JP2011173736A - Cement mortar, curing agent for concrete and curing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paraffin-based curing agent having workability improved to eliminate the need to remove the curing agent through sanding, surface polishing or high pressure cleaning after the curing agent is applied. <P>SOLUTION: The cement mortar or concrete emulsion type curing agent contains 10-30 wt.% lower alcohol alkylene oxide adduct and paraffin having ≤0.85 μm average particle diameter. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention reduces the drying shrinkage in order to suppress the evaporation of moisture from the surface in the initial stage after the casting of cement concrete, appropriately promote the hydration reaction of the cement, reduce the drying shrinkage and improve the durability. The present invention relates to a cement-based cured body curing agent having an effect, and a method for curing cement mortar or concrete.

  In order for the cement-based hardened body to have a dense structure capable of exhibiting the required strength and durability, it is necessary to carry out sufficient curing at the initial stage of the hydration progress process to reduce shrinkage. For this reason, “JASS 5” of the Architectural Institute of Japan defines the curing period, method, and amount of drying shrinkage, and wet curing is indispensable in order to prevent rapid drying after placing the cement-based cured body.

  Curing methods include a method of supplying moisture to concrete (such as underwater curing, submerged curing, watering curing, and compressing curing) and a method of preventing moisture dissipation (such as film curing and sheet curing). Underwater curing and submerged curing are the most effective wet curing, but are often difficult to perform with actual structures. On the other hand, film curing is a method in which a film curing agent is sprayed or applied on a concrete surface to form a film on the surface, thereby preventing evaporation of moisture to the outside and promoting hydration.

  As the curing agent, there are a solvent type obtained by dissolving a polymer or wax in an organic solvent, and an aqueous type emulsified in water, and various curing agents have been proposed (see Patent Documents 1 to 3).

  As a typical curing agent, there is a paraffinic curing agent. The paraffinic curing agent is excellent in a curing effect that prevents evaporation of moisture in concrete and mortar, and has high safety. In addition, there is no bleeding, and the finishing work of high-strength concrete with high viscosity is facilitated, and there is an effect of suppressing plastic cracks.

  However, when the finishing material is applied after applying the curing agent to the conventional paraffin-based curing agent, the adhesion strength decreases, and there is a concern that the finishing material may be peeled off, cracked, floated, or the like. Therefore, when the finishing material is applied after the application of the paraffinic curing agent, the curing agent is removed by ground polishing by sanding or high-pressure cleaning (see Non-Patent Documents 1 to 3).

  By the way, it is excellent in the effect which reduces the alkylene oxide addition 2 shrinkage amount of a lower alcohol as a typical shrinkage reducing agent. By reducing the amount of drying shrinkage, the occurrence of cracks in the structure is reduced and the durability is improved. Moreover, when using the conventional shrinkage reducing agent for concrete or mortar, it is necessary to select a combination of concrete and mortar, and much labor is required (see Patent Documents 4 and 5). Further, there is a shrinkage reducing agent sprayed at the time of surface finishing of cement concrete to suppress cracking, but there are cases where predetermined strength development cannot be obtained due to poor curing (see Patent Document 6).

Japanese Patent Laid-Open No. 5-208879 Japanese Patent Laid-Open No. 11-21184 JP 2004-244255 A Special table 2007-529397 JP 2008-260687 A JP 2006-143481 A

Present state of technology regarding test methods for concrete / polymer composites, Japan Architectural Institute Material Construction Committee Concrete / Polymer Composite Test Methods Subcommittee, pp. 110-129, 2005 "Monthly building finishing technology", Vol. 30, no. 357, pp. 68-69, 2005 Experimental study on curing of concrete using film curing agent (Part 2. Effect of finishing material adhesion), Susumu Nishimura, Akio Iwasaki, Kenji Yatsu, Masato Okura, Abstracts of Annual Conference of Architectural Institute of Japan, pp. 801-802, 2001

  An object of the present invention is to provide a curing agent with improved workability that does not require removal of the curing agent by sanding, ground polishing or high-pressure cleaning after application of a paraffinic curing agent.

  Accordingly, the present inventor paid attention to emulsion type curing agents among paraffinic curing agents and studied various types of paraffins and the like. As a result, the particle size of paraffin dispersed in the emulsion type curing agent was determined to be a cement-based cured body. It was found that the adhesion strength between the surface and the finishing material is greatly affected. As a result of further investigation, it was found that by adjusting the average particle size of the paraffin in the emulsion type curing agent to 0.85 μm or less, the adhesion strength is remarkably improved and no ground polishing or high pressure cleaning is required. It was. Further, when the paraffin of 0.85 μm or less was combined with a drying shrinkage reducing agent of an alkylene oxide adduct of a lower alcohol and examined for its curing effect, by adding 10 to 30% by weight of the drying shrinkage reducing agent, The present inventors have found that the curability is good and the drying shrinkage is reduced, thereby completing the present invention.

