JP3242397B2 - Cement admixture and cement composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a flowable low-shrinkage cement admixture and a cement composition, which are mainly used for celebrity flooring in the construction field. .

(Prior art and its problems) In recent years, a slurry of a hydraulic composition mainly composed of gypsum, cement, or the like is poured into a floor surface such as a concrete slab or a foamed concrete, and is naturally fluidized. A self-leveling material that forms an excellent horizontal surface has been developed and put into practical use.

In general, self-leveling materials have excellent fluidity when kneaded with water and poured on uneven floors, and have the ability to form a uniform horizontal surface without causing solid-liquid separation until they harden,
It is required that after curing, it is physically stable against repetition of wet and dry conditions, has a small amount of shrinkage even under dry conditions, and is hardly cracked.

In response to these requirements, the gypsum self-leveling material has poor water resistance, and the cement self-leveling material has a fatal problem of generating dry cracks.

Conventionally, various attempts have been made to solve these problems, for example, a method of adding an expanding material to a water-resistant cement-based self-leveling material to prevent cracking (Japanese Patent Application Laid-Open No. 56-84358). Proposed.

However, it has not yet reached a sufficient crack-preventing effect.

On the other hand, a cement composition comprising adding calcium aluminate mineral and gypsum mixture Portland inorganic cement (KOKOKU 1-43702 JP) and _{11CaO · 7Al 2 O 3 · CaF} 2
And CaSO ₄ are mixed with each other, and milk casein and urea are added to the mixture to provide a cement composition (Japanese Patent Application Laid-Open No. 56-84357). Had not been reached.

The present inventors have made various studies in order to solve the above _{problems, xCaO · yAl 2 O 3 ·} zCaF 2 ( where, x / y / z = 1 / 0.65~1.
5 / 0.01-0.32) Calcium fluoroaluminate, inorganic sulfates, pozzolans and setting retarders, or by using casein or urea in combination with them, has excellent fluidity and small drying shrinkage, The present inventors have found that a hardened cement material in which cracks hardly occur, for example, a cement-based self-leveling material can be obtained, and have completed the present invention.

(Means for Solving the Problems) That is, the present invention provides xCaO.yAl ₂ O ₃ .zCaF ₂ (where x / y / z
= 1 / 0.65 to 1.5 / 0.01 to 0.32) is a cement admixture containing calcium fluoroaluminate, inorganic sulfate, pozzolans and a setting retarder as main components, which are mainly composed of caseins and urea. And a cement composition containing cement and the cement admixture as main components.

 Hereinafter, the present invention will be described in detail.

Calcium Fluorochemicals aluminate according to the present invention, the composition is _{xCaO · yAl 2 O 3 · zCaF} 2 ( where, x / y / z = 1 / 0.65~1.
5 / 0.01 to 0.32), each of which is mainly composed of calcareous raw material, alumina raw material and fluoride, for example,
Limestone, bauxite, fluorite, etc.
If the molar ratio of CaO, Al ₂ O ₃ and CaF ₂ is 1 for CaO, Al ₂
It is obtained by blending so that O ₃ is 0.65 to 1.5 and CaF ₂ is 0.01 to 0.32, and firing at 1,200 ° C. or more. The ratio of CaO, Al ₂ O ₃ and CaF _{2 in} the calcium fluoroaluminate is preferably in the above-mentioned range, and when the ratio deviates from this range, the amount of shrinkage tends to increase.

The firing method of calcium fluoroaluminate, in particular,
It is not limited, and for example, an electric furnace or a rotary kiln can be used, and the firing time is not particularly limited.

The method of cooling the fired product may be any method such as rapid cooling by water or high-pressure air or slow cooling by standing, and is not particularly limited.

Calcium fluoroaluminate may be crystalline, amorphous, or a mixture thereof.

Practically, it is preferable to further pulverize and use the calcined product of calcium fluoroaluminate.

The fineness of calcium fluoroaluminate is preferably from 1,000 to 8,000 cm ² / g in Blaine value.

As the inorganic sulfate according to the present invention, various gypsums of dihydrate, hemihydrate and anhydrous salt can be used.
Insoluble or poorly soluble ones such as anhydrous gypsum are preferred.

