JP2023071565A - Fire-proof protected mortar and fire-proof protected structure - Google Patents

Abstract

To provide a fire-proof protected mortar capable of being used for civil engineering structures, the mortar: being difficult to explode even when subjected to a fireproof test using a RABT heating curve whose furnace temperature reaches 1,200°C in 5 minutes from the start of heating; having excellent consistency immediately after mixing; and having excellent integrity with a substrate, and to provide a fire-proof protected structure capable of being used for civil engineering structures, the structure: having excellent integrity with the fire-proof protected mortar; and being difficult to explode even when subjected to the fireproof test using the RABT heating curve whose furnace temperature reaches 1,200°C in 5 minutes from the start of heating.MEANS: In a fire-proof protected mortar, a specific fiber content, the amount of aggregate, the amount of cement polymer, and water content are each made in a specific proportion. When the fibers are dispersed in water, a fiber diameter thereof is 1 to 100 μm; the fiber content thereof is 0.05 to 1.0 vol.% with respect to the volume of the mortar; the amounts of aggregate and cement polymer are 80 to 300 pts.mass and 1 to 30 pts.mass, respectively, based on 100 pts.mass of a cement; and a water-cement ratio is 35% to 60%.SELECTED DRAWING: None

Description

The present invention relates to a refractory coating mortar. Specifically, the hardened mortar after kneading with water reaches 1200 ° C. in 5 minutes from the start of heating, is maintained at 1200 ° C. for 25 minutes, and then returns to room temperature in 110 minutes. RABT heating curve It is a fireproof coating mortar that does not easily explode even when a fire resistance test is performed by heating for 30 minutes (RABT 30 minutes heating) and has excellent consistency after kneading with water. The present invention also relates to fire resistant coating structures. More specifically, it relates to a fire-resistant coating structure that does not easily explode even when subjected to a fire-resistant test by heating RABT for 30 minutes.

When concrete or the like is exposed to high temperatures due to fire or the like, a phenomenon called "explosion" may occur in which the surface layer of the concrete is blown off due to tensile strain due to the pressure of water vapor generated inside the concrete and the restraint stress. A fire-resistant coating material (fire-resistant coating mortar) composed of an inorganic binding material containing hydraulic cement, an endothermic material, an inorganic lightweight aggregate, and an organic lightweight aggregate is disclosed in order to suppress the explosion of concrete. (For example, see Patent Document 1.). Also disclosed is an explosion-resistant cement mortar containing cement, water, cellulose fibers, a water-soluble polymer and various additives (materials), and a concrete coating method for coating the cement mortar (see, for example, Patent Document 2). ).

In conducting the fire resistance test, the heating curve of ISO834 (equivalent to the standard heating curve A of JIS A 1304:2017, hereinafter referred to as "ISO heating curve”). Prior to the revision of JIS A 1304 in 2017, in the fire resistance test of building structures, the heating curve (JIS A 1304 : Same as the standard heating curve B of 2017, hereinafter referred to as "old JIS heating curve"). On the other hand, civil engineering structures such as tunnels are often subjected to fire resistance tests using the RABT heating curve, in which the temperature inside the furnace reaches 1200° C. within 5 minutes from the start of heating. This is because a fire in a tank truck carrying petroleum products is assumed, which is a more severe condition than building structures. As a result of investigations by the inventors of the present application, it has been found that even mortar that does not explode in the fire resistance test using the ISO heating curve may explode in the fire resistance test using the RABT heating curve. In the fire resistance test, in Patent Document 1 (Japanese Patent Application Laid-Open No. 11-116357), the test is performed using the old JIS heating curve, and in Patent Document 2 (Japanese Patent Application Laid-Open No. 2004-331450), the test is performed using the ISO heating curve. ing.