That is, the present invention provides a cement mortar or concrete emulsion type curing agent containing 10 to 30% by weight of a lower alcohol alkylene oxide adduct and paraffin having an average particle size of 0.85 μm or less.
The present invention also provides a curing method for cement mortar or concrete, characterized in that the curing agent is applied to the surface of the cured body at the time of finishing or after curing of the cement-based cured body.
Furthermore, this invention provides the cement-type hardened | cured material formed by the surface layer impregnating the said curing agent from the surface.

  The curing agent of the present invention can prevent moisture dissipation at the early age and can effectively improve the compressive strength by effectively hydrating the cement. Moreover, by improving the adhesion strength, which has been a problem in the past, it is possible to easily apply a finish without removing the curing agent, and to reduce drying shrinkage and improve durability. It becomes possible.

  The curing agent of the present invention contains paraffin and a lower alcohol alkylene oxide adduct, and the paraffin is known as paraffin wax, that is, paraffin that is solid at room temperature (25 ° C.), That is, what is also called petroleum wax is preferable. As a specific example, the same paraffin wax as that contained in “Master Cure” manufactured by BASF Pozzolith, “Procure” manufactured by Knox, or the like is preferable.

The curing agent of the present invention is an emulsion type, in which paraffin particles are emulsified in water. Moreover, it is important that the average particle diameter of the paraffin particles emulsified in water is 0.85 μm or less from the viewpoint of improving the adhesion strength between the cement cement surface and the finishing material. Regarding the adhesive strength of cement-based hardened bodies, there are various standards depending on the materials used, the environment used, the materials used, etc., and it cannot be generally specified, but as a typical specification, the common specifications for construction work (Ministry of Land, Infrastructure, Transport and Tourism Minister's Secretariat Office) 1.0N / mm ² or more is specified in the Supervision of the Maintenance Department), and if it is 1.0N / mm ² or more, most standards will be satisfied, and if it is 1.0N / mm ² or more, it will be implemented If there is no problem, the adhesion strength is sufficient. Therefore, when the average particle diameter at which an adhesion strength of 1.0 N / mm ² or more was obtained was examined, it was 0.85 μm or less. If the average particle diameter of the paraffin particles in the emulsion exceeds 0.85 μm, sufficient adhesion strength cannot be obtained. More preferably, it is 0.8 micrometer or less, More preferably, it is 0.1-0.8 micrometer, Most preferably, it is 0.2-0.8 micrometer.
The average particle size of the emulsified paraffin particles is measured with a laser diffraction particle size distribution analyzer, for example, SALD-2100 (manufactured by Shimadzu Corporation). From this measurement result, 10% passage diameter (D10), 50% passage diameter ( D50: average particle diameter) and 90% passage diameter (D90) were calculated.

  Further, the particle size distribution of the paraffin particles of the curing agent of the present invention is preferably 20% or less, particularly preferably 10% or less, for particles of 2 μm or more. The total particle size distribution is preferably 0.05 to 3 μm, particularly preferably 0.05 to 2 μm.

  The average particle diameter of the paraffin emulsified particles in the curing agent of the present invention can be adjusted by adding paraffin and an emulsifier to water and stirring vigorously. As the emulsifier, any emulsifier known in the art that exhibits a predetermined emulsification effect can be used. For example, a cationic surfactant, an anionic surfactant or a nonionic surfactant can be used. Examples of such surfactants include sucrose fatty acid ester, polyoxyethylene hydrogenated castor oil, sorbitan monostearate, polysorbate, glyceryl monostearate, sodium lauryl sulfate, lauromacrogol, and nonionic coconut oil fatty acid triethanolamine. Although it can be used, it is not limited to these, and any one of these can be used, or two or more can be used in combination. Here, the content of the emulsifier is preferably 0.001 to 10% by weight, particularly 0.01 to 5% by weight in the curing agent.

  The content of paraffin in the curing agent of the present invention is preferably 5 to 30% by weight. If the paraffin to be emulsified is less than 5% by weight, it is difficult to prevent the escape of initial moisture as a curing agent. On the other hand, if it exceeds 30% by weight, poor curing occurs and the adhesion strength decreases. Because of concern, 5 to 30% by weight, more preferably 5 to 20% by weight is desirable. Moreover, about what exceeds 30 weight%, it can be used by making it 30 weight% or less by water dilution.

