JP6830826B2 - Self-smooth mortar - Google Patents

Description

The present invention relates to cement-based self-smoothing mortars.

High-fluidity mortar containing cement as a binding component can easily form a horizontal surface when poured into, for example, a floor slab of a building structure, so it can be used as a flooring material or as a foundation leveler for buildings. There are many. Since a mortar in a highly fluid state generally contains a large amount of kneaded water, cracks are likely to occur during material separation and drying processes, and it is difficult to obtain high strength and uniformity of internal properties. As a countermeasure, a thickener containing cellulose derivatives, dextrin, polysaccharides, etc. as active ingredients is blended, but since the viscosity increases, the kneading resistance increases and the fluidity decreases, resulting in deterioration of construction workability and during kneading. It was not easy to use an amount of thickener that could sufficiently suppress material separation because the entrained air bubbles could not easily escape and remained as surface marks. In particular, construction in cold regions or in a low temperature environment in winter, for example, in a low temperature environment of about 5 ° C, the viscosity increases considerably, which deteriorates construction workability, and the hydration reaction activity of cement decreases, resulting in vaporization of water content. However, since it becomes slow, hardening after construction is delayed, and there is a problem that it is not easy to shorten the construction period.

In a self-smoothing mortar containing alumina cement, which is a hard-hardening material (see, for example, Patent Document 1), curing after construction proceeds quickly even in a low temperature environment. Moreover, since the condensation is completed before the material separation progresses, the material separation is suppressed and it is easy to obtain a material having high initial strength, which is used as a measure for shortening the construction period. However, mortars using alumina cement generally have a large shrinkage, which increases 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 of using a coagulation retarder in combination is known. (For example, refer to Patent Document 2.) In this method, the pot life increases as the amount of the setting retarder is increased. (For example, refer to Patent Document 3.) However, when the setting retarder is increased, the progress of curing and the initial strength development are considerably slowed down at a low temperature. For this reason, at low temperatures, the effect of shortening the construction period by using alumina cement does not appear sufficiently, and if it is attempted to secure a certain amount of pot life, for example, it is good enough to have sufficient strength so that it can be used sufficiently within about one day from the end of construction work. It is difficult to obtain mortar with properties. There is a demand for a mortar that has a pot life required for construction work and can shorten the construction period more reliably even in a low-temperature construction environment.

JP-A-2009-161360 Japanese Unexamined Patent Publication No. 2011-195413 Japanese Unexamined Patent Publication No. 2014-15348

The present invention solves the above-mentioned problem concerning self-smooth mortar when alumina cement is used as a means for shortening the construction period, and provides a pot life suitable for construction work even in a low temperature construction environment such as 5 ° C. Within 24 hours from the end of construction work, we will provide self-smooth mortar that has sufficient strength to be used as a building / construction member such as flooring, has a short construction period, and is resistant to material separation and cracking in terms of properties. Make it an issue.

As a result of studies for solving the above-mentioned problems, the present inventor has made a specific amount of alumina cement, gypsum, a mixed dispersant of a polyether-based dispersant and a polycarboxylic acid-based dispersant, and a setting retarder. The present invention was completed because a mortar containing at least cement and fine aggregate was added with an alkali metal carbonate to form a self-smooth mortar that could solve the above problems as a whole.

That is, the present invention is a self-smoothing mortar represented by the following (1) to (5).
(1) 100 parts by mass of Portoland cement, 4 to 12 parts by mass of alumina cement, 6 to 8 parts by mass of plasters, and a polyether water reducing agent having a content of 50 to 80% by mass of a polyether water reducing agent and a polycarboxylic acid type. Mixing with water reducing agent 0.3 to 0.7 parts by mass of water reducing agent, 0.12 to 0.16 parts by mass of setting retarder, 0.2 to 0.5 parts by mass of thickener, and alkali metal carbonate 0. A self-smoothing mortar containing 06 to 0.1 parts by mass and 140 to 180 parts by mass of fine aggregate , wherein the polyether water reducing agent has a carboxyl group .
(2) Further, the self-smoothing mortar according to (1) above , which contains an antifoaming agent .
(3) The self-smoothing mortar according to (1) or (2), which further contains an alkali metal sulfate defoaming agent.
(4) The self-smoothing mortar according to any one of (1) to (3) above, which is used for the floor material .

