JP6137837B2 - Admixtures and applications for cement extrusion - Google Patents

Description

  The present invention relates to an admixture for extrusion molding and uses thereof. More specifically, the present invention relates to an admixture for cement extrusion excellent in extrudability, quality, and equipment antifouling, and its use.

Conventionally, cement extrudates are obtained by adding water to a cement mixture containing 1) hydraulic materials such as ordinary Portland cement and fine aggregates such as silica sand, as well as reinforcing fibers and lightweight aggregates used as necessary. A mortar that is a clay-like highly viscous substance is prepared, and then 2) the obtained mortar is formed into a desired shape such as a flat plate or a hollow shape using a vacuum extrusion molding machine.
Because mortar is a clay-like highly viscous substance, when manufacturing a cement extrusion using a vacuum extruder, the vacuum screw machine's bag screw, vacuum degassing chamber wall, auger screw, barrel inner surface Mortar small particles adhere to the extruded mortar path, and the small particles accumulate over a long period of operation, and gradually become a solid cement cement. The quality of the molded product decreases due to the cement fixed body dropping off with some momentum and mixing or adhering to the molded product, or depositing as a mean near the mold outlet and streaking on the surface of the molded product. The molded product becomes a defective product.

In order to prevent the generation of defective products, it is essential to stop the operation of the extrusion molding equipment for a certain period of time and to disassemble and clean the equipment. However, it is very difficult to remove a dry and strong cement-fixed body, which requires a lot of labor and time. Therefore, it is preferable to prevent or suppress the adhesion of the cement-fixed body to prevent the equipment from being soiled by the mortar, to lengthen the continuous operation time of the extrusion molding equipment, and to reduce the cost of the obtained molded product.
For hydraulic materials such as cement, an organic admixture for extrusion molding is used. At this time, the setting delay of mortar is excessively expressed, and there is a high possibility that a problem will occur in cement hardening. In order to cope with the problem of the setting delay, agents such as a setting adjuster, a curing adjuster and a quick setting agent are generally widely used, but the quality and strength of the molded product are adversely affected. At present, there are no drugs that do not adversely affect the quality and strength of extrusion, so the use of these agents is kept to a minimum, and careful admixture of cement molding and its formulation is required.

Conventionally, the following techniques are known for improving extrudability, quality, and antifouling properties of equipment.
In Patent Document 1, it is said that by selectively using a high-viscosity cellulose ether binder, it is possible to efficiently produce a cement extruded product with improved shape retention with a small addition amount. Indeed, it teaches that extrusion is possible even if the amount of cellulose ether binder added is reduced. However, in Patent Document 1, it is said that the performance of maintaining the shape and dimensions in a state in which the extruded product comes out of the mold is good, but other important quality, a good surface state, There is no improvement in extrudability such as extrusion pressure and extrusion speed, and the antifouling performance of the equipment is not achieved.

In Patent Document 2, a cement-based extrusion aid containing 50 to 80% by weight of water-soluble hydroxyalkylalkylcellulose having a 2% aqueous solution at 20 ° C. and a viscosity of 30000 mpa · s or more and 50 to 20% by weight of water-soluble hydroxypropyl starch. Has been proposed. However, although Patent Document 2 suggests improvement in surface properties, the quality of surface properties and the like is very inferior and inadequate. Moreover, the setting delay effect of the cement by water-soluble hydroxypropyl starch has a great influence, and shows about 2 times or more of the setting delay time exhibited by the water-soluble cellulose ether in the normal case. For this reason, there are enormous restrictions on the usage and application. In order to obtain an appropriate setting delay time, if a setting adjusting agent, a curing adjusting agent, a rapid setting agent, or the like is used, a significant deterioration in quality cannot be avoided. Moreover, the antifouling performance of the equipment does not come out.
On the other hand, in order to prevent the adhesion of mortar and improve the problem of equipment contamination, it is attempted to examine the surface adhesion technology such as the formation of a coating layer on the mortar contact surface of mechanical equipment and the plating treatment on metal materials. It has been. However, at present, there is no known surface treatment agent or surface treatment technology that satisfies the wear resistance required for cement extrusion equipment. There are also no admixtures that reduce equipment fouling in cement extrusion.

  As shown above, it solves the problem of extrudability when manufacturing cement extrudates, the quality of cement extrudates, and the problem of dirt on equipment due to mortar, and satisfies the setting delay. Currently, no admixture is known.

Japanese Patent Publication No. 07-115908 Japanese Patent Laid-Open No. 10-017348

  The object of the present invention is to solve the problem of extrudability, the problem of fouling of the extruder and the problem of setting delay when producing a cement extrusion, and the problem of the quality of the resulting cement extrusion. It is to provide a molding admixture, a cement extrusion mixture and a cement extrusion using the same.

In order to solve the above-mentioned problems, the present inventors have intensively studied, and as a result, used a cement extrusion molding admixture in which a cellulosic binder and starch ether are blended at a specific ratio and the viscosity and thixotropy index are optimized. The knowledge of solving the above problems was obtained by performing cement extrusion, and the present invention was completed.
The cement extrusion molding admixture of the present invention is an admixture containing a cellulose binder and starch ether, and the cellulose binder has a weight ratio of 85 to 95% by weight based on the total amount of the cellulose binder and starch ether. The viscosity of a 1% by weight aqueous solution of the admixture is 4000-30000 mPa · s (B-type viscometer, measurement temperature 20 ° C.), and the TI value (thixotropic index) of the 1% by weight aqueous solution of the admixture is 2. .6 or less.

It is preferable that the admixture for cement extrusion molding of the present invention further contains a nonionic surfactant, and the blending ratio thereof is 1 to 10 parts by weight with respect to 100 parts by weight of the total of the cellulose binder and starch ether.
The nonionic surfactant may be a polyalkylene oxide adduct represented by the following general formula (1).

RO-[(PO) _p / (EO) _q ] -H (1)
(However, R is a hydrogen atom, an alkyl group or an alkenyl group having 1 to 30 carbon atoms, and may be composed of a linear or branched structure. PO is an oxypropylene group, and EO is oxyethylene. P and q represent the average number of moles added, respectively, and p = 20 to 100 and q = 5 to 500. [(PO) _p / (EO) _q ] represents p moles of PO and It is a polyoxyalkylene group formed by adding q mol of EO randomly or by block.)
The polyalkylene oxide adduct is a block polymer represented by the following general formula (2), and the number average molecular weight is preferably 1400 to 28000.