The lower alcohol alkylene oxide adduct used in the curing agent of the present invention is known as a shrinkage reducing agent, and preferably has a lower alcohol alkylene oxide adduct as a main component.
Here, as a lower alcohol, C1-C6 alcohol is preferable and methanol, ethanol, isopropanol, n-propanol, n-butanol, etc. are more preferable.
Examples of the alkylene oxide adduct include an ethylene oxide adduct, a propylene oxide adduct, and an ethylene oxide-propylene oxide adduct. The number of moles of alkylene oxide added is preferably 1 to 300, more preferably 30 to 200.
As a specific example of the lower alcohol alkylene oxide adduct, the same shrinkage reducing agent as that contained in "Pacific Tetragard AS21" manufactured by Taiheiyo Materials Co., Ltd. is preferable.

  The content of the lower alcohol alkylene oxide adduct in the curing agent of the present invention is 10 to 30% by weight. When the lower alcohol alkylene oxide adduct is less than 10% by weight, it is difficult to obtain a shrinkage reduction effect. On the other hand, when it exceeds 30% by weight, there is a concern about poor curing. % By weight is desirable.

  The curing agent of the present invention preferably contains an antifoaming agent in order to prevent air entrainment in the concrete when the curing agent is sprayed during rough finishing. Examples of antifoaming agents include mineral oils, ethers, and silicones, but are not limited to these, and any one of these may be used, or two or more may be used in combination. You can also The property may be liquid or powder. The content of the antifoaming agent is preferably 0.02 to 1% by weight, particularly 0.03 to 0.8% by weight as a solid content in the curing agent.

  The curing agent of the present invention is not particularly limited to contain any of the components other than the main components, paraffin, emulsifier, the shrinkage reducing agent, antifoaming agent and water, as long as the effects of the present invention are not hindered. Absent. The water content is preferably 40 to 85% by weight, particularly 50 to 75% by weight in the curing agent.

  The curing agent of the present invention may be applied to the surface of the cement-based cured body at the time of finishing or after curing the cement-based cured body (cement mortar or concrete cured body). Specifically, it can be applied to the cured body as a finishing aid when finishing the cement-based cured body, or after curing and demolding of the cement-based cured body. The construction method is not particularly limited as long as it can be applied uniformly, and can be performed by spraying, coating, spraying, spraying, or the like.

The amount of the curing agent of the present invention is not particularly limited, it is preferably used in a range of 1 m ² per 50 to 300 g. It is more preferable to use in the range of 100 to 200 g per 1 m ² . If it is less than 50 g, it is difficult to obtain smooth trowel leveling and moisture dissipation prevention effects at the time of finishing, and if it exceeds 300 g, there is a concern that the adhesive strength will be reduced by an excessive amount. Moreover, both mortar and concrete are included as a cementitious hardened | cured material used as object.

  EXAMPLES Hereinafter, although an Example and a test example demonstrate this invention further in detail, this invention is not restrict | limited at all to the following Example and test example.

<Materials used>
Cement C: Hayashi Portland Cement, Taiheiyo Cement Fine Aggregate S: Mountain sand from Shizuoka Prefecture, surface dry density 2.61 g / cm ³ , water absorption 1.66%
Coarse aggregate G: Ibaraki prefecture crushed stone, coarse aggregate maximum size 20 mm, surface dry density 2.64 g / cm ³ , water absorption 0.67%
AE water reducing agent Ad: (trade name) Pozzolith 70, manufactured by BASF Pozzolith, a complex of lignin sulfonic acid compound and polyol Paraffin A: (main component) Average particle diameter of paraffin wax, emulsified paraffin 0.44 μm
Paraffin B: (main component) paraffin wax, emulsified paraffin average particle diameter 0.85 μm
Paraffin C: (trade name) Master Cure, manufactured by BASF Pozzolith, (main component) paraffin wax, average particle size 0.90 μm
Paraffin D: (main component) paraffin wax, average particle diameter of emulsified paraffin 1.28 μm
Lower alcohol alkylene oxide adduct: Shrinkage reducing agent, (trade name) Taiheiyo Tetragard AS21, manufactured by Taiheiyo Materials Co., Ltd.