JP-A-11-116357 Japanese Patent Application Laid-Open No. 2004-331450

An object of the present invention is to provide a fireproof coating mortar that can be used for civil engineering structures. More specifically, it is a refractory coated mortar that does not easily explode even when subjected to a fire resistance test according to the RABT heating curve, where the furnace temperature reaches 1200 ° C in 5 minutes from the start of heating, has excellent consistency immediately after kneading, and has excellent integration with the substrate. intended to provide Another object of the present invention is to provide a fireproof coating mortar that can be used for civil engineering structures, particularly concrete civil engineering structures. More specifically, concrete civil engineering that does not easily explode even when subjected to a fire resistance test according to the RABT heating curve where the furnace temperature reaches 1200 ° C in 5 minutes from the start of heating, has excellent consistency immediately after kneading, and is excellent in integration with the foundation. An object of the present invention is to provide a refractory coating mortar that can be used for structures. Another object of the present invention is to provide a fireproof covering structure that can be used for civil engineering structures. More specifically, it is intended to provide a fire-resistant coating structure that is excellent in the integrity of the fire-resistant coating mortar and the substrate, and that does not easily explode even in a fire-resistant test using the RABT heating curve, where the furnace temperature reaches 1200°C in 5 minutes from the start of heating. aim.

As a result of intensive studies to solve the above problems, the present inventors found that the above problems can be solved by setting the content of specific fibers, the amount of aggregate, the amount of polymer for cement, and the amount of water to be used to specific ratios. , completed the present invention. That is, the present invention is a fire-resistant coating mortar represented by (1) or (2) below, and a fire-resistant coating structure represented by (3).
(1) It contains cement, aggregates, fibers, and a polymer for cement, and the fiber diameter when the fibers are dispersed in water (the diameter of the fiber bundle when the fibers are dispersed in a converged state). ) is 1 to 100 μm, with respect to 100 parts by mass of cement, 80 to 300 parts by mass of aggregate, 1 to 30 parts by mass of cement polymer in terms of nonvolatile content at 105 ° C., and the content of fiber is Refractory coated mortar with a content of 0.05 to 1.0% by volume relative to the volume of the mortar and a water-cement ratio of 35 to 60%.
(2) The refractory coated mortar according to (1) above, wherein the fibers are organic fibers.
(3) A fire-resistant coating structure in which the surface of the structure is coated with the fire-resistant coating mortar of (1) or (2) above.

According to the present invention, a refractory coating mortar that can be used for civil engineering structures is obtained. According to the present invention, it is possible to obtain a refractory-coated mortar that does not easily explode even in a refractory test according to the RABT heating curve, where the furnace temperature reaches 1200° C. in 5 minutes from the start of heating, and that has excellent consistency after kneading.

Moreover, according to the present invention, a fireproof coating mortar that can be used for civil engineering structures, particularly concrete civil engineering structures, can be obtained. In addition, according to the present invention, since the consistency immediately after kneading is excellent, the integrity with the base is excellent, and the temperature inside the furnace reaches 1200 ° C. in 5 minutes from the start of heating. A refractory coating mortar that is difficult to explode is obtained.

Further, according to the present invention, a fireproof covering structure that can be used for civil engineering structures, particularly concrete civil engineering structures, is obtained. More specifically, a fire-resistant coating structure that does not easily explode even when subjected to a fire-resistant test according to the RABT heating curve, where the furnace temperature reaches 1200° C. in 5 minutes from the start of heating, can be obtained.

Containing cement, aggregate, fiber and polymer for cement, the fiber diameter when the fibers are dispersed in water (refers to the diameter of the fiber bundle when the fibers are dispersed in a converged state) is 1 ~100 μm, with respect to 100 parts by mass of cement, it contains 80 to 300 parts by mass of aggregate, 1 to 30 parts by mass of cement polymer in terms of non-volatile content at 105 ° C., and the content of organic fibers is that of mortar. It is characterized by a content of 0.05 to 1.0% by volume and a water-cement ratio of 35 to 60%.