Fineness of inorganic sulfate is 2,000 to 8,000cm in Blaine value
^{About 2} / g is preferable.

In the present invention, a rapidly hardened material is formed from calcium fluoroaluminate and an inorganic sulfate, and the rapid hardening has an effect of reducing the shrinkage amount of the hardened cement.

The amount of the inorganic sulfate used in the hardened material is preferably 0.5 to 3 times by weight based on 100 parts by weight of calcium fluoroaluminate. If it is less than 0.5 times by weight, the setting time is short, and the effect of low shrinkage is not seen. If it exceeds 3 times by weight, the amount of expansion tends to be large, which tends to cause expansion cracking.

The pozzolans according to the present invention are necessary to further reduce the low shrinkage of the rapidly hardened material, and can be either natural or artificial. Specifically, as natural pozzolans, basalts, weathered andesite, tuffs,
Examples include volcanic ash, granite and Beppu clay, and examples of artificial pozzolans include clay slag, alum slag, blast furnace slag, fly ash, silica flower, and the like.

Examples of the setting retarder according to the present invention include organic acids and salts thereof such as citric acid, tartaric acid, gluconic acid, succinic acid and maleic acid; alkali carbonates such as sodium carbonate and potassium carbonate; phosphoric acids and salts thereof; Examples thereof include acids, alkali borates, silicofluorides, starch, sugars and alcohols, and mixtures thereof, and among them, the use of organic acids is preferred. In particular, a combination of an alkali carbonate and an organic acid is most preferable.

The amount of setting retarder used should be 10% in terms of obtaining an appropriate open time (working time).
It is preferably about 0.1 to 30 parts by weight with respect to 0 parts by weight.

Further, in the present invention, caseins and urea can be blended as a fluidizing agent.

The caseins according to the present invention impart fluidity to mortar or concrete, and include, for example, casein and sodium caseinate.

Further, the urea according to the present invention imparts the fluidity of mortar or concrete.

Even if caseins or urea are added alone, a self-leveling material having good fluidity and less cracking cannot be obtained. That is, caseins have the drawback that the viscosity of the half-sided slurry that improves the flowability is too high, and it is possible to lower the viscosity while maintaining an appropriate flowability as a self-leveling material only by using urea in combination. It is.

Examples of the cement used in the present invention include various Portland cements such as ordinary, early-strength, and ultra-high-strength, various mixed cements obtained by mixing blast furnace slag, silica, and the like with Portland cement, moderate heat cement, white cement, colloid cement, and the like. Can be

In addition, aggregate can be used if necessary. The aggregate used in the present invention is not particularly limited, and generally used artificial sands such as silica sand and crushed sand, and natural sands can be used.

In the present invention, in order to obtain low shrinkage of the self-leveling material after curing, the proportions of cement, rapidly hardened material and pozzolans are extremely important.

In the present invention, the use amount of the rapid hardening material is preferably 5 to 60 parts by weight, more preferably 10 to 25 parts by weight, based on 100 parts by weight of cement. If it is less than 5 parts by weight, the effect of reducing dry shrinkage is not remarkable, and if it is more than 60 parts by weight, expansion cracks are liable to occur in water or wet curing.

The amount of pozzolans used is preferably 30 to 200 parts by weight, more preferably 50 to 100 parts by weight, based on 100 parts by weight of cement. If the amount is less than 30 parts by weight, it is not sufficient to further increase the low shrinkage effect of the rapidly hardened material.

Within the above range, the expansion and shrinkage after curing is small, and the effect of preventing cracking is large. Outside of these ranges, the effect tends to be small. In the present invention, the use amount of caseins is preferably 0.1 to 5 parts by weight, and
~ 2 parts by weight is more preferred. If the amount is less than 0.1 part by weight, fluidity cannot be obtained.

The amount of urea used is preferably from 0.1 to 10 parts by weight, more preferably from 0.2 to 5 parts by weight, based on 100 parts by weight of the cement, the hardened material and the pozzolans in total. If the amount is less than 0.1 part by weight, the effect of lowering the viscosity of the slurry is not sufficient, and if it exceeds 10 parts by weight, the strength is poor and efflorescence is generated, which is not preferable.