HO- (EO) _r (PO) _p (EO) _s- H (2)
(However, (EO) _r, (PO) _p and (EO) _s are added by blocks, and p = 20 to 100 and q = r + s = 5 to 500.)
The cellulose binder is at least one selected from the group consisting of alkyl cellulose, hydroxyalkyl cellulose, and hydroxyalkyl alkyl cellulose, and the viscosity of a 1% by weight aqueous solution thereof is 5000 to 40000 mPa · s (B-type viscometer, measurement temperature). 20 ° C.).

The starch ether is a water-soluble hydroxypropylated starch having a hydroxylpropyl group substitution degree of 0.1 to 15%, and the viscosity of a 1% by weight aqueous solution thereof is 5 to 100 mPa · s (Heppler viscometer, measuring temperature 20 ° C).
The cellulosic binder is preferably hydroxyethyl methylcellulose.

The cement extrusion molding mixture of the present invention is a mixture containing an inorganic material essential for cement and fine aggregate, and the cement extrusion molding admixture, wherein the blending ratio of the cement extrusion molding admixture is the above It is 0.5-3 weight part with respect to 100 weight part of inorganic materials.
It is preferable that the mixture for cement extrusion molding of the present invention further contains water and the blending ratio thereof is 18 to 28 parts by weight with respect to 100 parts by weight of the inorganic material.
Method for producing a cement extruded product of the present invention is formed by solidifying extruding the cement extrusion mixture.

In the cement extrusion admixture and the cement extrusion mixture of the present invention, the problem of extrudability in the production of a cement extrusion, the problem of extruder fouling, the problem of setting delay, and the resulting cement extrusion Can solve the problem of quality.
In the production of the cement extruded product of the present invention, the problem of extrudability, the problem of fouling of the extruder and the problem of setting delay are solved, and the quality of the obtained cement extruded product is high.

[Admixture for cement extrusion and its production]
The admixture for cement extrusion of the present invention (hereinafter sometimes simply referred to as an admixture) is an admixture used for cement extrusion including a cellulosic binder and starch ether.
The cellulosic binder is a main component of the cement extrusion admixture, and imparts plasticity and water retention to a cement extrusion molding mixture containing water described below (hereinafter, this mixture may be referred to as mortar). It is a component that gives good extrudability and high quality to a cement extruded product obtained by extruding mortar. Cellulosic binders are usually solid and powder.

Examples of the cellulose binder include alkyl celluloses such as methyl cellulose; hydroxyalkyl celluloses such as hydroxyethyl cellulose and hydroxypropyl cellulose; hydroxyalkylalkyl celluloses such as hydroxyethyl methyl cellulose and hydroxypropyl methyl cellulose. More than one species may be used in combination. Among these cellulose-based binders, hydroxyalkylalkylcelluloses such as hydroxyethylmethylcellulose and hydroxypropylmethylcellulose are preferable, high water retention and shape retention, dispersibility of inorganic materials due to surfactant function of cellulose ether itself, extrudability Excellent workability due to its contribution to and high gelation temperature.
The viscosity of the cellulosic binder greatly affects the viscosity of the admixture and the cement extrusion mixture (hereinafter sometimes simply referred to as a mixture). Moreover, when the viscosity is within this range, the shape retention of a cement extruded product obtained by extruding mortar becomes high. The shape-retaining property as used in the present invention refers to the ability to maintain the shape of the extruded product discharged from the mold, and is a physical property that greatly affects the quality.

The viscosity of the 1% by weight aqueous solution of the cellulose binder (JIS K 7117, measured with a B-type viscometer, measurement temperature 20 ° C.) is not particularly limited, but is preferably 5000 to 40000 mPa · s, more preferably 5100 to 35000 mPa. · S, more preferably 5200 to 30000 mPa · s, particularly preferably 5300 to 25000 mPa · s.
If the viscosity of the 1% aqueous solution of the cellulose binder is less than 5000 mPa · s, the shape retention may be insufficient and the blending of the cellulose ether may need to be increased. On the other hand, when the viscosity of the 1% aqueous solution of the cellulose binder exceeds 40,000 mPa · s, it becomes difficult to dissolve in water, and it is inferior in water retention to a low viscosity cellulose ether. The lubrication effect at the time of extrusion is insufficient, and good extrudability may not be obtained.

In addition, the cellulose binder itself has the effect of increasing the setting delay of cement. However, since it is now widely used by cement extrusion operators, the length of setting delay time due to the cellulose binder is limited in this industry. Standard.
Starch ether is a polymeric material having water retention, but generally has a significantly lower viscosity than cellulosic binders. In particular, the viscosity and viscosity of the cellulose binder can be modified by using it together with a highly viscous cellulose binder. Starch ether has the effect of greatly increasing the setting delay of the cement, and if it adversely affects the curing properties, it naturally causes problems in the strength of the molded product. Therefore, careful attention is required for blending into admixtures.

It is preferable that the starch ether is a water-soluble hydroxypropylated starch having a hydroxylpropyl group substitution degree of 0.1 to 15% because of good solubility in water. The water-soluble hydroxypropylated starch used here has a hydroxylpropyl group introduced into starch so that the substitution degree is 0.1 to 15%. The degree of substitution of the hydroxylpropyl group of the water-soluble hydroxypropylated starch is more preferably 0.2 to 14%, particularly preferably 0.3 to 13%, and most preferably 0.4 to 12%. If the degree of substitution of the hydroxylpropyl group is less than 0.1%, a large amount of mutual hydrogen bonding due to the unsubstituted OH group in the starch remains, and the solubility in water may decrease. On the other hand, when the degree of substitution of the hydroxylpropyl group exceeds 15%, the influence of the hydrophobic hydroxypropyl group is strongly exerted, so that the solubility in water may also be lowered.
There is no particular limitation on the viscosity of the 1% by weight aqueous solution of starch ether (measured with a Heppler viscometer, measurement temperature 20 ° C.), preferably 5 to 100 mPa · s, more preferably 6 to 95 mPa · s, and even more preferably 7 It is -90 mPa * s, Most preferably, it is 8-85 mPa * s. When the viscosity of the starch ether is within this range, it is effective for the viscosity modification of the admixture. If the viscosity of the starch ether is less than 5 mPa · s, the setting retarding effect is excessively exhibited, which may cause a problem in cement hardening. On the other hand, when the viscosity of starch ether exceeds 100 mPa · s, it is difficult to obtain a viscosity-modifying effect, and the antifouling effect may be lowered.

