JP6647979B2 - Roadbed material containing expansion inhibitor, and method of suppressing expansion of roadbed material - Google Patents

Description

The present invention, roadbed material containing Rise Zhang inhibitors, and to the expansion method of suppressing roadbeds. Roadbed materials used for roads, parking lots, and the like include, in addition to natural crushed stone, steel slag and recycled materials. When expandable minerals such as CaO and MgO are contained in these roadbed materials, they react with moisture to form CaO hydrate and MgO hydrate. Since these hydrates have a larger volume per unit material amount than the original mineral, they may expand in volume, cause uplift or destruction of the roadbed, etc., and may even destroy structures adjacent to the pavement. . The present invention relates to a roadbed material containing an expansion inhibitor capable of sufficiently suppressing the expansion of a roadbed material such as steel slag containing expandable minerals such as CaO and MgO, and a method of suppressing the expansion of a roadbed material. About. In the present invention, the roadbed material also includes earthwork materials used for leveling of unpaved roads, unpaved parking lots, open spaces, material storage areas, and the like.

  Conventionally, when steel slag is used as a roadbed material, a normal aging treatment for promoting a hydration reaction of expansive minerals contained in the steel slag and an accelerated aging treatment with warm water or steam have been performed. However, such a normal aging treatment and an accelerated aging treatment actually have a problem in that when the steel slag subjected to such treatment is used as a roadbed material, the expansion of the roadbed material may not be sufficiently suppressed.

  It has been pointed out that such a problem is caused by the fact that the hydration reaction of CaO is fast but the hydration reaction of MgO is slow (for example, see Non-Patent Document 1). The hydration rate reaches 100% at 20 ° C., but the hydration rate of MgO stays at 57% in water at 20 ° C. for 180 days, and the hydration rate of MgO is very slow, about 1/100 of that of CaO. (For example, see Non-Patent Document 2).

Jurgen Geiseler, Ruth Schlosser, Rudiger Scheel, Klaus Koch and Dieter Janke: Steel Research 58 (1987), p. 210 GAO Peiwei, LU Xiaolin, GENG Fei, LI Xiaoyan, HOU Jie, LIN Hui, SHI Nannan. Production of MgO-type expansive agentin dam-concrete by use of industrial by-products, Build Environ, Vol. 43 No. 4 Page. 453-457 (2008.04)

The problem to be solved by the present invention is that the expansion of a roadbed material such as steel slag containing an expandable mineral such as CaO or MgO can be performed for a long time without performing an ordinary aging treatment or an accelerated aging treatment. roadbed material containing swelling inhibitors which can be suppressed above sufficiently, and the processing to provide an expansion method for suppressing roadbeds.

  The present inventors have conducted research to solve the above-mentioned problems, and as a result, a water-insoluble superabsorbent resin is used as an expansion inhibitor for use in roadbed materials such as steel slag containing expandable minerals such as CaO and MgO. It has been found that it is correct and suitable.

That is, the present invention relates in roadbed material containing Rise tonicity minerals, the roadbed expansion inhibitor comprising a superabsorbent polymer water-insoluble, characterized in that it is contained 1 wt% or less in roadbeds .
Further, the present invention relates to a method for suppressing the expansion of a roadbed material containing an expansive mineral, wherein an expansion inhibitor comprising a water-insoluble superabsorbent resin is blended in the roadbed material at 1% by mass or less. The present invention relates to a method for suppressing expansion of a roadbed material to be performed.

  In the present invention, the water-insoluble superabsorbent resin used as a swelling inhibitor is generally used for sanitary materials such as disposable diapers and sanitary articles, and is also used for non-sanitary materials such as soil water retention agents and cold preservatives. It is a resin with a crosslinked structure that is almost insoluble in water, swells by absorbing water to a high degree, and has a property that once absorbed, it is difficult to separate even if a slight pressure is applied. When such a water-insoluble superabsorbent resin is used as an expansion inhibitor for a roadbed material, when CaO or MgO, which is an expansive mineral in the roadbed material, becomes a hydrate and expands, the surrounding superabsorbent resin is compressed. As a result, the roadbed material does not expand in volume due to water release and contraction, and the hydration reaction water of CaO or MgO decreases due to the water absorption of the highly water-absorbent resin, so that the hydration expansion itself decreases.

