KR102376889B1 - Cement composition for extrusion molding - Google Patents

Abstract

The present invention relates to a cement composition for extrusion molding, and to a cement composition obtained by enhancing adhesion and reducing adhesive force such that the shape preservation that is necessary to produce an extrusion molded product among secondary cement products can be enhanced. More specifically, the present invention relates to a cement composition which comprises: a thixotropic agent such as bentonite and attapulgite; a thickener, and a water reducing agent for strength enhancement. Accordingly, when an extrusion-molded product is being produced by using cement, the shape of a produced product is not deformed, no damage occurs during transport between processes for curing, and the occurrence of defective filling in an edge of a product does not occur. The cement composition for extrusion molding, according to the present invention, comprises 0.01-3.0 parts by weight of a viscosity controlling agent, 0.01-10 parts by weight of a thixotropic agent, 0.01-3 parts by weight of a water reducing agent for strength enhancement, and 0.01-5 parts by weight of a retardant with respect to 100 parts by weight of a binder including ordinary Portland cement.

Description

Cement composition for extrusion molding

The present invention relates to a cement composition for extrusion molding that improves the preservation of a shape required for the production of an extrusion-molded product among secondary products using the cement composition by increasing the adhesiveness and reducing the adhesive force, and more particularly, a thixotropic agent; By further including a thickener and a water reducing agent for strength improvement, the shape of the product is not deformed when an extrusion-molded product is produced using cement, and there is no damage during transport between processes for curing, and poor filling in the corners of the product. It relates to a cement composition for extrusion molding that can be made not to occur.

Cement extrusion products refer to products made by mixing cement, cement, or aggregate with water and passing it through a certain frame by means of an extruder in a very strong state.

At this time, the cement is generally used in the form of a paste by reducing the amount of water used, but when used, a change in workability due to the cement reaction occurs greatly, so that it is hardened in a mixer, pipe, etc. or is not extruded by an excessive load in the extruder. It happens very frequently.

Among these secondary cement products, an appropriate viscosity is required for the production of secondary extruded products using the extrusion process. This is because when the cement dough does not have the same appropriate viscosity, it is in the part where friction occurs with the mold passing through the extrusion molding of the product. A smooth surface may not be obtained or partial scratches may occur, so the viscosity and slipperiness of this cement paste are very important factors.

As prior art related thereto, Korean Patent Laid-Open No. 10-2009-0080333, etc. exist, and the document No. 10-2009-0080333 (extrusion molding cement mortar additive, cement mortar for extrusion molding containing the additive, and In the method of manufacturing cement mortar for extrusion molding using the additive), 10 to 60 wt% of hydroxyethyl cellulose is added to hydroxyethylmethyl cellulose (HEMC) and hydroxypropylmethyl cellulose (HPMC), and an antifoaming agent is optionally added. Thus, the green density of cement panels for extrusion molding is improved.

However, the above literature does not provide an in-depth solution to the problems caused by dehydration and material separation in a high-temperature environment due to long-term residence of the mortar in the extruder for actual specification change. In addition, the cement panel for extrusion molding is basically produced by removing the air inside the mortar through a vacuum extrusion process during extrusion.

Therefore, there is an urgent need for a cement composition for extrusion molding that does not deform the shape of the product when producing an extruded product, does not cause damage during transport between processes for curing, and does not cause filling defects in the corners of the product.

The present invention was devised to solve the above problems, and since it is possible to maintain the viscosity and slippery of the dough at the same time, it can be produced easily compared to conventional cement when manufacturing secondary cement products by extrusion, and works by heat generated during manufacturing An object of the present invention is to provide a cement composition for extrusion molding that can reduce the energy required for the process and the production time because the property is not deteriorated.

In addition, when producing extruded products, the shape of the products produced is not deformed, there is no damage during transport between processes for curing, and the provision of cement compositions for extrusion molding that can prevent filling defects in the corners of products. The purpose.

