JP4563599B2 - Cement admixture and cement composition - Google Patents

Description

【００２３】
表１より、本発明のセメント混和材を使用したモルタルは、優れた膨張特性を示していることがわかる。また、遊離石灰、Ｃ₁₁Ｓ₄ＣａＦ₂、ＣａＦ₂を別々に合成し混合したものは、本発明の効果が得られないことがわかる。
【００２４】
実施例１のセメント混和材Ｃを使用し、セメント組成物１００部中のセメント混和材の配合量を表２に示すように変え、圧縮強度を測定したこと以外は、実施例１と同様に行った。結果を表２に併記する。
【００２５】
＜測定方法＞
圧縮強度：ＪＩＳ Ｒ ５２０１に準じて測定。
【００２６】
【表２】

【００２７】
表２より、本発明のセメント混和材を添加したモルタルは、その配合量が増加するに従い長さ変化率が大きくなり、優れた膨張特性を示すことがわかる。
【００２８】
【本発明の効果】
本発明のセメント混和材を使用することにより、混和率が少なくてもコンクリートに優れた膨張特性を付与することが可能となる。[0001]
BACKGROUND OF THE INVENTION
The present invention mainly relates to a cement admixture and a cement composition used in the civil engineering and construction industries.
[0002]
[Prior art]
Reducing cracks and improving bending strength of cement and concrete are important from the viewpoint of reliability, durability, aesthetics, etc. of concrete structures, and cement admixtures that have the effect of improving these, i.e., cement-based expansion materials. Further technical progress is desired. Conventional cement admixtures that give expansibility to cement and concrete include, for example, free lime-auin-anhydrous gypsum-based expansive material (Japanese Patent Publication No. 42-21840) and free lime-calcium silicate-anhydrous gypsum-based expansion. There were materials (Japanese Patent Publication No. 53-31170). On the other hand, in recent years, development of high-fluidity concrete and high-strength concrete has been actively conducted for the purpose of improving the performance of concrete.
Here, concrete is a general term for cement paste, mortar, and concrete.
[0003]
[Problems to be solved by the invention]
However, it has been pointed out that these high-performance concretes do not sufficiently exert the effect of the expansion material. At present, the development of an expansion material having excellent expansion characteristics that can impart a large expansion property even when the expansion material is low in the mixing ratio is awaited.
Also, recently, the transition from the conventional specification-based design system to the performance-based design system has been studied, and it is considered that a clear performance specification will be established for durability that has been neglected until now. It is done. In other words, the effect of cracking on durability is quantified, so reducing cracking is an important issue, but in order to use cement-based expansion materials that are effective in reducing cracking, the amount used is small. Therefore, it is essential to reduce the economic burden.
As a result of various studies to solve these problems, the present inventors have obtained the knowledge that the above problems can be solved by using a specific cement admixture, and have completed the present invention. It was.
[0004]
[Means for Solving the Problems]
That, CaO material, a material obtained by heat-treating the SiO ₂ raw material and CaF ₂ raw material, Ri name contains free lime, calcium fluorosilicone silicates and CaF ₂ is CaO-SiO ₂ -CaF ₂ compounds, during a total of 100 parts of free lime, calcium fluorosilicone silicates and CaF _2, the free lime is 30 to 65 parts of calcium fluorosilicone silicate 20 to 55 parts of a cement admixture is a CaF ₂ 5-30 parts, and cement, Ri Na contained and the cement admixture, a cement composition 100 parts consisting of cement and a cement admixture, a cement admixture is a cement composition is 3 to 11 parts.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
[0006]
The cement admixture of the present invention is a substance obtained by heat-treating a CaO raw material, a SiO ₂ raw material and a CaF ₂ raw material, and contains free lime, calcium fluorosilicate and CaF ₂ . For the ratio is not particularly limited, free lime, clinker in 100 parts consisting of calcium fluorosilicone silicate and CaF _2, the free lime is preferably from 30 to 65 parts, 35-55 parts is more preferable. Further, the calcium fluorosilicate is preferably 20 to 55 parts, more preferably 30 to 50 parts. Further, CaF ₂ is preferably 5 to 30 parts, more preferably 10 to 25 parts. If the composition ratio of each compound in the clinker is not within the above range, excellent expansion characteristics may not be obtained.
In addition, the part and% which show the mixture ratio used by this invention are a mass unit.
[0007]
The calcium fluorosilicate of the present invention is a generic term for CaO—SiO ₂ —CaF ₂ -based compounds. When CaO is represented by C and SiO ₂ is represented by S, C ₁₁ S ₄ CaF ₂ and C ₃ S ₂ CaF _{2 are represented.} In the present invention, the calcium fluorosilicate is hereinafter referred to as C ₁₁ S ₄ CaF ₂ .
[0008]
When the cement admixture of the present invention is manufactured, a clinker composed of free lime, C ₁₁ S ₄ CaF ₂ and CaF ₂ is synthesized by heat treatment of the CaO raw material, the SiO ₂ raw material and the CaF ₂ raw material. And this is crushed and manufactured. In the case where free lime, C ₁₁ S ₄ CaF ₂ and part or all of CaF ₂ are synthesized separately and mixed, the effects as in the present invention cannot be obtained.
Whether or not it is manufactured by heat-treating a mixture of CaO raw material, SiO ₂ raw material and CaF ₂ raw material to synthesize clinker composed of free lime, C ₁₁ S ₄ CaF ₂ and CaF _2, and crushing this As a method for confirming this, for example, coarse particles of cement admixture, specifically, particles larger than 100 μm are observed with a microscope or the like, composition analysis is performed, and free lime, C ₁₁ S ₄ CaF _{2 is} contained in the particles. It can be easily determined by confirming that CaF ₂ is mixed.
[0009]
The heat treatment temperature at the time of producing the cement admixture of the present invention is not particularly limited because the decomposition temperature of CaF ₂ varies greatly depending on the blending ratio of the raw material mixture and the content of impurities. The range of -1350 degreeC is preferable, and the range of 1050-1300 degreeC is more preferable. Is less than 1000 ° C., there is a case where expansion properties of the resultant cement admixture is not sufficient, CaF ₂ is melted exceeds 1350 ° C..
[0010]
The mixing method of the raw materials is not particularly limited, and a normal method is possible.
It does not specifically limit as the heat processing method which manufactures an expansion | swelling substance, It can carry out by using a rotary kiln, an electric furnace, etc.
[0011]
The CaO raw materials, raised limestone or slaked lime, etc., as the SiO ₂ raw materials, silica, include silica sand and clay, etc., as the CaF ₂ raw materials, fluorite and to naturally occurring, CaF ₂ or the like as an industrial by-products Is mentioned.
[0012]
The particle size of the cement admixture of the present invention is not particularly limited, is preferably 1500~6000cm ² / g in Blaine specific surface area, 2500~4000cm ² / g is more preferable. The particle size of the cement admixture is 1500cm less than ² / g, sometimes long-term durability is deteriorated, in some cases 6000 cm ² / g by weight, a sufficient expansion properties are not obtained.
[0013]
Although the usage-amount of the cement admixture of this invention is not specifically limited, Usually, 3-11 parts are preferable in 100 parts of cement compositions which consist of a cement and a cement admixture, and 5-9 parts are more preferable. . If it is less than 3 parts, sufficient expansion characteristics may not be obtained, and if it exceeds 11 parts, it may be excessively expanded.
[0014]
As the cement of the present invention, ordinary cement, early strength, very early strength, low heat and moderate heat, various portland cements, various mixed cements in which blast furnace slag, fly ash and silica are mixed with these cements, limestone fine powder, etc. There are filler cements and the like.
[0015]
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 coagulation One or more of accelerators, setting retarders, cement hardeners, clay minerals such as bentonite and anion exchangers such as hydrotalcite, boric acid and its salts, etc. It is possible to use in the range which does not inhibit.
[0016]
In this invention, the mixing method of each material is not specifically limited, Each material may be mixed at the time of construction, and the part or all may be mixed beforehand. Any existing apparatus can be used as the mixing apparatus, and examples thereof include a tilting cylinder mixer, an omni mixer, a Henschel mixer, a V-type mixer, and a Nauta mixer.
[0017]
【Example】
Hereinafter, the present invention will be described in detail by way of examples.
[0018]
Example 1
A CaO raw material, a SiO ₂ raw material, and a CaF ₂ raw material were blended, mixed and pulverized, then heat treated at 1200 ° C. for 3 hours using an electric furnace to synthesize clinker having the composition shown in Table 1, and pulverized to obtain a Blaine specific surface area of 3300 A cement admixture of ± 200 cm ² / g was produced. The compound was identified by X-ray diffraction, and the ratio was calculated from the composition determined by chemical analysis.
[0019]
Using 100 parts of cement composition consisting of cement and cement admixture, 7 parts of cement admixture was used to prepare a mortar with a water / cement composition ratio = 50% and a cement composition / sand ratio = 1/3. Then, the length change rate of the material age 7 days was measured. For comparison, free lime, C ₁₁ S ₄ CaF ₂ , and CaF ₂ were separately synthesized and mixed (Experiment No. 1-20: Cement admixture T) were also tested in the same manner. The results are also shown in Table 1.
[0020]
<Materials used>
Cement: Commercial Portland cement Water: Tap water Sand: Himekawa, Niigata Prefecture, specific gravity 2.62
CaO raw material: Reagent primary calcium carbonate SiO ₂ raw material: Reagent primary silicon dioxide CaF ₂ raw material: Reagent primary calcium fluoride
<Measurement method>
Length change rate: Measured according to JIS A 6202.
[0022]
[Table 1]

