JP4937520B2 - Cement admixture, cement composition, and cement mortar using the same - Google Patents

Description

  The present invention relates to a cement admixture, a cement composition, and a cement mortar using the cement admixture, particularly a cement admixture excellent in electrical conductivity, a cement composition for use in an anticorrosion method for a concrete structure, and the same. It relates to the cement mortar used.

  When the reinforcing bar in the concrete structure exceeds a certain amount of salinity, the non-conductive film formed on the reinforcing bar surface is destroyed and the corrosion progresses, and the concrete is destroyed by the expansion pressure of the rust generated on the reinforcing bar, Cracks, floats, flaking of concrete pieces, etc. occur.

Currently, there is a cathodic protection method as means for preventing such corrosion of reinforcing bars (see Non-Patent Document 1).
This method is a method in which an anticorrosive current is passed from the concrete surface to the internal reinforcing bars, and the reinforcing bars in the concrete must be used as cathodes, and the anode that is the counter electrode of the reinforcing bars must be installed on the concrete surface.

As the anode installation method, titanium mesh anode method, panel anode method, conductive paint method, titanium spraying method, titanium zinc spraying method, titanium ribbon mesh anode method, titanium grid method, titanium rod method, zinc sheet method, zinc- There are an aluminum pseudo-alloy spraying method and a conductive mortar method (see Non-Patent Document 1).
Among them, the conductive mortar method is adopted because it is less expensive than other anode installation methods and is easy to install.

  Conventionally, mortar containing carbon fiber is known as conductive mortar used by a conductive mortar system (refer to patent documents 1-3).

  On the other hand, conductive polymers are used in electrical and electronic fields such as batteries, capacitors, paints, antistatic materials, organic EL light-emitting materials, electromagnetic wave shields, and printed boards, but are not used in cement concrete. Absent.

Edited by the Japan Society of Civil Engineers' Concrete Committee Electrochemical Repair Method Research Subcommittee, Electrochemical Protection Method Design Guidelines (Draft), Electrocorrosion Method Design and Construction Manual, pp55-116, 2001 Japanese Patent Application Laid-Open No. 07-206502 Japanese Patent No. 2550093 Japanese Patent No. 2624269

In order to give sufficient conductivity in the conductive mortar, it is necessary to mix a relatively large amount of carbon fibers, and there is a problem in the mixing property when mixing.
If the amount of carbon fiber added is increased, fiber balls may be formed, the fresh properties of the mortar may be hindered, and workability may be deteriorated.
Furthermore, the surface of the mortar mixed with fibers may become fuzzy and the finish may be poor. For this reason, it is preferable in terms of aesthetics and workability to mix the fibers as little as possible or to prepare the conductive mortar with a small addition amount.
In addition, the carbon fiber is difficult to uniformly disperse in the mortar, and there is a problem that the current does not flow uniformly.

  As a result of intensive studies to solve the above problems, the present inventor obtained the knowledge that a cement mortar suitable for an anticorrosion construction method can be obtained by using a cement composition containing a conductive polymer, The present invention has been completed.

The present invention provides a heteroatom-containing conductive polymer of polypyrroles, polyanilines, polythiophenes, and polythienylene vinylenes, polyacetylenes, polyazulenes, polyphenylenes, polyphenylene vinylenes, polyacenes, polyphenylacetylenes, and Conductive polymer selected from hydrocarbon-based conductive polymers of polydiacetylene, fibrous clay mineral , and fiber, the fiber length is 0.2-20mm, the amount of fiber used is cement mortar against 1 m ^3, 0.1 to 1 parts by volume in the case of non-convergence type, if the convergence type is 0.03 to 0.5 parts by volume der Rousset instrument admixture for cement specified in JIS a 6203 A non-conductive polymer that is a polymer, and the amount of non-conductive polymer used is 0.5 to 20 parts per 100 parts of cement. A said cement admixture, a cement composition comprising a cement and the cement admixture, a cement mortar composed using the cement composition.

  The cement composition of the present invention exhibits excellent electrical conductivity, and by using it, it is possible to construct cement mortar with excellent aesthetics and workability, and the construction speed is increased, and the current is evenly supplied. An anti-corrosion method that can be flowed becomes possible.

Hereinafter, the present invention will be described in detail.
Unless otherwise specified, parts and% in the present invention are shown on a mass basis.
The cement mortar of the present invention is a general term for cement paste, mortar, and concrete.

