JP2012232887A - Surface protection method for improving durability of concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface coating method and a surface heat treatment method contributing to reduction of a life cycle cost by protecting concrete structures from deterioration factors such as salt damage, frost damage, neutralization, alkali-aggregate reactions, or the like, on the basis of proper selection of a plurality of surface coating materials with durability for a long term and proper application of treatment methods, and by improving the durability with fine sight maintained by imparting water repellency or hydrophilicity to the surfaces.SOLUTION: The surface coating method and the surface coating and heat treatment method apply a silicate-based inorganic modifier combined with an alkali metal ion source, or an inorganic coating agent with high performance principal ingredients of which are a silane-based permeable water-repellent agent and a polysilazane compound.

Description

The present invention protects a concrete structure from deterioration factors such as salt damage, frost damage, neutralization, alkali aggregate reaction, etc. by applying a plurality of surface coating agents having long-term durability, and has a water-impervious and water-repellent surface. It is related with the surface coating method which contributes to the reduction of life cycle cost, improving the durability of concrete while providing aesthetics.

Concrete structures are inherently highly durable and have a service life of 50 to 100 years at the time of design. However, due to changes in the social environment and the increased use and construction in harsh natural environments, the service life is increased. Many cases have been reported in which deterioration of concrete becomes prominent before progress. Deterioration of concrete structures due to freezing and thawing, salt damage, combined deterioration, neutralization, ASR (alkaline aggregate reaction), etc., has become a social problem, especially in cold snowy areas and salt damage areas. Various measures have been taken as research progresses. Specifically, concrete strength changes by reducing the concrete water cement ratio, mixing of admixtures such as expansive agents, silica fume, blast furnace slag, etc., changing the composition of the cement that makes up the concrete, and specifying good aggregate components and production areas For newly placed concrete, methods such as mist curing and balloon curing after placement, methods of applying a drying shrinkage reducing agent and curing agent to the surface, polymer cement, epoxy resin, etc. on the surface of newly installed and existing concrete There are proposed methods of coating with, coating formation with organic / inorganic paints, cement-based, siliceous-based, and silane-based materials, surface strengthening by infiltration and injection.

JP 2000-044317 A JP2002-193686A

However, among the above construction methods and measures, for new concrete, it has become difficult to procure excellent aggregates due to depletion of domestic resources in recent years. As for overseas procurement, demand in emerging countries has increased and procurement costs have increased. Procurement itself is expected to become difficult. Similarly, changes in cement composition and increases in the amount of admixture used are also increasing costs, and with regard to concrete surface treatment and coating measures after placement, the materials themselves deteriorate quickly and at short intervals. It is assumed that it will be difficult to take countermeasures for all existing structures that require maintenance and repair measures that are expected to increase in the future because life cycle costs will increase due to the need to reconstruct .
Therefore, the present invention adopts a material having high weather resistance and durability as compared with the conventionally used material, and is a surface coating method that is relatively easy to construct, and freezes and thaws existing and existing concrete structures. In addition to preventing or suppressing deterioration due to salt damage, neutralization, ASR (alkaline aggregate reaction), chemical erosion, etc. and composite deterioration due to these, we devised construction methods and methods that improve the durability of materials used in construction, Since the weather resistance and durability are higher than the conventional general construction method, it is possible to extend the interval between re-work. In addition, it is an object of the present invention to provide a construction method that contributes to reducing the life cycle cost of a concrete structure by reducing the cost required for maintenance by maintaining the surface design.

In order to solve the above problems, the first invention is a concrete deterioration prevention or deterioration suppression construction method characterized by applying a surface coating type impregnating agent and an inorganic high-performance coating agent mainly composed of a polysilazane compound. .

In order to solve the above-mentioned problems, the second invention is characterized by applying an inorganic high-performance coating agent mainly composed of a silicate modifier containing an alkali metal ion source and a polysilazane compound. Item 005 is a concrete deterioration prevention or deterioration suppression construction method.

The third invention relates to the prevention of concrete deterioration according to Item 005, characterized by applying a silane-based permeable water absorption preventing modifier having a silane compound as a main component and an inorganic high-performance coating agent having a polysilazane compound as a main component. Or it is a deterioration suppression construction method.

