JP2018123025A - Self-leveling mortar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a self-leveling mortar wherein: even when used for floor material and the like even under a low-temperature work environment, for example 5°C, the self-leveling mortar allows it to be used within 24 hours after the finish of construction work; and in this way, it has a short construction period, and yet ensures moderate construction work time, and sufficiently prevents material separation or cracking.SOLUTION: A self-leveling mortar contains Portland cement 100 pts.mass, a water-reducing agent 0.3-0.9 pts.mass made from a mixture of a polyether water-reducing agent 50-80 mass% and the balance of a polycarboxylic acid water-reducing agent, an expansion material 10-15 pts.mass, a thickener 0.2-0.4 pts.mass, a styrene-butadiene rubber emulsion with calcium nitrite dispersed therein of 32-36 pts.mass and a fine aggregate 150-200 pts.mass.SELECTED DRAWING: None

Description

  The present invention relates to a cement-based self-smooth mortar.

  High flow mortar containing cement as a binding component can easily form a horizontal surface when poured into a floor slab of a building structure, for example, so it can be used for flooring or as a basic leveler for a building. Many. Since the mortar in a high fluid state generally contains a large amount of kneaded water, cracks are likely to occur during material separation and drying processes, making it difficult to obtain high strength and uniform internal properties. As countermeasures, thickeners containing cellulose derivatives, dextrins, polysaccharides, etc. as active ingredients are blended. However, since the viscosity increases, the workability deteriorates due to increased kneading resistance and fluidity, and during kneading. The entrained bubbles are difficult to escape and may remain as surface marks, and it is not easy to use a thickener that can sufficiently suppress material separation. In particular, when the work is performed in a cold region or in a low temperature environment in winter, for example, in a low temperature environment of about 5 ° C., the viscosity is considerably increased, so that the workability is deteriorated and the hydration reaction activity of the cement is reduced, and the water content is evaporated. However, since it slows down, hardening after construction slows down and there is a problem that it takes a long construction period.

  In a self-smooth mortar (for example, see Patent Document 1) in which an alumina cement which is a rapid hardening material is blended, there is little curing delay after construction even in a low temperature environment. In addition, since the condensation is completed before the material separation proceeds, the material separation is suppressed, and it is easy to obtain a material having a high initial strength, which is used as a measure for shortening the construction period. However, mortars using alumina cement generally have large shrinkage and increase the possibility of cracking. In addition, it becomes difficult to secure the pot life required for construction work. As a means for securing the pot life, a method using a setting retarder in combination is known. (For example, refer to Patent Document 2.) In this method, the working time increases as the amount of the setting retarder is increased, but since the progress of curing and the initial strength development are considerably slowed in a low temperature environment, the work period is shortened. For example, it is difficult to obtain a good mortar flooring that can be used in about one day after the completion of construction work. For this reason, a mortar that can shorten the work period while securing the pot life necessary for construction work even in a low temperature construction environment without using calcium aluminate-based rapid hardening and fast hardening components such as alumina cement is desired. It is rare.

JP 2009-161360 A JP 2011-195413 A

  In the present invention, even in a low temperature construction environment of about 5 ° C., for example, when it is constructed as a flooring or the like, the construction period that can be used within 24 hours from the end of the construction work is short, and yet an appropriate construction work time can be secured. An object is to provide a self-smooth mortar in which separation and cracking are sufficiently suppressed.

  As a result of investigations for solving the above problems, the present inventor found that a specific amount of a mixed dispersant composed of a polyether-based dispersant and a polycarboxylic acid-based dispersant, an expanding material, and a specific inorganic salt The present invention has been completed because a compound obtained by adding a specific dispersed polymer to a mortar containing at least cement and fine aggregate becomes a self-smooth mortar that can solve the above-mentioned problems as a whole.

That is, the present invention is a self-smooth mortar represented by the following (1) to (6).
(1) Portland cement 100 parts by weight, polyether-based water reducing agent 50-80% by weight and the balance water-reducing agent 0.3-0.9 parts by weight of the remaining polycarboxylic acid-based water reducing agent, expansion material 10-15 parts by weight, Self-smooth mortar containing 0.2 to 0.4 parts by mass of a thickener, 32 to 36 parts by mass of a styrene butadiene rubber emulsion in which calcium nitrite is dispersed, and 150 to 200 parts by mass of fine aggregate.
(2) The self-smooth mortar according to (1), wherein the polyether-based water reducing agent has a carboxyl group.
(3) The self-smooth mortar according to (1) or (2), wherein the styrene-butadiene rubber emulsion in which calcium nitrite is dispersed has a calcium nitrite content of 1 to 5% by mass.
(4) The self-smooth mortar according to any one of (1) to (3), further comprising an antifoaming agent.
(5) The self-smooth mortar according to any one of (1) to (4), further comprising an alkali metal sulfate.
(6) The self-smooth mortar according to any one of (1) to (5), which is used for a flooring material.

