JP2002068813A - Cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cement composition making small the volume of contraction of a hardened body such as cement, mortar and concrete and giving high bending/cracking strength to the hardened body. SOLUTION: This cement composition contains the polyoxyalkylene derivative shown by the general formula: X O(AO)nR}m, wherein X is a residual group of the compound having 2-8 hydroxyl groups; AO is a 2-18C oxyalkylene group; R is a hydrogen atom, a 1-18C hydrocarbon group or a 2-18C acyl group; n is 30-1,000; m is 2-8; an oxyethylene group accounts for 60% or higher of the AO and is used as a powdery drying and contraction-reducing agent so that the mass ratio of cement : an expanding material : the drying and constriction- reducing agent is 80-98:2-20:0.2-10. The expanding material contains released lime, calcium alumino-ferrite and anhydrous gypsum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement composition such as cement, mortar, concrete and the like, which has a small drying shrinkage and a high bending crack strength.

[0002]

2. Description of the Related Art Conventionally, when manufacturing secondary concrete products such as fume pipes, steel pipe linings, sheet piles, and box culverts, the amount of expanding material used has been reduced to 1%.
a method of introducing chemical prestress by increasing the m ³ per 35～80Kg, concrete 1 m ³ the amount of expansive
30kg per unit and the amount of restraint expansion is 150 ~ 2
Prevent drying shrinkage and harden general buildings such as walls, roof slabs and flooring materials, hydraulic structures such as water tanks and pools, pavements, floor slabs and box culverts to 50 × 10 ^-6 A method used for the purpose of compensation for shrinkage and the like is known.

[0003]

However, these methods cannot completely prevent drying shrinkage and self-shrinkage, and depending on the conditions, a decrease in crack load due to a decrease in chemical prestress and a crack due to drying shrinkage occur. Therefore, a drying shrinkage reducing agent is also used in combination. Since the drying shrinkage reducing agent is different from the expanding material and the shrinkage reducing mechanism, it is possible to further reduce the amount of shrinkage by using them in combination.

As the drying shrinkage reducing agent, there are many compositions based on alkylene oxide polymers, for example, lower alcohol alkylene oxide adducts, lower alcohols, glycol ether amino alcohols. Those having as their main components, for example, derivatives, polyethers, and low molecular weight alkylene oxide copolymers are commercially available. These are liquid products that are used in large quantities, and raw concrete plants that manufacture mortar and concrete often cannot be weighed due to lack of weighing equipment, lack of weighing capacity, etc. When weighing with, the work becomes complicated and the viscosity becomes high at low temperature, which makes handling inconvenient.
There was a problem that it could not be premixed with the materials used. Therefore, powder products have high crack resistance,
There has been a demand for a shrinkage-reducing agent having good performance even with a small addition ratio, but none of them has satisfactory performance.

As a result of various studies, the present inventors have found that the above-mentioned problems can be solved by combining a drying shrinkage agent of a specific powder with an expanding material, and have completed the present invention.

[0006]

That is, the present invention provides a compound of the general formula represented by X ｛O (AO) nR 、 m, wherein X is a residue of a compound having 2 to 8 hydroxyl groups, and AO is a carbon atom. 2 to 18 oxyalkylene groups, R is a hydrogen atom or a hydrocarbon group having 1 to 18 carbon atoms or an acyl group having 2 to 18 carbon atoms, n is 30 to 1
000, m is 2 to 8, and 60 of the oxyalkylene group
The mixing ratio of the dry shrinkage reducing agent in the powder containing at least mol% of the polyoxyalkylene derivative which is an oxyethylene group is cement: expanding material: drying shrinkage reducing agent by mass ratio =
80 to 98: 2 to 20: 0.2 to 10 is a cement composition, wherein the expanding material is a CaO raw material,
The material according to claim 1, wherein the material is obtained by heat-treating an Al ₂ O ₃ raw material, a Fe ₂ O ₃ raw material, and a CaSO ₄ raw material, and contains free lime, calcium aluminoferrite, and anhydrous gypsum. It is a cement composition. Here, the cement composition is a general term for cement, mortar and concrete.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

[0008] The cement used in the present invention includes portland cement having ordinary, fast strength, super fast strength, low heat and moderate heat, cement mixed with blast furnace slag, fly ash and silica, fine limestone powder and the like. And a filler-cement mixed therewith.