Another object of the present invention is to provide a cement composition for extrusion molding that can smoothly manufacture cement milk, cement mortar, concrete, etc. without any additives by reducing the stress generated in the secondary extrusion product.

Cement composition for extrusion molding according to the present invention for the purpose of solving the above problems, relative to 100 parts by weight of a binder containing portland cement, and 0.01 to 3.0 parts by weight of a viscosity modifier, and 0.01 to 10 parts by weight of a thixotropic agent, and 0.01 to 3 parts by weight of a water reducing agent for strength enhancement, and 0.01 to 5 parts by weight of a retarder.

In addition, the viscosity modifier includes at least one of methyl cellulose, hydroxypropyl ethyl cellulose, hydroxypropyl methyl cellulose, starch, polyvinyl alcohol (PVA), and xanthan gum.

The thixotropic agent also includes bentonite, attapulgite, or both.

In addition, the water reducing agent includes at least one of lignin-based, naphthalene-based, polycarboxylic acid-based and acrylic-based.

The present invention having the above configuration and features can maintain the viscosity and slippery of the dough at the same time, so that it can be easily produced compared to conventional cement when manufacturing secondary cement products by extrusion, and workability is not reduced by heat generated during manufacturing. It has the advantage of being able to shorten the energy required for the process and the production time.

In addition, there is an advantage that the shape of the product is not deformed when producing an extruded product, there is no damage during transport between processes for curing, and no filling defects occur in the corners of the product.

In addition, it has the advantage of being able to smoothly manufacture cement milk, cement mortar, concrete, etc. without any additives by reducing the stress generated in the secondary extrusion product.

A drawing showing the input hopper used in the cement paste input step.

Since the present invention can have various changes and can have various forms, implementation examples (態樣, aspects) (or embodiments) will be described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

The terminology used herein is only used to describe a specific embodiment (aspect, aspect, aspect) (or embodiment), and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as comprises or consists of are intended to designate that the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification exist, but one or more other features It is to be understood that it does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

~1~, ~2~, etc. described in the present specification are only to be referred to to distinguish that they are different components, and are not limited to the order of manufacture, and their names in the detailed description and claims of the invention are may not match.

The present invention relates to a cement composition for extrusion molding, which can improve the shape retention of an extruded product using the above-described cement composition by increasing the adhesiveness and reducing the adhesive force as a cement composition for extrusion molding.

Here, the extrusion-molded product using the cement composition refers to a product made by mixing cement or cement, aggregate, and water and passing a material in a very strong state through an extruder through a constant frame.

First, 100 parts by weight of the binder is included, and components to be described later are described based on 100 parts by weight of the binder. The binder may be, for example, ordinary Portland cement (Ordinary Portland Cement: OPC).

And as another embodiment of the binder, a predetermined amount of the normal Portland cement may be replaced with another composition. The above-mentioned other composition corresponds to fine slag powder, fly ash, CSA (Calium Sulfoaluminate), and anhydrite.

First, the slag may be used up to 40% by weight based on the total weight of the binder, and when it exceeds 40% by weight, it is preferable to increase the fineness of the slag fine powder and use it, and the fineness of the fine slag powder is 3,000 ~8,000 g/cm ³ is preferred.

And, when the fineness is less than 3,000 g/cm ³ , it is difficult to secure initial strength and the curing rate is lowered. And when it exceeds 8,000 g/cm ³ , the active reaction becomes excessively high, which may adversely affect physical properties and is not economical. A more preferable fineness is 4,000 to 8,000 g/cm ³ .

In addition, the fine slag powder is generated during the iron making process in a blast furnace and may contain ions such as Ca, Si, and Al. Preferably, it may be water-based slag formed in an amorphous granular state of less than 5 mm by spraying and quenching the slag in a high-temperature molten state, but is not limited thereto.

