JP4809278B2 - Intumescent material, cement composition, and hardened cement body using the same - Google Patents

Description

  The present invention relates to an expansion material, a cement composition, and a hardened cement body using the same, mainly used for civil engineering and construction work.

  Inhibiting cracks in concrete structures is important from the standpoints of improving durability, aesthetics, and reducing maintenance and repair costs.

  So far, various methods for suppressing cracks in concrete have been proposed, and in particular, the expandable material plays a central role.

As the expansion material, for example, free lime-auin-anhydrite-based expansion material and free lime-calcium silicate-anhydrite-based expansion material are generally known. A high-performance expansion material that can reduce cracks has been developed (see Patent Document 1 and Patent Document 2).
In addition, it has been proposed to use quick lime grains adjusted to a specific particle size configuration as an expansion material (see Patent Document 3, Patent Document 4, and Patent Document 5).

  However, none of them mentions the definition of the maximum particle size and the specific surface area of Blaine to prevent the expansion material having the specific active ingredient of the present invention from popping out.

Japanese Patent Application Laid-Open No. 07-232944 JP 2002-226243 A JP 2005-162564 A Japanese Patent Laid-Open No. 2005-213072 JP 2006-181895 A

The conventional expansion material has a problem that when the expansion material contains particles having a relatively large particle size, the surface of the hardened cement body peels off, a so-called pop-out phenomenon occurs, and the surface properties are impaired. It was.
Therefore, in order to suppress the pop-out phenomenon, it is necessary to reduce the large particles of the expansion material. However, if the large particles of the expansion material are decreased, there is a problem that the expansion performance is deteriorated.

  The present inventor has found that the above problems can be variously solved by using a specific expansion material having a specific particle size configuration, and has completed the present invention.

That is, the present invention is prepared by blending a CaO raw material, an Al ₂ O ₃ raw material, an Fe ₂ O ₃ raw material, an SiO ₂ raw material, and a CaSO ₄ raw material, and heat-treating them at 1,100 to 1,600 ° C. One or two or more hydraulic compounds selected from the group consisting of lime, anhydrous gypsum, Auin, calcium silicate, and calcium aluminoferrite, the maximum particle size is 300 μm or less, and the Blaine specific surface area value a There 3,500cm ² / g or less is expanding material, below a maximum particle size of 250 [mu] m, an the expanding material Blaine specific surface area value is less than or equal 3,500cm ² / g, with a maximum particle size of 200μm or less, Blaine The expansion material having a specific surface area value of 3,500 cm ² / g or less, free lime is the expansion material that is 10 to 70 parts in 100 parts of the expansion material, and anhydrous gypsum is in 100 parts of the expansion material, The expansion material is 10-70 parts, the maximum particle size is sieved, the whole amount passes Without a said expandable material is a sieve size in the case sieve remaining amount is 0.1% or less, a cement composition comprising a cement and said expandable member, by using the cement composition The hardened cement body is a hardened cement body in which the number of generated pop-outs is less than 20.

  By using the expandable material of the present invention, the pop-out phenomenon that the surface of the hardened cement body peels does not occur, and an expandability equal to or more than the amount of conventional expandable material can be imparted.

Hereinafter, the present invention will be described in detail.
In the present invention, “parts” and “%” are based on mass unless otherwise specified.
Moreover, the cement concrete in this invention is a general term for cement paste, mortar, or concrete.

The expansion material used in the present invention comprises free lime, anhydrous gypsum, one or more hydraulic compounds selected from the group consisting of Auin, calcium silicate, and calcium aluminoferrite as active ingredients. The maximum particle size is 300 μm or less, the Blaine specific surface area value (hereinafter referred to as “brain value”) is 3,500 cm ² / g or less, the maximum particle size is 250 μm or less, and the brain value is 3,500 cm ² / g. The maximum particle size is preferably 200 μm or less, and the brain value is more preferably 3,500 cm ² / g or less. If the maximum particle size exceeds 300 μm, the surface properties may be impaired, and if the brain value exceeds 3,500 cm ² / g, the expansibility may decrease.
Here, the maximum particle size is the maximum value of the particle size. For example, the maximum particle size can be set to the size of the sieve when the entire amount does not pass through the sieve and the remaining amount of the sieve is 0.1% or less. is there.

