JP5541776B2 - Self-healing cement admixture and cement composition - Google Patents

Description

The present invention mainly relates to a cement admixture and a cement composition that promote waterproofness of cement concrete used in the civil engineering and construction fields.
The cement concrete as used in the present invention is a general term for mortar and concrete.

  Conventionally, as a method for promoting the waterproof property of cement concrete, in order to make the water / cement ratio as small as possible, as specified in JIS A 6204 “Chemical admixture for concrete”, water reducing agents and high performance water reducing agents are used. It is generally popular to use.

  On the other hand, regardless of the reduction in the water / cement ratio, for example, an admixture containing a calcium sulfoaluminate compound and an active siliceous material, waterproofing containing calcium sulfoaluminates and a latent hydraulic material as active ingredients A method for improving the waterproofness of cement concrete using a material has been proposed (see Patent Documents 1 and 2). In addition, a water repellent agent is coated on a filler (aggregate) (see Patent Document 3), and a water repellent agent is applied to the surface of a hardened cement concrete (see Patent Document 4). However, mixing a water repellent with cement is not performed.

JP-A-2-88451 Japanese Patent No. 2899066 JP-A-1-317140 Japanese Patent Laid-Open No. 2004-231488

  The present invention provides self-healing cement admixtures and cement compositions that enhance the waterproofness of concrete.

The present invention includes (1) a water repellent that is calcium stearate, a calcium sulfoaluminate that is an out-in of 3CaO.3Al ₂ O ₃ .CaSO ₄ having a brain specific surface area value of 2500 cm ² / g or more, and a brain surface area value of 3000 cm. ² / g or more of fly ash silica powder, and 30 to 70 parts of silica powder with respect to 30 to 70 parts of calcium sulfoaluminate in a total of 100 parts of calcium sulfoaluminate and silica powder. The water repellent is 3 to 8 parts with respect to a total of 100 parts of calcium sulfoaluminate and silica powder, or (2) water repellent, calcium sulfoaluminate and silica powder are mixed or (1) self-healing cement admixture, (3) cement, (1) Is (2) and also contains a self-healing cement admixture, a cement composition 100 parts consisting of cement and cement admixture, self-healing cement admixture is 2-6 parts cement composition .

  By using the self-healing cement admixture and the cement composition of the present invention, the waterproofness of cement concrete is improved.

Side view of concrete specimen Cross section of concrete specimen (1) Cross section of concrete specimen (2) External view of reinforcement Cross section of split specimen Side view of split test specimen (units for numerical values in FIGS. 1 to 6 are mm)

1: Concrete specimen 2: Water injection hole (water pressure 0.2 kg / cm ² )
3: Hoop rebar (φ6mm)
4: Straight rebar (φ6mm)
5: Crack position at the time of split 6: Water permeability position when water is injected by crack 7: Loading point at the time of split 8: Water stop surface of crack

Hereinafter, the present invention will be described in detail.
Parts and% in the present invention are based on mass unless otherwise specified.

  The water repellent used in the present invention is not particularly limited as long as it wraps the powder and repels water. For example, hydrocarbons such as liquid paraffin, squalane, paraffin, petroleum jelly, Waxes such as beeswax, jojoba oil, carnauba wax, triglycerides such as glyceryl triisostearate and glyceryl trioctanoate, ester oils such as isocetyl myristate and cetyl palmitate, higher alcohols such as cetanol and stearyl alcohol, olive oil, castor oil, etc. And fatty acids such as stearic acid, calcium stearate, sodium stearate, myristic acid and isostearic acid. Among them, it is particularly preferable to use fatty acids. The water-repellent protective coating wraps the powder to prevent contact with water during kneading, thereby suppressing the reaction. This protective film is broken by water passing through the cracked portion for a long time, and the surface of the powder particles is exposed, and the reaction starts.

The calcium sulfoaluminate used in the present invention (hereinafter referred to as CS aluminate) is, for example, a kiln or the like using a calcareous raw material such as lime, a sulfate raw material such as gypsum, and an alumina raw material such as bauxite as a raw material. It is manufactured by firing at about 1500 ° C. and pulverization.
The CS aluminate is not particularly limited. For example, there is a material in which the raw material is blended at a molar ratio of CaO: Al ₂ O ₃ : CaSO ₄ of 3: 3: 1, baked, and pulverized. . This is called Auin (3CaO.3Al ₂ O ₃ .CaSO ₄ ). Moreover, the expansion material (For example, Denka CSA # 20 by Denki Kagaku Kogyo KK) containing commercially available Auin can be used.
Blaine specific surface area value of CS aluminate (hereinafter referred to as Blaine value) is preferably not less than ^{2500cm 2 / g, 3000cm 2 /} g or more is more preferable. If it is less than 2000 cm ² / g, the waterproofness may not be expected to increase.