The expanding material used in the present invention is not particularly limited, and examples thereof include a conventional calcium sulfoaluminate-based or lime-based expanding material.
In particular, CaO raw material, Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material and Ca
It is a substance obtained by heat-treating the SO ₄ raw material, and is preferably an expanding material containing free lime, calcium alumino-ferrite and anhydrous gypsum (hereinafter referred to as a calcium alumino-ferrite expanding material). The proportion of free lime, calcium aluminoferrite and anhydrous gypsum in this expanding material is not particularly limited, but in 100 parts of the expanding material, free lime is preferably 30 to 60 parts, and more preferably 40 to 50 parts. preferable. The calcium alumino ferrite is preferably 10 to 40 parts, and more preferably 15 to 3 parts.
Five parts are more preferred. The amount of anhydrous gypsum is preferably from 10 to 40 parts, more preferably from 20 to 35 parts. In addition, the part which shows the mixture ratio used by this invention and% show a mass unit.

[0010] The calcium alumino ferrite of the present invention
Is CaO-Al_TwoO_Three-Fe_TwoO_ThreeGeneric term for compounds
And is not particularly limited, but in general,
CaO is C, Al_TwoO_ThreeTo A, Fe_TwoO_ThreeIs F, C
_FourAF, C₆A_TwoF and C₆AF _TwoAre well known compounds
ing. Usually, C_FourThinking that it exists as AF
good. Hereinafter, calcium alumino ferrite is referred to as C_FourAF
Abbreviated.

In producing the expanding material of the present invention, a CaO raw material, an Al ₂ O ₃ raw material, a Fe ₂ O ₃ raw material and a CaSO ₄ raw material are heat-treated to synthesize a clinker composed of free lime, C ₄ AF and anhydrous gypsum. It is preferable to manufacture it. Even if free lime, C ₄ AF and anhydrous gypsum are separately synthesized and mixed to produce a cement admixture, the effects of the present invention cannot be obtained. That is, a CaO raw material, an Al ₂ O ₃ raw material, and a Fe ₂ O ₃ raw material are heat-treated to synthesize a clinker composed of free lime and C ₄ AF, and then mixed with anhydrous gypsum to produce a clinker. Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material and C
The effect of the present invention cannot be obtained when the aSO ₄ raw material is heat-treated to synthesize clinker composed of free lime and C ₄ AF, and then mixed with anhydrous gypsum. Whether the clinker composed of free lime, C ₄ AF, and anhydrous gypsum was synthesized by heat-treating the CaO raw material, the Al ₂ O ₃ raw material, the Fe ₂ O ₃ raw material, and the CaSO ₄ raw material is, for example, 100 μm or more in the pulverized material. Microscopic observation of coarse particles (SEM-E
DS) or the like, and confirming that free lime, C ₄ AF and anhydrous gypsum are mixed in the particles.

The method of heat-treating the raw material is not particularly limited.
It is preferable to bake at a temperature of 600 ° C.
1500 ° C. is more preferred. If the temperature is lower than 1100 ° C., the expansion performance of the obtained cement admixture is insufficient, and
If the temperature exceeds ℃, anhydrous gypsum may be decomposed.

[0013] As the CaO material, limestone or slaked lime and the like, and the Al ₂ O ₃ raw material, include bauxite, aluminum residual ash, etc., Fe as the ₂ O ₃ raw material, copper Karami and commercial iron oxide As the CaSO ₄ raw material,
Examples include dihydrate gypsum, hemihydrate gypsum and anhydrous gypsum. There are impurities in these raw materials. Specific examples thereof include SiO ₂ , MgO, TiO ₂ , P ₂ O ₅ , Na
Examples include ₂ O, K ₂ O, fluorine, chlorine and the like, which do not pose any particular problem as long as the object of the present invention is not substantially inhibited.

