JPH0925151A - Primer composition for underwater curing resin concrete and underwater curing resin mortal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a primer composition for improving the adhesive strength to a base concrete at the time of constructing or repairing an underwater concrete structure by placing a resin mortal or a resin concrete on the base concrete in underwater. SOLUTION: This primer composition for the resin concrete or the resin mortal is a cement paste consisting of Portland cement, a cellulose based underwater inseparable concrete admixture, a fluidizing agent and water, and the cellulose based underwater inseparable concrete admixture is blended thereto by 0.3-3wt.% based on the total quantity of water and the fluidizing agent and the initial setting time is 30min to 8hr. The primer composition is used as the primer for repairing the underwater structure by placing the resin concrete or the resin mortal on the surface of a cement concrete or a mortal cured in underwater.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underwater-curable resin mortar and a primer for underwater-curable resin concrete, and more specifically, construction and partial repair of an underwater concrete structure and a water use structure in the ocean, rivers and lakes. The present invention relates to a primer when using water-curable resin mortar and water-curable resin concrete, and the present invention relates to a method for repairing an underwater structure using the primer.

[0002]

2. Description of the Related Art Various mortars and concretes that can be hardened in water are used to partially repair underwater structures such as the ocean, rivers and lakes, and irrigation structures. As these mortars and concretes that can be cured in water, in addition to quick-setting cement mortars and concretes, recently resin mortars made from synthetic resins such as epoxy, unsaturated isocyanate, acrylic, unsaturated polyester, etc. Compositions and resin concrete compositions have also been widely used. Especially, acrylic resin mortar or resin concrete has excellent workability in a wide temperature range and fast curing property, and also has excellent weather resistance and chemical resistance. Therefore, it is regarded as an excellent repair material.

[0003]

However, there is a problem in that the resin mortar or resin concrete composition does not have sufficient adhesiveness even if it is applied as it is on the base concrete, and a large strength cannot be obtained.

As a result of studying a method for solving the above-mentioned problems, the inventors of the present invention applied a primer having a specific composition to a cement concrete base in water and then splicing the resin concrete or resin mortar to form a base concrete. It has been found that the adhesion of the resin is good and a structure or repair material having high strength can be obtained.

[0005]

The first invention of the present invention is a cement paste comprising portland cement, a cellulosic underwater non-separable concrete admixture, a superplasticizer and water, which is a cellulosic underwater non-separable concrete. A primer composition for resin concrete or resin mortar, in which an admixture is blended in an amount of 0.3 to 3% by weight based on the total amount of water and a fluidizing agent and the initial setting time is 30 minutes to 8 hours.

The primer composition of the present invention has an initial setting time of 30 minutes to 8 hours, and contains cement, a cellulose-based non-separable concrete admixture in water, a superplasticizer, and water as essential components.

Here, the setting time of condensation is ASTM C 4
The penetration resistance measured by the Proctor penetration resistance method of 03-65T is 500 psi, and the fast-setting cement used in the present invention has an initial setting time of 30 minutes to 8 hours, preferably 1 hour to 6 hours. Is. Cement having a slow hardening such that the initial setting time exceeds 8 hours has insufficient adhesive strength with resin concrete and a structure or repair material having high strength cannot be obtained. If the initial setting time is less than 30 minutes, the curing time will be too fast and the adhesive strength will be insufficient.

In order to obtain a cement having such a specific initial setting time, a setting retarder is added to the ultrafast setting cement to delay the setting time, or a setting accelerator is added to the ultrafast setting Portland cement. There are methods such as shortening the curing time.

Here, the ultra-rapid hardening cement is obtained by adding calcium aluminate or the like to the raw material of Portland cement so as to obtain the ultra-rapid hardening property, and is sold under the trade name of "jet cement" or the like. As the setting retarder, compounds such as oxycarboxylic acid salt-based compounds and magnesium silicofluoride-based compounds are used. Although depending on the types of the ultra-rapid hardening cement and the setting retarder, the amount of the setting retarder to be added to the ultra-rapid hardening cement is preferably 0.5 to 2% by weight.

Ultra fast cement is JIS R521
It is a kind of Portland cement defined by 0, and its composition is 3CaO ・ SiO _{2 which has} high strength development.
It is characterized by a high content of (C ₃ S).