In the present invention, further, if necessary, celluloses such as methylcellulose, hydroxymethylcellulose and carboxymethylcellulose, polymer emulsions such as vinyl acetate emulsion, ethylene-vinyl acetate emulsion and acrylic emulsion, and polymer substances such as poval and the like Alternatively, it is possible to add various admixtures or admixtures such as a water retention agent, an organic acid such as citric acid, tartaric acid and gluconic acid or a salt thereof, a setting regulator such as an inorganic carbonate, and an antifoaming agent.

The mixing method is not particularly limited.

(Example) Hereinafter, an example will be described in more detail.

Example 1 Using the composition shown in Table 1, 43 parts by weight of No. 6 silica sand and 30 parts by weight of water were mixed with 100 parts by weight of cement, a hardened material and pozzolans in total, and the mortar was kneaded. . A test specimen was formed using this mortar.

In the case of using a hardened material, 0.4 and 0.3 parts by weight of potassium carbonate and tartaric acid were further added as a setting retarder to 100 parts by weight of the hardened material.

To measure the flow value, place a flow cone specified in JIS R 5201 “Physical Testing Method for Cement” on a horizontally supported smooth acrylic plate, and pour the kneaded mortar into the top of the flow cone. Immediately, the flow cone was raised vertically, and the spread of the mortar was measured to obtain a flow value.

In addition, the molding of the test piece is performed in a 4 × 4
Fill the mortar with a × 16 cm triple formwork, 20 ° C, 80
After curing for 1 day at% RH, air drying curing shrinkage, water curing expansion, and air drying curing compressive strength were performed. The results are shown in Table 2.

Expansion and contraction were measured according to the comparator method of length change measurement method shown in JIS A1125. Curing is 20 ℃ each
In water, 20 ° C and 60% RH. The curing of compressive strength is 20
° C and 80% RH.

Cement: Ordinary Portland cement calcium fluoroaluminate A: x / y / z = 1 / 0.6 / 0, Blaine value 4,350 cm ² / g B: x / y / z = 1/1 / 0.15, manufactured by Denki Kagaku Kogyo Co., Ltd. , Blaine value 4,250 cm ² / g C: x / y / z = 1 / 1.7 / 0.35, Blaine value 4,250 cm ² / g Inorganic sulfate: anhydrous type II gypsum, Brain value 5,100 cm ² / g Pozzolans D: Fry Ash, manufactured by Tokiwa Thermal Power Co., Ltd.
Brain value 3,200cm ² / g E: Granulated blast furnace slag, manufactured by Nippon Steel Corporation, Brain value
4,500cm ² / g Setting retarder: Glucon trisodium, reagent Example 2 Table 1 A casein and a urea were blended at a ratio shown in Table 2 with a total of 100 parts by weight of the cement, the hardened material and the pozzolans of Experiment No. 1-5. On the other hand, the same procedure as in Example 1 was carried out except that 43 parts by weight of No. 6 silica sand and 30 parts by weight of water were mixed and mortar was kneaded. The results are shown in Table 3.

(Materials used) Caseins: Commercial products Urea: Industrial use, manufactured by Nissan Chemical Industries [Effects of the Invention] By using the cement admixture and the cement composition of the present invention, a slurry having excellent fluidity can be obtained, and a low shrinkage enables formation of a smooth floor substrate that is less likely to crack. became.

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁷ Identification code FI C04B 28/04 C04B 28/04

Claims (3)

(57) [Claims] (1) xCaO.yAl ₂ O ₃ .zCaF ₂ (where x / y / z = 1/0.
65-1.5 / 0.01-0.32) A cement admixture containing calcium fluoroaluminate, inorganic sulfate, pozzolans and a setting retarder as main components. (2) xCaO.yAl ₂ O ₃ .zCaF ₂ (where x / y / z = 1/0.
65-1.5 / 0.01-0.32) A cement admixture containing calcium fluoroaluminate, inorganic sulfate, pozzolans, setting retarders, caseins and urea as main components. 3. A cement composition comprising a cement and the cement admixture according to claim 1 or 2 as a main component.