  According to the present invention, for example, a material that can secure a working time suitable for a construction work even at a low temperature such as 5 ° C. and can start use within 24 hours after the construction work is finished. A self-smooth mortar that is sufficiently suppressed in occurrence of separation and cracking and good in properties can be obtained.

  The self-smooth mortar of the present invention uses Portland cement as a binder phase forming component. The type of Portland cement is not particularly limited. For example, in addition to various Portland cements such as normal, early strength, very early strength, moderate heat, low heat, sulfate resistance, blast furnace cement and fly ash cement containing the Portland cement, etc. Mixed cement may be used. Two or more types of Portland cement can be used in combination. Preferably, normal portland cement and early-strength Portland cement are preferably used in combination since the simminess during construction becomes good. The mixing ratio of each Portland cement when used in combination is not limited, but it is preferable to use early-strength Portland cement in an amount approximately equal to ordinary Portland cement.

  Further, the self-smooth mortar of the present invention contains a mixed water reducing agent comprising a polyether water reducing agent of 50 to 80% by mass and the remaining polycarboxylic acid water reducing agent. Such a water reducing agent may be a so-called dispersant, high performance water reducing agent, AE water reducing agent, high performance AE water reducing agent or fluidizing agent for mortar concrete. By using the mixed water reducing agent, it is possible to secure both mortar dispersibility in the kneading stage immediately after pouring and mortar dispersibility at the time of pouring, for example, because of the difference in the dispersion action characteristics of both, and thus stable throughout the pot life. Since the dispersion state can be maintained, material separation hardly occurs and fluidity suitable for self-smoothing is maintained. If the content ratio of the polyether-type water reducing agent in the mixed water reducing agent is less than 50%, it is not preferable because the rapid hardening property and initial strength development are low, and if it exceeds 80%, the material is separated immediately from the end of the water injection kneading. This is not preferable because there is a risk of occurrence. Further, the polyether-based water reducing agent and the polycarboxylic acid-based water reducing agent are not particularly limited, and any commercially available product can be used. Preferably, for the polyether water reducing agent, by using a polyether water reducing agent having a carboxyl group, the adsorption rate to the cement is increased, and high dispersibility can be obtained even if not much time has passed since water injection. It is good because it is obtained. Content of the mixed water reducing agent in this mortar shall be 0.3-0.9 mass part in conversion of solid content with respect to 100 mass parts of bolt land cement content. Preferably, it is 0.4 to 0.8 parts by mass in terms of solid content. If it is less than 0.3 part by mass, it is difficult to ensure dispersibility and fluidity suitable for construction without increasing the water content, and it is not preferable, and if it exceeds 0.9 part by mass, setting delay or poor curing is caused. It is not appropriate because there is a fear.

  The self-smooth mortar of the present invention contains an expansion material. The expansion material is not particularly limited as long as it can be used for mortar and concrete. Preferably, an expansion material that expands in volume by a hydration reaction such as quicklime or ettringite is used. Examples of the quicklime-based expansion material include a clinker pulverized product in which free quick lime is generated and a limestone calcined pulverized product as an active ingredient. The ettringite-based expansion material is not limited as long as it reacts with water to produce an ettringite phase, and examples thereof include those containing calcium sulfoaluminate as an active ingredient. Quick lime-based and ettringite-based expansion materials may be used in combination. The expansion material suppresses relatively large-scale shrinkage from the curing to the drying period, and can particularly prevent the occurrence of initial cracks. Content of the expansion material in this mortar shall be 10-15 mass parts with respect to 100 mass parts of Portland cement content. If it is less than 10 parts by mass, shrinkage during curing cannot be sufficiently suppressed, and if it exceeds 15 parts by mass, there is a possibility of expansion cracks due to overexpansion, which is not preferable.