The cement used in the present invention refers to an inorganic binder, and is preferably a hydraulic cement. Or various mixed cements that are made by mixing fly ash, blast furnace slag, silica fume or limestone fine powder with ecocement, Taiheiyo Cement Co., Ltd. “Super Jet Cement” (trade name), Sumitomo Osaka Cement Co., Ltd. “Jet Cement” (trade name) ) and other ultra-rapid hardening cements, alumina cements, etc., and one or more of these can be used. The cement used in the present invention also includes blast furnace slag powder, which is a latent hydraulic substance, alkali silicates such as sodium silicate and water glass, and those containing pozzolanic powder in these.

The aggregate used in the present invention is not particularly limited, and examples thereof include river sand, land sand, sea sand, crushed sand, silica sand, river gravel, land gravel, crushed stone, artificial aggregate, slag aggregate, recycled aggregate, and the like. It is preferable to use one or more of these. The content of the aggregate in the fireproof coating mortar composition of the present invention is 80 to 300 parts by mass with respect to 100 parts by mass of cement. If the amount is less than 80 parts by mass, the shrinkage after curing is large, especially when heated, and peeling easily occurs. . Since it is difficult for delamination and explosion to occur when exposed to high temperatures, it is preferable to use 100 to 280 parts by mass, more preferably 200 to 280 parts by mass, of the aggregate with respect to 100 parts by mass of cement. preferable.

The fibers used in the present invention have a fiber diameter of 1 to 100 μm when dispersed in water (the diameter of the fiber bundle when the fibers are dispersed in a bundled state). The fiber diameter when the fibers are dispersed in water refers to the diameter of the fiber bundle when the fibers are dispersed in water in a converged state. The fiber diameter when the fibers are dispersed in water is measured by measuring the fiber diameter (the diameter of the fiber bundle when the fibers are dispersed in a converged state) that appears in the field of view under a microscope while the fibers are dispersed in water. and use the average value. In order to make the fibers dispersed in water, 0.1 g of the fibers are put into 200 g of water in a glass beaker and stirred with a stirrer such as AS ONE's stirrer (trade name: AS ONE HIGH-POWER MIXER (Tornado)). , model number; STM-102), 400r. p. m. is preferably stirred for 5 minutes.
If the fiber diameter is less than 1 μm when the fibers are dispersed in water, a sufficient consistency cannot be obtained when kneaded with water. Further, if the fiber diameter exceeds 100 μm when the fibers are dispersed in water, the explosion tends to occur and it becomes difficult to stop.
As for the fibers used in the present invention, since sufficient consistency is easily obtained and explosion is unlikely to occur, the fiber diameter when the fibers are dispersed in water (the fiber diameter when the fibers are dispersed in a converged state is The diameter of the bundle) (hereinafter sometimes simply referred to as "fiber diameter") is preferably 10 to 60 µm, more preferably 20 to 50 µm.
In addition, when exposed to high temperatures, the fibers used in the present invention evaporate, disappear, or melt to form a path for water vapor, which makes it difficult for the mortar or underlying concrete to explode. Organic fibers are preferred.

The fiber content in the present invention is 0.05 to 1.0% by volume relative to the volume of the mortar (refractory coated mortar) of the present invention. It is preferable to make it 0.1 to 0.5% by volume based on the volume of the mortar because a sufficient consistency can be easily obtained and the mortar or the underlying concrete is unlikely to explode. When the amount of polymer for cement contained is 20 parts by mass or more per 100 parts by mass of cement in terms of non-volatile content at 105° C., the content of fibers in the present invention is the volume of the mortar (refractory coated mortar) of the present invention. From the viewpoint of explosion resistance, the content is preferably 0.3% by volume or more, more preferably 0.5% by volume or more. When fibers other than the above fibers (fibers with a fiber diameter of 1 to 100 μm) are included in the fibers, the content of the total fibers is 10% by volume or less, preferably 5% by volume or less, more preferably 1% by volume or less, Most preferably, it does not contain fibers other than the above fibers.