The fourth invention is a method in which the surface of the concrete is dried by heat treatment at the time of application, and a surface coating type impregnating agent is applied and impregnated on the concrete surface, and then the coating surface is heated and sufficiently dried, and then the polysilazane compound is a main component. By applying and heat-treating inorganic high-performance coating agent, it is possible to shorten or eliminate the curing period after construction, shortening the time required for construction, shortening the construction period, and reducing construction costs The concrete deterioration prevention or deterioration suppression construction method according to item 005, characterized in that

A fifth invention is a concrete and a concrete secondary product to which the first, second, third, and fourth inventions are applied and imparted with deterioration prevention or suppression performance.

According to the present invention, a permeability modifier mainly composed of a silicate compound containing an alkali metal silicate penetrates into a concrete surface layer portion and reacts with calcium hydroxide and water of the concrete component to produce C—S—H. The gel product closes and densifies the pores and microcracks in the concrete surface layer. Next, the high-functional coating agent mainly composed of the polysilazane compound has a high bonding strength with the concrete surface (including surface pores and cracks), and produces an inorganic film with high durability and weather resistance. Prevents or suppresses penetration of deterioration factors such as water, chloride, carbon dioxide, oxygen, corrosive gas, etc., and further provides anti-corrosion performance for chemicals.

According to the present invention, the permeable water absorption preventing modifier mainly composed of a silane-based compound prevents or suppresses the penetration of water by penetrating into the concrete surface layer portion and imparting water repellency and water impermeability to the concrete surface layer portion. To do. Next, the high-functional coating agent mainly composed of the polysilazane compound has a high bonding strength with the concrete surface (including surface pores and cracks), and produces an inorganic film with high durability and weather resistance. Prevents or suppresses penetration of deterioration factors such as water, chloride, carbon dioxide, oxygen, corrosive gas, etc., and further provides anti-corrosion performance for chemicals.

By heat-treating the inorganic film produced by the high-functional coating agent containing a polysilazane compound as a main component, water repellency and permeation suppression performance of deterioration factors can be imparted to the concrete surface layer immediately after the treatment.

Immediately after the heat treatment work is completed, the concrete constructed by the method of the present invention can be used (used), and there is no need for drying / heating (about 20 ° C.) curing after construction, which is usually required when applying the same type of product or method. Therefore, it is not necessary to protect the concrete surface to be protected from rain with a waterproof sheet or the like for a long period after construction, and the winter workability in a snowy cold region is improved, and year-round construction is possible. In addition, sub-costs for application (cost for warming, temporary construction, etc.) will be reduced.

1 shows an embodiment of the present invention. The surface coating type impregnating agent penetrates 2 to 40 mm to make the surface layer hydrophobic and dense, and the inorganic high-performance coating agent coats the concrete surface, the inside of the pores, and the inside surface of the microcrack. A concrete water absorption test method to which the present invention is applied. Water absorption test data. Concrete surface water repellency (silicate modifier + polysilazane coating) Specimen after neutralization promotion test (left) No application (right) Invention method applied. Freeze-thaw scaling test data. Change in the condition of the specimen surface (no application) in the freeze-thaw scaling test. (Left) Before test (Right) After test Changes in the condition of the specimen surface (Invention Method 1) in the freeze-thaw scaling test. (Left) Before test (Right) After test

In the present invention, a high-performance coating agent mainly composed of a silicate-based modifier, a silane-based permeable water absorption preventing modifier and a polysilazane compound is applied, and a heat treatment step is further added to form a protective film in a short time. It is a construction method that generates and improves the durability of concrete. Hereinafter, the configuration requirements of the present invention will be described.

A silicate type modifier is a product in which an alkali metal ion source is blended with an aqueous solution of sodium silicate or an aqueous solution of lithium silicate.

Silicate-based modifiers include products containing silane-based compounds.

Silane-based water-absorbing modifiers are products mainly composed of alkylalkoxysilane, alkylalkoxysiloxane and the like.

A suitable high-performance coating agent according to the present invention is obtained by blending a polysilazane compound (10 to 40% by weight) and hexamethyldisiloxane (60 to 90% by weight) to a total of 100% by weight, or hexa It is a mixture obtained by properly blending methyldisilazane and hexamethyldisiloxane, and the skeleton structure of the resulting coating film is composed of an inorganic substance.