According to the present invention, even if construction is performed in a low temperature environment such as 5 ° C., it is possible to secure a working time suitable for the construction work, and to start using the construction material as a floor material, for example, within 24 hours from the completion of the construction work. It is possible to obtain a self-smooth mortar that exhibits such high initial strength development, sufficiently suppresses material separation and cracking, and has good properties.

The self-smoothing mortar of the present invention uses Portland cement as a bonding phase forming component. The type of Portland cement is not particularly limited, and for example, various Portland cements such as ordinary, early-strength, ultra-fast-strength, moderate heat, low heat, and sulfate-resistant, as well as blast furnace cement and fly ash cement containing the Portland cement, etc. Mixed cement is also possible. It is also possible to use two or more types of Portland cement together. It is preferable to use ordinary Portland cement, which is compatible with alumina cement and is inexpensive in terms of cost.

Further, the self-smoothing mortar of the present invention contains alumina cement. The inclusion of alumina cement imparts rapid hardness to the mortar and contributes most to shortening the construction period. It also contributes to the suppression of material separation. The alumina cement contained in the mortar of the present invention is not limited as long as it is an alumina cement containing calcium aluminate as an active ingredient, and for example, any commercially available product in Japan or overseas can be used. The content of alumina cement in the self-smoothing mortar of the present invention is 4 to 12 parts by mass with respect to 100 parts by mass of the Portland cement contained. It is preferably 8 to 12 parts by mass. If the content is less than 4 parts by mass, the desired rapid hardness cannot be imparted, and it becomes difficult to shorten the construction period, which is not preferable. Further, if the content exceeds 12 parts by mass, the pot life required for work cannot be secured, which is not preferable.

In addition, the self-smoothing mortar of the present invention contains gypsum. The gypsum may be anhydrous gypsum, hemihydrate gypsum or dihydrate gypsum. Preferably, the use of anhydrous gypsum is recommended due to its high hydration activity. There are no restrictions on the transformation of anhydrous gypsum upon use. The inclusion of gypsum improves the strength development and alleviates the shrinkage caused by the use of alumina cement. The content of gypsum in this mortar shall be 6 to 8 parts by mass with respect to 100 parts by mass of the contained Boltland cement. If it is contained in an amount of less than 6 parts by mass, the strength development, particularly the increase in strength over time is lowered, which is not preferable. Further, if the content exceeds 8 parts by mass, the condensation may be delayed, which is not preferable.

Further, the self-smoothing mortar of the present invention contains a mixed water reducing agent composed of 50 to 80% by mass of a polyether water reducing agent and a remaining polycarboxylic acid water reducing agent. Such a water reducing agent may be what is called a dispersant, a high performance water reducing agent, an AE water reducing agent, a high performance AE water reducing agent or a fluidizing agent for mortar / concrete. By using the mixed water reducing agent, it is possible to secure both the mortar dispersibility at the kneading stage immediately after water injection and the mortar dispersibility at the time of pouring, for example, due to the difference in the dispersion action characteristics between the two, so that it is stable throughout the pot life. Since the dispersed state can be maintained, material separation is unlikely to occur, and fluidity suitable for self-smoothing is maintained. If the content mass ratio of the polyether water reducing agent in the mixed water reducing agent is less than 50%, the rapid hardness and the initial strength development will be low, which is not preferable, and if it exceeds 80%, the material will be separated as soon as the water injection kneading is completed. Is not preferable because it may cause. Further, the polyether-based water reducing agent and the polycarboxylic acid-based water reducing agent are not particularly limited, and for example, any commercially available product can be used. Preferably, for the polyether-based water reducing agent, by using a polyether-based water reducing agent having a carboxyl group, the adsorption rate to cement is increased, and high dispersibility is achieved even if a short time has passed since water injection. It is good because it can be obtained. The content of the mixed water reducing agent in this mortar is 0.3 to 0.7 parts by mass in terms of solid content with respect to 100 parts by mass of the Boltland cement content. Preferably, it is 0.4 to 0.6 parts by mass in terms of solid content. If it is less than 0.3 parts by mass, it becomes difficult to secure dispersibility and fluidity suitable for construction without increasing the water content, and if it exceeds 0.7 parts by mass, condensation delay and curing failure occur. Not suitable as there is a risk.

