JPS6215498B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a repair method, that is, a reinforcing or repair method, which is suitable for increasing the durability of existing cement mortar structures, cement concrete structures, etc., especially outdoor cement structures, from the viewpoint of waterproofness. Conventionally, as a method for repairing damaged parts of existing cement structures, after applying an epoxy adhesive consisting of a base agent and a hardening agent to the damaged area, a cement composition consisting of water, cement, and aggregate is applied. Attempts have been made to firmly adhere the cement composition to the structure. However, in this case, the optimum leaving time from applying the adhesive to applying the cement composition differs slightly depending on the environmental temperature, the presence or absence of wind, strength, etc., so it is necessary to set and adhere to this optimum time at the site. The disadvantage was that it was difficult to That is, if the above-mentioned standing time is too short, the adhesive will not be sufficiently cured and its viscosity will be low, causing the cement composition to slip and fail to achieve its intended purpose.
Furthermore, if the adhesive layer is left for too long, the adhesive layer will completely harden and the applied cement composition will easily peel off. Therefore, the durability of cement structures repaired by this method varied greatly. In addition, in recent years, water, cement,
It is also known to use polymer cement compositions containing cement polymers and, if necessary, aggregates, but these compositions provide sufficient adhesive strength to existing cement structures without the use of epoxy adhesives or the like. Although initial adhesive strength was achieved, over time there were many cases in which the layer provided by the repair peeled off from the underlying existing cement structure. In view of the above-mentioned conventional repair methods, the present invention provides a cement structure that does not require the use of epoxy adhesive or the like, and in which the polymer cement layer provided by the repair does not peel off from the existing cement structure over a long period of time. The purpose of this research is to provide a method for repairing existing cement structures using a polymer cement composition. The molar ratio of silicon dioxide is 1:1 to 1:10
After applying the amorphous aluminum silicate, a polymer cement composition is applied to make the interface between the cement structure at the repair site and the new layer created by the repair impermeable. The main feature lies in the repair method of cement structures. The polymer cement composition in the present invention is:
Conventionally known products containing water, cement, cement polymers, and aggregates if necessary are widely used, and are called polymer cement paste, polymer cement mortar, polymer cement concrete, etc. depending on the presence or absence of aggregate, type, etc. be done. As the cement, Portland cement, alumina cement, mixed cement, etc. are often used, and these are used alone or in an appropriate mixture. Cement polymers are also called polymer admixtures, and they exist as polymers in cured polymer cement products and are mixed with them for the purpose of improving their impact resistance, adhesion to existing structures, etc. Examples include natural rubber, chloroprene rubber, butadiene rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, synthetic rubber such as methyl methacrylate-butadiene rubber, polyvinyl acetate, ethylene-vinyl acetate copolymer, styrene-
Examples include thermoplastic resins such as acrylic copolymers, polyacrylic acid esters, polyvinyl chloride, polyvinylidene chloride, and vinyl propionate, and thermosetting resins such as epoxy resins. Most of these, with the exception of natural rubber and epoxy resins, are synthesized by emulsion polymerization, and then stabilizers, antifoaming agents, etc. are added as necessary, and they are usually used in the form of emulsion or latex. In addition to cement polymers, water-soluble polymers such as polyvinyl alcohol, polyacrylates, polyethylene oxide, methyl cellulose, and hydroxyethyl cellulose are also used as workability improvers. Among the above polymers, styrene-butadiene rubber, acrylonitrile-butadiene rubber, ethylene-vinyl acetate copolymer, styrene-butadiene rubber, etc.
Acrylic copolymers and the like are particularly preferred. These polymers are usually added in solid amounts of 10 to 30 parts by weight per 100 parts by weight of cement. The type and amount of aggregate to be used as necessary is determined depending on the state of damage and scale of the existing cement structure to be repaired, as well as the mode of repair described below. Silica sand mainly composed of anhydrous silicic acid with a diameter of 2.5 m/m or less is preferably used, and is usually used in terms of workability, shrinkage properties during curing of the polymer cement composition, various strengths after curing, and economic efficiency. It is used in an amount of 400 parts by weight or less per 100 parts by weight of cement, and as the coarse aggregate, chestnut stone and crushed stone for cement concrete, which are conventionally known, are widely used. The aluminum silicate used in the present invention has a molar ratio of aluminum oxide to silicon dioxide of 1:1 to 1:10 and is amorphous, and its hydrate may also be used. Amorphous aluminum silicate means that the periodic arrangement of each atom of aluminum silicate, that is, almost no crystal lattice is observed. When taking an X-ray powder diffraction spectrum of the above aluminum silicate with the intensity of the diffraction line as It is judged from. The above-mentioned amorphous aluminum silicate can be produced, for example, by dissolving aluminum sulfate and sodium silicate in appropriate amounts of water, mixing the aqueous solutions, and allowing the two to react in the reaction solution while adjusting the pH, temperature, etc. can get. By adjusting reaction conditions such as temperature, an appropriate molar ratio of aluminum oxide to silicon dioxide can be synthesized. In terms of good solubility in aqueous alkaline solutions, the more silicon dioxide in aluminum silicate, that is, the lower the above molar ratio, the better; however, when considering ease of production, the molar ratio of aluminum oxide to silicon dioxide The ratio of approximately 1:9 is most preferred. On the other hand, the above-mentioned amorphous aluminum silicate also exists as a hydrate in the clay minerals of volcanic ash layers, and is collectively called allofene, including cases containing a small amount of crystalline part. There have been no reports of the existence of a crystal lattice. The molar ratio of aluminum oxide to silicon dioxide in allofuene is 1:1 to 1:2, but when comparing the above synthetic amorphous aluminum silicate with the same molar ratio of allofuene, the reason for this is not clear, but the alkalinity Synthetic amorphous aluminum silicate has extremely good solubility. In the present invention, the above synthetic amorphous aluminum silicate is usually used, but natural amorphous aluminum silicate may be used in some cases. The amount of amorphous aluminum silicate to be used is determined depending on the molar ratio of aluminum oxide and silicon dioxide, the weather and environmental conditions at the repair site, and whether it is a synthetic or natural product.
Usually cement and aggregate (but not necessarily)
The amount is 0.5 to 10 parts by weight, preferably 1 to 6 parts by weight, based on 100 parts by weight of the total amount. These amorphous aluminum silicates have the property of being dissolved in an alkaline aqueous solution with a pH similar to that occurring in a cement composition containing water and cement, and therefore, in the present invention, they are usually used mixed into polymer cement. In some cases, it is used after being dissolved in the above alkaline aqueous solution in advance. Preferred embodiments of repairing an existing cement structure using the method of the present invention will be described below. First, to a composition obtained by mixing 100 parts by weight of cement, 0 to 100 parts by weight of aggregate, and an appropriate amount of the above amorphous aluminum silicate, a polymer latex or a polymer emulsion and, if necessary, further added. The primer is prepared by adding water and applied to the area of the existing cement structure to be repaired. In this case, the existing structure that comes into contact with the primer may be in a wet state. On the other hand, a composition obtained by mixing 100 parts by weight of cement, 100 to 400 parts by weight of aggregate, and optionally alkali-resistant glass fibers is added with a polymer latex or polymer emulsion and, if necessary, water. In addition, a topcoat material made of a polymer cement composition is obtained, and the topcoat material is applied or sprayed with a trowel, mortar gun, etc. onto the undercoat layer to be laminated, covered, or optionally injected. The above-mentioned undercoat material and topcoat material may be obtained by mixing each material by a procedure other than the above. The undercoating material does not necessarily need to contain cement or a cement polymer, but it is preferable to mix as much cement polymer as possible in order to improve the adhesion of the top coat material. For this purpose, it is preferable to use the same cement polymer for both the base coat and the top coat. The undercoating material is usually applied to the surface of the existing structure from 0.1 to
It is used in the range of 1Kg/ ^m2 . Another possible repair method is to apply an undercoat material that does not contain aluminum silicate to the area to be repaired, and then apply and impregnate it with an appropriate alkaline aqueous solution in which the aluminum silicate is dissolved. Examples include a method of applying a top coat material. The method of the present invention can be freely applied to cement structures with no damaged parts immediately after construction, for the purpose of reinforcing durability such as waterproofness and acid resistance. Since the amorphous aluminum silicate in the present invention dissolves in an alkaline aqueous solution having the above pH level,
For example, if it is mixed into an undercoat material containing cement and applied to an existing cement structure, it will be dissolved by the alkali content in the undercoat material and the alkali content eluted from the surface of the existing structure; Even if it is mixed in, it will be dissolved by the alkaline content in the top coat material and the alkaline content eluted from the surface of the existing structure. The dissolved amorphous aluminum silicate component penetrates into the capillary voids existing inside the existing cement structure and reacts with free lime to form insoluble crystals, while hardening due to the hydration reaction. It also penetrates into the capillary voids in the base coat or top coat to form similar insoluble crystals, and in combination with the presence of the cementitious polymer, the cement structure in the repaired area is coated with a new layer created by the repair. It is estimated that the boundary area between the two is impermeable for several centimeters. The method for repairing a cement structure according to the present invention is configured as described above, and amorphous aluminum silicate with a molar ratio of aluminum oxide to silicon dioxide of 1:1 to 1:10 is applied to the part of the cement structure to be repaired. According to the present invention, since the boundary between the cement structure at the repair site and the layer newly created by the repair is made impermeable, the present invention prevents rainwater or groundwater from entering the existing cement structure. Even if the polymer cement composition penetrates, it does not reach the interface with the polymer cement layer and stay there, and it is not subject to peeling action due to water staying at the interface, so the polymer cement composition has good adhesion to existing cement structures. Coupled with this property, the polymer cement layer provided by the repair will not peel off or fall off over a long period of time. Furthermore, since the method of the present invention does not require the use of a two-component curing adhesive such as an epoxy adhesive, there is no need to manage the optimum leaving time after applying the adhesive, and therefore, the present invention improves durability. A uniform repair layer made of polymer cement is formed.
Furthermore, in the above-mentioned repair, only a small amount of aluminum silicate can be used, which is economical. Next, examples of the method of the present invention will be shown. Example 1 100 parts by weight of ordinary Portland cement, silica sand
60 parts by weight, synthetic amorphous aluminum silicate (molar ratio of aluminum oxide to silicon dioxide, 1:9)
8 parts by weight and 40 parts by weight of styrene-butadiene rubber latex (hereinafter referred to as SBR latex) (rubber particle solid content: 18 parts by weight, water 22 parts by weight), 40 parts by weight of water was further added and kneaded to form a polymer. A cement composition was obtained. Next, the cement-concrete floorboards, which have been constructed for about 3 years, were washed with water and then the polymer cement composition was applied as an undercoat to the floorboards at a rate of 0.5Kg/ ^m2 to cause damage to an area of 1m wide and 2m long. I brushed the parts. Thereafter, a top coating material having the composition shown below was filled into the damaged area at a rate of 10 kg/m ² , a smooth coating layer was formed on the surface using a trowel, and the coating material was cured by air-drying at room temperature.