  The self-smooth mortar of the present invention contains a thickener. As the thickener used, any water-soluble thickener that can be used in mortar and cement can be used. Preferably, a cellulose derivative having a viscosity at 20 ° C. of 1500 to 35000 mPa · s is used. As the cellulose derivative, hydroxypropylmethylcellulose, hydroxyethylmethylcellulose and the like are recommended because the viscosity at 20 ° C. can easily be adjusted to 1500 to 35000 mPa · s. The inclusion of the thickening agent contributes to the prevention of the separation of the sex material and the prevention of cracks, warpage and surface peeling due to the drying of the mortar floor after construction, while ensuring an appropriate fluidity. When the viscosity value at 20 ° C. of the suitable thickener is less than 1500 mPa · s, such a function and effect may not be obtained sufficiently, and when it exceeds 35000 mPa · s, the self-smoothness is reduced due to a decrease in fluidity or construction work. There is a risk of deterioration. The content of the thickener in the mortar is 0.2 to 0.5 parts by mass (in terms of solid content in the case of a liquid thickener) with respect to 100 parts by mass of the Portland cement content. If it is less than 0.2 parts by mass, material separation and cracking may not be sufficiently suppressed, which is not preferable, and if it exceeds 0.5 parts by mass, the viscosity increases, the desired fluidity cannot be obtained, and construction workability is reduced. Since it falls, it is not preferable.

  The self-smooth mortar flooring of the present invention contains a styrene butadiene rubber emulsion in which calcium nitrite is dispersed. The styrene butadiene rubber emulsion is an emulsion of synthetic rubber containing a styrene / butadiene copolymer as an active ingredient. The emulsifier for emulsification is not limited, and any emulsifier may be used as long as it can be used for emulsification of a polymer for mortar, concrete, polymer cement and the like. The content of calcium nitrite in the styrene butadiene rubber emulsion in which calcium nitrite is dispersed is not particularly limited. Preferably, the content ratio of calcium nitrite with respect to the total amount of the styrene-butadiene rubber emulsion in terms of solid content and the mass of dispersed calcium nitrite is 1 to 5% by mass. The state of calcium nitrite to be dispersed may be either fine powder or granule, but a coarse lump of approximately 5 mm or more is desirably avoided because it may be difficult to obtain property uniformity. By using a styrene-butadiene rubber emulsion in which calcium nitrite is dispersed, it is possible to increase the early strength development while securing the pot life, and the material separation resistance and the crack resistance during shrinkage and drying increase. . The content of the styrene butadiene rubber emulsion in which calcium nitrite is dispersed in the mortar is 32 to 36 parts by mass with respect to 100 parts by mass of the Portland cement content. If it is less than 32 parts by mass, it takes too much time to reach the desired strength, and the construction period is delayed, which is not preferable. On the other hand, if the content exceeds 36 parts by mass, the viscosity becomes too high, and it is difficult to ensure the required working time, which is not preferable. In addition, when the calcium nitrite and the styrene butadiene rubber emulsion are added separately in the formation of the self-smooth mortar of the present invention, it is difficult to obtain the synergistic effect exhibited by both components, and both components are uniformly distributed throughout the mortar. It is not preferable because it does not act and a mortar having good properties may not be obtained.

  The self-smooth mortar of the present invention contains fine aggregate. The fine aggregate to be used is not particularly limited as long as it has a maximum particle size of 5 mm or less and can be used for mortar. Specific examples include natural sand such as mountain sand, river sand, and sea sand, crushed stone powder, and artificial ordinary aggregate. Lightweight aggregates such as porous and foam aggregates are generally strong. For example, it is not suitable for use in mortar for flooring. Preferably, the use of a plurality of types of fine aggregates having different particle size ranges is recommended because it is easy to suppress cracking due to suppression of material separation and reduction of shrinkage. More preferably, if one of the plurality of types of fine aggregates is composed of fine aggregates having a particle size of less than 100 μm, a denser structure can be obtained and a smooth floor surface can be easily obtained. good. In this case, at least one other kind of fine aggregate is composed of particles having a particle size of about 0.5 mm or more, and if the content is equal to or greater than that of the fine aggregate, shrinkage is further suppressed and crack suppression is promoted. Therefore, it is most preferable. The content of the fine aggregate in the mortar is 150 to 200 parts by mass with respect to 100 parts by mass of the bolt land cement content. If it is less than 150 parts by mass, the shrinkage of the mortar becomes too large and there is a possibility that shrinkage cracks may occur, and if it exceeds 200 parts by mass, the strength is lowered, which is not preferred.

  The self-smooth mortar of the present invention preferably further contains an antifoaming agent. Any antifoaming agent may be used as long as it can be used for mortar and concrete. For example, a commercially available antifoaming agent, defoaming agent, antifoaming agent, or the like can be used. By containing an antifoaming agent, there is no air bubbles remaining inside, and it becomes easy to form a beautiful floor with no bubble marks on the surface. When the antifoaming agent is contained, the content of the antifoaming agent necessary for the expression of the efficacy without affecting other properties is 0.1 to 0 with respect to 100 parts by mass of the boltland cement content. .3 parts by mass is preferred.