The silica powder used in the present invention is a generic term for powders of substances having a siliceous main component and latent hydraulic properties, and is not particularly limited. For example, silica fume, silica dust, diatomaceous earth, diatom Examples thereof include powders such as clay, fly ash, and blast furnace slag. In the present invention, one or more of these can be used.
The particle size of the silica powder is a 3000 cm ² / g or more in Blaine value is preferably at least ^{4000cm 2 / g, 6000cm 2 /} g or more is more preferable. If it is less than 3000 cm ² / g, sufficient waterproofing may not be obtained.

  The amount of each component used in the cement admixture of the present invention is not particularly limited. However, when the cement admixture is composed of a water repellent and CS aluminate, the water repellent is used from the viewpoint of enhancing waterproofness. Is preferably 0.5 to 7 parts, more preferably 1 to 5 parts per 100 parts of CS aluminate. Moreover, when it consists of a water repellent and a silica powder, 0.5-7 parts are preferable with respect to 100 parts of silica powder, and 1-5 parts are more preferable. Furthermore, when it consists of 20-80 parts of water repellent and CS aluminate and 20-80 parts of silica powder, 0.5-7 parts are preferable with respect to 100 parts of CS aluminate and silica powder, and 1-5 parts. More preferred. If it is less than 0.5 part, sufficient waterproofing may not be obtained, and if it exceeds 7 parts, waterproofing may not be expected.

  The amount of cement admixture used is not particularly limited, but when the cement admixture is a water repellent and CS aluminate, a cement composition comprising cement and cement admixture from the viewpoint of waterproofing enhancement. In 100 parts, 3-7 parts are preferable and 4-6 parts are more preferable. Moreover, when a cement admixture consists of a water repellent and a silica powder, 3-7 parts are preferable in 100 parts of cement compositions consisting of a cement and a cement admixture, and 4-6 parts are more preferable. If it is less than 3 parts, the waterproofness may not be improved, and if it exceeds 7 parts, the waterproofness cannot be improved. Furthermore, when a cement admixture consists of a water repellent, CS aluminate, and a silica powder, 1-5 parts are preferable in 100 parts of cement compositions consisting of cement and a cement admixture, and 2-4 parts are more preferable. . If it is less than 1 part, the improvement in waterproofness may not be obtained, and if it exceeds 5 parts, the improvement in waterproofness cannot be expected.

  The cement used in the present invention is not particularly limited, and normal cement can be used. Specifically, various portland cements such as normal, early strength, super early strength, low heat, and moderate heat, These portland cements include various mixed cements mixed with blast furnace slag, fly ash, or silica, filler cement mixed with limestone powder or blast furnace slow-cooled slag fine powder, waste-use type cement, so-called eco-cement, etc. One or more of these can be used in combination.

  In the present invention, in addition to cement, cement admixture, aggregate such as sand, gravel, water reducing agent, AE water reducing agent, high performance water reducing agent, high performance AE water reducing agent, AE agent, thickener, etc. It is possible to use together 1 type, or 2 or more types in the range which does not inhibit the objective of this invention.

The components of the cement admixture of the present invention are mixed or mixed and ground, but the method is not particularly limited. As the mixing device, for example, a tilting cylinder mixer, an omni mixer, a V-type mixer, a Henschel mixer, a Nauta mixer, and the like can be used. Examples of the mixing and grinding apparatus include a ball mill and a vibration mill.
Further, any existing stirring device can be used as the mixing device for the cement composition. For example, a forced biaxial mixer, a tilting drum mixer, an omni mixer, or the like can be used.

  Hereinafter, the present invention will be described in detail by way of examples.

<Materials used>
Water repellent A: calcium stearate (reagent)
Water repellent B: Sodium stearate (reagent)
CS aluminate: crystalline 3CaO.3Al ₂ O ₃ .CaSO ₄ (auin),
Ignition loss 1.0%, Blaine value 3500cm ² / g
Silica powder: fly ash (made by Tohoku Electric Power Industry Co., Ltd.) Brain value 3950 cm ² / g
Cement: Ordinary Portland cement, commercial product, specific gravity 3.16
Fine aggregate: natural sand from Himekawa, Niigata Prefecture, density 2.62
Coarse aggregate: Crushed stone from Himekawa, Niigata Prefecture, maximum size 20 mm, density 2.64
Water reducing agent: Super 300K-102 (Grace Chemicals)

"Experiment 1"
Cement admixture prepared by mixing water repellents A and B and CS aluminate with the formulation shown in Table 1 is blended with 3 parts of cement admixture in 100 parts of cement composition consisting of cement and cement admixture. A cement composition was prepared. Cement composition a unit amount of various materials in concrete 330 kg / ^{m 3,} sand 816kg / ^{m 3,} gravel 969 kg / ^{m 3,} water 176 kg / ^{m 3,} and a water reducing agent 2.64 kg / ^{m 3.} A water permeability test was performed on the produced concrete.
A test was also conducted for the case of mixing and grinding the water repellent and CS aluminate (Experiment No. 1-7). The results are also shown in Table 1.