The polymer for cement used in the present invention may be any one that can be used as a binder for polymer cement mortar or polymer cement concrete. Synthetic rubber such as methacrylate/butadiene copolymer, natural rubber, polyolefin such as polyethylene and polypropylene, polychloropyrene, polyacrylate, styrene/acrylic copolymer, all-acrylic copolymer, polyvinyl acetate, vinyl acetate/acryl Copolymers, vinyl acetate/acrylic acid ester copolymers, modified vinyl acetate, ethylene/vinyl acetate copolymers, ethylene/vinyl acetate/vinyl chloride copolymers, vinyl acetate vinyl versatate copolymers, acrylic/vinyl acetate・Vinyl acetate resins such as VEOVA (trade name of vinyl t-decanoate) copolymer, synthetic resins such as unsaturated polyester resins, polyurethane resins, alkyd resins and epoxy resins, bituminous substances such as asphalt, rubber asphalt and paraffin etc. are mentioned as preferable examples, and one or more of these can be used. Polymers for cement used in the present invention include polyvinyl acetate, vinyl acetate-acrylic copolymer, vinyl acetate-acrylic acid ester copolymer, modified vinyl acetate, ethylene-acetic acid, and ethylene-acetic acid. Vinyl acetate resins such as vinyl copolymer, ethylene/vinyl acetate/vinyl chloride copolymer, vinyl acetate vinyl versatate copolymer, acrylic/vinyl acetate/Veova (trade name of vinyl t-decanoate) copolymer Acrylic resins such as polyacrylates, polymethacrylates, acrylic acid ester/styrene copolymers, styrene/acrylic copolymers, and all-acrylic copolymers; Polyolefin resins such as polyethylene and polypropylene; Styrene/butadiene It is preferable to use one or more selected from synthetic rubbers such as copolymers, chloroprene rubbers, acrylonitrile-butadiene copolymers and methyl methacrylate-butadiene copolymers. The polymer for cement used in the present invention may be in the form of a liquid, an emulsion, or a re-emulsified powdered resin obtained by pulverizing an emulsion.

The content of the polymer for cement in the fireproof coating mortar of the present invention is 1 to 30 parts by weight per 100 parts by weight of cement in terms of non-volatile content (hereinafter referred to as "solid content") at 105°C. If the content is less than 1 part by mass, the coating mortar has a low adhesion to the substrate and is therefore easily peeled off. On the other hand, if the amount exceeds 30 parts by mass, the viscosity of the mortar is too high, making it difficult to coat the substrate and easily resulting in defective construction. When coated on the base (surface of the structure), it has a large adhesive force with the base, does not easily peel off, does not easily explode, and is easy to coat the base and does not cause poor construction. The content of the polymer for cement is preferably 2 to 25 parts by mass, more preferably 10 to 20 parts by mass, more preferably 15 to 20 parts by mass in terms of solid content, based on 100 parts by mass of cement. is most preferred.

The refractory coating mortar of the present invention contains water in such an amount that the water-cement ratio (W/C) is 35-60%. If the amount of water contained is less than the amount at which W/C is 35%, the consistency of the mortar immediately after kneading cannot be obtained, and it is difficult to coat the substrate, resulting in poor construction. Also, if the amount of water contained is larger than the W/C ratio of 60%, the shrinkage after curing is large, especially when heated, and/or the adhesion to the substrate is small, so that when the coating mortar is formed, the Delamination is likely to occur and explosion is likely to occur. In the refractory coating mortar of the present invention, the amount of water contained is preferably W/C 40 to 55%, because the consistency of the mortar immediately after kneading can be easily obtained and explosion is unlikely to occur.

In the refractory coating mortar of the present invention, in addition to cement, cement polymers and aggregates, one or more of other admixtures can be used in combination within a range that does not impair the effects of the present invention. Such admixtures include, for example, water reducing agents such as high performance water reducing agents and high performance AE water reducing agents, setting retarders, foaming agents, foaming agents, waterproofing materials (agents), rust inhibitors, shrinkage reducing agents, thickeners, Viscous agents, pigments, antifoaming agents, swelling agents, water repellents, anti-efflorescence agents, quick setting agents (materials), curing accelerators (materials), strength accelerators (materials), surface curing agents and the like.

