JP6582599B2 - Low carbon neutralization-inhibiting mortar composition and low carbon neutralization-inhibiting mortar cured product - Google Patents

Description

  The present invention relates to a low carbon neutralization-inhibiting mortar composition that suppresses neutralization and is excellent in compressive strength. The present invention also relates to a method for producing a low-carbon neutralization-inhibited mortar cured product using the low-carbon neutralization-inhibited mortar composition.

  In recent years, from the viewpoint of suppressing global warming, there is an increasing demand for low carbon in the construction material field. Concrete, the core construction material, is manufactured by mixing water, cement, admixture, fine aggregate, coarse aggregate, etc., but cement is more carbon dioxide than other materials at the time of manufacture. In order to reduce carbon, it is common to replace part of the cement with an admixture.

However, when the carbon content is reduced and the amount of replacement of the admixture is increased, the amount of cement decreases, so the strength of the hardened cement (concrete and mortar) generally decreases. In general, the use of admixtures reduces the resistance to neutralization. This is due to the fact that the amount of Ca contained in the admixture is less than that of cement. When the amount of Ca is small, the amount of Ca (OH) ₂ which is a hydrate of the main factor that counteracts neutralization is small. It is to become.

  Blast furnace slag fine powder is obtained by pulverizing granulated blast furnace slag, has latent hydraulic properties, and is a commonly used admixture. Similarly, it is superior in strength expression compared to fly ash which is often used as an admixture, but the strength is reduced when a large amount is substituted.

  Gypsum is often used as a stimulant for promoting the reaction of blast furnace slag fine powder. In Non-Patent Document 1, the ratio of gypsum / (cement + blast furnace slag fine powder) is 0.0 when the ratio of blast furnace slag fine powder / (cement + blast furnace slag fine powder) ranges from 28.9 to 79.2%. Gypsum is added in a range of ˜11.1%, and gypsum addition is effective for neutralization suppression only when the pre-curing period is short (3-day underwater curing). On the other hand, Non-Patent Document 2 shows that when the ratio of blast furnace slag fine powder / (cement + blast furnace slag fine powder) is 47.4 to 50.0%, the ratio of gypsum / (cement + blast furnace slag fine powder) is 0.0. Gypsum is added in a range of ˜5.3%, and the strength development is improved by adding gypsum, but the neutralization tends to be promoted conversely. Further, in Non-Patent Document 3, when the ratio of fine blast furnace slag powder / (cement + blast furnace slag fine powder) is about 66.5%, the ratio of gypsum / (cement + blast furnace slag fine powder) is 0.0-11. Gypsum is added in the range of 1%, and the addition of gypsum shows an increase in the initial strength and a suppression of the long-term strength, but the neutralization rate is said to increase.

Goro Sakai, Masaki Daimon, Kiyoshi Kiyoshi, Takao Chikada, “Carbonation of hardened blast furnace cement with different chemical composition and fineness”, Annual report on concrete engineering, Vol.18, No.1, pp.735 740, 1996 Minoru Morioka, Yasuyuki Nikaido, Ken Kubota, Kiyoshi Asaga, “Neutralization of hardened blast furnace slag cement mixed with various stimulants”, Annual Report of Concrete Engineering, Vol.18, No.1, pp.741 -746, 1996 Masahiro Wachi, Ryo Kanai, Daijiro Tsuji, Kazumasa Inoue, Takeo Mitsui, Toshio Yonezawa, “Study on Basic Properties of Concrete Using High-cement Blast Furnace Slag Fine Powder”, Takenaka Technical Research Report, No. 67, pp. 1-6, 2011

  As described above, when carbon is reduced and a large amount of cement is replaced with fine blast furnace slag powder, strength is lowered and resistance to neutralization is lowered. Even when gypsum is used as an irritant, it is particularly effective in improving the initial strength, but there are also cases where neutralization is promoted conversely.

  Then, an object of this invention is to provide the low carbon neutralization suppression mortar composition which is excellent in compressive strength while suppressing neutralization.

  As a result of intensive studies to achieve the above object, the present inventors have found that the above object can be achieved by using gypsum and a high pH solution containing Ca ions and the like typified by supernatant water. I found out.