  The particle size can be measured by, for example, JCAS K-03-1996 “Method of testing fineness by air jet sieving apparatus” prescribed by the Japan Cement Association. It can also be measured by the mesh sieve test method described in JIS R 5201 “Cement physical test method”. The Blaine specific surface area can be measured based on JIS R 5201 “Cement physical test method”.

The expansion material used in the present invention is a predetermined amount of CaO raw material, Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material, SiO ₂ raw material, CaSO ₄ raw material, etc., heat treated, free lime, anhydrous gypsum, and A clinker composed of a hydraulic compound, for example, a clinker containing free lime, anhydrous gypsum, and one or more hydraulic compounds selected from the group consisting of Auin, calcium silicate, and calcium aluminoferrite is synthesized. It is preferable. Even if all or a part of free lime, anhydrous gypsum, and hydraulic compound are synthesized separately and mixed, they can be used as the expansion material of the present invention, but in order to obtain excellent expansion performance Is preferably heat-treated, and free lime, anhydrous gypsum, and hydraulic compound are all made into clinker at a time.

Examples of the CaO raw material include limestone and slaked lime. Examples of the Al ₂ O ₃ raw material include bauxite and aluminum residual ash. Examples of the Fe ₂ O ₃ raw material include copper calami, iron powder, and commercially available iron oxide. Examples of the SiO ₂ raw material include commercially available silicon dioxide and silica stone, and examples of the CaSO ₄ raw material include dihydrate gypsum, hemihydrate gypsum, and anhydrous gypsum.
Of course, various impurities can be present in these raw materials. Specific examples thereof include Na ₂ O, K ₂ O, MgO, TiO ₂ , and P ₂ O _5, and are not particularly problematic as long as the object of the present invention is not substantially inhibited.

  The heat treatment temperature for producing the clinker used for the expansion material of the present invention is preferably 1,100 to 1,600 ° C, more preferably 1,200 to 1,500 ° C. If it is less than 1,100 ° C., the resulting expansion material may not have sufficient expansion performance, and if it exceeds 1,600 ° C., anhydrous gypsum may be decomposed.

  The expandable material of the present invention comprises, as active ingredients, one or two or more hydraulic compounds selected from the group consisting of free lime, anhydrous gypsum, Auin, calcium silicate, and calcium aluminoferrite.

  The anhydrous gypsum is not particularly limited, and any form of type I, type II, or type III can be used.

Auin is generally represented by 3CaO.3Al ₂ O ₃ .CaSO ₄ .
Calcium silicate (hereinafter referred to as C ₃ S) is a general term for CaO—SiO ₂ system and is not particularly limited, but generally 2CaO · SiO ₂ and 3CaO · SiO _{2 are} often used. Are known. Usually, it is considered to exist as 3CaO · SiO ₂ .
Furthermore, calcium aluminoferrite (hereinafter referred to as C ₄ AF) is a generic term for CaO—Al ₂ O ₃ —Fe ₂ O ₃ based compounds, and is not particularly limited. -Compounds such as Al ₂ O ₃ · Fe ₂ O ₃ and 6CaO · Al ₂ O ₃ · 2Fe ₂ O ₃ are well known. Normally, it is considered to be present as _{4CaO · Al 2 O 3 · Fe} 2 O 3.
In the present invention, one or more of Auin, C ₃ S, and C ₄ AF are used as the hydraulic compound.

  The content of free lime in the expansion material of the present invention is preferably 10 to 70 parts, more preferably 30 to 50 parts, in 100 parts of the expansion material. If it exceeds 70 parts, the fluidity of cement concrete may be reduced, and if it is outside the above range, the expansibility may be reduced.

  The content of anhydrous gypsum in the expanding material of the present invention is preferably 10 to 70 parts, more preferably 20 to 40 parts, in 100 parts of the expanding material. Outside this range, the expandability may be reduced.