Among these, it is particularly preferable that SiO ₂ has a silicate ratio of less than 0.5. Silicate rate is 0.
If it exceeds 5, excellent expansion performance may not be obtained.
The silicic acid ratio as referred to in the present invention means the amount of SiO ₂ in the expanding material, Al ₂
It is calculated from the following formula based on the O ₃ amount and the Fe ₂ O ₃ amount. Silicic acid ratio = SiO ₂ / (Al ₂ O ₃ + Fe ₂ O ₃ ) The amount of SiO ₂ in the expanding material is preferably 5.0% or less, more preferably 3.0% or less. If it exceeds 5.0%, excellent expansion performance may not be obtained.

Although the particle size of the expanding material is not particularly limited, it is usually preferably 2000 to 4000 cm ² / g. 2000cm is less than ² / g remained unreacted substances a long period of time, may reduce the durability, 4000 cm ² /
If it exceeds g, the hydration reaction may be too fast and the desired expansion may not be obtained.

The amount of the expanding material used is preferably 2 to 20 parts per 80 to 98 parts of cement. If it is less than 2 parts, the effect of reducing drying shrinkage cannot be obtained, and if it exceeds 20 parts, the amount of expansion may be too large and the strength may be reduced.

The powder drying shrinkage reducing agent used in the present invention has a general formula of X ｛O (AO) nR｝ m, where X is 2
AO is a residue of a compound having 8 to 8 hydroxyl groups, and AO has 2 carbon atoms.
To 18 oxyalkylene groups, R is a hydrogen atom or a carbon atom 1
To 18 hydrocarbon groups or acyl groups having 2 to 18 carbon atoms, n
Is from 30 to 1000, m is from 2 to 8, and 60 mol% or more of the oxyalkylene group is composed of a polyoxyalkylene derivative which is an oxyethylene group. If the value of n is less than 30, the melting point becomes low and it becomes difficult to use the powder,
If the value of n exceeds 1000, the viscosity becomes high and the production becomes difficult. If the oxyalkylene group is less than 60 mol%, the melting point will be low and it will be difficult to use the powder, and the solubility in a calcium hydroxide (cement) solution will be poor.

In the general formula X ｛O (AO) nR｝ m,
X is a residue of a compound having 2 to 8 hydroxyl groups, and examples of the compound having 2 to 8 hydroxyl groups include ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, styrene glycol, and having 8 to 8 carbon atoms.
18, alkylene glycols, glycols such as neopentyl glycol, glycerin, diglycerin, polyglycerin, trimethylolethane, trimethylolpropane, 1,3,5-pentanetriol, erythritol, pentaerythritol, dipentaerythritol,
Sorbitol, sorbitan, sorbide, condensate of sorbitol and glycerin, adonitol, arabitol,
Xylitol, polyhydric alcohols such as mannitol, or their partially etherified or esterified products,
Xylose, arabinose, ribose, rhamnose, glucose, fructose, galactose, mannose,
Examples thereof include saccharides such as sorbose, cellobiose, maltose, isomaltose, trehalose, sucrose, raffinose, gentianose, and melezitose, and partially etherified or esterified products thereof.

In the general formula X ｛O (AO) nR｝ m,
The oxyalkylene group having 2 to 18 carbon atoms represented by AO includes ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, α-
Derived from olefin oxide and the like, oxyethylene group, oxypropylene group, oxybutylene group, oxytetramethylene group, oxyalkylene group having 6 to 18 carbon atoms and the like, when two or more are added, Block addition or random addition may be used. In the general formula, R represents a hydrogen atom, a hydrocarbon group having 1 to 18 carbon atoms, or an acyl group having 2 to 18 carbon atoms.