That is, the present invention relates to the following.
(1) A low carbon neutralization-inhibiting mortar containing fine inorganic powder, gypsum, fine aggregate and mixed water, the fine inorganic powder comprising cement and fine blast furnace slag fine powder, and the fine cement and blast furnace slag fine powder. The powder mass ratio (cement: blast furnace slag) is 10: 90-30: 70, the amount of the gypsum is 6-10 parts by mass with respect to 100 parts by mass of the inorganic fine powder, and the pH of the mixing water 10 to 14 and the Ca ion concentration is 100 to 5000 mg / L. Even if a large amount of blast furnace slag fine powder is used for carbon reduction, neutralization is suppressed and strength is enhanced by using a high pH solution containing Ca ions, such as gypsum and supernatant water. Is possible.

(2) The low carbon neutralization-suppressing mortar composition according to the above (1), wherein the kneaded water has a Na ion concentration of 10 to 500 mg / L and a Ka ion concentration of 10 to 500 mg / L.

(3) The low carbon neutralization-suppressing mortar composition according to the above (1) or (2), wherein the mixing water has a SO ₄ ion concentration of 10 to 5000 mg / L and a Cl ion concentration of 1 to 100 mg / L. object.

  (4) The low carbon neutralization-suppressing mortar composition according to any one of (1) to (3), further including 1 to 10 parts by mass of calcium hydroxide with respect to 100 parts by mass of the inorganic fine powder. By using calcium hydroxide in combination, neutralization can be further suppressed.

(5) A step of mixing the inorganic fine powder, gypsum, fine aggregate and mixing water to prepare the low-carbon neutralization-inhibiting mortar composition, and a step of curing the low-carbon neutralization-inhibiting mortar. The manufacturing method of the low carbon neutralization suppression mortar hardening body containing.

  (6) In the said curing, manufacture of the low-carbon neutralization suppression mortar hardening body as described in said (5) including the process of carrying out underwater curing for 1 to 10 weeks, and the process of carrying out air curing for 1 to 10 weeks Method.

<Low carbon neutralization inhibiting mortar composition>
The low-carbon neutralization-suppressing mortar composition of the present invention contains fine inorganic powder, gypsum, fine aggregate, and mixed water. The inorganic fine powder is composed of cement and blast furnace slag fine powder.

  Examples of the cement used in the present invention include Portland cement and mixed cement specified by JIS. Specifically, ordinary Portland cement, early-strength Portland cement, ultra-high-strength Portland cement, medium heat Portland cement, low heat Portland cement, sulfate-resistant Portland cement, and their low alkali type Portland cement, blast furnace cement, fly ash Examples thereof include cement and silica cement.

Blast furnace slag is produced as a by-product during the refining of steel. In the present invention, finely ground blast furnace slag powder is used. The blast furnace slag fine powder of the present invention is preferably obtained by pulverizing blast furnace granulated slag. There blast furnace slag in, CaO content 40-45 wt%, SiO ₂ content 30 to 35 wt%, _Al 2 _{O 3} content 10 to 18 wt%, in the range of SO ₃ content 1.5-2.0 wt% It is preferable to use blast furnace slag. The blast furnace slag fine powder has a brain surface area of preferably 4000 to 4900, more preferably 4200 to 4900, and still more preferably 4400 to 4900.

  In the present invention, the mass ratio of the cement and the blast furnace slag fine powder (cement: blast furnace slag) is 10:90 to 30:70, preferably 13:87 to 27:73, and more preferably 16: 84-24: 76.

  In the low carbon neutralization inhibiting mortar composition of the present invention, the amount of gypsum is 6 to 10 parts by mass, preferably 6 to 9 parts by mass, more preferably 100 parts by mass of the inorganic fine powder. Is 6-8 parts by mass. The gypsum used in the present invention is preferably anhydrous gypsum.

  The kneading water used in the present invention is a high pH solution containing Ca ions, typified by supernatant water.

  In this invention, pH of the said mixing water is 10-14, Preferably it is pH10.5-14, More preferably, it is pH11-14.

  In this invention, Ca ion concentration of the said mixing water is 100-5000 mg / L, Preferably it is 120-4000 mg / L, More preferably, it is 140-3000 mg / L.

  The kneaded water preferably has a Na ion concentration of 10 to 500 mg / L, more preferably 15 to 480 mg / L, and still more preferably 20 to 460 mg / L. The mixing water has a Ka ion concentration of preferably 10 to 500 mg / L, more preferably 15 to 480 mg / L, and still more preferably 20 to 460 mg / L.

