JP2008137841A - Self-levelling material for high temperature use - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cement based self levelling material in which occurrence of material separation and cracks caused by rapid drying is suppressed even when being placed under high temperature environments of about 35°C, and with which deterioration in the strength of the surface of a placed product, an efflorescence phenomenon or the like caused by dry out are not caused as well without exerting trouble on execution property such as self-flatness and surface smoothness as a self-leveling material. <P>SOLUTION: The self-levelling material for high temperature use comprises: a fine aggregate having bone-dry density of 0.2 to 2 g/cm<SP>3</SP>and a water absorption of 10 to 500%; water soluble cellulose ether; a dispersant; and cement. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a self-leveling material that can provide stable workability even when casting at a high temperature of about 35 ° C.

Self-leveling materials that can form a smooth surface just by pouring into the floor, etc., are widely used with cement as the curing component, but are easy to dry because the casting thickness is thin, In addition, since the amount of kneaded water is relatively large because of the need for high fluidity, drying shrinkage is increased, and thus dry cracks are likely to occur. In particular, in the case where the casting thickness is about 10 mm or less, the drying is quick, and a dry crack is likely to occur. Furthermore, the possibility that the cement in the cast material will be dried while there is an unhydrated portion is increased, often resulting in dryout and a decrease in surface strength. As a method for suppressing the drying of the self-leveling material, for example, it is known to incorporate a methylcellulose-based water retention agent. (For example, refer to Patent Document 1.) It is also known to mix an acrylic or polyethylene oxide water-soluble polymer as a water retention component. (See, for example, Patent Document 2.) Methylcellulose-based water retention agents are more powerful in water retention than acrylic and polyethylene oxide water-soluble polymers, and have a water retention capability that is less temperature dependent. Some are also known. (For example, refer to Patent Document 3.) On the other hand, as a means not using a water retention component, a specific synthetic resin is used, and the surface of the cast article is densified with a synthetic resin to form a cured resin-like surface state to evaporate moisture. There is also a known method of suppressing this. (For example, refer to Patent Document 4) In the use of a synthetic resin, it is difficult to obtain a sufficient water evaporation inhibiting effect unless the blending concentration is considerably increased. As a result, the fluidity is lowered and the workability may be hindered. Therefore, in general, the use of a methylcellulose-based water-retaining agent having a high water-retaining ability suppresses a reduction in strength of the cast body surface due to dry-out of the self-leveling material, a white flower phenomenon, and the like.
JP-A-57-92558 Japanese Patent Laid-Open No. 62-171955 JP 2000-103662 A JP 2003-20263 A

  However, in general, cellulose derivatives tend to have lower water retention performance as the temperature increases. For example, when an attempt is made to place a self-leveling material containing a methylcellulose-based water retention agent in an environment of 30 ° C. or higher, the water evaporation tends to proceed quickly due to the high temperature environment in addition to the water retention decrease of the water retention agent itself. It was difficult to prevent out and dry cracks. Even if a cellulosic water retention agent having a low temperature dependency and having a water retention capability is used, it is difficult to suppress the deterioration of the surface condition of the construction to a degree that the moisture reduction rate can be somewhat suppressed under a high temperature environment. Increasing the amount of kneading water decreases the elastic modulus and improves deformation followability. However, drying shrinkage becomes too large and cracks tend to occur, and bleeding water due to material separation tends to occur. Therefore, the present invention suppresses the occurrence of cracks due to material separation and drying even if it is placed in a high temperature environment of about 35 ° C. without affecting the workability as a self-leveling material, and is also provided by dryout. The present invention provides a cement-based self-leveling material that does not cause a decrease in strength on the surface of a work or a white flower phenomenon.

  As a result of intensive studies for solving the problems, the present inventors have given water retention function to particles having a high water absorption and a methylcellulose-based water retention agent. Since moisture release into the material progresses slowly, the moisture inside the material is not lost suddenly, it can prevent rapid drying as a self-leveling material, and use low density aggregate Therefore, the elastic modulus can be lowered without increasing the amount of kneading water, the deformation followability is improved, and cracking and dryout during high temperature casting can be suppressed without affecting various properties. Completed the invention.