The weight ratio of the cellulose binder to the total amount of the cellulose binder and starch ether is usually 85 to 95% by weight, preferably 86 to 94% by weight, more preferably 87 to 93% by weight, and still more preferably 88 to 94%. 92% by weight, particularly preferably 89 to 91% by weight, most preferably 90% by weight. When the weight ratio of the cellulose binder is less than 85% by weight, there is a high possibility that the setting delay effect is excessively exhibited and a problem is caused in the hardening of the cement. On the other hand, when the weight ratio of the cellulose binder exceeds 95% by weight, it is difficult to obtain a viscosity modifying effect, and the antifouling effect is lowered.
The admixture for cement extrusion according to the present invention preferably further contains a nonionic surfactant, and acts on inorganic materials and fibers in the mortar to improve the extrudability by exerting dispersibility and a bearing effect. In particular, it is possible to contribute to the improvement of the extrusion speed.

The blending ratio of the nonionic surfactant is preferably 1 to 10 parts by weight, more preferably 1.5 to 9 parts by weight, and still more preferably 2 to 8 parts per 100 parts by weight of the total of the cellulose binder and starch ether. Part by weight, particularly preferably 2.5 to 7 parts by weight. Most preferably, it is 3 to 6 parts by weight. When the blending ratio of the nonionic surfactant is less than 1 part by weight, a decrease in extrudability, particularly extrusion speed, may be observed. On the other hand, when the blending ratio of the nonionic surfactant exceeds 10 parts by weight, the surface property of the extruded product may be adversely affected and the quality may be lowered.
The nonionic surfactant is not particularly limited. For example, polyoxyalkylene alkyl such as polyoxyethylene cetyl ether, polyoxyethylene lauryl ether, and a polyalkylene oxide adduct represented by the following general formula (1) Ethers; polyoxyalkylene alkyl phenyl ethers such as polyoxyethylene nonylphenyl ether and polyoxyethylene octylphenyl ether; polyoxyalkylene fatty acid esters such as polyoxyethylene monolaurate and polyoxyethylene monooleate; polyoxyethylene sorbitan mono Polyoxyalkylene sorbitan fatty acid esters such as stearate and polyoxyethylene sorbitan monooleate; polyoxyalkylene alkylamines; fatty acid alkanolamides; Polyoxyalkylene fatty acid amides; polyoxyalkylene hardened castor oil; polyoxyalkylene sorbitol fatty acid esters; polyglycerol fatty acid esters, alkyl glycerol ether; polyoxyalkylene cholesteryl ether; alkylpolyglucosides; sucrose fatty acid esters. Among these nonionic surfactants, mention may be made of polyoxyalkylene alkyl ethers, polyoxyalkylene alkyl phenyl ethers and the like.

When the number average molecular weight of the nonionic surfactant is 1400 to 28000, it is low in foaming properties, it is difficult to bring bubbles into the mortar, and the dispersibility of inorganic materials and the like is good, and the low shrinkage of the molded product Property is improved.
Moreover, as a polyoxyalkylene alkyl ether as a nonionic surfactant, the polyalkylene oxide adduct represented by following General formula (1) is preferable.

RO-[(PO) _p / (EO) _q ] -H (1)
(However, R is a hydrogen atom, an alkyl group or an alkenyl group having 1 to 30 carbon atoms, and may be composed of a linear or branched structure. PO is an oxypropylene group, and EO is oxyethylene. P and q represent the average number of moles added, respectively, and p = 20 to 100 and q = 5 to 500. [(PO) _p / (EO) _q ] represents p moles of PO and It is a polyoxyalkylene group formed by adding q mol of EO randomly or by block.)
The average added mole number p of the oxypropylene group (PO) is not particularly limited as long as it is 20 to 100, but is preferably 21 to 95, more preferably 22 to 90, still more preferably 23 to 85, and particularly preferably. 24 to 80, most preferably 25 to 75. If p is less than 20, the compatibility with the hydrophobic material may not be sufficient. On the other hand, when p is more than 100, the hydrophobicity becomes too strong, and depending on the material, aggregation may occur.

The average added mole number q of the oxyethylene group (EO) is not particularly limited as long as it is 5 to 500, but is preferably 6 to 480, more preferably 7 to 460, still more preferably 8 to 440, and particularly preferably. 9-420, most preferably 10-400. If q is less than 5, the compatibility with the hydrophilic material may not be sufficient. On the other hand, if q exceeds 500, the hydrophilicity becomes too strong, and the setting delay may be adversely affected.
The ratio (p / q) of the average number of moles added (p) of oxypropylene groups and the average number of moles added (q) of oxyethylene groups is preferably 0.04 to 20, more preferably 0.05 to 19, More preferably, it is 0.06-18, More preferably, it is 0.07-17, Most preferably, it is 0.08-16, Most preferably, it is 0.09-15. If p / q is less than 0.04, the compatibility with the hydrophilic material may not be sufficient. On the other hand, when p / q is more than 20, hydrophobicity becomes too strong and aggregation may occur depending on the material.

The polyalkylene oxide adduct represented by the general formula (1) has water retention, the admixture is easily dissolved in water, enhances the dispersion effect of cement particles and fine aggregates, and improves mortar fluidity. , Mainly improve the extrusion speed. Moreover, as this polyalkylene oxide adduct, unlike the AE agent used for normal cement, concrete, etc., the thing with low foaming power is good.
Since the polyalkylene oxide adduct represented by the general formula (1) is easy to uniformly disperse with the cellulose binder or cement, the appearance at 20 ° C. is preferably solid, and more preferably powder. When the polyalkylene oxide adduct is a powder or a powdery product in which a liquid polyalkylene oxide adduct is adsorbed on inorganic particles such as silica stone powder or silica, the particle size of the powder is the cellulose-based binder. When the particle size is about the same as the particle size, for example, particles having a mesh size of 24 mesh (aperture 740 μm) or less is 80% by weight or more, the cellulose-based binder and the surfactant are not separated or unevenly distributed, and a uniform powder is obtained. It is preferable because an admixture for cement extrusion is obtained.

When the polyalkylene oxide adduct represented by the general formula (1) is a block polymer represented by the following general formula (2), the repulsion between the molecular chains is strong, and the dispersibility of the cement-based inorganic material is increased. It is preferable for further improvement.
HO- (EO) _r (PO) _p (EO) _s- H (2)
(However, (EO) _r, (PO) _p and (EO) _s are added by blocks, and p = 20 to 100 and q = r + s = 5 to 500.)

As shown in the general formula (2), the block polymer represented by the general formula (2) is a polyoxypropylene group (PO) _p having an average addition mole number of oxypropylene groups (PO) of 20 to 100. And polyoxyethylene group (EO) r in which the average addition mole number of oxyethylene group (EO) is _r , and a polyoxyethylene group in which the average addition mole number of oxyethylene group (EO) is s. (EO) A block polymer having a structure in which _s are bonded to each other. Both ends of this block polymer are hydroxyl groups.
The descriptions of p and q in the general formula (2) are the same as those described in the general formula (1).