  The self-smooth mortar of the present invention preferably contains an alkali metal sulfate. Examples of the alkali metal include sodium, potassium, and lithium. Alkali metal sulfates generally have a setting-promoting action, but the self-smooth mortar of the present invention is useful for accelerating hardening while ensuring a somewhat longer pot life necessary for construction work. is there. When the alkali metal sulfate is contained, the content of the alkali metal sulfate necessary for expression of the effect in the mortar is 0.4 to 0.8 parts by mass with respect to 100 parts by mass of the boltland cement content. Is preferred.

  In addition, the self-smooth mortar of the present invention may contain components other than those described above as long as the effects of the present invention are not substantially lost. Examples of such components include a drying shrinkage reducing agent, a whitening inhibitor, a water repellent, a clay mineral, and a pigment, but are not limited to the examples shown.

  Moreover, the amount of the kneading water added when kneading the self-smooth mortar of the present invention is not particularly limited. What is necessary is just to determine suitably according to a construction object, construction environment, mortar mixture, etc. For example, when kneading and applying at 5 ° C., the cement and fine particles contained in the self-smooth mortar of the present invention have good fluidity suitable for casting and good strength. It is desirable to use water having a mass corresponding to 25 to 28% of the total mass of the aggregate as the kneading water.

  Moreover, the manufacturing method of the self-smooth mortar of this invention is not specifically limited. For example, it can be obtained by adding a compounding material other than kneaded water to a kneader, preferably adding kneaded water while mixing, and further kneading for about 1 to 2 minutes depending on the amount. Moreover, this mortar is suitable for construction by pouring onto a floor surface such as a floor slab, and after pouring, the surface of the construction may be leveled with a dragonfly or the like, if necessary.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely in detail, this invention is not limited to an Example. Further, unless otherwise specified, the following examples were conducted in an environment of 5 (± 0.5) ° C. including evaluation.

  Each material shown below was put into a kneading container so as to have the composition shown in Table 1, water was added while mixing, and kneading was performed for about 90 seconds after the addition of water to prepare a high-flowing mortar.

Cement: The following C1 or C2 is used.
C1: Ordinary Portland cement (commercial product, Blaine approx. 3200 cm ² / g)
C2: Portland cement comprising 50% by mass of ordinary Portland cement (commercial product, Blaine about 3200 cm ² / g) and 50% by mass of early strength Portland cement (commercial product, Blaine about 3300 cm ² / g)

Water reducing agent: Use any of the following D1 to D6 D1: Polyether powder high performance water reducing agent having a carboxyl group (commercially available)
D2: Polycarboxylic acid powder high-performance water reducing agent (commercially available)
D3: Naphthalenesulfonic acid formalin condensate powdery high-performance water reducing agent (commercially available)
D4; a mixed water reducing agent D5 composed of 50% by mass of D1 and 50% by mass of D2, a mixed water reducing agent D6 composed of 63% by mass of D1 and 37% by mass of D2, and 80% by mass of D1 Mixed water reducing agent consisting of 20% by mass of D2

Inflatable material; E1 below is used.
E1: Quicklime-based expansion material (commercial product manufactured by Taiheiyo Materials Co., Ltd.)

Thickener: Use the following V1.
V1: Hydroxypropyl methylcellulose thickener (commercially available) having a viscosity at 20 ° C. of about 30000 mPa · s

Styrene butadiene rubber emulsion in which calcium nitrite is dispersed; B1 below is used.
B1: Styrene butadiene rubber emulsion in which calcium nitrite is dispersed at a content of 3% by mass (commercially available product)

Fine aggregate: Use one of the following S1 to S3.
S1: Silica sand No. 5 26.4% by mass, silica sand No. 6 34.7% by mass, calcium carbonate particles (75 μm sieve pass rate> 98%) 17.4% by mass and limestone crushed stone (average particle size 0.4 mm) 21 Fine Aggregate S2 comprising 5% by mass; Silica sand No. 5 13.2% by mass, Silica sand No. 6 42.7% by mass, calcium carbonate particles (75 μm sieve pass rate> 98%) 25.4% by mass and limestone crushed stone Fine aggregate comprising 18.7% by mass (average particle size 0.4 mm).
S3: Fine aggregate composed of 30.0% by mass of calcium carbonate particles (75 μm sieve pass rate> 98%) and 70.0% by mass of limestone crushed stone (average particle size 0.4 mm).