The quantification of the mineral content in the expansion material of the present invention can be measured by, for example, the following X-ray diffraction Rietveld method.
For example, it can be measured by adding a predetermined amount of an internal standard substance such as aluminum oxide or magnesium oxide to the pulverized expansion material, mixing it well in an agate mortar, and then performing powder X-ray diffraction measurement. For example, it is possible to analyze using “SIROQUANT” of Sietronics.

  The blending amount of the expansion material of the present invention is not particularly limited because it varies depending on the purpose, but usually 2 to 10 parts are preferable, and 5 to 7 parts are more preferable in 100 parts of a binder composed of cement and an expansion material. . If the amount of the expanding material is too large, the amount of expansion may be too large and the strength may be reduced. Conversely, if the amount is too small, the predetermined crack suppressing effect may not be obtained.

  As the cement used in the present invention, various portland cements such as normal, early strength, ultra-early strength, low heat, and moderate heat, mixed with blast furnace granulated slag, blast furnace slow-cooled slag, fly ash, or silica are mixed with these Portland cements. Various mixed cements, filler cements mixed with limestone powder, etc., and environmentally friendly cements (eco-cements) manufactured using municipal waste incineration ash and sewage sludge incineration ash as raw materials. Two or more types can be used.

  In the present invention, a water reducing agent, a high performance water reducing agent, an AE water reducing agent, a high performance AE water reducing agent, a fluidizing agent, an antifoaming agent, a thickening agent, a rust preventive agent, a defrosting agent, a shrinkage reducing agent, a polymer emulsion, and a powder One or more of polymers, setting modifiers, sugars such as dextrin, cement hardeners, clay minerals such as bentonite and zeolite, and anion exchangers such as hydrotalcite, etc. It is possible to use in the range which does not inhibit substantially.

  Any existing apparatus can be used as a mixing apparatus for blending the expansion material of the present invention with cement concrete. For example, a tilting mixer, an omni mixer, a Henschel mixer, a V-type mixer, a forced biaxial mixer, and a nauta mixer Etc.

  The curing method for cement concrete of the present invention is not particularly limited, and outdoor curing, underwater curing, air drying curing, steam curing, autoclave curing, and the like can be employed.

  Hereinafter, the present invention will be described in more detail based on experimental examples, but the present invention is not limited thereto.

Experimental example 1
Reagent primary calcium carbonate as CaO raw material, Reagent primary aluminum oxide as Al ₂ O ₃ raw material, Reagent primary ferric oxide as Fe ₂ O ₃ raw material, Reagent primary silicon dioxide as SiO ₂ raw material, and A predetermined amount of reagent grade 1 dihydrate gypsum as a raw material for CaSO _{4 is} mixed and pulverized, then heat treated at 1,350 ° C for 3 hours using an electric furnace, 50 parts of free lime, 30 parts of anhydrous gypsum, 10 parts of auin, Clinkers of 5 parts of C ₃ S and 5 parts of C ₄ AF were synthesized and pulverized to a particle size composition shown in Table 1 to prepare an expansion material.
The unit quantity of each material, water 170 kg / m ^3, cement 298 kg / m ^3, the expansion member 20 kg / m ^3, the fine aggregate 807kg / m ^3, and coarse aggregate 997kg / m ^3, and water, and cement expansion The water binder ratio is 53.5%, the fine aggregate ratio is 45%, and the air volume is 4.5%. The water reducing agent is used so that the slump immediately after kneading shows a fluidity of 15cm ± 1cm. What adjusted the addition rate was made into the concrete sample, and expansion property and surface property were evaluated. The results are also shown in Table 1.
For comparison, a similar experiment was performed using a commercially available expansion material.