Next, looking at fly ash, replacement of a predetermined amount with fly ash is not preferable because an initial strength decrease usually occurs, but it can be used at 20% by weight or less of the total weight of the binder in summer. And, all types of fly ash can be used, but in particular, types 1 and 2 are preferable, and in the case of types 3 and 4, it is necessary to check whether the strength can be secured through testing and use.

Next, looking at CSA (Calium Sulfoaluminate), CSA can be used for the purpose of preventing cracks, and the amount that can be replaced is preferably 1 to 12% by weight based on the total weight of the binder, and for the purpose of increasing the curing rate As a result, it can be used in less than 1 wt%, but the effect is insignificant and crack suppression cannot be realized. And when used in excess of 12% by weight, there is a disadvantage that there is no economic feasibility. A more preferable amount is 5 to 10% by weight, and in particular, when 5% by weight is used, there is an advantage that an excellent curing rate can be obtained while achieving the purpose of preventing cracks.

Next, in the case of anhydrite, the hardening properties of the cement composition according to the present invention can be improved, but it can have a bad effect on the expansion, so it is preferable to check the expansion amount by experiment. And the amount of the anhydrite used is preferably within 7% by weight based on the total weight of the binder.

And when used in excess of 7% by weight, if the hardening body is continuously submerged in water, it may expand and collapse, so it should be used with caution.

Then, a thickener may be used to control the viscosity and secure viscoelasticity. As an example of the thickener, at least one or more of cellulose such as methyl cellulose, hydroxypropyl ethyl cellulose, and hydroxypropyl methyl cellulose, starch, polyvinyl alcohol (PVA), and xanthan gum may be used.

And in particular, PVA fiber used as PVA is brittle, causing sudden fracture under tensile and dynamic loads, and mechanically, such as increasing tensile resistance and inhibiting local crack formation and growth in areas where it is difficult to suppress crack formation and growth. A fiber-reinforced cement composition is prepared by dispersing a discontinuous and monophasic fibrous material in the cement composition to improve and reinforce properties.

In addition, PVA-based fibers show very high resistance to solvents, oils, salts, and alkalis containing carbon, and have excellent resistance even when exposed to direct sunlight.

In particular, hydrophilic PVA-based fibers have a hydrophilic structure with hydroxyl groups on the fiber surface, so they are well dispersed and have high adhesion performance. They have a relatively small diameter to suppress and stabilize microcracks, and increase mechanical properties through crosslinking of fibers. It is very effective in preventing cracks caused by fatigue and impact loads, and it is not exposed to the surface, so the finish is very good.

In addition, 0.01 to 3.0 parts by weight of the thickener may be used based on 100 parts by weight of the binder. When used in an amount of less than 0.01 parts by weight, there is a disadvantage in that the securing of viscosity or the lubricity of the dough is insufficient, and exceeding 3.0 parts by weight In the case of using it, there is a disadvantage that hardening of the cement composition is not performed well. More preferably, the amount used is 0.05 to 2.0 parts by weight.

And the viscosity of the thickener may be used that corresponds to 3,000 ~ 100,000 cPs.

Next, looking at the thixotropic agent, first, thixotrophy refers to the property that the suspension has no fluidity in a stationary state but has fluidity when vibrated.

That is, the thixotropic agent exhibits high viscosity in the absence of stress, and the viscosity decreases rapidly in the stress state, and the viscosity increases reversibly when the stress is removed again. There is little change.

In addition, the thixotropic agent is to facilitate the flowability of moisture to match the flowability, and it does not form a barrier film on the surface of moisture while catching a large amount of moisture, so that moisture retention is maintained while moisture movement is easy. Crack resistance due to separation has a great effect.

Such a thixotropic agent includes at least one or more of attapulgite, bentonite, and silica. In particular, attapulgite does not form a moisture barrier film, so the effect of facilitating the movement of moisture is very large, and therefore the cement composition according to the present invention Since there is no difference in the drying speed between the surface and the inside of the cured body formed by the , cracking phenomenon is remarkably reduced.