The refractory coating mortar of the present invention can be premixed mortar in the form of powder or granules, in which part or all of the materials other than water and the liquid admixture are dry-mixed in advance. By simply weighing and kneading the premixed mortar and a predetermined amount of water, or a mixture of water and an aqueous solution and/or emulsion, the mortar can be immediately used as the refractory coating mortar of the present invention. When making a premixed mortar including a polymer for cement among the ingredients of the refractory coating mortar of the present invention, the fact that the polymer for cement used is a re-emulsified powdered resin deteriorates the performance of the premixed mortar for about half a year. It is preferable because the fireproof coating mortar of the present invention can be produced by kneading water and the premixed mortar with a mixer or the like.

The method of premixing some of the ingredients of the fireproof coating mortar of the present invention is not limited, and includes gravity mixers such as V-type mixers and tilting concrete mixers, Henschel mixers, injection mixers, ribbon mixers, and paddles. A mixer or the like can be used. When the fireproof coating mortar of the present invention contains a lightweight aggregate as an aggregate, it can be used when premixing a ribbon mixer or a paddle mixer to maintain the shape and quality of the lightweight aggregate. preferable. Alternatively, the fireproof coating mortar (part thereof) of the present invention can be premixed by a method of weighing and charging each material directly into a container such as a bag or polyethylene container.

It is preferable to use a mixer for kneading (manufacturing) the fireproof coating mortar of the present invention, because a large amount can be uniformly kneaded in a short time. A mixer that can be used may be a continuous mixer or a batch mixer, and examples thereof include a pan concrete mixer, a pug mill concrete mixer, a gravity concrete mixer, a grout mixer, a hand mixer, and a plastering mixer. In addition, a part of the premixed fireproof coating mortar of the present invention is pneumatically fed, and water and / or an admixture containing water are added in the middle of pneumatic feeding and then mixed (confluence mixing). The refractory coating mortar of the present invention can also be produced.

The fireproof coating structure is characterized in that the surface of the structure is coated with the fireproof coating mortar. The method of coating the surface of the structure with the refractory coating mortar is not particularly limited, and a conventional method can be used. For example, plastering methods such as painting with a trowel, spraying methods such as mortar spraying, methods combining plastering methods and spraying methods, placing a formwork on the surface of the structure and filling the gap between the surface of the structure and the formwork A suitable example is a method of Before coating the surface of the structure (substrate surface), or the concrete surface that will be the substrate when the structure is a concrete structure, with the fireproof coating mortar, apply synthetic rubber, natural rubber, vinyl acetate resin, or acrylic to the substrate surface. A water absorption adjusting material made of a synthetic resin such as a base resin or a primer may be applied.

[Example 1]
<Measurement of fiber diameter>
0.1 g of organic fiber was added to 200 g of water in a glass beaker, and stirred at 400 r.p.m. p. m. The organic fibers were dispersed in the water by stirring for 5 minutes at . The water in which the organic fibers were dispersed was placed on a slide and observed under a microscope. The fiber diameter of the fibers within the field of view of the microscope was measured. For the fibers converging at this time, the width of the fiber bundle, that is, the diameter of the fiber bundle was measured, and the average value was obtained.
The following two kinds of fibers were used as the organic fibers.
- Fiber 1: Nylon fiber - Fiber 2: Polypropylene fiber Table 1 shows the measurement results of the fiber diameter.