  Examples of the water-insoluble superabsorbent resin that can be used as an expansion inhibitor include polyacrylic acid (salt), polysulfonic acid (salt), maleic anhydride (salt), polyacrylamide, polyvinyl alcohol, and polyethylene oxide. And polyaspartic acid (salt), polyglutamic acid (salt), polyalginic acid (salt), starch, and cellulose. The term “system” as used herein means that these are the main components, and may be composed of a single structural unit or two or more types of structural units. An initiator, an internal crosslinking agent, a chain transfer agent, a chelating agent, a crosslinking inhibitor, a surfactant and the like may be contained. The production method may be any method such as aqueous solution polymerization, reversed-phase emulsion polymerization, and reversed-phase suspension polymerization.

  As described above, the water-insoluble superabsorbent resin which can be used as the expansion inhibitor has been exemplified. Among the water-insoluble superabsorbent resins, the structural unit A represented by the following chemical formula 1 in all the structural units and the following A water-insoluble, highly water-absorbing acrylic acid-based crosslinked polymer having a total of 50 mol% or more of the structural unit B represented by Chemical Formula 2 is preferable.

In Chemical Formula 2,
M: alkali metal, alkaline earth metal, ammonium or organic amine

  The monomer that forms the structural unit A is acrylic acid. Examples of the monomer that forms the structural unit B include: 1) alkali metal acrylates such as sodium acrylate, potassium acrylate, and lithium acrylate; 2) alkali acrylates such as calcium acrylate and magnesium acrylate. Earth metal salts; 3) ammonium salts of acrylic acid; 4) organic amine salts of acrylic acid such as triethanolamine acrylate and diethanolamine acrylate. In the structural unit B, after polymerization using acrylic acid as a monomer, an alkali metal, an alkaline earth metal salt, an ammonium salt, an organic compound obtained by neutralizing with an alkali metal, an alkaline earth metal or an organic amine are used. Amine salts are included. Among them, the salt of the structural unit B is preferably an alkali metal salt, and more preferably a sodium salt.

  The above-mentioned water-insoluble and highly water-absorbing acrylic acid-based crosslinked polymer can have other structural units in addition to the structural units A and B. Examples of the monomer that forms such another structural unit include: 1) methacrylic acid, methacrylic acid salt, crotonic acid, crotonic acid salt, itaconic acid, itaconic acid salt, maleic acid, and maleic acid salt. Α, β-unsaturated carboxylic acids such as maleic anhydride, fumaric acid, and salts of fumaric acid or salts thereof, 2) acrylamide, methacrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, vinyl acetate, etc. Among them, acrylamide is preferable.

  In the above-mentioned water-insoluble and highly water-absorbing acrylic acid-based crosslinked polymer, the monomers that form the structural unit of the crosslinked structure portion include: 1) N, N-methylenebisacrylamide and other amide-based crosslinked polymers. 2) ethylene glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, etc. Ester crosslinkable monomers, 3) glycerin diallyl ether, glycerin triallyl ether, trimethylolpropane diallyl ether, trimethylolpropane triallyl ether, pentaerythritol triallyl ether, pentaerythritol tetraallyl ether, etc. And 4) polyvalent glycidyl compound-based crosslinkable monomers such as ethylene glycol diglycidyl ether and diethylene glycol diglycidyl ether.

  The above-mentioned water-insoluble and highly water-absorbing acrylic acid-based crosslinked polymer has a total of 50 mol% or more of the structural unit A and the structural unit B in all the structural units. It is preferable that the total amount of the structural unit A and the structural unit B is 60 mol% or more, and the structural unit A / the structural unit B = 85/15 to 5/95 (molar ratio). It is more preferable to have 90% by mole or more, and to have the ratio of structural unit A / structural unit B = 70/30 to 10/90 (molar ratio). Further, as such an acrylic acid-based crosslinked polymer, a polymer having 0.001 to 1 mol% of a structural unit of a crosslinked structure portion formed from the above crosslinkable monomer in all the structural units is preferable. Those having 0.01 to 0.5 mol% are more preferable.

  The water-insoluble and highly water-absorbing acrylic acid-based crosslinked polymer itself can be synthesized by a known method. For example, a method described in JP-A-3-56513 can be mentioned. More specifically, first, an acrylic acid aqueous solution and a sodium hydroxide aqueous solution are added to a stainless steel pressure reaction vessel to partially neutralize acrylic acid, then a crosslinkable monomer is added, and the mixture is further subjected to a nitrogen atmosphere. After adding the sulfate and the promoter, the compound can be synthesized by performing a polymerization reaction at a temperature of 60 to 110 ° C. under pressure.