In addition, the attapulgite does not undergo volume deformation even when absorbed, so that a stable hardened body can be made. It can also be equipped with a function of absorbing/removing various heavy metals in concrete.

In addition, 0.01 to 10 parts by weight of the thixotropic agent may be used based on 100 parts by weight of the binder, and when less than 0.01 parts by weight is used, it is difficult to secure thixotropy, so sagging may occur after manufacturing, and use in excess of 10 parts by weight In this case, a rough surface can be obtained during molding. More preferably, the amount used is 0.03 to 5.0 parts by weight.

Next, as a water reducing agent for strength enhancement, lignin-based, naphthalene-based, polycarboxylic acid-based, acrylic-based, and the like may be used.

And in the case of such a high-performance water reducing agent, 0.01 to 3 parts by weight may be used based on 100 parts by weight of the binder. And when it is used in less than 0.01 parts by weight, there is a difficulty in securing strength (compressive strength and bending strength decrease) due to an increase in the amount of water used. This could be bad. More preferably, the amount used is 0.02 to 2.0 parts by weight.

Next, in order to maintain workability, a composition in which citric acid, tartaric acid, and the like are mixed with saccharides may be used as a series of cement reaction retardants. And 0.01 to 5 parts by weight of the retarder may be used based on 100 parts by weight of the binder.

And when the retarder is used in less than 0.01 parts by weight, it is difficult to maintain workability, so the pot life after mixing can be shortened, which causes difficulties in use, and when used in excess of 2.0 parts by weight, the curing time may be too long. It can be difficult to secure economic feasibility.

Tables 1 and 2 below are tables for showing the physical properties of the concrete composition, and the content of the composition in Table 1 is described in parts by weight.

In addition, the slipperiness and viscosity of the cement dough can be viewed as opposite characteristics, but when a thickener, a thixotropic agent, and a water reducing agent are properly mixed with cement, it is possible to obtain workability suitable for extruded products by controlling the slippage and viscosity. found.

The shape of the dough could not be calculated by the flow value, slump, or slump flow value, which are the existing workability standards. As a method to check workability, the workability check method using the existing flow table is used. However, when the deformed form from the initial form is broken or occurs in the form of cracks, abnormalities may occur in the process. In this case, a cement composition for secondary products using extrusion was invented by manufacturing cement to which it was applied by confirming that there was no process abnormality.

In addition, since the compression process takes a lot of time, sufficient workability must be maintained. Accordingly, the pot life should be increased by about several times that of conventional cement. .

First, looking at the flow value, after 20 blows were applied for 30 seconds by filling the mold of the table specified in KS L 5111 with the material of Table 1, the shape was observed. As a result, in Comparative Examples 1 and 2, crumbling occurred as in the photo. If you make a product that is extruded and molded, it may not be filled or may be damaged.

On the other hand, in the case of the embodiment, it has a relatively stable shape and does not cause damage in shape or shape even after hitting, so it can maintain the extrusion shape as it is, and maintain a smooth surface. There is this.

Compressive strength was also measured to be higher at 3, 7, and 28 days than in the comparative example, and the strength characteristics were also evaluated to be excellent.

And in the case of economic feasibility or lack of manufacturing equipment, a certain amount of the composition excluding the binder may be added in the composition to be used in the form of an additive, and the same result may be obtained.

On the other hand, for the production of secondary cement products, it is necessary to first form and input a uniformly mixed cement dough using a cement composition. In addition, there was a problem in that the remaining cement dough remained in the cement paste input machine, causing a residual failure of the dough input machine.

The present invention includes a cement paste input step of forming a uniformly mixed cement dough using the cement composition for extrusion molding according to the present invention and then putting it into an extruder, wherein the cement dough input step is performed by the input hopper (2) However, the input hopper 2 includes a mixing chamber 20 having a mixing space and a mixing unit 24 provided in the mixing chamber 20, and the mixing unit 24 has a center of rotation. It includes a mixing rod 241 disposed along the mixing blade 242 spirally formed on the outer surface of the mixing rod 241. (Of course, the mixing unit 24 is rotated by a motor.)