That is, the present invention is a high-temperature self-leveling material represented by the following (1) to (3). (1) A high-temperature self-leveling material comprising a fine aggregate having an absolute dry density of 0.2 to 2 g / cm ³ and a water absorption of 10 to 500%, a water-soluble cellulose ether, a dispersant, and cement. (2) The high-temperature self-leveling material according to (1), wherein the water-soluble cellulose ether is hydroxyalkylalkylcellulose. (3) The high-temperature self-leveling material according to (1) or (2), further comprising one or more selected from the group consisting of shrinkage reducing agents, expansion materials, and antifoaming agents.

  According to the present invention, a self-leveling material particularly suitable for placement at a high temperature such as 35 ° C. can be obtained. Moreover, the self-leveling material can be used stably in a wide temperature range because there is no problem in the workability and the physical properties of the work even if it is placed at room temperature or lower.

The high-temperature self-leveling material of the present invention contains fine aggregate having an absolutely dry density of 0.2 to 2 g / cm ³ and a water absorption of 10 to 500%. Here, the water absorption is expressed as a percentage by weight. Absolute dry density of 0.2 g / cm ³ less than the particles tend to float in the surface of the material is not preferable because the reason the surface smoothness and surface strength decreases, and in particles greater than absolute dry density 2 g / cm ^3, the elastic modulus This is not preferable because it is difficult to reduce the deformation and the follow-up property of the deformation is not improved. In addition, it is not preferable that the water absorption is less than 10% because it is difficult to secure a sufficient amount of water retention. Fine aggregates having a water absorption of more than 500% are extremely fragile and may be easily crushed during kneading or construction. This is not preferable. As long as it is a fine aggregate having an absolute dry density and water absorption rate as described above, any aggregate can be used as long as it is an aggregate made of a material that is substantially inert to water. Artificial or natural lightweight fine aggregates that have a certain rate. The content of such fine aggregate in the high-temperature self-leveling material is preferably 1 to 50 parts by mass with respect to 100 parts by mass of the high-temperature self-leveling material excluding the kneaded water. If it is less than 1 part by mass, the amount of water supplied from the fine aggregate is insufficient, which is not suitable. On the other hand, if it exceeds 50 parts by mass, it is not suitable because it tends to be a self-leveling material with low surface strength.

  The high-temperature self-leveling material of the present invention includes natural fine aggregates such as quartz sand, land sand, sea sand, river sand, coal ash, in addition to the fine aggregate having the above-mentioned dry density and water absorption rate. Ordinary fine aggregates made mainly of industrial byproducts such as slag and iron ore, and one or more of lightweight fine aggregates deviating from the above-mentioned absolute dry density and water absorption range may be used in combination. The amount of such fine aggregate contained in the high-temperature self-leveling material is preferably about 50% or less of the total aggregate content because a desired low elastic modulus can be secured.

  Moreover, the self-leveling material for high temperature of this invention contains water-soluble cellulose ether. Since water-soluble cellulose ether generally has water retention, it can suppress dry cracking and white flower, and also has a thickening property, so that material separation can be suppressed. The water-soluble cellulose ether is not particularly limited, but the higher the water retention capacity, the better. The content of the water-soluble cellulose ether in the high-temperature self-leveling material is preferably 0.05 to 1 part by mass with respect to 100 parts by mass of the high-temperature self-leveling material excluding the kneaded water. If it is less than 0.05 parts by mass, it may not be possible to suppress dry cracking or white flower, which is not suitable. On the other hand, if the amount exceeds 1 part by mass, hydration delay occurs and dryout tends to occur, which is not suitable.

  Moreover, since the high-temperature self-leveling material of the present invention has high water retention performance as the water-soluble cellulose ether, it is preferable to use hydroxyalkylalkyl cellulose. Any hydroxyalkylalkylcellulose can be used, and specific examples include hydroxypropylmethylcellulose and hydroxyethylmethylcellulose.