The cement used in the concrete to which the present invention is applied is a mixed cement obtained by mixing various Portland cements such as normal, early strength, moderate heat, low heat, sulfate resistance, and white, blast furnace slag and ordinary fly ash with Portland cement. Ecocement, super early strength cement, rapid hardening cement, etc. A cement obtained by mixing an arbitrary amount of a plurality of these cements can also be used.

Next, the method of the present invention will be specifically described with reference to examples. The present invention is not limited in any way by the examples.

First, when applying the “silicate-based inorganic modifier” according to the present invention, the stock solution or the diluted material is well stirred as necessary (step 1). Apply the standard amount of use (100ml to 250ml / m2) with a low-pressure sprayer, brush, roller, etc. (select depending on the construction site) with the coated surface wet. (Step 2). Confirm that the surface has dried (preferably measure with a moisture meter and check that the surface moisture content is 10% or less), and apply a high-performance coating agent at a time using a low-pressure sprayer, brush, roller, etc. . In this case, it is important to apply evenly (step 3). When the “silicate inorganic modifier” is changed to the “silane-based permeable water absorption preventing modifier” or the “silicate inorganic modifier” contains a silane component (step 2) ) Coated surface must be in a dry state (preferably measured with a moisture meter and having a surface moisture content of 10% or less).

Next, the heating method of the fourth invention will be described. The heating time is 0.01 seconds to 15 minutes (increase or decrease depending on the surface heating temperature), and heating is performed with an electric heating element (halogen, carbon heating element, etc.), a gas burner, or the like. When heating with a gas burner, it is important to control the concrete surface temperature with a far-infrared surface thermometer or the like so as not to destroy the concrete composition.

As for the heating method, in heating by an electric heating element (halogen, carbon heating element, etc.), automatic control combining a thermostat, a computer, etc., and manual control by an infrared thermometer are performed. As for the burner heating, there is no particular limitation on the type of gas as long as it is a flame temperature of 1300 to 2000 ° C. by gas, but caution is required for a sudden rise in concrete surface temperature. It is preferable to measure the concrete surface temperature with an infrared thermometer or the like to strictly control the temperature management.

When concrete surface heating is performed, it is important that the concrete is constructed after standard curing after placing (in the atmosphere on the 28th), and construction immediately after placing is avoided.

The outside air temperature at the time of construction is preferably + 5 ° C. or more, and when it is less than + 5 ° C., it is preferable to perform temperature management of the work environment by heating and curing.

Performance Confirmation Test Various tests shown in Table 1 were conducted to verify the above performance.

1. Water absorption comparison test "Summary"
Materials used:
The test specimen is ordinary cement concrete (W / C 50%), age is 28 days.
The treated surface was the side of the mold and was in the range of □ 50 × 100 mm.
FIG. 2 shows an outline of the test apparatus.

"Test results and discussion"
The treated surface of the test body of the invention method was coated with 100 ml / m2 of silicate mineral modifier, air-cured for 24 hours, then coated with 70 ml / m2 of polysilazane inorganic high-performance coating agent, and then aired at 20 ° C for 14 days. Curing. On the treated surface of the commercial silicate-based modifier, 100 ml / m2 of chemical is applied to the treated surface of the specimen and sprayed after 90 minutes, and then 100 ml / m2 is applied and sprayed again after 90 minutes. Test specimens were aged at 20 ° C. for 14 days. The amount of water supply was measured with the test apparatus of FIG. The test results are shown in FIG. 3 by comparison with an uncoated specimen. The surface treated with the invention method (Example) is 1/2 of the surface treated with the silicate modifier (comparative example), and 1/3 the water absorption compared to the uncoated specimen, and the water produced by the invention method. The penetration control effect of the deterioration factor was confirmed.

2. Water repellent comparison test "Summary"
Materials used:
The test specimen is ordinary cement concrete (W / C 50%), age is 28 days.
The treated surface was the side of the mold and was in the range of □ 50 × 100 mm.
FIG. 3 shows the water repellency of the surface treated by the inventive method.

"Test results and discussion"
The treated surface of the test body of the invention method was coated with 100 ml / m2 of silicate mineral modifier, air-cured for 24 hours, then coated with 70 ml / m2 of polysilazane inorganic high-performance coating agent, and then aired at 20 ° C for 14 days. Curing. On the treated surface of the silicate-based modifier, 100 ml / m2 of chemical is applied to the treated surface of the specimen and sprayed after 90 minutes, and then sprayed with 100 ml / m2 and sprayed again after 90 minutes. The specimen was subjected to air curing at 20 ° C. for a day. The surface treated with the inventive method (Example) has a water droplet contact angle of 116.5 °, which is higher in water repellency than the contact angle test results of 38.5 ° and 19.7 ° with no silicate modifier (comparative example). It was confirmed that The surface water repellency of the invention method is shown in FIG.