In addition, the self-smoothing mortar of the present invention contains a setting retarder. The setting retarder can be contained in any one that can be used for mortar and concrete. Examples of the caking accelerator include aliphatic hydroxycarboxylic acids such as citric acid and tartaric acid, sugar alcohols, phosphates, boric acid and the like. Preferably, even when used in combination with alumina cement, it is suitable for imparting pot life without delaying curing so much, and thus aliphatic hydroxycarboxylic acids such as citric acid and tartaric acid can be mentioned. The content of the setting retarder in this mortar is 0.12 to 0.16 parts by mass in terms of solid content with respect to 100 parts by mass of the Boltland cement content. If it is less than 0.12 parts by mass, the desired pot life cannot be secured, and if it exceeds 0.16 parts by mass, curing is delayed and it takes too much time for the floor material to reach usable strength, which is not preferable.

In addition, the self-smoothing mortar of the present invention contains a thickener. The thickener used can be any water-soluble thickener that can be used in mortar and cement. Preferably, it contains and uses a cellulose derivative having a viscosity of 1500 to 35000 mPa · s at 20 ° C. As the cellulose derivative, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose and the like are recommended because those having a viscosity at 20 ° C. of 1500 to 35000 mPa · s can be easily adjusted. The inclusion of the viscous thickener contributes to the suppression of separation of sex materials and the suppression of cracks, warpage and surface peeling due to drying of the mortar after construction, while ensuring appropriate fluidity. If the viscosity value of the suitable thickener at 20 ° C. is less than 1500 mPa · s, such an action effect may not be sufficiently obtained, and if it exceeds 35000 mPa · s, self-smoothness is reduced due to a decrease in fluidity and construction work. There is a risk of sexual deterioration. The content of the thickener in this mortar shall be 0.2 to 0.5 parts by mass (in the case of a liquid thickener, the amount converted to solid content) with respect to 100 parts by mass of 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 the workability of construction is improved. It is not preferable because it decreases.

Further, the self-smoothing mortar of the present invention contains an alkali metal carbonate. The use of alkali metal carbonates promotes coagulation and contributes to the early development of strength. Examples of the alkali metal include lithium, potassium, and sodium, and any of them may be used. The content of the alkali metal in this mortar shall be 0.16 to 0.1 parts by mass with respect to 100 parts by mass of the Boltland cement content. If it is less than 0.16 parts by mass, it may be difficult to develop the strength after setting, which is not preferable. If it exceeds 0.1 parts by mass, the pot life cannot be secured for a desired time, which is not preferable.

In addition, the self-smoothing mortar of the present invention contains a 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 thereof include natural sand such as mountain sand, river sand, and sea sand, crushed stone powder, and artificial ordinary aggregate, but lightweight aggregate such as porous or effervescent aggregate is generally strong. It is not suitable for use in flooring mortar, for example, because it is fragile. Preferably, it is recommended to use a plurality of types of fine aggregates having different particle size ranges because it is easy to suppress material separation and cracks due to a reduction in the amount of shrinkage. More preferably, when one of the plurality of types of fine aggregates is composed of fine aggregates having a particle size of less than 100 μm, a finer structure can be obtained and a smooth floor surface can be easily obtained. good. In this case, at least one other fine aggregate is composed of a particle size of about 0.5 mm or more, and when the content is equal to or higher than that of the fine aggregate, shrinkage is further suppressed and crack suppression is promoted. It is most preferable because it is used. The content of the fine aggregate in the mortar shall be 150 to 200 parts by mass with respect to 100 parts by mass of the Boltland cement content. If it is less than 150 parts by mass, the shrinkage of the mortar becomes too large and shrinkage cracks may occur, which is not preferable. If it exceeds 200 parts by mass, the strength is lowered, which is not preferable.

Further, the self-smoothing mortar of the present invention preferably further contains an antifoaming agent. The defoaming agent may be any one that can be used for mortar or concrete, and for example, a commercially available defoaming agent, defoaming agent, defoaming agent and the like can be used. The inclusion of the defoaming agent facilitates the formation of a beautiful floor or the like with no internal residual air bubbles and no air bubble marks on the surface. When a defoaming agent is contained, the content of the defoaming agent necessary for exhibiting the effect in this mortar without interfering with other properties is 0.2 to 0.2 to 100 parts by mass of the Boltland cement content. 0.4 parts by mass is preferable.