  Moreover, the self-leveling material for high temperature of this invention contains a dispersing agent. By using the dispersant, fluidity suitable for workability as a self-leveling material can be ensured without increasing the amount of kneading water. The dispersant is not particularly limited as long as it can be used in mortar or concrete, and may be a water reducing agent, an AE water reducing agent, a high performance water reducing agent, a high performance AE water reducing agent, a fluidizing agent, or the like. Examples of chemical components include dispersants such as lignin sulfonic acid, melamine sulfonic acid, naphthalene sulfonic acid, polycarboxylic acid, polyether, aminosulfonic acid, polystyrene, and oxycarboxylic acid. be able to. Furthermore, the form of the dispersant may be either liquid or powder. The content of the dispersant is preferably 0.02 to 1 part by mass in terms of solid content with respect to 100 parts by mass of the high-level self-leveling material excluding kneaded water. If it is less than 0.02 parts by mass, fluidity suitable for workability as a self-leveling material may not be ensured, which is not appropriate. On the other hand, if the amount exceeds 1 part by mass, hydration delay occurs and dryout tends to occur, which is not suitable.

  The self-leveling material for high temperature of the present invention is a self-leveling material containing cement as a hardening component, and the cement used may be any hydraulic cement. Specific examples include various portland cements such as normal, early strength, ultra-early strength, medium heat, and low heat, various mixed cements such as blast furnace cement and silica cement, and special cements such as white cement and ecocement. The content of the cement is preferably 10 to 90 parts by mass with respect to 100 parts by mass of the high-temperature self-leveling material excluding the kneaded water. If the amount is less than 10 parts by mass, the binder phase forming component is insufficient, so that the strength of the construction is lowered, which is not appropriate. On the other hand, if it exceeds 90 parts by mass, the self-shrinkage becomes too large and cracks are likely to occur, which is not appropriate.

  Moreover, it is preferable that the self-leveling material for high temperature of this invention contains the 1 type (s) or 2 or more types selected from the group of a shrinkage reducing agent, an expansion material, and an antifoamer. By using a shrinkage reducing agent or an expanding material, shrinkage at the time of hydraulic or drying can be suppressed, and occurrence of cracks due to excessive shrinkage can be prevented. The shrinkage reducing agent and the expansion material are not particularly limited as long as they can be used for mortar and concrete. The content of the shrinkage reducing agent is preferably 0.05 to 5 parts by mass with respect to 100 parts by mass of the high-temperature self-leveling material excluding the kneaded water. When the content of the shrinkage reducing agent is less than 0.05 parts by mass, the use effect is hardly obtained, and when it exceeds 5 parts by mass, the surface strength may be easily lowered due to delayed hydration. Moreover, the content of the expansion material is preferably 1 to 20 parts by mass with respect to 100 parts by mass of the high-temperature self-leveling material excluding the kneaded water. When the content of the expansion material is less than 1 part by mass, the use effect is hardly obtained. When the content of the expansion material exceeds 20 parts by mass, overexpansion occurs and a crack may occur. In addition, the use of antifoaming agent prevents the generation of bubbles due to gas such as air taken into the pores of fine aggregates, and prevents the surface of the construction from being reduced in strength and difficult to obtain. Can do. The antifoaming agent is not particularly limited as long as it can be used for mortar and concrete. The content of the antifoaming agent is preferably 0.005 to 0.5 parts by mass with respect to 100 parts by mass of the high-temperature self-leveling material excluding the kneaded water. If it is less than 0.005 parts by mass, the use effect hardly appears, and if it exceeds 0.5 parts by mass, curing is delayed and there is a possibility of causing dryout.

  Further, the high-temperature self-leveling material 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. For example, any fiber, setting accelerator, and setting agent that can be used for mortar and concrete. Examples thereof include retarders, anti-whitening agents, polymer resins, pigments, slag fine powder, silica fume, silica stone fine powder, limestone fine powder, coal ash, and inorganic fine powder having no substantial hydration reaction activity.

  The amount of the kneading water used in the high-temperature self-leveling material of the present invention is preferably 20 to 50 parts by mass with respect to 100 parts by mass of the high-temperature self-leveling material excluding the kneading water. If it is less than 20 parts by mass, it is difficult to obtain fluidity suitable for the expression of self-leveling properties, so this is not appropriate. On the other hand, if the amount exceeds 50 parts by mass, there is a risk of strength reduction, cracking and material separation, which is not appropriate.

  The manufacturing method of the self-leveling material for high temperature of this invention does not have a restriction | limiting in particular, For example, it can manufacture easily by pouring a compounding material with kneading water collectively into mixers, such as a mortar mixer, and mixing and kneading. In addition, the construction method can be handled in the same manner as the cement-based self-leveling material generally used in the world, and it can be constructed not only in a high temperature environment but also at a room temperature or a relatively low temperature of 10 ° C. or less. .