For (EO) _r and (EO) _s which are respective blocks composed of oxyethylene groups (EO) of this block polymer, the ratio (r / s) of the average addition moles r and s is preferably 1 To 500, more preferably 1.1 to 490, still more preferably 1.2 to 480, even more preferably 1.3 to 470, particularly preferably 1.4 to 460, most preferably 1.5 to 450. . If r / s is larger than 500, repulsion between molecular chains is weakened, and the dispersibility of the cement-based inorganic material may be lowered.
The number average molecular weight of the block polymer is not particularly limited, but is preferably 1400 to 28000, more preferably 1500 to 26000, and further preferably 1600 to 24000 from the viewpoint of dispersion of the cement-based inorganic material in water. Especially preferably, it is 1700-22000. If the number average molecular weight of the block polymer is less than 1400, it may precipitate at a low temperature of 30 to 40 ° C., and may not function as a surfactant, causing destabilization of the process during vacuum extrusion. There is. On the other hand, when the number average molecular weight of the block polymer exceeds 28000, the dispersibility effect of the material may be lowered.

In addition to the cellulose-based binder and starch ether described above and the nonionic surfactant to be blended as necessary, the following components may be blended in the admixture for cement extrusion.
The admixture for cement extrusion has a 1% by weight aqueous solution viscosity (JIS K 7117, B-type viscometer, measurement temperature 20 ° C.) of usually 4000 to 30000 mPa · s, preferably 4200 to 29000 mPa · s, Preferably it is 4400-28000 mPa * s, Most preferably, it is 4500-27000 mPa * s. If the viscosity of a 1% by weight aqueous solution of a cement extrusion admixture is less than 4000 mPa · s, the shape retention may be insufficient, and the blending into the extrusion mixture as a cement extrusion admixture is increased. There is a need. On the other hand, if the viscosity of a 1% by weight aqueous solution of an admixture for cement extrusion exceeds 30000 mPa · s, the solubility in water becomes difficult and the water retention is inferior to that of a low-viscosity product. Is insufficient, and good extrudability cannot be obtained.

The admixture for cement extrusion has a 1% by weight aqueous solution having a TI value (thixotropic index) of usually 2.6 or less, preferably 0.9 to 2.6, more preferably 0.95 to 2.55, Preferably it is 1.0-2.5, Most preferably, it is 1.05-2.45, Most preferably, it is 1.1-2.4. Here, the TI value refers to an aqueous solution containing 1% by weight of an admixture for cement extrusion, and when the viscosity is measured at a measurement temperature of 20 ° C. using a B-type viscometer according to JIS K 7117, the rotational speed at the time of measurement is 6 rpm. It is defined as TI = B ₆ / B ₆₀ where the viscosity is B ₆ at the time and the viscosity B ₆₀ is ₆₀ rpm at the time of measurement.
When the TI value of a 1% by weight aqueous solution of an admixture for cement extrusion exceeds 2.6, the adhesiveness of the mortar becomes strong and the antifouling effect is lowered, which is not suitable. On the other hand, if the TI value is less than 0.9, the mortar may become hard and hard to form. In addition, in many cases, clay-based minerals can provide an admixture with a low TI value. However, cement extrusion molding admixtures containing viscosity minerals can be used in combination with cement. It is desirable to refrain from blending in mortar because of the action of adsorbing calcium components, etc., which are active substances.

In the present invention, the setting delay time of the admixture for cement extrusion is measured according to “JIS R5201 8. Setting Test”. That is, the setting time at 50 ° C. is measured in the case where the admixture for cement extrusion is mixed with cement so that the amount is 0.5% by weight. Separately from this, when a cellulosic binder considered to be a standard (in this application, Marporose ME-350T, which is currently considered a standard for industrial use) is blended with cement, the start time is about 2.5 hours and the end time is about Is about 3.5 hours, and this time is set as the standard time. Because of the fact that setting around this time is optimal as the pot life of mortar, the setting delay time of the admixture for cement extrusion is about the starting time (standard starting time within ± 1 hour) Time is preferred (standard termination time ± 1 hour or less).
The setting delay time of the cement extrusion admixture is more preferably about the initial time (within standard start time ± 50 minutes) and with respect to the end time (within standard end time ± 50 minutes), more preferably with respect to the initial time ( Standard start time within ± 40 minutes) and end time (within standard end time ± 40 minutes), particularly preferably for start time (within standard start time ± 30 minutes) and for end time (standard end time ± 30 minutes) Within).

If the setting delay time of the admixture for cement extrusion is later than the initial start time (standard start time + 1 hour) or the end time is later than (standard end time + 1 hour), excessive setting delay will be manifested. This may cause a problem of reduced strength of the molded product. On the other hand, if the setting delay time of the admixture for cement extrusion is earlier than the end time (standard start time -1 hour) or the end time is earlier than (standard end time -1 hour), the setting is very quick. It is thought to have occurred and the pot life is shortened, making it difficult to handle mortar and molded products.
In addition to the cellulose-based binder and starch ether described above and the nonionic surfactant to be blended as necessary, the following components may be blended in the admixture for cement extrusion.
Admixture for cement extrusion mixes cellulose-based binder and starch ether, nonionic surfactants and other components described below, for example, using a Nauta mixer mixer, Henschel mixer mixer, ribbon mixer mixer, etc. Can be obtained.

[Cement extrusion mixture and its production]
The cement extrusion molding mixture of the present invention is a mixture containing an inorganic material essential for cement and fine aggregate and the cement extrusion molding admixture described above, and the blending ratio of the cement extrusion molding admixture. Is a mixture of 0.5 to 3 parts by weight with respect to 100 parts by weight of the inorganic material.
Examples of the cement include ordinary Portland cement, blast furnace cement, early-strength cement, fly ash cement, alumina cement, and the like, and one or more kinds may be used in combination.

In the present invention, the inorganic material requires a fine aggregate. The fine aggregate is an inorganic aggregate composed of 85% by weight or more passing through a 10 mm opening sieve and passing through a 5 mm opening sieve. Inorganic aggregates exceeding 85% by weight that do not pass through a 5 mm aperture sieve may not be suitable as a cement extrusion. Examples of the inorganic aggregate include silica sand, silica stone powder, blast furnace slag, silica fume, fly ash, kaolin fired product, limestone powder, and the like, and one or more kinds may be used in combination.
The inorganic material may contain a coarse aggregate that is coarser than the fine aggregate, but it is preferable not to include the coarse aggregate because the surface property of the extruded product is improved. Here, the coarse aggregate means an inorganic aggregate that does not pass through a 5 mm mesh and exceeds 85% by weight.