The mixing water has an SO ₄ ion concentration of preferably 10 to 5000 mg / L, more preferably 15 to 4000 mg / L, and still more preferably 20 to 3000 mg / L. The mixing water preferably has a Cl ion concentration of 1 to 100 mg / L, more preferably 5 to 80 mg / L, and still more preferably 10 to 60 mg / L.

  The amount of the kneading water is preferably 20 to 70 parts by mass, more preferably 22 to 68 parts by mass, and still more preferably 24 to 66 parts by mass with respect to 100 parts by mass of the inorganic fine powder.

  In the ready mixed concrete plant, the water from which the aggregate is removed from the washing wastewater generated by washing is called recovered water, and among them, highly alkaline water containing calcium hydroxide and the like eluted from the cement is called supernatant water. In the present invention, it is preferable to use supernatant water that satisfies the above pH and Ca ion concentration.

  The low carbon neutralization-suppressing mortar composition of the present invention further comprises 1 to 10 parts by mass of calcium hydroxide (excluding calcium hydroxide contained in the mixed water) with respect to 100 parts by mass of the inorganic fine powder. Is included, more preferably 2 to 9 parts by mass, still more preferably 3 to 8 parts by mass. By further including calcium hydroxide, neutralization can be further suppressed.

  As the fine aggregate used in the present invention, river sand, land sand, sea sand, crushed sand, blast furnace slag fine aggregate, limestone fine aggregate and the like can be used. The fine aggregate may be used alone or in combination of two or more. The fine aggregate contained in the sulfuric acid resistant mortar composition is preferably 150 to 400 parts by mass, more preferably 160 to 380 parts by mass, and still more preferably 170 to 360 parts by mass with respect to 100 parts by mass of the inorganic fine powder. Part.

  In addition, the low carbon neutralization-inhibiting mortar composition of the present invention has an AE agent, an AE water reducing agent, a high performance compound such as a lignin-based, naphthalene-based, polyol-based, or polycarboxylic acid-based compound to adjust fresh properties. Chemical admixtures such as water-reducing agents, high-performance AE water-reducing agents, medium-performance water-reducing agents, high-performance water-reducing agents, multifunctional water-reducing agents, thickeners, antifoaming agents, air amount adjusting agents, curing accelerators, curing retarders Moreover, well-known additives, such as a reinforcing bar rust preventive agent, can be added.

  The low carbon neutralization-suppressing mortar composition of the present invention can be produced by mixing inorganic fine powder, gypsum, fine aggregate, and mixing water. It is possible to pre-mix each component prior to kneading, but when adding kneading water to the cement, the blast furnace slag fine powder, gypsum, fine aggregate and any other admixtures and additives It is preferable to prepare by adding. Thus, the low carbon neutralization-inhibiting mortar composition of the present invention can be prepared by a simple method, and can be easily and inexpensively prepared in a facility or the like that forms a normal cured mortar. .

  The low-carbon neutralization-suppressing mortar composition of the present invention can further include a coarse aggregate to obtain a low-carbon neutralization-suppressing concrete composition. As the coarse aggregate used in the present invention, gravel, crushed stone, blast furnace slag coarse aggregate, limestone coarse aggregate and the like can be used. The coarse aggregate is preferably 150 to 400 parts by mass, more preferably 160 to 380 parts by mass, and still more preferably 170 to 360 parts by mass with respect to 100 parts by mass of the inorganic fine powder. If the blending amount of the coarse aggregate is within the above range, good fresh properties can be obtained.

<Method for Producing Low Carbon Neutralization Inhibited Mortar>
The present invention also relates to a method for producing a low carbon neutralization-inhibited mortar cured body. The method for producing a low-carbon neutralization-suppressing mortar cured product of the present invention comprises a step of mixing the inorganic fine powder, gypsum, fine aggregate and mixing water to prepare the low-carbon neutralization-suppressing mortar composition, Curing the low carbon neutralization inhibiting mortar composition.

  The method for preparing the low carbon neutralization-inhibiting mortar composition is as described in the method for producing the low carbon neutralization-inhibiting mortar composition.