<Method of making concrete and permeability test>
(1) The mixing device uses a 50 liter biaxial forced mixer.
(2) For material input, sand, gravel, cement and cement admixture are simultaneously added, empty kneading is performed for 30 seconds, then water and a water reducing agent are added, and mixing is performed for 90 seconds.
(3) The test specimen was prepared by using a φ150 mm × 300 mm mold, setting a φ2 cm steel rod in the center, and extracting it after curing (FIGS. 1 and 2).
(4) As for mold filling, one layer is packed using a table vibrator.
(5) The specimen size is φ150 mm × 150 mm with the reinforcing bars shown in FIGS.
(6) The water permeability test is performed at the position 5 shown in FIGS. 5 and 6 in the manner of the split test (according to JIS A 1113) shown in FIG. A crack width of 0.2 mm is generated.
(7) The crack width was adjusted using a π-type gauge. Use an adhesive for cracks on the top and bottom of the specimen (5 in Fig. 5) and one hole in 8 in Fig. 6 (8 in Fig. 2) so that water can penetrate through the crack on the circumferential side (6 in Fig. 6). Block it.
(8) A water pressure of 20 kPa (0.2 kg / cm ² ) is applied to measure the water permeability.
(9) The 24-hour water permeability (A) after the start of the permeability test for concrete of 28-29 days old is the 24-hour water permeability (B) after the start of the permeability test for concrete of 1-2 days old. The divided value is the water leakage rate. Leakage rate (%) = (A) / (B) × 100

"Experimental example 2"
It was carried out in the same manner as in Experimental Example 1 except that a cement admixture prepared by blending water repellents A and B and silica powder as shown in Table 2 was used. The results are also shown in Table 2.

"Experiment 3"
The experiment was carried out in the same manner as in Experimental Example 1 except that a cement admixture prepared by blending water repellents A and B, CS aluminate and silica powder as shown in Table 3 was used. The results are also shown in Table 3.

"Experimental example 4"
It was carried out in the same manner as in Experimental Example 1 except that a cement admixture prepared by blending water repellent A, CS aluminate and silica powder as shown in Table 4 was used. The results are also shown in Table 4.

“Experimental Example 5”
The amount of cement admixture shown in Table 5 in 100 parts of a cement composition comprising cement and a cement admixture prepared by mixing 3 parts of water repellent A with 100 parts of CS aluminate Was carried out in the same manner as in Experimental Example 1 except that. The results are also shown in Table 5.

"Experimental example 6"
The amount of the cement admixture shown in Table 6 in 100 parts of a cement composition composed of cement and cement admixture was prepared by mixing 3 parts of water repellent A with 100 parts of silica powder. It implemented similarly to Experimental Example 1 except having mix | blended. The results are also shown in Table 6.

"Experimental example 7"
In 100 parts of a cement composition composed of cement and a cement admixture, a cement admixture prepared by blending 3 parts of water repellent A with respect to 100 parts in total of 50 parts of CS aluminate and 50 parts of silica powder, It carried out like the experiment example except having mix | blended the quantity of the cement admixture shown in Table 7. The results are also shown in Table 7.

  By using the self-healing cement admixture and the cement composition of the present invention, the waterproofness of cement concrete is improved, so that it can be widely applied in the civil engineering and construction fields.

Claims (3)

Calcium stearate water repellent and 3000 cm ² / g or more fly ash with Blaine specific surface area value of calcium sulfoaluminate and Blaine specific surface area value is Auin of 2500 cm ² / g or more _{3CaO · 3Al 2 O 3 · CaSO} 4 In the total 100 parts of calcium sulfoaluminate and silica powder, 30 to 70 parts of silica powder with respect to 30 to 70 parts of calcium sulfoaluminate, and the water repellent is calcium sulfate. Self-healing cement admixture that is 3-8 parts per 100 parts total of aluminate and silica powder. The self-healing cement admixture according to claim 1, wherein the water repellent, calcium sulfoaluminate and silica powder are mixed or mixed and pulverized. The self-healing cement admixture is 2 to 6 parts in 100 parts of a cement composition comprising the cement and the self-healing cement admixture according to claim 1 or 2 and comprising the cement and the cement admixture. , Cement composition.

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