<Materials used>
Cement: Ordinary Portland cement, fine aggregate manufactured by Denki Kagaku Kogyo Co., Ltd .: River sand from Himekawa Water System, specific gravity 2.62
Coarse aggregate: Himekawa water system river gravel, specific gravity 2.65
Water-reducing agent: Commercially available polycarboxylate-based high-performance AE water-reducing agent water: Tap water Commercial expansion material: Calcium sulfoaluminate-based expansion material, commercial product

<Measurement method>
Expansion property: According to JIS A 6202, the expansion rate of the material age of 7 days was measured, and the expansion rate was 200μ or more, good, 150μ or more, less than 200μ, or less than 150μ.
Surface properties: Concrete samples are packed in a 20cm wide, 20cm long, 10cm high mold, and the number of popouts generated is measured by observing the surface. As mentioned above, less than 10 was considered good, 10 or more, less than 20 allowed, and 20 or more failed.

  As shown in Table 1, when the expandable material of the present invention is used, the pop-out phenomenon that the surface of the hardened cement body is peeled off is less likely to occur than when a conventional expandable material is used, and the surface properties are good. It can be seen that the expandability equal to or greater than that of the expansion material can be imparted. Moreover, the crack suppression effect is also high.

Experimental example 2
The same procedure as in Experimental Example 1 was conducted except that the clinker of the active ingredient shown in Table 2 was synthesized, pulverized, and the expansion material shown in Table 2 was prepared with a maximum particle size of 250 μm. The results are also shown in Table 2.

Experimental example 3
A clinker composed of free lime, anhydrous gypsum, 10 parts of Auin, 5 parts of C ₃ S and 5 parts of C ₄ AF shown in Table 3 was synthesized and adjusted to the brain value shown in Table 3 with a maximum particle size of 220 μm. Except for this, the same procedure as in Experimental Example 1 was performed. The results are also shown in Table 3.

It can be seen that by using the expandable material of the present invention, the pop-out phenomenon in which the surface of the hardened cement body peels off hardly occurs, the surface property is good, and the expandability equal to or higher than that of the conventional expandable material can be imparted.
In addition, it is highly effective in suppressing cracks and can be used in the civil engineering and construction fields that use concrete.

Claims (10)

It is prepared by blending CaO raw material, Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material, SiO ₂ raw material, and CaSO ₄ raw material, and heat-treating at 1,100 to 1,600 ° C., and free lime, anhydrous gypsum and One or two or more hydraulic compounds selected from the group consisting of auin, calcium silicate, and calcium aluminoferrite are used as active ingredients, the maximum particle size is 300 μm or less, and the specific surface area of branes is 3,500 cm ² / g. Expandable material that is: It is prepared by blending CaO raw material, Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material, SiO ₂ raw material, and CaSO ₄ raw material, and heat-treating at 1,100 to 1,600 ° C., and free lime, anhydrous gypsum and One or two or more hydraulic compounds selected from the group consisting of auin, calcium silicate, and calcium aluminoferrite are used as active ingredients, the maximum particle size is 250 μm or less, and the Blaine specific surface area is 3,500 cm ² / g. Expandable material that is: It is prepared by blending CaO raw material, Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material, SiO ₂ raw material, and CaSO ₄ raw material, and heat-treating at 1,100 to 1,600 ° C., and free lime, anhydrous gypsum and One or two or more hydraulic compounds selected from the group consisting of auin, calcium silicate, and calcium aluminoferrite are used as active ingredients, the maximum particle size is 200 μm or less, and the Blaine specific surface area is 3,500 cm ² / g. Expandable material that is: Free lime is 10-70 parts in 100 parts of expansion | swelling materials, The expansion | swelling material as described in any one of Claims 1-3. The expansion material according to any one of claims 1 to 4, wherein the anhydrous gypsum is 10 to 70 parts in 100 parts of the expansion material. The expansion according to any one of claims 1 to 5, wherein the maximum particle size is the size of the sieve mesh when the sieve is sieved so that the entire amount does not pass through and the remaining amount of the sieve is 0.1% or less. Wood. A cement composition comprising cement and the expansion material according to any one of claims 1 to 6 . The cement composition according to claim 7 , wherein the expansion material is 2 to 10 parts in 100 parts of a binder composed of cement and an expansion material. A hardened cement body using the cement composition according to claim 7 or 8 . The hardened cement body according to claim 9 , wherein the number of generated pop-outs is less than 20.