  The step of curing the low carbon neutralization inhibiting mortar composition preferably includes a step of curing in water for 1 to 10 weeks and a step of curing in air for 1 to 10 weeks. The order of the underwater curing and the aerial curing is preferably such that the underwater curing is performed first and then the aerial curing is performed. The period of underwater curing is 1 to 10 weeks, preferably 2 to 8 weeks, more preferably 3 to 6 weeks. The temperature of underwater curing is preferably 10 to 30 ° C, more preferably 12 to 28 ° C, and still more preferably 14 to 26 ° C. The period of air curing is 1 to 10 weeks, preferably 1 to 8 weeks, more preferably 1 to 6 weeks. The temperature of the air curing is preferably 10 to 30 ° C, more preferably 12 to 28 ° C, and still more preferably 14 to 26 ° C. The humidity of the air curing is preferably 50 to 100%, more preferably 52 to 100%, still more preferably 54 to 100%.

  The curing process may include steam curing and heat curing in addition to the above-described underwater curing and air curing.

  The low carbon mortar composition of this invention can be used for mortar and concrete as a low carbon mortar.

  Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. Note that the present invention is not limited to these examples.

[1. Materials used]
The following materials were used.
(1) Cement, ordinary Portland cement (density 3.16 g / cm ³ , manufactured by Ube Mitsubishi Cement Co., Ltd.)
・ Early strength Portland cement (density 3.14 g / cm ³ , manufactured by Ube Mitsubishi Cement Co., Ltd.)
(2) Admixture ・ Blast furnace slag fine powder (density 2.90 g / cm ³ , CaO content 41.9 mass%, SiO ₂ content 31.6 mass%, Al ₂ O ₃ content 14.0 mass%, SO ₃ content 1.7 mass%, Blaine specific surface area 4760 cm ² / g, JIS A 6206 blast furnace slag fine powder 4000 equivalent, manufactured by Ube Industries, Ltd.)
The brain specific surface area is a value measured according to JIS A 6206 “Blast Furnace Slag Fine Powder for Concrete”.
・ Anhydrous gypsum (density 2.97 g / cm ³ , manufactured by Hitachi Chemical Co., Ltd.)
Calcium hydroxide (density 2.21 g / cm ³ , reagent special grade, manufactured by Wako Pure Chemical Industries, Ltd.)
(3) Fine aggregate / sea sand (density 2.57 g / cm ³ , coarse particle ratio 2.97, produced in Fukuoka Prefecture)
・ Crumbled sand (density 2.68 g / cm ³ , coarse grain ratio 2.71, hard sandstone, produced in Fukuoka Prefecture)
(4) Chemical admixtures ・ Product name: SEICAMENT 1100NT, high-performance AE water reducing agent, manufactured by Nihon Sika Co., Ltd. ・ Product name: Micro Air 404, air amount adjusting agent, manufactured by BASF Japan Ltd. Water-saturated calcium hydroxide solution (produced using tap water and calcium hydroxide (density 2.21 g / cm ³ , reagent special grade, manufactured by Wako Pure Chemical Industries, Ltd., solubility at 20 ° C .: 0.16 g))
-Simulated supernatant water (ordinary Portland cement (density 3.16 g / cm ³ , manufactured by Ube Mitsubishi Cement Co., Ltd.) and tap water, pH 12.1, Ca ion concentration 1270 mg / L, Na ion concentration 182 mg / L Ka ion concentration 404 mg / L, SO ₄ ion concentration 1790 mg / L, Cl ion concentration 25 mg / L)

[2. Formulation of mortar composition]
Using the material, the formulation of the mortar composition of the No. 1 to No. 10, a summary of the formulations shown in Table 1, Table 2 shows the unit amount per 1 m ^3. In Comparative Examples 1, 2, 4, 5, and 7, tap water is used as the mixing water, and in Comparative Example 3, a saturated calcium hydroxide solution is used as the mixing water, Comparative Examples 6 and 8, In Examples 1 and 2, simulated supernatant water was used as the mixing water.

  In the table, normal Portland cement is indicated as N, early strong Portland cement as H, blast furnace slag fine powder as BFS, anhydrous gypsum as gypsum, calcium hydroxide as CH, unit water amount as W, and unit cement amount as C. In Tables 1 and 2, W is a value including a chemical admixture.

  Compound No. In 1 to 10, the mass ratio of cement and blast furnace slag fine powder is constant at 20:80, and the mass ratio of water / binder (cement + blast furnace slag fine powder) is constant at 45%.