The weight ratio of the coarse aggregate and the fine aggregate in the inorganic material (coarse aggregate / fine aggregate) is not particularly limited, but is preferably 0.1 or less, more preferably 0.08 or less, particularly preferably. 0.07 or less, most preferably 0.06 or less. When the coarse aggregate / fine aggregate is more than 0.1, the surface property of the extruded product may be deteriorated.
In the inorganic material, the optimum blending according to the application should be carried out. The weight ratio of the cement and the inorganic aggregate contained in the inorganic material (cement / inorganic aggregate) is preferably 80/20 to 30/70, More preferably, it is 75 / 25-35 / 65, Most preferably, it is 70 / 30-40 / 60. If the cement / inorganic aggregate exceeds 80/20, the dimensional change before and after hydraulic hardening becomes too large, which is inappropriate. On the other hand, if the cement / inorganic aggregate is smaller than 30/70, a problem occurs in the strength after curing of the resulting cement extruded product.

The compounding amount of the cement extrusion admixture contained in the cement extrusion mixture is usually 0.5 to 3 parts by weight, preferably 0.6 to 2.8 parts by weight, based on 100 parts by weight of the inorganic material. Preferably it is 0.7-2.5 weight part. When the blending amount of the admixture for cement extrusion is less than 0.5 parts by weight, when the mortar obtained from the mixture for cement extrusion is extruded to produce a cement extrusion, the extrusion pressure is high and the extrusion speed is high. Occurrence of unstable phenomenon, that is, extrudability is deteriorated, and the surface condition and discharge state of the resulting cement extrusion molding are irregular, and the problem that the dimensional accuracy is low, that is, the quality is lowered, etc. There are things to do. On the other hand, when the blending amount of the admixture for cement extrusion exceeds 3 parts by weight, the performance improvement corresponding to the blending amount is not seen. Rather, the mortar obtained from the mixture for cement extrusion molding is extruded to cement extrusion molding. When manufacturing a product, the mortar hardness is low, the extrusion speed becomes unstable, the extrudability is lowered, the design property of the edge part is lowered, and the quality due to undulation may be lowered. . Moreover, the setting delay effect by the starch ether in an admixture generate | occur | produces, and the fall of the quality by defective hardening may generate | occur | produce.
The cement extrusion molding mixture is obtained by mixing a cement extrusion molding admixture and an inorganic material using, for example, a Nauta mixer mixer, a Henschel mixer mixer, a ribbon mixer mixer, or the like.

The cement extrusion mixture may further comprise water. Below, the mixture for cement extrusion molding containing water may be called mortar. When the cement extrusion mixture contains water, the blending ratio is preferably 18 to 100 parts by weight of the inorganic material because the cement is hydraulic and the mortar can be adjusted to a hardness suitable for extrusion. 28 parts by weight, more preferably 18.5 to 27.5 parts by weight, still more preferably 19 to 27 parts by weight, and particularly preferably 19.5 to 26.5 parts by weight. When the blending ratio of water is less than 17 parts by weight, the mortar becomes incoherent and extrusion molding may be difficult. On the other hand, when the mixing ratio of water exceeds 28 parts by weight, the hardness of the mortar is extremely low and extrusion molding becomes difficult, and the strength of the extrusion-molded plate may be lowered.
The mortar is obtained, for example, by dry-dispersing a cement extrusion molding mixture in a mixer, adding a predetermined amount of water while dry-dispersing, and kneading with a kneader or the like as necessary. As the mixer used for the production of mortar, a mixer having a liquid addition mechanism is preferable. For example, a mixer having two functions of floating diffusion mixing by main blades and high-speed shear dispersion by chopper blades; A Ladige mixer, a diffusion kneading mixer; an omni mixer, a reverse flow high-speed mixer, an Eirich mixer, and the like are preferable.

[Cement Extrusion and its Production]
The cement extrusion molding of the present invention is a molding formed by extruding a cement extrusion molding mixture (mortar) containing water. The cement extruded product is preferably a molded product obtained by vacuum extrusion molding of mortar.
The cement extrusion is obtained by extruding mortar, but if the extrusion performed here is vacuum extrusion, bubbles in the extrusion are reduced, and the appearance and dimensional stability are improved. Further, it is preferable because spring back and the like when the extruded product is discharged from the mold can be prevented.

As a molding machine (vacuum extrusion molding machine) used for vacuum extrusion molding, for example, a screw extruder for a cement or a ceramic, a plunger extruder, and the like can be given. As a commercially available molding machine, for example, a vacuum extrusion molding machine for cement (manufactured by Ishikawa Tokiko Co., Ltd.), a kneading-vacuum extrusion molding machine (manufactured by Miyazaki Tekko Co., Ltd.), a vacuum extrusion molding machine (Honda Honda) Manufactured). In particular, the kneading-vacuum extrusion molding machine has a series of steps from preparation of a mixture for cement extrusion molding to extrusion molding, where the above-mentioned mixer and the portion having the functions of the kneading machine are connected to the extrusion molding machine. Equipment.
Cement extrusion molding is performed as follows, for example. 1) The mortar is pre-kneaded in a pug mill / pug screw part of a vacuum extrusion molding machine, and then the mortar is sent to a vacuum deaeration chamber to remove bubbles taken in the mortar. 2) The mortar is further dropped into the barrel, sent to a die attached to the end of the barrel by a screw or a plunger, and passed through the die to obtain cement extrusions having various cross-sectional shapes.

Cement extrusion molding can be performed with reference to “extrusion changes cement-based materials” (Moriko, Baba Akio; Cement Concrete, No. 598, p.9-20, issued in December 1996). it can.
Examples of important extrusion conditions in this vacuum extrusion include extrusion pressure and extrusion speed. If the extrusion pressure is too high, the load on the machine may increase and the life of the mold, screw, barrel, etc. may be shortened. It may also be a problem with increasing power consumption. Therefore, generally a low extrusion pressure is desired.

Moreover, since extrusion speed is directly related to productivity, it is generally better to be faster. When the extrusion speed is slow, poor extrusion of the barrel wall and mortar of the extruder often leads to a decrease in extrusion speed, process instability due to slow speed, increase in extrusion pressure, etc. The quality may also be degraded.
The resulting cement extruded product is dried and cured, and is subjected to curing, steam curing, cutting, finishing, etc. using an autoclave as necessary. Widely used for materials.

[Other ingredients]
In the cement extrusion molding admixture and cement extrusion molding mixture described above, other components described below can be blended within a range that does not have a significant adverse effect on the effects obtained by the present invention. It should be noted that the extrusion admixture is solid and preferably in powder form, and other components that prevent such a state from being formed should not be added to the extrusion admixture. It is desirable to blend in the mixture for use.