  In the present invention, the water-insoluble superabsorbent resin used as the expansion inhibitor of the roadbed material preferably has a particle size of 10 to 2000 μm, more preferably 10 to 1000 μm. The water-insoluble superabsorbent resin preferably has a water absorption of 20 g / g or more, more preferably 30 to 70 g / g. The water absorption here is a measured amount when 0.9% by mass of saline is used in accordance with the method defined in JIS K7223-1996.

  The water-insoluble superabsorbent resin used as the expansion inhibitor of the roadbed material is used so as to be 1% by mass or less with respect to the mass of the roadbed material containing expandable minerals, for example, steel slag. The water-insoluble superabsorbent resin may be used alone or, if necessary, in combination of two or more. Water-soluble acrylic acid (salt) -based polymers and salts thereof, oxycarboxylic acids and salts thereof, monosaccharides, polysaccharides, defoamers, foaming agents, as long as the essential functions of the water-insoluble superabsorbent resin are not impaired , Pozzolanic substances, hydraulic substances and the like. The water-insoluble superabsorbent resin may be added as it is to the roadbed material containing the expansible mineral, or may be added after absorbing water, or both may be used in combination. The roadbed material containing the expansive mineral may be one in which a water-insoluble superabsorbent resin is added to the roadbed material in advance, or the roadbed material containing the expansive mineral that has already been constructed may be used. After taking out and adding the superabsorbent resin thereto, it may be used again as a roadbed material. Commercial products of the water-insoluble superabsorbent resin described above include Sunfresh GT and Aquapearl DS, both manufactured by Sanyo Chemical Industries, and Aquaric CA, Sumitomo Seimitsu, manufactured by Nippon Shokubai Co., Ltd. Aqua keep SA and the like are available under the trade name of Kakesha Co., Ltd.

It roadbed material containing Rise Zhang inhibitor of the present invention, and a method of expansion suppressing roadbed material, such or normal aging time, without purposely performed accelerated aging process costly steel containing intumescent mineral There is an effect that expansion of a roadbed material such as slag can be sufficiently suppressed in practical use for a long period of time.

  Hereinafter, examples and the like will be described in order to make the configuration and effects of the present invention more specific, but the present invention is not limited to these examples. In the following Examples and Comparative Examples, parts mean parts by mass, and% means mass%.

Test Category 1 (Synthesis of acrylic acid-based crosslinked polymer)
・ Synthesis of acrylic acid-based crosslinked polymer (A-1) To a stainless steel pressure reaction vessel, add 110.5 parts of acrylic acid, 232 parts of water, and 143.2 parts of a 30% sodium hydroxide aqueous solution while stirring, and add acrylic. The acid was partially neutralized. After cooling to room temperature, 0.4 parts of N, N-methylenebisacrylamide was added and mixed by bubbling with nitrogen. Further, 0.3 part of a 10% concentration aqueous sodium persulfate solution and 0.015 part of a 10% concentration sodium erythorbate were added, and a polymerization reaction was performed at a pressure of 300 kPa and a maximum temperature of 90 ° C. for 60 minutes. The product was separated from the reaction system, cut into pieces, dried in a hot air drier at 120 ° C., pulverized and classified with a sieve to obtain a water-insoluble and powdery acrylic acid-based crosslinked polymer (A- 1) was obtained.

・ Synthesis of acrylic acid-based crosslinked polymer (A-2) to (A-5) Similarly to acrylic acid-based crosslinked polymer (A-1), acrylic acid-based crosslinked polymer (A-2) to (A-5) was obtained. Table 1 summarizes the contents of each of the acrylic acid-based crosslinked polymers synthesized as described above.

In Table 1,
(1) + (2): total ratio (mol%) of the structural unit A represented by Chemical Formula 1 and the structural unit B represented by Chemical Formula 2 in all the structural units
(1) / (2): ratio (molar ratio) of the structural unit A represented by the chemical formula 1 / the structural unit B represented by the chemical formula 2
Water absorption (g / g): measured amount using 0.9% by mass of saline according to the method defined in JIS K 7223-1996 M-1: Structural unit formed from methacrylic acid M- 2: Structural unit formed from acrylamide L-1: Structural unit formed from N, N-methylenebisacrylamide L-2: Structural unit formed from diethylene glycol diglycidyl ether