A mortar having the composition shown in Table 2 was prepared using the organic fibers and the materials shown below.
<Materials used>
・Cement: Ordinary Portland cement ・Aggregate: Silica sand (absolute dry density 2.64 g/cm ³ , water absorption 0.3%)
・Cement polymer: Acrylic re-emulsified powder resin ・Water: Sakura city water supply, Chiba prefecture

The following quality evaluation tests were performed on the prepared mortar. Table 3 shows the test results.
<Flow test>
JIS R 5201 "Physical Test Method for Cement" immediately after kneading 11. A flow value (with falling motion) (hereinafter referred to as "flow value") was measured according to the flow test.
<Compressive strength test>
According to JIS A 1171: 2016 "Testing methods for polymer cement mortar" 7.3 Flexural strength and compressive strength test, the compressive strength (compressive strength) at the age of 28 days was measured.
<Adhesion strength test>
According to JIS A 1171: 2016 "Testing method for polymer cement mortar" 7.4 Adhesion strength test, adhesion strength (adhesion strength) was measured at 28 days of material age.
The results of the adhesion strength test are evaluated as “excellent” when the adhesion strength (adhesion strength) is 1 N/mm ² or more and the fracture rate of the test piece is 50% or more inside the base (mortar substrate). Symbol: ○)”, and when the bond strength (adhesive strength) is less than 1 N/mm ² or the fracture rate of the test piece is less than 50% inside the base (mortar substrate), it is “defective (symbol: × )”.
<Unit volume mass>
The unit volume mass immediately after kneading was measured according to JIS A 1171: 2016 "Testing methods for polymer cement mortar" 6.4 Unit volume mass test.
<Explosion test>
An explosion test was conducted according to JCI-S-014-2018 "Concrete Explosion Test Method-Ring Restraint Specimen Method (A Method)-" (including Annex A) of the Japan Concrete Institute. The heating curve used is the RABT heating curve (RABT 30 minutes heating) (notation: RABT 30) and the ISO heating curve (heating time 60 minutes, hereinafter referred to as "ISO 60 minutes heating" (notation: ISO834).) Explosion test (heating test ) was performed.
The results of the explosion test were evaluated as "excellent (symbol: ◎)" when no explosion occurred, "good (symbol: ○)" when the explosion stopped halfway, and "bad" when the explosion did not stop. (Symbol: x)”.

Formulation No. corresponding to an example of the present invention. The mortars of 5 and 7 have excellent consistency (flow value) of 150 (mm) or more immediately after kneading, are easy to apply to the substrate, and have excellent compressive strength of 30 MPa (N/mm ² ) or more. It was a fire-resistant coating mortar because it was excellent in adhesion and integrity with the substrate, and also excellent in the results of the explosion test (explosion resistance). In particular, formulation No. 1, in which the content of the polymer for cement is 15 to 25 parts by mass per 100 parts by mass of cement in terms of solid content. The mortar No. 7 had an excellent consistency (flow value) of 180 (mm) or more immediately after kneading, was easy to apply to the substrate, and had excellent results in the explosion test (explosion resistance). Moreover, formulation No. The mortars of Nos. 5 and 7 do not easily explode even when subjected to a fire resistance test by RABT heating for 30 minutes using a RABT heating curve in which the furnace temperature reaches 1200°C in 5 minutes from the start of heating, so they can be used for civil engineering structures. It had the performance of coating mortar.

It is possible to obtain a fire-resistant coating mortar that is excellent in integration with the substrate and does not easily explode even when a fire resistance test is performed, and it is possible to obtain a coating structure that is excellent in integration between the fire-resistant coating mortar and the substrate and has excellent explosion resistance. , can be suitably used for civil engineering structures and building structures that require fire resistance.

Claims (3)

Containing cement, aggregate, fiber and polymer for cement, the fiber diameter when the fibers are dispersed in water (refers to the diameter of the fiber bundle when the fibers are dispersed in a converged state) is 1 ~100 μm, 80 to 300 parts by mass of aggregate per 100 parts by mass of cement, 1 to 30 parts by mass of cement polymer in terms of non-volatile content at 105 ° C., and the content of fibers is kneaded with water. A refractory coating mortar with a water-cement ratio of 35-60% with a volume percentage of 0.05-1.0% relative to the volume of the mortar afterward. 2. The refractory coating mortar according to claim 1, wherein said fibers are organic fibers. A fire-resistant coating structure in which the surface of the structure is coated with the fire-resistant coating mortar according to claim 1 or 2.