(Ingredients that can be incorporated into cement extrusion admixture or cement extrusion mixture)
As materials that are used to improve the strength of cement-extruded products and have no influence on safety and health, inorganic materials such as glass fibers; fibrous materials such as organic fibers such as pulp, vinylon fibers, and polypropylene fibers can be blended. The inorganic fiber is preferably one that does not contain asbestos.
For lightweighting, inorganic lightweight aggregates such as perlite; organic foaming agents such as polystyrene-based organic foaming agents, fly ash, and organic hollow microspheres can be blended.

As a setting time adjusting agent, silicofluoride such as magnesium silicofluoride; boric acids such as boric acid; oxycarboxylic acids such as gluconic acid, glucoheptonic acid, citric acid and tartaric acid and salts thereof; lignin sulfonic acid, humic acid, tannic acid, etc. A high-molecular-weight organic acid and a set retarder such as a salt thereof can be blended.
As a setting time adjusting agent, chlorides such as calcium chloride, sodium chloride and potassium chloride; thiocyanates such as sodium thiocyanate; nitrites such as calcium nitrite, sodium nitrite and potassium nitrite; calcium nitrate and sodium nitrate Nitrates such as potassium nitrate; sulfates such as calcium sulfate, sodium sulfate and potassium sulfate; carbonates such as calcium carbonate, sodium carbonate and potassium carbonate; coagulation accelerators and rapid setting by inorganic compounds such as sodium silicate (water glass) An agent etc. can be mix | blended.

As setting time adjusting agents, amines such as diethanolamine (DEA) and triethanolamine (TEA); coagulation accelerators and rapid setting agents by organic compounds such as calcium salts of organic acids such as calcium formate and calcium acetate Can be blended.
In order to prevent excessive shrinkage of the extruded plate and the extruded product before and after hydraulic hardening, a shrinkage reducing agent such as polyalkylene glycols such as polypropylene glycol and polypropylene polyethylene glycol, and alkoxy polypropylene glycol acrylates can be blended.

Examples of what can be expected to have a thickening effect and separation reduction effect similar to cellulose binders: polyvinyl alcohol; cellulose water-soluble polymers such as carboxymethyl cellulose; acrylic water-soluble polymers such as polyacrylamide and polyacrylic acid soda; xanthan gum , Biopolymers such as guar gum; emulsion systems such as anionic acrylic resin, EVA (ethylene vinyl acetate emulsion), PAE (polyacrylate emulsion), PVAC (polyvinyl acetate emulsion), VAVeoVa (vinyl acetate vinyl versatate emulsion) Thickeners and separation reducing agents can be blended.
Next, components that are preferably blended into the cement extrusion mixture will be described.

(Ingredients that can be incorporated into cement extrusion molding mixture)
As an antifoaming agent, a polyoxyalkylene antifoaming agent mainly composed of ethylene oxide or propylene oxide, a polypropylene glycol antifoaming agent, a mineral oil antifoaming agent, a modified silicone antifoaming agent, dimethylpolysiloxane, or the like can be blended. .
As a swelling agent, aluminum powder or the like can be blended. Moreover, a rust preventive, a coloring agent, etc. can be mix | blended.

As waterproofing and water repellents, calcium chloride, sodium silicate, siliceous powder, zirconium compounds, fatty acid soaps, fatty acids, fatty acid esters, fatty acid compounds obtained by emulsifying these, silicone oil, silicone emulsion, paraffin, paraffin emulsion Asphalt emulsion, oil-containing waste clay, rubber latex, etc. can be blended.
In order to contribute to fluidization of cement and inorganic materials and improve fluidity and workability, the following ingredients are blended as AE agent, water reducing agent, AE water reducing agent, fluidizing agent, high performance AE water reducing agent, etc. can do.

As an AE agent, an anionic surfactant, a nonionic surfactant, an amphoteric surfactant, etc. can be mix | blended.
As water reducing agent / AE water reducing agent, lignin sulfonate or its derivatives, oxycarboxylate, polyol derivative, polyoxyethylene alkylallyl ether derivative, alkylallylsulfonate formalin condensate, melamine sulfonate formalin condensate Polycarboxylic acid polymer compounds can be blended.

As a fluidizing agent, naphthalene sulfonate formalin condensate, melamine sulfonate formalin condensate, polycarboxylic acid compound, polystyrene sulfonate, and the like can be blended.
As a high-performance AE water reducing agent, a mixture of naphthalene sulfonate formalin condensate and lignin sulfonic acid, a mixture of naphthalene sulfonate formalin condensate and polycarboxylic acid polymer compound, melamine sulfonate formalin condensate and slump loss A mixture of a reducing agent, a polycarboxylic acid compound, a polycarboxylic acid ether compound, an aromatic aminosulfonic acid compound, and the like can be blended as necessary within a range that does not adversely affect the effects of the present invention.

It goes without saying that the cement extrusion molding mixture is mainly composed of an inorganic material essential for cement, and it is preferable to avoid blending components other than the inorganic material essential for cement. Therefore, the weight ratio of the inorganic material essential to cement and the other components (inorganic material essential to cement / other components) is preferably 100/12 to 100 / 0.3.
In the present invention, the admixture for cement extrusion, the mixture for cement extrusion, and the cement extrusion product do not contain any asbestos.

Examples of the present invention will be specifically described below together with comparative examples. The present invention is not limited to these examples.
In Examples and Comparative Examples, a cement extrusion mixture was prepared using a cement extrusion admixture, water was added to produce a mortar, and extrusion was performed to obtain a cement extrusion. Of the mixture for cement extrusion described above, a mixture containing 25 to 26 parts by weight of water is called mortar in the following examples and comparative examples, and a mixture not containing a predetermined amount of water is called a mixture for cement extrusion. To.

[Example 1]
(Admixture for cement extrusion)
The components of the admixture for extrusion shown in Table 1 (total 1.2 parts by weight) were put into a juicer mixer (National MX-X53 type), stirred for 15 seconds at 19000 rpm and mixed well, and then cement extrusion An admixture for use was obtained.
When the viscosity of the obtained 1% by weight aqueous solution of the admixture was measured at 20 ° C. using a B-type viscometer according to JIS K 7117, using a NO4 rotor, 7500 mPa · s at 12 rpm and 6 rpm at 6 rpm. It was 4150 mPa · s at 9600 mPa · s and a rotation speed of 60 rpm. From this result, the viscosity is 7500 mPa · s (NO4, 12 rpm). The TI value is (viscosity at 6 rpm) / (viscosity at 60 rpm) = 9600/4150 = 2.31.
Moreover, the setting delay time measurement (based on "JIS R5201 8. Setting test") of the admixture was carried out, and the suitability as an admixture for extrusion molding was determined.