[Table] For the specimen created in this way, after construction
After 1 day, water removal equipment was used to remove water from the top of the polymer cement layer that had been repaired for 60 minutes during the day and 60 minutes at night over an area of about 5 m ² including the entire surface of the polymer cement layer. performed water.
The amount of water withdrawn was set to be approximately 100/hour per ^1m2 . Under these conditions, changes over time in the peeling of the newly provided polymer cement layer were measured. The measurement method was a hammer test. In other words, if you hit the surface of the polymer cement layer with a hammer,
If the cement layer is lifted, a hollow sound can be heard, so it is possible to confirm that the cement layer has peeled off. The results were as shown in Table 1. Example 2 A specimen was prepared in exactly the same manner as in Example 1, except that a synthetic amorphous aluminum silicate with a molar ratio of aluminum oxide to silicon dioxide of 1:6 was used, and the same test as in Example 1 was carried out. I did this. The results were as shown in Table 1. Comparative Example 1 A specimen was prepared in exactly the same manner as in Example 1, except that amorphous aluminum silicate was not mixed into the undercoat composition, and the same tests as in Example 1 were conducted. The results were as shown in Table 1. Example 3 An undercoat material with the following composition was applied to the damaged part of a concrete soundproof wall constructed almost vertically on a railway viaduct.
It was brushed at a rate of Kg/ ^m2 .