The cellulosic underwater non-separable concrete admixture (hereinafter sometimes referred to as a cellulosic admixture or simply admixture) has a function of giving viscosity to cement mortar and preventing the components from diffusing into water. Examples thereof include hydroxypropyl methyl cellulose (HPMC), hydroxyethyl methyl cellulose (HEMC) and hydroxyethyl cellulose (HEC).

The fluidizing agent is for recovering the fluidity lowered by the addition of the admixture, and includes a naphthalenesulfonic acid formalin condensate salt (naphthalin type), a melamine resin sulfonic acid formalin condensate salt (melamine type), an olefin. Maleic acid copolymer salt (carboxylic acid type), lignin sulfonate (lignin type), etc. can be used, but when a cellulose type admixture is used as an admixture as in the present invention, a melamine type fluidizing agent Is suitable for use.

In addition to the above-mentioned essential components, the primer composition of the present invention may optionally contain various additives such as an AE (air entrainment) agent and a water reducing agent.

The content of the cellulosic admixture in the primer composition of the present invention is 0.
It is 3 to 3% (weight). If it is less than 0.3%, the inseparability in water disappears, and if it is 3% or more, the viscosity becomes too high and it becomes difficult to apply. The water / cement ratio is preferably 40 to 55%, particularly 45 to 55%.

The primer composition of the present invention can be used for repairing an underwater structure by splicing resin concrete or resin mortar on the surface of cement concrete or mortar hardened in water. That is, the second aspect of the present invention is to apply 0.5% of the primer composition of the first aspect to the surface of cement concrete or mortar cured in water.
It is a method for hardening concrete underwater, characterized in that it is applied in an amount of not less than mm, and then resin concrete or resin mortar is spliced.

The coating amount of the primer must be 0.5 mm or more. If the thickness is less than 0.5 mm, the adhesive strength will be insufficient.

It is preferable to drive the resin concrete after applying the primer as quickly as possible, and at the latest, within 40 minutes after applying the primer. After 40 minutes or more, the adhesive strength becomes insufficient.

As the resin concrete, epoxy, unsaturated polyester, vinyl ester, furan and acrylic type can be used, but acrylic (methacrylic acid ester or acrylic acid ester) type resin concrete is particularly preferable.

[0019]

EXAMPLES The present invention will be specifically described below with reference to examples. The cement mortar base and resin mortar used in Examples and Comparative Examples were manufactured by the following method. (1) Preparation of cement mortar base Cement: standard sand = according to JIS R5201
Mix 1: 2 (weight ratio), cement mortar with water cement ratio 65%, size 50 × 100 × 200m
Molded into m blocks. After molding, moist air (20
C, 80% R.C. H. ), 24 hours warm water (70 ° C) and 7
Curing was carried out for a day by drying (20 ° C., 50% RH). After curing, one surface of the block of 100 × 200 mm is used as an adherend, and AA-150 specified in JIS R 6252 is used.
Polishing was carried out using a No. polishing paper, and dust on the adhered surface was removed with compressed air to obtain a cement mortar base.

(2) Manufacture of resin mortar As liquid resin for binder (1) Methyl methacrylate ... 67.4%, (2) Trimethylolpropane trimethacrylate ... 1.8%, (3) Orthophthalic acid-based Unsaturated polyester resin [Brand name: Epolak G-13PC (manufactured by Nippon Shokubai Co., Ltd.) ... 23.1%, (4) Isobutyl methacrylate resin [Brand name: Dianal BR Resin BR-101 (Mitsubishi Rayon ( Co., Ltd.] ... 7.7%, (5) N, N-dimethylparatoluidine (polymerization accelerator) ... 0.5%, (6) Benzoyl peroxide (polymerization initiator) [Kawaguchi Yakuhin ( Co., Ltd., 50% diluted plasticizer] ... 2% (added just before mortar adjustment) is used, and 15 parts by weight of this liquid resin, heavy calcium carbonate filler (trade name) : A mark (Mitsui Powder Co., Ltd.) 15 parts by weight, No. 4 silica sand 35 parts by weight (Tohoku silica sand Ltd.), No. 7 Silica sand (Tohoku silica sand Co.
(Manufactured) was mixed and kneaded.