(Cement extrusion mixture)
The components of the mixture for extrusion molding shown in Table 1 (104.2 parts by weight in total) were put into a Laedige mixer (M20 type, manufactured by Matsubo) and stirred for 5 minutes under stirring conditions of rotation of 100 rpm and chopper of 2400 rpm. Mixing was performed to obtain a cement extrusion mixture.

(mortar)
While stirring the obtained cement extrusion mixture in a Laedige mixer, 26 parts by weight of water is sprayed on the cement extrusion mixture in about 2 to 2.5 minutes, and the water spray starts from the start. The mixture was stirred for 5 minutes under stirring conditions of 100 rpm and chopper 2400 rpm and dissolved to obtain a homogeneous mixture.
The obtained homogeneous mixture was placed in a 10 L double-arm kneader (HBN-10D, manufactured by Honda Seiko Co., Ltd.) and sufficiently kneaded for 3 minutes, and then a mortar that was a clay-like highly viscous substance was prepared. .
When this ball was made of rubber mortar to make a ball-like dumpling, the rubber glove was very dirty but the mortar was very well organized.

(Extrusion molding)
The obtained mortar was extrusion molded using a vacuum extrusion molding machine (DE-50D, manufactured by Honda Seiko Co., Ltd.) to produce a cement molded plate (cement extruded product).
The molding conditions are as follows: the internal temperature of the vacuum extruder is 30 ° C., the degree of vacuum is −0.096 MPa or less, a mold (40 mm × 10 mm) is used, and the room temperature is 25 ° C. and the humidity is 60%. A flat cement extrusion was obtained.
The quality of the resulting cement extrusion (surface condition, discharge condition, dimensional accuracy), extrudability during extrusion (extrusion pressure, extrusion speed, standard deviation of speed), and contamination status of each equipment after extrusion ( The antifouling property and the hardness of the cement extruded product were evaluated according to the following evaluation criteria, and the results are shown in Table 1. The evaluation was performed at room temperature of 25 ° C. and humidity of 60%.

[Examples 2 to 10]
In Example 1, except that the type and amount of the admixture were changed to those shown in Table 1, mixing was performed in the same manner as in Example 1 to obtain cement extrusion molding mixtures, respectively.
From the obtained cement extrusion molding mixture, mortars were respectively prepared in the same manner as in Example 1, extruded to produce cement extrusion moldings, evaluated in the same manner as in Example 1, and the results are shown in Table 1. It was shown in 1.

[Comparative Examples 1-9]
In Example 1, except that the type and amount of the admixture were changed to those shown in Table 1, mixing was performed in the same manner as in Example 1 to obtain cement extrusion molding mixtures, respectively.
From the obtained cement extrusion molding mixture, mortars were respectively prepared in the same manner as in Example 1, extruded to produce cement extrusion moldings, evaluated in the same manner as in Example 1, and the results are shown in Table 1. It was shown in 1.

A conventional standard extrusion example was set as Comparative Example 1.
In Comparative Example 1, both the quality and the extrudability are reasonable, but the antifouling property is inferior. When a mortar prepared with a 10-liter double-arm kneader (HBN-10D, manufactured by Honda Seiko Co., Ltd.) was used to create a ball-like dumpling with rubber gloves, this cement extrusion molding mixture was used as a mortar. The rubber gloves were very dirty.

[Quality of cement extrusions]
(Surface condition)
The cement extrusion molded product extruded from the mold at the time of cement extrusion molding was visually observed, and the surface condition was evaluated according to the following evaluation criteria.
○: The surface of the cement extruded product is smooth and good.
Δ: Some unevenness is observed on the surface of the cement extrusion.
X: Concavities and convexities are observed on the surface of the cement extrusion, or cracks are observed in the cement extrusion.

(Discharge state)
The cement extrusion molded product extruded from the mold at the time of cement extrusion molding was visually observed, and the discharge state was evaluated according to the following evaluation criteria.
○: Cement extrudate is extruded straight and stably.
(Triangle | delta): A slight change is seen when a cement extrusion molding is extruded.
X: Changes such as meandering, waving, blistering, etc. are observed when a cement extruded product is extruded, and it is not extruded straight and stably.

(Dimensional accuracy)
The dimension of the cement extrusion molded product extruded from the mold at the time of cement extrusion molding was measured and compared with the mold dimension to evaluate the dimensional accuracy according to the following evaluation criteria.
○: Both the width and thickness error of the cement extrusion product are 0.2 mm or less. Δ: Both the width and thickness error of the cement extrusion product are 0.2 mm or more and 0.3 mm or less. Both errors are 0.3mm or more

[Extrudability during extrusion]
(Extrusion pressure)
At the time of cement extrusion, the average pressure reading indicated by the pressure gauge attached to the vacuum extrusion molding machine is x, and the average pressure reading in Comparative Example 1 considered as a standard extrusion example is y. x / y) × 100 was calculated as the extrusion pressure. Then, the extrusion pressure was evaluated according to the following evaluation criteria. Here, the lower the extrusion pressure, the lower the load on the extruder and the better the extrudability.
×: 115 or more Δ: 105 or more and less than 115 ○: 95 or more and less than 105 ◎: less than 95

(Extrusion speed)
The value obtained by measuring the flow rate of the cement extruded product when extruded from a vacuum extruder during cement extrusion is a, and the speed reading in the case of Comparative Example 1 considered as a standard extrusion example is b. (A / b) × 100 was calculated as the extrusion speed. Then, the extrusion speed was evaluated according to the following evaluation criteria. Here, the higher the extrusion speed, the higher the productivity and the better the extrudability.
◎: 105 or more ○: 95 or more and less than 105 Δ: 85 or more and less than 95 ×: less than 85

(Standard deviation of speed)
The standard deviation of the flow rate of the cement extruded product when it is extruded from the vacuum extruder at the time of cement extrusion is A, and the standard deviation of the velocity in the case of Comparative Example 1 considered as a standard extrusion example is B. , (A / B) × 100 was calculated as the standard deviation of speed. Then, the standard deviation of speed was evaluated according to the following evaluation criteria. Here, the smaller the standard deviation of the speed, the more uniform the finished state of the mortar and the better the extrudability.
×: 150 or more Δ: 125 or more and less than 150 ○: 75 or more and less than 125 ◎: less than 75