The conductive polymer used in the present invention is a heteroatom-containing conductive polymer such as polypyrroles, polyanilines, polythiophenes, and polythienylene vinylenes, polyacetylenes, polyazulenes, polyphenylenes, polyphenylene vinylenes, polyacene. , Hydrocarbon-based conductive polymers such as polyphenylacetylenes and polydiacetylenes. These conductive polymers can be used in either a powder form or a dispersion in which water is dispersed. Of these, use of polythiophenes exhibiting relatively high conductivity is preferable.
The amount of the conductive polymer used is preferably 0.1 to 20 parts, more preferably 0.5 to 10 parts, relative to 100 parts of cement. If it is less than 0.1 part, it may be difficult to impart conductivity to the cement mortar, and if it exceeds 20 parts, the strength of the cement mortar may be lowered.

The fibrous clay mineral used in the present invention is used to prevent dripping of cement mortar, and examples thereof include sepiolite, attapulgite, and wollastonite.
The fiber length of the fibrous clay mineral is not particularly limited as long as it does not adversely affect the fluidity and workability of the blended cement mortar, but usually 1 to 10 μm can be used.
The amount of fibrous clay mineral used is preferably 0.1 to 10 parts, more preferably 0.3 to 5 parts, per 100 parts of cement. If it is less than 0.1 part, it may be difficult to reduce dripping, and if it exceeds 10 parts, the fluidity of cement mortar may be hindered.

  The cement used in the present invention is not particularly limited, but various portland cements defined in JIS R 5210, various mixed cements defined in JIS R 5211, JIS R 5212, and JIS R 5213, In addition, one or two or more types selected from the group consisting of blast furnace cement, fly ash cement, silica cement, limestone powder mixed with blast furnace cement, fly ash cement manufactured at the above admixture ratio specified in JIS may be mentioned.

The fibers used in the present invention include a convergence type bundled with an adhesive and a non-convergence type in which the fibers are separated one by one, reducing dripping and cracking of cement mortar, and supplementing conductivity. It is used for the purpose of doing.
Examples of the fiber include, but are not particularly limited to, polymer fibers represented by vinylon fibers and propylene fibers, steel fibers, glass fibers, and inorganic fibers represented by carbon fibers.
The length of the fiber is preferably 0.2 to 20 mm in consideration of the mixing property for both the convergence type and the non-convergence type. If it is less than 0.2 mm, the effect of reducing sagging and cracking may be small. If it exceeds 20 mm, it is difficult to disperse uniformly during kneading, and fluffing may be noticeable when finishing the iron.
In the case of a non-converging type, the amount of fiber used is preferably 0.1 to 1 part by volume, more preferably 0.2 to 0.5 part by volume with respect to 1 m ^{3 of} cement mortar. If the amount is less than 0.1 part by volume, the effect of improving sagging and cracking resistance may be small. If the amount exceeds 1 part by volume, the fluidity of cement mortar may be adversely affected. Moreover, in the case of a convergence type, 0.03-0.5 volume part is preferable and 0.05-0.3 volume part is more preferable. If the amount is less than 0.03 part by volume, the effect of improving sagging and cracking resistance may be small, and if it exceeds 0.5 part by volume, the fluidity may be deteriorated.

The non-conductive polymer used in the present invention is a polymer for cement admixture specified in JIS A 6203, and is a polymer that has been generally used as an admixture for cement from the past. It is used for the purpose of improving durability such as salt damage and frost damage. For example, rubber latex such as acrylonitrile-butadiene rubber, styrene-butadiene rubber, chloroprene rubber, and natural rubber, ethylene-vinyl acetate copolymer, polyacrylate ester copolymer, vinyl acetate vinyl versatate copolymer, styrene -Synthetic resin emulsions such as acrylic acid ester copolymers, and liquid polymers typified by epoxy resins and unsaturated polyester resins can be used, and one or a mixture of two or more of these can also be used.
The amount of the non-conductive polymer used is preferably 0.5 to 20 parts, more preferably 2 to 10 parts with respect to 100 parts of cement. If the amount is less than 0.5 part, it may be difficult to improve the durability. If the amount exceeds 20 parts, the conductive effect may be lost even when used in combination with a conductive polymer.

In the present invention, it is preferable to use an electron donor in combination with cement mortar containing a conductive polymer because the conductivity can be further improved.
Examples of the electron donor include halogens such as chlorine, bromine, iodine, and compounds thereof, and Lewis acids such as phosphorus pentafluoride, arsenic pentafluoride, and antimony pentafluoride.

  The cement mortar of the present invention has an AE agent, a water reducing agent, an AE water reducing agent, a fluidizing agent, a high performance AE water reducing agent, a separation reducing agent, a foaming agent, a setting accelerator, and a setting retarder as long as the quality is not adversely affected It is possible to use various additives such as a rust inhibitor, an antifreeze agent, a shrinkage reducing agent, a waterproof agent, and an antibacterial agent.