The hydrocarbon group having 1 to 18 carbon atoms includes methyl, ethyl, allyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, amyl, isoamyl, hexyl, Hebutyl, octyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl, isotridecyl, tetradecyl, hexadecyl, isocetyl, octadecyl, isostearyl, oleyl, benzyl, cresyl Butylphenyl group, dibutylphenyl group, octylphenyl group, nonylphenyl group, dodecylphenyl group, styrenated phenyl group and the like.

Examples of the acyl group having 2 to 18 carbon atoms include acetic acid, propionic acid, butyric acid, isobutyric acid, caproic acid, caprylic acid, 2-ethylhexanoic acid, pelargonic acid, capric acid, lauric acid, myristic acid, and palmitic acid. And acyl groups derived from isopalmitic acid, margaric acid, stearic acid, isostearic acid, acrylic acid, methacrylic acid, palmitoleic acid, oleic acid, linoleic acid, linolenic acid, benzoic acid and the like.

The amount of the powder used for reducing the drying shrinkage is 0.2 to 10 parts by mass based on 100 parts in total of the cement and the expanding material.
Parts are preferred. If it is less than 0.2 part, the effect of reducing drying shrinkage cannot be obtained, and if it exceeds 10 parts, the strength may be impaired.

The cement composition of the present invention contains river sand, land sand,
It is possible to use fine aggregates such as crushed sand and sea sand and coarse aggregates such as river gravel, crushed stone, recycled aggregate and artificial lightweight aggregate together,
There is no particular limitation as long as it is used for ordinary mortar or concrete. In addition, the admixture A
E water reducer, high performance water reducer, AE high performance water reducer, AE agent,
Antifoaming agent, antifreeze / coldproofing agent, rustproofing agent, waterproofing agent, pigment, breath
Blast-furnace slag fine powders such as steel fibers, vinylon fibers, glass fibers, carbon fibers, and hydraulic powders, fly ash, silica fume, and polymer dispersions. SBR, EVA, P
It can be used in combination with latex such as AE.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.

Example 1 Cement, swelling agent, drying shrinkage reducing agent and water in various mixing ratios shown in Table 1 were added to 0.05 parts of a defoaming agent and a water reducing agent E0 for a total of 100 parts of cement and swelling agent. .25 parts were put into a mortar mixer and kneaded at a low speed for 30 seconds, and 300 parts of fine aggregate was added over a period of 30 seconds with respect to a total of 100 parts of cement and expansive material, followed by high-speed kneading for 30 seconds. ,
Dropping was performed during 60 seconds, and high-speed kneading was further performed for 120 seconds to knead the mortar. Mortar flow
The value was 220 ± 10 mm, the amount of air was 4.0 ± 1.0%, and the temperature was 20 ° C. Form the kneaded mortar, 2
Cured at 0 ° C, demolded after 1 day of age, 20 ° C, 80 ° C
% RH at 7% RH.
The curing was performed at 20 ° C. and 60% RH, and the length change rate of the cured product was measured. Thereafter, the bending crack strength was tested. The results are also shown in Table 1.

<Materials Used> Cement: ordinary Portland cement, commercially available expansion material A: calcium sulfoaluminate-based expansion material, commercially available expansion material B: calcium alumino-ferrite expansion material, C
aO raw material (reagent primary calcium carbonate), Al ₂ O ₃ raw material (reagent primary aluminum oxide), Fe ₂ O ₃ raw material (reagent 1
Grade (ferric oxide) and CaSO ₄ raw material (reagent grade 1 dihydrated gypsum) are mixed and pulverized, and then heat-treated at 1350 ° C. to obtain 50 parts of free lime, 25 parts of C ₄ AF and 25 parts of anhydrous gypsum. The clinker was synthesized and pulverized using a ball mill to a Blaine specific surface area of 3500 ± 300 cm ² / g to prepare an expanding material. The constituent compound of the expanding material was identified by a powder X-ray diffraction method (hereinafter, XRD), and the compound composition was calculated by calculation based on the chemical composition and the result of XRD identification.
The chemical composition was determined according to JIS R5202. Drying shrinkage reducing agent C: polyalkylene derivative powder HO
(CH ₂ CH ₂ O) ₆₈ H, commercial product Antifoaming agent: polyether, commercial product Water reducing agent E: Pozzolith No. 70 AE water reducing agent, commercial product Fine aggregate: river sand, 5mm below, specific gravity 2.60

<Measurement method> Flow: Measured according to JIS R5201 Air volume: Measured according to JIS A 1174 Length change rate: Measured according to Annex 1 of JIS A6202 Bending crack test: See Annex 1 of JIS A 6202 The specimen used for the measurement was measured according to the bending strength test of JIS R5201. The bending crack load was the first inflection point of the load.