In addition, the self-smoothing 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-smoothing mortar of the present invention is useful for accelerating curing while ensuring a somewhat longer pot life required for construction work. is there. When an alkali metal sulfate is contained, the content of the alkali metal sulfate required for the manifestation of the effect in the mortar is 0.45 to 0.65 parts by mass with respect to 100 parts by mass of the Boltland cement content. Is preferable.

Further, the self-smoothing mortar of the present invention may contain components other than the above as long as the effects of the present invention are not substantially lost. Examples of such a component include a drying shrinkage reducing agent, an efflorescence inhibitor, a water repellent, a clay mineral, a polymer for polymer cement, a pigment, and the like, but are not limited to the posted examples.

Further, the amount of kneaded water added when kneading the self-smoothing mortar of the present invention is not particularly limited. It may be determined as appropriate according to the construction target, construction environment, mortar composition, etc. As an example, when kneading and constructing at 5 ° C., the boltland cement contained in the self-smoothing mortar of the present invention has good fluidity suitable for pouring construction and good strength development. It is desirable to use water having a mass corresponding to 25 to 28% of the total mass of the alumina cement and the fine aggregate as the kneading water.

Further, the method for producing the self-smoothing mortar of the present invention is not particularly limited. For example, it can be obtained by putting a compounding material other than kneading water into a kneader, preferably adding kneading water while mixing, and further kneading for about 1 to 2 minutes depending on the amount. In addition, this mortar is suitable for construction by pouring it onto the floor surface such as a floor slab, and after pouring, the surface of the work piece may be leveled with a dragonfly or the like, if necessary.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the Examples. Unless otherwise specified, the following examples, including evaluation, were performed in an environment of 5 (± 0.5) ° C.

Each of the following materials was put into a kneading container so as to have the composition shown in Table 1, then water was added while mixing, and kneading was performed for about 90 seconds after adding water to prepare a highly fluid mortar.

Cement; use the following C1 or C2.
C1; Ordinary Portland cement (commercially available, brain approx. 3200 cm ² / g)
C2; Early-strength Portland cement (commercially available, brain approx. 3300 cm ² / g)

Alumina cement; the following AC is used.
AC; Alumina cement (commercially available, brain approx. 3500 cm ² / g)

Gypsum; use the following G1.
G1; Type II anhydrous gypsum (commercially available chemical gypsum)

Water reducing agent; Use any of the following D1 to D6 D1; High-performance water reducing agent in the form of a polyether powder having a carboxyl group (commercially available)
D2; Polycarboxylic acid powder high-performance water reducing agent (commercially available)
D3; Naphthalene sulfonic acid formalin condensate powder high-performance water reducing agent (commercially available)
D4; mixed water reducing agent D5 consisting of 50% by mass of D1 and 50% by mass of D2; mixed water reducing agent D6 consisting of 63% by mass of D1 and 37% by mass of D2; 80% by mass of D1. A mixed water reducing agent consisting of 20% by mass of D2

Coagulation retarder; use the following F1.
F1; citric acid (commercially available reagent)

Thickener; use the following V1.
V1: Hydroxypropyl methylcellulose thickener with a viscosity of about 30,000 mPa · s at 20 ° C (commercially available)

Alkali metal carbonate; use the following MA MA; lithium carbonate (commercially available reagent)

Fine aggregate; use the following S1 or S2.
S1; Calcium carbonate No. 5 26.4% by mass, Calcium carbonate No. 6 34.7% by mass, Calcium carbonate grains (75 μm sieve passage rate> 98%) 17.4% by mass and limestone crushed stone (average particle size 0.4 mm) 21 Fine aggregate S2 consisting of .5% by mass; silica sand No. 5 13.2% by mass, silica sand No. 6 42.7% by mass, calcium carbonate grains (75 μm sieve passage rate> 98%) 25.4% by mass and limestone crushed stone (Average particle size 0.4 mm) Fine aggregate consisting of 18.7% by mass

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

Defoamer; use the following A2 A2; silica-polyester antifoaming agent (commercially available)

[Evaluation of mortar liquidity]
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 the kneading was completed (about 2 minutes after the water injection). The results are shown in Table 2.