Test Category 2 (Evaluation Part 1:10 Water Immersion Expansion Ratio)
The composition of the steel slag as the roadbed material subjected to the test was 36 to 39% of CaO and 3.5 to 5.7% of MgO, and the grain size was adjusted to crusher-run steel slag CS-40. According to JIS A 5015, the water immersion swelling ratio was measured at 80 ° C. for 10 days (retention time at 80 ° C. is 6 hours a day). The results are summarized in Table 2. The steel slag used for each comparative example and example is as follows.
Comparative Example 1: Steel slag not aged.
Comparative Example 2: Steel slag subjected to normal (atmospheric) aging for 8 months.
Comparative Example 3: Steel slag subjected to steam aging, which is accelerated aging, for 48 hours.
Example 1: 0.05% of an acrylic acid-based crosslinked polymer or the like (A-1) synthesized in Test Category 1 was added as an expansion inhibitor to an unaged steel slag.
Examples 2 to 8: The same procedures were performed as in Example 1 except that the type and amount of the expansion inhibitor were changed as shown in Table 2.

In Table 2,
A-1 to A-5: Acrylic acid-based crosslinked polymer synthesized in test category 1, etc. C-1: Cellulose-based water-absorbing resin (trade name Sunrose SLD-F1, manufactured by Nippon Paper Industries, catalog value: average particle diameter 50) ６０60 μm, water-insoluble, water absorption 17 g / g)

  As is clear from the results in Table 2, even in the case of iron and steel slag having a low content of MgO, the immersion expansion ratio reaches 2.5% if aging is not performed, but normal aging or accelerated aging is required. It can be seen from the result that the water immersion expansion ratio satisfies the JIS standard. Further, according to the present invention in which a water-insoluble superabsorbent resin is used as the expansion inhibitor, the water immersion expansion ratio satisfies the JIS standard without aging.

Test Category 3 (Evaluation 2: Water immersion expansion ratio at 10 days and 90 days)
The composition of the steel slag as the roadbed material subjected to the test was CaO of 40 to 43%, MgO of 12 to 18%, and the grain size was adjusted to crusher-run steel slag CS-40. This was added to the water immersion swelling ratio at 10 days of holding at 80 ° C. for 6 hours a day according to JISA5015, and the water immersion swelling ratio of continuously holding at 80 ° C. for 90 days was measured. The results are summarized in Table 3. The steel slag used for each comparative example and example is as follows.
Comparative Example 4: Steel slag subjected to normal (atmospheric) aging for 8 months.
Examples 9 to 16: As shown in Table 2, an acrylic acid-based crosslinked polymer synthesized in Test Category 1 was added as an expansion inhibitor to an unaged steel slag.

In Table 3,
A-1 to A-5: Acrylic acid-based crosslinked polymer synthesized in Test Category 1, etc. C-1: Cellulose-based water-absorbing resin (Sunrose SLD-F1, trade name, manufactured by Nippon Paper Industries Co., Ltd., average particle diameter 50 μm, water Insoluble, water absorption 17g / g)

  As is clear from the results in Table 3, even in the case of steel slag containing a large amount of MgO, the water immersion expansion ratio at 80 ° C. for 10 days (retained for 6 hours at 80 ° C. ± 3 ° C.) by performing normal aging. After that, an operation of allowing to cool in the curing device is performed once a day, and this operation is repeated for 10 days to achieve a water immersion expansion ratio of 1.5% or less of the standard. However, when the water immersion expansion ratio measured at 80 ° C. continuously for 90 days is more than 10%, in the case of steel slag containing a large amount of MgO, sufficient aging over a long period of time is usually sufficient in the case of steel slag containing a large amount of MgO. The expansion suppression effect cannot be expected. On the other hand, in each of the examples, in the case of steel slag having a high MgO content, the water immersion expansion ratio at 80 ° C. for 10 days was 0.1 to 0.2% in all cases without performing the normal aging. In addition, depending on the type and amount of the expansion inhibitor, the water immersion expansion ratio when continuously maintained at 80 ° C. for 90 days can be suppressed to less than 1%.

Claims (2)

In roadbed materials containing expansive minerals,
A roadbed material characterized in that the roadbed material contains 1% by mass or less of an expansion inhibitor made of a water-insoluble superabsorbent resin. A method for suppressing the expansion of a roadbed material containing an expandable mineral,
A method for suppressing the expansion of a roadbed material, wherein an expansion inhibitor comprising a water-insoluble superabsorbent resin is incorporated in the roadbed material in an amount of 1% by mass or less.