[Example 1] Preparation of primer (A) (1) Super fast cement [Product name: Jet cement (manufactured by Chichibu Onoda Cement Co., Ltd.)] ... 100 parts by weight (2) Water ...・ ・ 47.68 parts by weight (3) Methylcellulose-based admixture for non-separable concrete in water [Brand name: UWB-D (manufactured by Mitsui Petrochemical Co., Ltd.) HPMC-based admixture] ・ ・ 0.58 parts by weight ( 4) Fluidizing agent for water-separable concrete [Brand name: Pozzolith UC-150 (manufactured by NMB Co., Ltd., melaminesulfonic acid salt-based fluidizing agent] (hereinafter referred to as fluidizing agent) ... 2.32 parts by weight ( 5) Set retarder (trade name: Jet Setter (manufactured by Chichibu Onoda Cement Co., Ltd.)) 1 part by weight was mixed and kneaded to prepare a primer, and the initial setting time of this cement was 3 hours and 40 minutes. It was

A mold having a size of 10 × 100 × 200 mm was set on the adherend of the cement mortar base prepared in (1) above, and allowed to stand still in water (20 ° C.) for 24 hours, and then the primer in water. Apply (A) a coating thickness of 1.5 mm,
Immediately afterwards, apply the resin mortar (2) above to 10 mm
I succeeded.

After curing for one day in water, a diamond cutter is used to make a cut with a diamond cutter to the depth of 2 mm of the base cement mortar on the joining surface according to JIS.
According to A6915, attach a steel jig to the joint,
The tensile adhesive strength was measured with a simple tensile tester (trade name: pull gauge (manufactured by Motofuji Co., Ltd.)). The value of tensile adhesive strength was 2.1 MPa.

Comparative Example 1 A primer was prepared by mixing and kneading in the same manner as in Example 1 except that the setting retarder was not added. The initial setting time of this cement was 10 minutes. In the same manner as in Example 1, resin mortar was spliced on the cement mortar base, and tensile adhesive strength was measured in the same manner as in Example 1. The value of tensile adhesive strength was 0.0 MPa.

[Examples 2 to 4 and Comparative Example 2] Resin mortar was applied to a cement mortar substrate in the same manner as in Example 1 except that the coating thickness of the primer in Example 1 was changed to the thickness shown in Table 1. The splicing was performed and the tensile adhesive strength was measured in the same manner as in Example 1. The results are shown in Table 1 together with the results of Example 1.

[0026]

[Table 1]

[Examples 5 to 7 and Comparative Example 3] In Example 1, the amounts of the admixture, superplasticizer and water added in the primer were changed. The initial setting time also varied slightly depending on the blending amount of the admixture, and in Example 7, the initial setting time was 4 hours. The obtained primer was applied to a cement mortar underlayer in the same manner as in Example 1 and then the resin mortar was spliced to measure the tensile adhesive strength. The results are shown in Table 2 together with the results of Example 1.

[0028]

[Table 2]

[Example 9 and Comparative Example 4] In Example 1, the primer was applied and the time until the resin mortar was driven was changed from immediately after, and range mortar was applied to the cement mortar substrate in the same manner as in Example 1. Splicing and tensile adhesive strength were measured. The results are shown in Table 2 together with the results of Example 1.
Shown in

[0030]

[Table 3]

[0031]

[Effect of the Invention] When the resin concrete or resin mortar is spliced on the cement concrete substrate in water, by using the composition of the present invention as a primer,
Since an underwater structure having a high adhesive strength with the base concrete can be obtained, it has great utility value as a material for construction and repair of the underwater structure.

Claims (3)

[Claims] 1. A cement paste comprising Portland cement, a cellulosic water inseparable concrete admixture, a fluidizing agent and water, wherein the cellulosic water inseparable concrete admixture is added to the total amount of water and fluidizing agent. On the other hand, 0.3 to 3% by weight is added, and the initial setting time is 30 minutes.
A primer composition for resin concrete or resin mortar for 8 hours. 2. The primer composition for resin concrete or resin mortar according to claim 1, wherein the Portland cement is an ultra-rapid setting cement mixed with a setting retarder. 3. The surface of a cement concrete or mortar hardened in water is coated with the primer composition according to claim 1 in an amount of 0.5 mm or more, and then resin concrete or resin mortar is spliced. Underwater curing method.