[0028]

[Table 1]

From Table 1, it can be seen that the mortar using the cement composition of the present invention has a small amount of drying shrinkage and a high bending crack strength.

Example 2 The total unit amount of the cement and the intumescent material B used in Example 1 was 350 kg / m ^3, and the amount of cement and the intumescent material shown in Table 2 and the total of 100 parts of the cement and the intumescent material were used. And 2
29 parts of fine aggregate and 279 parts of coarse aggregate are put into a mixer,
After kneading for 10 seconds, 50 parts of water and the amounts of the drying shrinkage reducing agent and the water reducing agent F shown in Table 2 were added and kneaded for 90 seconds to prepare concrete. Concrete slump is 18 ± 1cm, air volume is 4.5 ± 0.5%, temperature is 2
It was 0 ° C. Form the kneaded concrete,
Curing at ℃, demold after one day of age, curing in water at 20 ℃ until the age of 7 days, then aging at 20 ℃, 60% RH to measure the rate of change in length of the cured body did. Table 3 shows the results.

<Materials> Drying shrinkage reducing agent D: polyalkylene derivative powder HO
(CH ₂ CH ₂ O) ₁₈₉ H, commercially available water reducing agent F: polycarboxylic acid-based water reducing agent having a polyalkylene group and an acid anhydride group, commercially available fine aggregate: river sand, 5 mm below, specific gravity 2.60 coarse aggregate: Crushed stone, Gmax 20mm, specific gravity 2.70

<Measurement method> Slump: Measured according to JIS A 1101 Air volume: Measured according to JIS A 1128 Length change rate: Measured according to JIS A6202 B method Bending crack test: A sample prepared according to JIS A 6202B method Specimens were measured according to the flexural strength test method of concrete of JISA 1106. The bending crack load was the first inflection point of the load.

[0033]

[Table 2]

[0034]

[Table 3]

From Table 3, it can be seen that the concrete using the cement composition of the present invention has a small amount of drying shrinkage and a high bending crack strength.

[0036]

According to the present invention, the cement, mortar, concrete and the like are hardened by using the cement composition having the specific mixing ratio of the cement, the expanding material and the agent for reducing the drying shrinkage of the powder. The amount of shrinkage of the body is small, and a high bending crack strength is obtained. In addition, the cement composition can be premixed.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C04B 22:08 C04B 22:08 Z 24:32) 24:32) A 103: 60 103: 60

Claims (2)

[Claims] 1. A compound represented by the general formula X ｛O (AO) nR｝ m, wherein X is a residue of a compound having 2 to 8 hydroxyl groups, AO
Is an oxyalkylene group having 2 to 18 carbon atoms, R is a hydrogen atom or a hydrocarbon group having 1 to 18 carbon atoms or an acyl group having 2 to 18 carbon atoms, n is 30 to 1000, m is 2 to 8, The mixing ratio of the dry shrinkage reducing agent of the powder containing a polyoxyalkylene derivative in which 60% by mole or more of the alkylene group is an oxyethylene group is expressed by mass ratio of cement: expansion material: drying shrinkage reducing agent = 80 to 98. : 2 to 20: 0.2 to
10. A cement composition, which is 10. 2. An inflating material comprising: a CaO raw material, an Al ₂ O ₃ raw material,
A Fe ₂ O ₃ raw material and a CaSO ₄ material obtained by heat-treating the material, cement composition according to claim 1, characterized in that it contains free lime, calcium alumino ferrite and anhydrite.