[Evaluation of mortar material separation]
Further, the prepared mortar is poured into a plastic container having an inner dimension of 13 cm in length, 8.5 cm in width and 1.8 cm in height, which is horizontally installed on the ground, so that the mortar in a fluid state has a height of 5 mm. It is. As an evaluation of the material separation of this mortar, it was visually examined whether or not bleeding water was generated on the surface of the work piece which was left to stand for 30 minutes after being poured into the container. Material separation was judged to be "absent" when bleeding water was not generated, and material separation was judged to be "presence" when the situation was other than that. The results are shown in Table 2.

[Evaluation of mortar levelness]
In addition, a horizontal plane is formed by placing a spirit level (bubble level) at four corners and a central part of the surface of the mortar work 24 hours after the pouring work. I checked if it was. If all five locations are horizontal without causing unevenness, the horizontality is judged to be "good", and if even one location is in any other condition, the horizontality is considered "poor". It was judged. The results are shown in Table 2.

[Evaluation of smoothness]
Next, the smoothness of the surface of the work was visually inspected. Those in which no bubble swelling, pinholes, wrinkles, or floating of film formation were observed on the surface were judged to have "good" surface smoothness, and others were judged to be "poor". In addition, the presence or absence of cracks and the presence or absence of peeling of the construction work were visually confirmed. For those that had large-scale cracks and broke, the evaluation of surface smoothness and the above-mentioned levelness was stopped. The above results are shown in Table 2.

[Evaluation of pot life]
In addition, a mortar after water injection prepared as described above was subjected to a proctor penetration test by a method according to JIS A 1147. The elapsed time (minutes) from the time of water injection of the mortar having reached the Procter penetration resistance value of 28 N / mm ² was defined as the termination time, and the time until this termination was defined as the pot life. As the Proctor needle, a needle having a cross-sectional area of 0.125 cm ² was used. The results are shown in Table 3. In addition, mortar having a Procter penetration resistance value of 3.5 N / mm ² or less for 12 hours or more after water injection was considered to have virtually no condensation and was indicated by "x".

[Evaluation of strength expression]
Further, the mortar prepared as described above after water injection was immediately filled in a molding mold having an inner size of 40 × 40 × 160 mm. This was allowed to stand in the air for 9 hours to remove the mold. The demolded material was placed in a constant temperature chamber at 5 ° C. (± 0.5 ° C.) until it reached a predetermined age, and specimens of 24 hours and 7 days of age were obtained, respectively. The uniaxial compressive strength of each specimen was measured with an Amsler compression strength tester. The results are shown in Table 3. It should be noted that the strength of the uncured material at a predetermined age could not be measured because the specimen could not be prepared, and "x" was marked in the table.

From Table 2, since the self-smoothing mortar according to the present invention has material separation resistance and high fluidity, a horizontal plane can be easily formed by pouring construction, and a smooth surface thereof can be obtained. Understand. In addition, the self-smooth mortar according to the present invention having such construction properties has high early strength development even though a sufficient pot life can be secured from Table 3, and the material age is one day. It can be seen that the compressive strength that can withstand practical use (in the case of floor materials, approximately ^2.5 N / mm ² or more) can be reached.

Claims (4)

Portoland cement 100 parts by mass, alumina cement 4 to 12 parts by mass, plasters 6 to 8 parts by mass, polyether water reducing agent containing 50 to 80% by mass of polyether water reducing agent and polycarboxylic acid water reducing agent 0.3 to 0.7 parts by mass of the mixed water reducing agent, 0.12 to 0.16 parts by mass of the setting retarder, 0.2 to 0.5 parts by mass of the thickener, and 0.06 to 0 parts of the alkali metal carbonate. . A self-smoothing mortar containing 1 part by mass and 140 to 180 parts by mass of fine aggregate , wherein the polyether water reducing agent has a carboxyl group . The self-smoothing mortar according to claim 1 , further containing an antifoaming agent . The self-smoothing mortar according to claim 1 or 2, further containing an alkali metal sulfate . The self-smoothing mortar according to any one of claims 1 to 3 used for a floor material .