Alkali metal sulfate; use the following A1 A1; sodium sulfate (commercially available reagent)

Antifoaming agent: Use A2 below A2; Silica-polyether antifoaming agent (commercially available)

[Evaluation of fluidity of mortar]
As an evaluation of the fluidity of the produced mortar, the flow was measured according to the flow test method of the Architectural Institute of Japan standard JASS 15M-103. The flow measurement was performed on the mortar immediately after completion of the kneading (when about 2 minutes have passed since the water injection). The results are shown in Table 2.

[Evaluation on material separation of mortar]
In addition, the mortar thus produced is poured into a plastic container having an inner dimension of 13 cm, a width of 8.5 cm, and a height of 1.8 cm, which is placed horizontally on the ground, so that the height of the mortar becomes 5 mm. It is. As an evaluation regarding the material separation of the mortar, it was visually checked whether bleeding water was generated on the surface of the construction object which was allowed to stand for 30 minutes after being poured into the container. In the case where no bleeding water was observed, the material separation was judged as “No”, and in other cases, the material separation was judged as “Yes”. The results are shown in Table 2.

[Evaluation of mortar level]
In addition, a level surface (bubble tube level) is formed by placing a level (bubble tube level) in the vicinity of the four corners and the central part of the mortar construction after 24 hours from the pouring construction. Investigate whether it is. If all five locations were level without any unevenness, the level was judged as “good”, and if one location was in any other situation, the level was judged as “bad”. It was judged. The results are shown in Table 2.

[Evaluation of smoothness]
Next, the smoothness of the surface of the construction was examined visually. The surface smoothness was judged to be “good” if no bubble bulge, pinholes, wrinkles, or film formation was observed on the surface, and “bad” was judged otherwise. In addition, the presence or absence of cracks and the presence or absence of peeling of the construction were also confirmed visually. In addition, the evaluation of the surface smoothness and the above-described horizontality was stopped when a large-scale crack occurred and broke. The above results are shown in Table 2.

[Evaluation of pot life]
In addition, a proctor penetration test was performed on the mortar prepared as described above according to JIS A 1147. The elapsed time (minutes) from the time of water injection of the mortar that reached a Proctor penetration resistance value of 28 N / mm ² was defined as the end time, and the time until this end was defined as the pot life. The proctor needle used was a needle having a cross-sectional area of 0.125 cm ² . The results are shown in Table 3. In addition, a mortar having a Proctor penetration resistance value of 3.5 N / mm ² or less that lasted for 12 hours or more after water injection was considered to be substantially free of condensation, and indicated as “x”.

[Evaluation of strength development]
Moreover, the mortar after water injection prepared as described above was filled in a molding mold with an internal size of 40 × 40 × 160 mm immediately after the preparation. This was left in the air for 9 hours to remove the mold. The demolded material was placed in a 5 ° C. (± 0.5 ° C.) constant temperature chamber until a predetermined material age, and specimens having a material age of 24 hours and a material age of 7 days were obtained. The uniaxial compressive strength of each specimen was measured with an Amsler type compressive strength tester. The results are shown in Table 3. In addition, since it was impossible to prepare a specimen for an uncured material at a predetermined age, strength measurement could not be performed, and “x” was indicated in the table.

From Table 2, since the self-smooth mortar according to the present invention has high fluidity while having material separation resistance, a horizontal surface can be easily formed by pouring work, and a good smooth surface can be obtained. Recognize. In addition, the self-smooth mortar according to the present invention having such construction properties has a high early strength development property in spite of being able to secure a sufficient pot life from Table 3, and at a material age of 1 day. It can be seen that it can reach a practical compressive strength (in the case of flooring, approximately ^2.5 N / mm ² or more).

Claims (6)

Portland cement 100 parts by weight, polyether water-reducing agent 50-80% by weight and the balance water-reducing agent 0.3-0.9 parts by weight of polycarboxylic acid water-reducing agent, expansion agent 10-15 parts by weight, thickener A self-smooth mortar containing 0.2 to 0.4 parts by mass, 32 to 36 parts by mass of a styrene butadiene rubber emulsion in which calcium nitrite is dispersed and 150 to 200 parts by mass of fine aggregate. 2. The self-smooth mortar according to claim 1, wherein the polyether water reducing agent has a carboxyl group. The self-smooth mortar according to claim 1 or 2, wherein the styrene-butadiene rubber emulsion in which calcium nitrite is dispersed has a calcium nitrite content of 1 to 5% by mass. Furthermore, the self-smooth mortar in any one of Claims 1-3 containing an antifoamer. Furthermore, the self-smooth mortar in any one of Claims 1-4 containing the sulfate of an alkali metal. The self-smoothing mortar according to any one of claims 1 to 5, which is used for a flooring material.