  Among the fine aggregates, the volume ratio of sea sand to crushed sand was 4: 6. Regarding anhydrous gypsum and calcium hydroxide (powder), the amount corresponding to a predetermined mass ratio (%) to the binder (cement + blast furnace slag fine powder) was replaced with respect to the fine aggregate.

  The saturated calcium hydroxide solution was prepared by completely dissolving 0.16 g of calcium hydroxide per 100 g of tap water in an environment of 20 ° C.

  For the simulated supernatant water, normal Portland cement and tap water are mixed at a mass ratio of 1: 4 in an environment of 20 ° C., sufficiently stirred with a hand mixer, sealed, and allowed to stand for 24 hours or more. Only samples were collected.

[3. Preparation and test method of mortar]
(1) Mixing of mortar Mixing No. shown in Table 2 1-10 mortars were kneaded according to JIS R 5201 according to the following procedure. That is, fine aggregate, cement, blast furnace slag fine powder, gypsum and other admixtures are put into a Hobart mixer and kneaded for 30 seconds, and then kneaded water in which a chemical admixture is dissolved in advance is added at a low speed of 30. After kneading for 2 seconds and scraping off, it was kneaded at high speed for 60 seconds.
(2) Mortar air content About 1-10, the air quantity was measured. The results are shown in Table 3. The amount of air was 6.0 to 9.0%.
(3) Curing of mortar specimens Regarding the curing of mortar specimens, after curing for 4 weeks in water, 20 ° C, R.P. H. Aged for 2 weeks in a 60% temperature-controlled room.
(4) Compressive strength test The compressive strength at the age of 28 days was measured according to JIS A 1108.
(5) Accelerated neutralization test The neutralization depth was measured according to JIS A 1153.

[4. Test results]
Table 3 shows the measurement results of the compressive strength and the neutralization depth.

[5. Evaluation]
From Table 3, when comparing the neutralization depth in the promotion periods 1, 4 and 12 weeks, the neutralization depth of the example is smaller than that of the comparative example, and the example is neutralized. Excellent resistance to In particular, as in Example 2, in the case of a combination of anhydrous gypsum, calcium hydroxide (powder) and simulated supernatant water, the neutralization depth becomes a smaller value because the mortar structure is densified. ing.
From Table 3, when the compressive strength at the age of 28 days is compared, the compressive strength of the example is larger than that of the comparative example, and the example is excellent in compressive strength. This is thought to be because the mortar structure is densified in the same way as the neutralization depth.

  Since the low carbon mortar composition of the present invention suppresses neutralization and is excellent in compressive strength, the utility value is high in improving the performance of low carbon mortar and concrete.

Claims (6)

Inorganic fine powder, gypsum, fine aggregate and mixed water,
The inorganic fine powder consists of cement and blast furnace slag fine powder,
The mass ratio of the cement and the blast furnace slag fine powder (cement: blast furnace slag) is 10:90 to 30:70,
The amount of the gypsum is 6 to 10 parts by mass with respect to 100 parts by mass of the inorganic fine powder,
A low carbon neutralization-inhibiting mortar composition characterized in that the mixing water has a pH of 10 to 14 and a Ca ion concentration of 100 to 5000 mg / L. The Na ion concentration 10 to 500 mg / L and K ion-concentration of Mixing water is 10 to 500 mg / L, according to claim 1 low carbon Carbonation inhibiting mortar composition. The low carbon neutralization-suppressing mortar composition according to claim 1 or 2, wherein the mixed water has an SO ₄ ion concentration of 10 to 5000 mg / L and a Cl ion concentration of 1 to 100 mg / L.   The low-carbon neutralization-suppressing mortar composition according to any one of claims 1 to 3, further comprising 1 to 10 parts by mass of calcium hydroxide with respect to 100 parts by mass of the inorganic fine powder. A step of mixing the inorganic fine powder, gypsum, fine aggregate and mixing water to prepare the low carbon neutralization-suppressing mortar composition according to any one of claims 1 to 4,
A method for producing a low-carbon neutralization-inhibited mortar cured product, comprising a step of curing the low-carbon neutralization-inhibited mortar composition.   The said curing is a manufacturing method of the low carbon neutralization suppression mortar hardening body of Claim 5 including the process of carrying out underwater curing for 1 to 10 weeks, and the process of carrying out air curing for 1 to 10 weeks.