[0023]
Table 1 shows that the mortar using the cement admixture of the present invention exhibits excellent expansion characteristics. Also, free _{lime, C 11 S 4 CaF 2,} CaF 2 those synthesized mixed separately, it can be seen that the effect of the present invention can not be obtained.
[0024]
The same procedure as in Example 1 was carried out except that the cement admixture C of Example 1 was used, the amount of cement admixture in 100 parts of the cement composition was changed as shown in Table 2, and the compressive strength was measured. It was. The results are also shown in Table 2.
[0025]
<Measurement method>
Compressive strength: Measured according to JIS R 5201.
[0026]
[Table 2]

[0027]
From Table 2, it can be seen that the mortar to which the cement admixture of the present invention is added has a larger rate of change in length as its blending amount increases and exhibits excellent expansion characteristics.
[0028]
[Effect of the present invention]
By using the cement admixture of the present invention, it is possible to impart excellent expansion properties to concrete even when the mixing ratio is small.

Claims (2)

CaO material, a material obtained by heat-treating the SiO ₂ raw material and CaF ₂ raw material, Ri name contains free lime, calcium fluorosilicone silicates and CaF ₂ is CaO-SiO ₂ -CaF ₂ compound, free lime A cement admixture containing 30 to 65 parts by mass of free lime, 20 to 55 parts by mass of calcium fluorosilicate, and 5 to 30 parts by mass of CaF _{2 in} a total of 100 parts by mass of calcium fluorosilicate and CaF ₂ . And cement, according to claim 1 Ri name contains the cement admixture according cement composition 100 parts by mass consisting of cement and cement admixture, cement composition cement admixture is 3-11 parts by weight.