[Table] The same applies below.
Thereafter, a top coat material of the following composition was applied with a trowel at a rate of 10 kg/m ² and left to cure.

[Table] Three days after construction, the specimen with a smooth surface was sprayed from diagonally above the specimen using a water sprayer, including the entire surface of the polymer cement layer provided by the repair. Water was sprayed over an area of approximately 5 m ² every day for 60 minutes during the day and 60 minutes at night.
The amount of water sprayed was approximately 100/hour per 1 m ² of the specimen. Thereafter, in the same manner as in Example 1, the state of peeling over time at the repaired area was confirmed, and the results are shown in Table 1. Comparative Example 2 A specimen of a soundproof wall of the same type in the same area as in Example 3, which was damaged to the same degree as in Example 3, was obtained using an undercoat material and topcoat material with the same composition as in Comparative Example 1. . Thereafter, the peeling status of the repaired area was confirmed in the same manner as in Example 3, and the results are shown in Table 1. Example 4 A specimen was prepared in the same manner as in Example 1 ^, except that an undercoat material with the following composition was brushed at a rate of 0.2 kg/m ² and then a top coat material with the following composition was applied at a rate of 10 kg/m 2 Then, the same test as in Example 1 was conducted. The results were as shown in Table 1.

【table】

【table】

Claims (1)

[Claims] 1. When repairing an existing cement structure using a polymer cement composition, a molar ratio of aluminum oxide to silicon dioxide of 1:1 to 1:1 is applied to the portion of the structure to be repaired. 10 amorphous aluminum silicate followed by application of a polymer cement composition to make the interface between the cement structure at the repair site and the new layer created by the repair impermeable. A method for repairing cement structures characterized by: 2 The first amorphous aluminum silicate in which the molar ratio of aluminum oxide to silicon dioxide is approximately 1:9.
Repair method described in section. 3 The polymer cement composition contains water, cement,
The repair method according to item 1 or 2, which contains sand and a cement polymer. 4. The repair method according to item 3, wherein 0.5 parts by weight or more of amorphous aluminum silicate is applied to 100 parts by weight of the total amount of cement and sand.