And, as shown in Figure 1, the input hopper (2) has an open top and includes a cement dough inlet into which cement dough can be put, and the input hopper (2) is the inner surface of the input hopper (2). It includes a stepped portion 21 formed along the.

As shown in FIG. 1 , the stepped portion 21 is provided above the mixing unit 24 , and the inner surface of the input hopper 2 has a different inclination with respect to the stepped portion 21 . The lower slope 23 provided at the lower portion with respect to the stepped portion 21 is formed more gently than the upper slope 22 provided at the upper portion.

And as shown in FIG. 1 , the cement dough inlet may be divided into four widths, where the width means a direction perpendicular to the mixing rod 241 of the cylindrical mixing unit 24 .

First, as shown in FIG. 1 , based on the second mixing unit 24 provided in the center, the first mixing unit 24 provided on one side, and the third mixing unit 24 provided on the other side. can be seen, is formed in the first width W1 between the first mixing unit 24 and one stepped portion 21a disposed on one side of the first mixing unit 24. (Here, one side When referring to FIG. 1, it refers to the left side.)

A second width W2 is formed between the first mixing unit 24 and the second mixing unit 24, and a third width W2 is formed between the second mixing unit 24 and the third mixing unit 24. W3) is formed, and a fourth width W4 is formed between the third mixing unit 24 and the other stepped portion 21b disposed on the other side of the third mixing unit 24. (Here The other side refers to the right side with reference to FIG. 1 ).

And, as shown in FIG. 1 , the second width W2 and the third width W3 are the same, and the first width W1 and the fourth width W4 are the same.

However, the first width (W1) and the fourth width (W4) form a wider width than the second width (W2) and the third width (W3), the cement dough is inputted in an excessively large amount toward the cement dough inlet. When done, it has the effect of making the cement dough spread widely in the width direction. And when the cement paste is spread out in the width direction, it can accommodate a larger amount of cement paste and balance the amount of cement paste entering the cement paste inlet side and the amount of cement paste flowing out to the cement paste outlet side. It will have the effect of preventing equipment failure in advance and providing continuity of cement paste input.

And as described above, based on the stepped portion 21, the lower slope 23 provided in the lower portion is formed more gently than the upper slope 22 provided in the upper portion, whereby the first width When the cement dough is put in (W1) and the fourth width (W4) part, the force in the depth direction of the cement dough can be greater by the upper slope 22, and by the lower slope 23 can be applied with a larger force in the width direction, which has the effect that the cement dough can be mixed evenly. (The depth direction here refers to the direction in which the inclination is formed.)

The reason this is important is that when the cement dough is supplied in the second width W2 and the third width W3, by the first mixing unit 24, the second mixing unit 24 and the third mixing unit 24 While the cement dough can be evenly mixed, in the case of the first width W1 and the fourth width W4, unlike the second width W2 and the third width W3, one side of the first width W1 And the other side of the fourth width (W4) is composed of the inner surface of the input hopper (2), it is relatively impossible to mix the cement dough evenly.

However, as described above, when the stepped portion 21 is used as a reference, the slopes of the upper slope 22 and the lower slope 23 are configured differently, so that the above disadvantage can be overcome.

And looking at the mixing blade 242 of the mixing unit 24 in detail, the mixing blade 242 is in contact with the inner surface of the input hopper 2, has a ring shape, and a support member surrounding the mixing rod 241 242a, the base member 242b extending in the height direction of the support member 242a, and the base member 242b extending in the lateral direction, while surrounding the mixing rod 241, the spiral slope It includes the spiral member 242c forming. (here, the height direction refers to the longitudinal direction of the mixing rod 241).