  Curing agents A, B, and D were mainly emulsified with paraffin wax and an anionic emulsifier. The particle size of the emulsified paraffin was measured using a laser diffraction particle size distribution analyzer (SALD-2100) manufactured by Shimadzu Corporation having a measurement range of 0.005 μm to 1000 μm. 10% passage diameter (D10) and 90% passage diameter (D90) simply showing the particle size distribution of each of the curing agents represented by the average particle diameter are the curing agent A (D10 = 0.332, D90 = 0.571). Curing Agent B (D10 = 0.563, D90 = 1.146), Curing Agent D (D10 = 0.816, D90 = 1.864). The conditions other than the particle size of the emulsified paraffin are exactly the same.

The concrete shown in Table 1 was manufactured in a constant temperature and humidity chamber at a temperature of 20 ° C. and a relative humidity of 80%, and a cylindrical specimen of φ10 × 20 cm, a prismatic specimen of 10 × 10 × 40 cm, and a flat specimen of 500 × 500 × 50 mm. Produced. The mold was removed 24 hours after placing the concrete, and 150 g / m ³ of a predetermined curing agent was applied to the entire surface of the test body at a level other than uncoated. Thereafter, the specimen was exposed to a constant temperature and humidity chamber at a temperature of 20 ° C. and a relative humidity of 60%. A cylindrical specimen having a diameter of 10 × 20 cm was tested for compressive strength at a material age of 28 days, and a prismatic specimen having a diameter of 10 × 10 × 40 cm was 91 days of age. The flat plate specimen having a length change rate of 500 × 500 × 50 mm was subjected to an adhesion strength test. A 500 × 500 × 50 mm flat plate test specimen was stored in the same temperature and humidity chamber until the age of 39 days, and an as-rubber adhesive was applied as a finishing material for an adhesion test. On the next day, an adhesion test was conducted in accordance with the test method of JIS A 6916 “Preparation base coat for finishing application”.

  As shown in Table 3, the compressive strength developability of the concrete coated with the curing agent was better than that in the air curing, although it did not reach the uncoated underwater curing. Adhesion tests showed that sufficient adhesion strength was not obtained with existing paraffin-based curing agents and curing agents with a large average particle size, whereas high adhesion strength was obtained with curing agents with a smaller average particle size than existing paraffin-based curing agents. was gotten. The fracture shape of the bond strength is such that the existing paraffinic curing agent and the curing agent with a large average particle diameter destroyed the interface between the curing agent and the finishing material, but the curing agent with a small average particle diameter locally Destruction was recognized, and the foundation fracture of the concrete accounted for the majority, and sufficient adhesion strength was obtained. When the curing agent of the present invention was used, the drying shrinkage ratio was smaller than that of the existing paraffinic curing agent and the curing agent having a large average particle diameter. The curing agent containing 30% by weight or more of the shrinkage reducing agent had a low drying shrinkage ratio, but a partial but poor hardening was observed on the surface of the concrete specimen, and the adhesion strength was lowered due to the influence. .

As shown in Table 4, a flat specimen of 500 × 500 × 50 mm was produced outdoors at a temperature of 33 ° C. and a relative humidity of 80%. After placing the concrete, 150 g / m ³ of a predetermined curing agent was applied to each test specimen at a level other than uncoated, and the finish was evaluated. The finish is No. Evaluation was based on 6. No. Compared with No. 6, it has less force when finishing the concrete surface with a trowel, and it can be easily made a smooth surface with ◎. X, No. 6 which requires more force when finishing compared to No. 6 and difficult to make a smooth surface. The thing equivalent to 6 was evaluated by ○. As a result, a curing agent containing curing agent B containing paraffin having a particle diameter of 0.85 μm or less and a lower alcohol alkylene oxide adduct of 10 to 30% by weight had the most excellent finish.

Claims (6)

  A cement mortar or concrete emulsion type curing agent containing 10 to 30% by weight of a lower alcohol alkylene oxide adduct and paraffin having an average particle size of 0.85 µm or less.   The curing agent according to claim 1, wherein the content of paraffin having an average particle size of 0.85 µm or less is 5 to 30% by weight.   The curing agent according to claim 1 or 2, which is applied to a cement mortar or concrete surface at the time of rough finishing and / or iron finishing.   The curing agent according to any one of claims 1 to 3, further comprising an antifoaming agent.   A cement-based cured product obtained by impregnating a surface layer from the surface with the curing agent according to claim 1.   A curing method for cement mortar or concrete, wherein the curing agent according to any one of claims 1 to 4 is applied to the surface of the cement-based cured body at the time of finishing or curing the cement-based cured body.