JP6655495B2 - 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 mass than the original mineral, they may expand in volume, cause the roadbed to protrude or break, and 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. It is an object of the present invention to provide a roadbed material containing an expansion inhibitor that can be sufficiently suppressed, and a method of suppressing the expansion of the roadbed material.

  The present inventors have studied to solve the above-described problems, and as a result, as a swelling inhibitor used for a roadbed material such as steel slag containing an swelling mineral such as CaO and MgO, a water-soluble acrylic acid-based polymer Has been found to be correct and suitable.

That is, the present invention provides a roadbed material containing Rise tonicity minerals, characterized in that the expansion inhibitor comprising a water-soluble acrylic acid-based polymer is contained 0.1 to 4% by mass in roadbeds Related to roadbed materials.
The present invention also relates to a method for suppressing the expansion of a roadbed material containing an expansive mineral, wherein an expansion inhibitor composed of a water-soluble acrylic polymer is incorporated in the roadbed material in an amount of 0.1 to 4% by mass. The present invention relates to a method for suppressing the expansion of a roadbed material, characterized in that:

  In the present invention, the water-soluble acrylic acid-based polymer used as a swelling inhibitor has a structural unit formed from acrylic acid and / or a salt thereof as a main structural unit. As the system polymer, a polymer having the structural unit A represented by the following chemical formula 1 in all the structural units is preferably 60 mol% or more, and more preferably a polymer having 70 mol% or more.

In Chemical Formula 1,
M: hydrogen atom, alkali metal, alkaline earth metal, ammonium or organic amine

  Examples of the monomer that forms the structural unit A include 1) acrylic acid, 2) alkali metal acrylates such as sodium acrylate, potassium acrylate, and lithium acrylate; 3) calcium acrylate and magnesium acrylate And the like. 4) Ammonium acrylate, 5) Triethanolamine acrylate, and organic amine salts of acrylate such as diethanolamine acrylate. In the structural unit A, an alkali metal salt, an alkaline earth metal salt, and an ammonium salt obtained by polymerizing using acrylic acid as a monomer, and then neutralizing the monomer with an alkali metal, an alkaline earth metal, ammonium or an organic amine. , Organic amine salts. Above all, acrylic acid and / or sodium acrylate are preferable as the monomer that forms the structural unit A.

  The water-soluble acrylic acid-based polymer may have other structural units in addition to the structural unit A. Monomers that form such other structural units include methacrylic acid, methacrylic acid salts, crotonic acid, crotonic acid salts, maleic acid, maleic acid salts, maleic anhydride, fumaric acid, and fumaric acid. Salt, alkyl acrylate, alkyl methacrylate, hydroxyalkyl acrylate, hydroxyalkyl methacrylate, acrylamide, allylsulfonic acid, salt of allylsulfonic acid, methallylsulfonic acid, salt of methallylsulfonic acid, styrenesulfonic acid, styrene One or more selected from sulfonic acid salts, 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid salts, styrene, vinyl acetate, ethylene, isoprene, isoamylene and the like. No. Of these, maleic acid, a salt of maleic acid, maleic anhydride, methacrylic acid, and a salt of methacrylic acid are preferable as the monomer that forms another structural unit.

  The weight-average molecular weight of the water-soluble acrylic polymer is not particularly limited, but is preferably 3000 to 200,000,000, more preferably 10,000 to 10000000.

  The water-soluble acrylic acid-based polymer itself can be synthesized by a known method. For example, a method described in JP-A-5-117306 can be mentioned. More specifically, an acrylic acid aqueous solution and a sodium hydroxide aqueous solution are first added to a stainless steel pressure reaction vessel to partially neutralize acrylic acid, and then a persulfate is added under a nitrogen atmosphere, followed by heating. It can be synthesized by performing a polymerization reaction below.