Hereinafter, the present invention will be described in detail by way of examples.
Using a material selected from the following A1 to A4, B1 to B5, C, D, and E1 to E3, water is added and mixed and kneaded with a hand mixer so that the composition shown in Table 1 is obtained. Produced. Incidentally, the absolute dry density and water absorption rate of the fine aggregate were measured by a method in accordance with JIS A1134 “Testing method for density and water absorption rate of structural lightweight aggregate”.

A1; Pearlite artificial lightweight fine aggregate (absolute dryness 0.92, water absorption 27%)
A2: Expanded shale-based artificial lightweight fine aggregate (absolute density 1.68, water absorption 16%)
A3: Silicon carbide-based foaming additive added shale-based porous artificial fine aggregate (absolute density 2.25, water absorption 12%)
A4: Limestone crushed sand (absolute dryness 2.65, water absorption 0.1%, maximum particle size about 1.2 mm)
B1; hydroxyethyl methylcellulose (commercially available)
B2: Hydroxypropyl methylcellulose (commercially available)
B3: Hydroxyethyl cellulose (commercially available)
B4: Carboxymethylcellulose (commercially available)
B5; ethylene vinyl acetate copolymer emulsion (trade name “Moltop Emulsion”, Taiheiyo Material Co., Ltd., solid content concentration 45%)
C: Ordinary Portland cement (manufactured by Taiheiyo Cement Co., Ltd.)
D: Polycarboxylic acid-based high-performance AE water reducing agent (trade name “OTS”, Takemoto Yushi Co., Ltd., solid concentration 20%)
E1: Antifoaming agent (trade name “SN Deformer”, manufactured by San Nopco)
E2: Shrinkage reducing agent (trade name "Pacific Tetra Guard", manufactured by Taiheiyo Material Co., Ltd.)
E3: Expansion material (trade name “Pacific Expan”, manufactured by Taiheiyo Material Co., Ltd.)

  According to the method of JASS (Architectural Institute of Japan Architectural Construction Standard Specification) 15M-103, the produced self-leveling material is evaluated as to whether or not it has fluidity suitable for self-leveling. And the flow value immediately after completion | finish of the kneading | mixing performed in a 35 degreeC test chamber (15 minutes after water injection) was measured. Those having a flow value of 190 mm or more were judged to have fluidity suitable for self-leveling. In addition, the self-leveling material for which the flow value measurement test was performed was placed at a thickness of 10 mm on a 30 × 30 cm concrete flat plate placed on a horizontal surface within 30 minutes after water injection, and was kept at the same temperature as the flow value measurement test. Left in the test room for 7 days. Subsequently, the presence or absence of generation of white flower or cracks on the surface of the self-leveling cured body with a material age of 7 days was examined visually. Those in which white flower and cracks were not seen at all were judged as the surface condition “good”, and those other than those were judged as the surface condition “bad”. Furthermore, for the self-leveling material determined to have a surface state of “good”, the surface adhesion strength of the self-leveling material that was brought to the age of 14 days in a constant temperature test chamber under the same temperature conditions as described above was measured according to JASS15M-103. It measured according to the method. The above results are summarized in Table 2.

  From Table 2, all of the products of the present invention show a stable flow value that can exhibit self-leveling, and even when placed at a high temperature of 35 ° C. as well as at room temperature, white flower and cracks do not occur, and the surface strength is also high. It turns out that a high hardening body is obtained. On the other hand, in the reference products outside the present invention, white flowers, cracks, and low surface strength were observed even when the flow value was such that self-levelness could be expressed.

Claims (3)

A self-leveling material for high temperature comprising a fine aggregate having an absolute dry density of 0.2 to 2 g / cm ³ and a water absorption of 10 to 500%, a water-soluble cellulose ether, a dispersant and cement. The high-temperature self-leveling material according to claim 1, wherein the water-soluble cellulose ether is a hydroxyalkylalkyl cellulose. Furthermore, the high temperature self-leveling material of Claim 1 or 2 formed by containing 1 type, or 2 or more types selected from the group of a shrinkage reducing agent, an expansion | swelling material, and an antifoamer.