3. Neutralization test “Summary”
Materials used:
The test specimen is ordinary cement concrete (W / C 50%), and the age is 28 days or more.
The treated specimen was a 6-sided treatment and □ 100 × 100 mm.
The untreated specimen was also shaped similarly.

"Test results and discussion"
The treated surface of the test body of the invention method was coated with 100 ml / m2 of silicate mineral modifier, air-cured for 24 hours, then coated with 70 ml / m2 of polysilazane inorganic high-performance coating agent, and then aired at 20 ° C for 14 days. Curing. On the treated surface of the silicate-based modifier, 100 ml / m2 of chemical is applied to the treated surface of the specimen and sprayed after 90 minutes, and then sprayed with 100 ml / m2 and sprayed again after 90 minutes. The specimen was subjected to air curing at 20 ° C. for a day. Next, the test body was left still in a polyethylene bag of 100, the internal air was discharged with a vacuum pump, filled with 100% carbon dioxide, sealed, and left for 180 days. After 180 days, the test specimen was split, and a phenolphthalein aqueous solution was sprayed on the cross section to confirm the neutralization depth. For comparison, an untreated specimen was also tested. The test results are shown in FIG. In this test, it was confirmed that there was an effect of suppressing the neutralization of concrete by the treatment by the invention method.

4). Freeze-thaw scaling test "Summary"
Materials used:
The test specimen is ordinary cement concrete (W / C 50%), and the age is 28 days or more.
The treated specimen was a mold side surface treatment, and was in a range of □ 50 × 100 mm.

"Test results and discussion"
The treated surface of the invention method test specimen is as follows. After applying silicate inorganic modifier 100ml / m2 and curing at 20 ° C in air for 24 hours, applying polysilazane inorganic high performance coating agent 70ml / m2 and then curing at 20 ° C in air for 14 days. 2. Silane water absorption inhibitor 100ml / m2 was applied and air-cured for 24 hours at 20 ° C, then polysilazane inorganic high-performance coating agent 70ml / m2 was applied, and air-cured at 20 ° C for 14 days. On the treated surface of the silicate-based modifier, 100 ml / m2 of chemical is applied to the treated surface of the specimen and sprayed after 90 minutes, and then sprayed with 100 ml / m2 and sprayed again after 90 minutes. Each specimen was subjected to 20 ° C air curing for a day. The silicate mineral modifier is a sodium silicate modifier, and a repair material is applied to the six surfaces of the test specimen, followed by air curing at 20 ° C for 14 days. When the surface peeling amount of the specimen was measured by freezing and thawing scaling with “RILEM TC 176-IDC CIF-Test”, the peeling amount after 56 cycles was about 1/3 compared to the non-coating method and the comparative method in both of the invention method 1.2. Thus, the inhibitory effect on freeze-thaw scaling was confirmed. A test result graph is shown in FIG. Further, the change in the surface condition of the specimen is shown in FIG. 7 (no application) and FIG. 8 (Invention Method 1).

Claims (5)

A concrete deterioration prevention or deterioration control method characterized by applying a surface coating type impregnating agent and an inorganic high-performance coating agent mainly composed of a polysilazane compound. 2. The concrete deterioration prevention or deterioration suppressing method according to claim 1, wherein an inorganic high-performance coating agent mainly composed of a silicate inorganic modifier and a polysilazane compound containing an alkali metal ion source is applied. 2. The concrete deterioration prevention or deterioration suppression method according to claim 1, wherein an inorganic high-performance coating agent mainly comprising a silane-based permeable water absorption inhibitor and a polysilazane compound is applied.
By applying heat treatment at the time of application, deterioration prevention or deterioration suppression effect and durability are increased, and there is no need for a curing period after construction, so there is an effect of reducing life cycle cost by shortening construction time, in snowy cold areas The construction method according to claim 1, wherein construction during winter is possible. Concrete and a concrete secondary product to which deterioration prevention or the permeation suppression performance of a deterioration factor was given by applying any one or a plurality of paragraphs of Claims 1-4.