  The cement composition of the present invention can be mixed with water and used as a paste containing no aggregate, or can be used as mortar or concrete containing aggregate.

  The method of constructing the cement composition of the present invention may be applied with a mortar that has been kneaded with a mixer with a trowel, may be filled into a mold, and may be blown off using compressed air. It is also possible to construct with.

Experimental example 1
To 100 parts of cement, add 200 parts of aggregate, 0.5 parts of fibrous clay mineral, and the conductive polymer shown in Table 1, and add water to 50 parts of 100 parts of cement, and add mortar. Prepared and conducted a conductivity test and a compressive strength test. The results are also shown in Table 1.

<Materials used>
Cement: Ordinary Portland cement, commercially available aggregate: Dry lime sand from Aomi, Niigata Prefecture, maximum particle size 1.2mm
Conductive polymer A: polyethylene oxydioxythiophene aqueous dispersion, solid content 1.2%, commercially available conductive polymer B: polypyrrole commercially available fibrous clay mineral a: attapulgite, commercially available

<Measurement method>
Resistivity: Conductivity test, kneaded mortar is molded into 4x4x16cm, embedded with aluminum electrodes, and then cured for 28 days at 20 ° C and 60% humidity. Calculate the resistivity of the specimen 28 days of age using an impedance measurement device from the equation: resistivity (Ω · cm) = (resistance × electrode area) / distance between electrodes. Compressive strength: compressive strength test, kneading Molded mortar into 4x4x16cm and measured according to JIS R 5201

Experimental example 2
200 parts of aggregate, 0.5 parts of conductive polymer A, and fibrous clay mineral shown in Table 2 are added to 100 parts of cement, and water is further added to 50 parts of 100 parts of cement. Mortar was prepared, and a flow test, a conductivity test, a compressive strength test, a sag test, and a thick coat test were performed. The results are also shown in Table 2.

<Materials used>
Fibrous clay mineral b: Sepiolite, commercial product Fibrous clay mineral c: Wollastonite, commercial product

<Measurement method>
Flow: Flow test, measurement according to JIS R 5201: Sag test: After applying a mortar to a 10mm thickness x 150mm x 250mm width mold using a concrete flat plate as the foundation, The frame was removed, and a flat plate was set up vertically.
Thick coatability: Thick coatability test, applied to a concrete flat plate 30cm long x 30cm wide x 6cm thick and sandblasted on the ceiling surface with a trowel to a thickness of 40mm, one day later The state was observed, and if there was a float or flaking, it was impossible.

Experimental example 3
The fibers shown in Table 3 were added to 1 m ^{3 of} mortar using 0.5 part of conductive polymer A per 100 parts of cement, and the conductivity test, compressive strength test, sagging test, and thick coat test were performed. Except for this, the same procedure as in Experimental Example 1 was performed. The results are also shown in Table 3.

<Materials used>
Fiber α: Carbon fiber, fiber length 6 mm, fiber diameter 0.2 mm, non-convergent type, commercially available fiber β: Vinylon fiber, fiber length 6 mm, fiber diameter 0.026 mm, convergent type, commercially available product

Experimental Example 4
The non-conductive polymer shown in Table 4 is added to 100 parts of cement in mortar using 0.5 part of conductive polymer A for 100 parts of cement, and the salt barrier test, conductivity test, and compressive strength test are performed. The same procedure as in Experimental Example 1 was performed except that the test was performed. The results are also shown in Table 4.

<Materials used>
Non-conductive polymer: Acrylic-vinyl acetate-vinyl versatic acid powder polymer

<Measurement method>
Salt penetration depth: Salt barrier test, compliant with JIS A 1171

Claims (4)

Heteroatom-containing conductive polymers such as polypyrroles, polyanilines, polythiophenes, and polythienylene vinylenes, and polyacetylenes, polyazulenes, polyphenylenes, polyphenylene vinylenes, polyacenes, polyphenylacetylenes, and polydiacetylenes. Conductive polymer selected from hydrocarbon-based conductive polymer, fibrous clay mineral, and fiber, the fiber length is 0.2 ~ 20mm, the amount of fiber used is 1m ^{3 of} cement mortar The cement admixture is characterized by 0.1 to 1 part by volume for the non-converging type and 0.03 to 0.5 part by volume for the converging type. It contains a non-conductive polymer that is a cement-mixing polymer specified in JIS A 6203, and the amount of non-conductive polymer used is 0.5 to 20 parts per 100 parts of cement. The cement admixture according to claim 1 . A cement composition comprising cement and the cement admixture according to claim 1 or 2 . A cement mortar using the cement composition according to claim 3 .