[Contamination status of each equipment after extrusion]
(Anti-fouling property)
Mortar residue in the machine after adjusting and discharging about 5.2 kg of mortar (containing 2 kg each of cement and quartzite powder, total mass of materials used) was collected, and antifouling property was evaluated by% residual mortar.
Mortar made with a Ladige mixer (M20 type, made by Matsubo), discharged, wings removed, mortar residue mass remaining in the machine: r grams

Mortar residue mass after mortar kneading with 10L double arm kneader (HBN-10D, manufactured by Honda Seiko Co., Ltd.) and mortar discharged: s grams Vacuum extrusion molding machine (DE-50D, manufactured by Honda Seiko Co., Ltd.) After the extrusion molding is finished, discharge from the mold until no discharge is seen, remove the pug screw, auger screw, etc., and the mortar residue mass remaining between the shredder and the vacuum deaeration chamber: t grams

Total mortar residual mass (TR) = (r + s + t) gram Mortar residual amount% = (total mortar residual mass) / (total mass of material used) × 100 was evaluated for antifouling property according to the following evaluation criteria.
○: 3% or less (passed, judged to have good antifouling property)
Δ: Over 3% to 5% or less (slightly poor)
×: Over 5% (defect)

[Applicability to cement materials as admixture]
(Setting delay)
7. Add JIS R5201 to each cement so that each admixture is 0.5% by weight. Based on the setting test, the setting delay time at 50 ° C. was measured.
Using the initial time (about 2.5 hours) and the end time (about 3.5 hours) of the admixture of Comparative Example 1 (Marporose ME-350T), which is considered as a standard, as the standard time, the setting delay was determined according to the following evaluation criteria Evaluation was performed.
○: Standard start time within ± 1 hour and end time within ± 1 hour (pass)
Δ: Standard start time ± 1 hour to 2 hours or less, and standard end time ± 1 hour to 2 hours or less (slightly poor)
X: Standard start time ± 2 hours and standard end time ± 2 hours (defect)
For the setting delay Δ, it is essential to add a setting accelerator, and a reduction in quality is inevitable. In addition, when the setting delay is x, the hydraulic property is likely to be inhibited, so the blending of the admixture must be reconsidered. When the setting delay is x, it is considered unsuitable for hydraulic materials such as cement.

[Hardness of cement extrusions]
The hardness of the cement extrusion molded product extruded from the mold during cement extrusion molding was measured with a clay hardness meter (manufactured by Nippon Isogo), and the hardness was evaluated according to the following evaluation criteria. Here, “hard” generally indicates that the extrusion pressure is high. “Soft” indicates that the extrusion pressure is low, but low extrusion pressure is necessary, but if the mortar hardness is “soft”, it will reduce the design of the edge part due to the decrease in shape retention and the dimensional accuracy. Problems may occur. In the case of “suitable”, there are few problems in terms of quality and extrudability.
Hard: 12.5 or more Suitable: 11.5 or more, Less than 12.5 Soft: Less than 11.5

[Comprehensive judgment on quality, extrudability, antifouling property, setting delay, etc.]
Among the three evaluation items of quality, the case where there were two or more ◯ and there was no x was determined as pass (go), and the others were determined as fail (fail).
Among the three evaluation items of extrudability, a case where ま た は and / or ○ was 2 or more and there was no x was judged as pass (go), and the others were judged as fail (fail).

Among the evaluation items of antifouling property, ○ was accepted (go), and the others were rejected (failed).
In addition, among the evaluations for setting delay, ○ was accepted (go), and the others were rejected (failed).

Anything that fails the setting delay is considered to be essentially unsuitable for hydraulic materials.
From these determination results, the admixture for cement extrusion and the mixture for cement extrusion according to the present application all pass (go).

Claims (10)

An admixture comprising a cellulosic binder and starch ether,
The weight ratio of the cellulose binder in the total amount of the cellulose binder and starch ether is 85 to 95% by weight,
The 1% by weight aqueous solution of the admixture has a viscosity of 4000-30000 mPa · s (B-type viscometer, measurement temperature 20 ° C.),
The TI value (thixotropic index) of a 1 wt% aqueous solution of the admixture is 2.6 or less,
Admixture for cement extrusion.   The admixture for cement extrusion according to claim 1, further comprising a nonionic surfactant, wherein the blending ratio is 1 to 10 parts by weight with respect to 100 parts by weight of the total of the cellulose binder and starch ether. The admixture for cement extrusion according to claim 2, wherein the nonionic surfactant is a polyalkylene oxide adduct represented by the following general formula (1).
RO-[(PO) _p / (EO) _q ] -H (1)
(However, R is a hydrogen atom, an alkyl group or an alkenyl group having 1 to 30 carbon atoms, and may be composed of a linear or branched structure. PO is an oxypropylene group, and EO is oxyethylene. P and q represent the average number of moles added, respectively, and p = 20 to 100 and q = 5 to 500. [(PO) _p / (EO) _q ] represents p moles of PO and It is a polyoxyalkylene group formed by adding q mol of EO randomly or by block.) The admixture for cement extrusion according to claim 3, wherein the polyalkylene oxide adduct is a block polymer represented by the following general formula (2), and the number average molecular weight is 1400 to 28000.
HO- (EO) _r (PO) _p (EO) _s- H (2)
(However, (EO) _r, (PO) _p and (EO) _s are added by blocks, and p = 20 to 100 and q = r + s = 5 to 500.)   The cellulose binder is at least one selected from the group consisting of alkyl cellulose, hydroxyalkyl cellulose, and hydroxyalkyl alkyl cellulose, and the viscosity of a 1% by weight aqueous solution thereof is 5000 to 40000 mPa · s (B-type viscometer, measurement temperature). The admixture for cement extrusion molding according to any one of claims 1 to 4, which is 20 ° C).   The starch ether is a water-soluble hydroxypropylated starch having a hydroxylpropyl group substitution degree of 0.1 to 15%, and the viscosity of a 1% by weight aqueous solution thereof is 5 to 100 mPa · s (Heppler viscometer, measuring temperature 20 ° C) The admixture for cement extrusion molding according to any one of claims 1 to 5.   The admixture for cement extrusion according to any one of claims 1 to 6, wherein the cellulosic binder is hydroxyethyl methylcellulose. A mixture comprising an inorganic material essentially comprising cement and fine aggregate, and an admixture for cement extrusion according to any one of claims 1 to 7,
The blending ratio of the admixture for cement extrusion is 0.5 to 3 parts by weight with respect to 100 parts by weight of the inorganic material.
Cement extrusion mixture.   The mixture for cement extrusion molding according to claim 8, further comprising water and having a blending ratio of 18 to 28 parts by weight with respect to 100 parts by weight of the inorganic material. A method for producing a cement-extruded product obtained by extruding and solidifying the cement-extruded mixture according to claim 9.