That is, the support member 242a is extended in the shape of a ring at the upper part in the form of a digut character based on the base member 242b, and the spiral member 242c forming a helical inclination is extended at the lower part.

As a result, as shown in FIG. 1 , the portion on the mixing rod 241 where the mixing blade 242 is not provided can be divided into a total of three sections based on any one direction.

Here, any one direction as a reference is, like the first mixing unit 24 or the third mixing unit 24 shown in FIG. 1 , the supporting member 242a and the lateral direction from the base member 242b. Refers to the direction in which the part in which the spiral member 242c is split is visible. When this direction is defined as the reference direction, the opposite direction will be described as the opposite direction to the reference direction.

That is, the direction in which the second mixing unit 24 is viewed is opposite to the reference direction. Here, the initial setting positions of the first mixing unit 24 , the second mixing unit 24 , and the third mixing unit 24 are configured to face different directions. Therefore, when rotating at the same speed (meaning the size of the same angular velocity), each mixing unit 24 always faces different directions, so that the cement dough can be mixed evenly.

And each support member 242a, the base member 242b, and the spiral member 242c provided in each mixing blade 242 of each mixing unit 24 are engaged while the cement dough is mixed, so the cement dough kneading period (2) It becomes possible to minimize the remaining cement paste that is not discharged to the cement paste outlet.

The present invention described above with reference to the accompanying drawings is capable of various modifications and changes by those skilled in the art, and such modifications and changes should be construed as being included in the scope of the present invention.

2: dosing hopper 20: mixing chamber
21: step portion 22: upper slope
23: lower slope 24: mixing unit

Claims (4)

relative to 100 parts by weight of a binder containing usually Portland cement;
0.05 to 2.0 parts by weight of viscosity modifier;
0.03 to 5.0 parts by weight of a thixotropic agent;
0.02 to 2.0 parts by weight of a water reducing agent for strength enhancement; and
0.01 to 5 parts by weight of a retardant;
including,
The binder contains 30% by weight of fine slag powder having a fineness of 4,000 to 8,000g/cm ³ , 10% by weight of fly ash, 5% by weight of CSA (Calium Sulfoaluminate), 6% by weight of anhydrite, based on the total weight of the binder and,
The slag fine powder includes water-based slag formed in an amorphous granular state of less than 5 mm by spraying and quenching the slag in a high-temperature molten state,
The viscosity modifier includes at least one of methyl cellulose, hydroxypropyl ethyl cellulose, hydroxypropyl methyl cellulose, starch, polyvinyl alcohol (PVA) and xanthan gum (Xanthan Gum),
The PVA is a hydrophilic PVA-based fiber is used,
The viscosity modifier is used that corresponds to 3,000 ~ 100,000 cPs,
The thixotropic agent comprises attapulgite,
The water reducing agent includes at least one of lignin-based, naphthalene-based, polycarboxylic acid-based and acrylic-based,
The retardant is a composition in which citric acid or tartaric acid and sugar are mixed,
The cement composition is prepared in the form of a dough by a dough input machine,
The dough input device includes an input hopper,
The input hopper includes a mixing chamber having a mixing space and a mixing unit provided inside the mixing chamber, wherein the mixing unit includes a mixing rod disposed along a center of rotation and a mixing blade spirally formed on the outer surface of the mixing rod. including,
The input hopper includes a cement dough inlet with an open top, and the input hopper includes a stepped portion formed along the inner surface of the input hopper,
The step portion is provided above the mixing unit,
The inner surface of the input hopper has a slope of different inclinations based on the stepped portion, and the lower slope provided in the lower portion based on the stepped portion is formed more gently than the upper slope provided in the upper portion,
The cement dough inlet has a first width between the first mixing unit on one side and one step portion, a second width between the first mixing unit and the central second mixing unit, and the second mixing unit and the third mixing unit. It is partitioned by a third width between
The cement composition for extrusion molding, characterized in that the first width and the fourth width have the same width as the second width and the third width. delete delete delete

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