g. A method for using a water-soluble ionic polymer, comprising adding a water-soluble ionic polymer obtained by oxidative decomposition of a cation exchange resin to fresh concrete or mortar.