  The water-soluble acrylic acid-based polymer used as the expansion inhibitor of the roadbed material is used in an amount of 0.1 to 4% by mass with respect to the mass of the roadbed material containing expandable minerals, for example, steel slag. Moreover, it is preferable to use it so that it may become 0.5 to 3 mass%. The water-soluble acrylic polymer may be used alone or in combination of two or more as needed. In addition, as long as the original function of the water-soluble acrylic acid polymer is not impaired, a water-insoluble superabsorbent resin, oxycarboxylic acid or a salt thereof, a monosaccharide, a polysaccharide, an antifoaming agent, a foaming agent, a pozzolanic substance, It may be used in combination with a hydraulic substance or the like. The water-soluble acrylic acid-based polymer may be added as it is to the roadbed material containing the expandable mineral, or may be added after being dissolved in water, or both may be used in combination. The roadbed material containing the expansible mineral may be used again as a roadbed material after removing the roadbed material containing the expansive mineral that has already been applied, adding a water-soluble acrylic acid-based polymer thereto. Commercial products of the water-soluble acrylic polymer as described above include Aqualic L and Aquaric H under the trade name of Nippon Shokubai Co., Ltd., and Aaron and Julimer under the trade name of Toagosei 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 polymer)
-Synthesis of acrylic acid polymer (P-1) In a reaction vessel, 72 g of acrylic acid, 3.5 g of 3-mercaptopropionic acid and 742 g of water were charged and mixed, and 66 g of a 30% aqueous sodium hydroxide solution was stirred. And neutralized. After the atmosphere was replaced with nitrogen, the temperature of the reaction system was maintained at 60 ° C. in a warm water bath, and 10 g of a 20% aqueous sodium persulfate solution was added dropwise to initiate polymerization. A 10% aqueous solution of the polymer (P-1) was obtained. The weight average molecular weight of this acrylic acid polymer (P-1) was 4,200.

-Synthesis of acrylic acid polymer (P-2) In the same manner as in the case of acrylic acid polymer (P-1), a 10% aqueous solution of acrylic acid polymer (P-2) described in Table 1 was used. Obtained. The weight average molecular weight of this acrylic acid polymer (P-2) was 27000.

・ Synthesis of acrylic acid polymer (P-3) In a reaction vessel, 49 g of maleic anhydride and 303 g of water were charged and mixed. After the atmosphere was replaced with nitrogen, the temperature of the reaction system was maintained at 90 ° C., and 84 g of acrylic acid was added. And a 20% aqueous sodium persulfate solution (20 g) was added dropwise over 4 hours to carry out the polymerization reaction. After that, 19 g of a 30% aqueous sodium hydroxide solution was added, and the mixture was added to the ion exchange water. Then, the mixture was diluted to a 10% aqueous solution to obtain a 10% aqueous solution of an acrylic acid polymer (P-3). The weight average molecular weight of this acrylic acid polymer (P-3) was 36,000.

-Synthesis of acrylic acid polymer (P-4) Into a reaction vessel, 260 g of ion-exchanged water was charged, the atmosphere was replaced with nitrogen while stirring, and the temperature of the reaction system was maintained at 60C. Next, 35 g of acrylic acid, 0.3 g of polypropylene glycol, 14 g of acetone, and 0.01 g of 2,2-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator were added. After the reaction due to cloudiness started, 156 g of a mixed solution of 120 g of acrylic acid and 36 g of acetone and 0.05 g of the above-mentioned polymerization initiator were added in portions. After completion of the charging, the mixture was further aged at 60 ° C. for 2 hours to obtain a polymer suspension. This suspension was filtered, and the solid content separated by filtration was dried. Then, an aqueous solution of ion-exchanged water adjusted to pH 6 with sodium hydroxide was added to obtain a 10% aqueous solution of an acrylic acid polymer (P-4). Was. The weight average molecular weight of this acrylic acid polymer (P-4) was 300,000.

-Synthesis of acrylic acid polymer (P-5) In the same manner as in the case of acrylic acid polymer (P-4), acrylic acid polymer (P-5) shown in Table 1 was synthesized, and water was synthesized. The mixture was neutralized with sodium oxide and dried to obtain an acrylic acid polymer (P-5). The weight average molecular weight of this acrylic acid polymer (P-5) was 5,000,000. Table 1 summarizes the contents of the acrylic acid polymers synthesized as described above.

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 expansion 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 A 10% aqueous solution of an acrylic acid polymer (P-1) synthesized in Test Category 1 was used as an acrylic acid polymer (P-1) in an unaged steel slag as an expansion inhibitor. 0.5%.
Examples 2 to 6: 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,
P-1 to P-5: Acrylic acid polymer synthesized in test category 1 Addition amount: Addition amount as acrylic acid polymer

  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-soluble acrylic acid polymer 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 7 to 12: To an unaged steel slag, an acrylic acid-based polymer in an aqueous solution synthesized in Test Category 1 was added as an expansion inhibitor as shown in Table 2.

In Table 3,
A-1 to A-5: Acrylic acid polymer synthesized in test category 1 Addition amount: Addition amount as acrylic acid polymer

  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. for 90 days is more than 10%, in the case of steel slag containing a large amount of MgO, sufficient aging for a long period of time is usually sufficient for 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%, even if ordinary aging was not performed. 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 comprising a roadbed material containing 0.1 to 4% by mass of an expansion inhibitor made of a water-soluble acrylic acid polymer. 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-soluble acrylic acid polymer is incorporated in the roadbed material in an amount of 0.1 to 4% by mass.