JP2022030252A - Surface treatment method on exposed-concrete surface and hardness improvement method of exposed-concrete - Google Patents

Abstract

To provide a surface treatment method and a hardness improvement method on an exposed-concrete surface which can prevent degradation of weather resistance and hardness on a concrete surface without impairing unique decorative expression on the exposed-concrete surface.SOLUTION: A surface treatment method on an exposed-concrete surface comprises formation of an insoluble crystallization layer configured to integrate a concrete structural body and laitance through infiltration of treatment agent including silicic acid in the laitance existing on the whole or a part of the concrete structure having an exposed surface and the exposed-concrete surface.SELECTED DRAWING: None

Description

The present invention relates to a method for surface-treating an exposed concrete surface and a method for improving the strength of exposed concrete.

The exposed surface of the concrete structure has a unique beauty expression that it is exposed immediately after removing the formwork, so it is evaluated from the strength, cleanliness, texture, etc. peculiar to concrete. There is. Especially, it is supported by designers with high authorship and people who seek urban taste.

However, when trying to utilize the unique texture or aesthetic expression of the exposed surface of the concrete structure, it is not appropriate to perform surface treatment or treatment that impairs them. For this reason, the exposed surface of the concrete structure is more prone to stains and molds than when tiling or applying paint with high concealing properties, and is deteriorated by the penetration of rainwater, its drying, ultraviolet rays, etc. It tends to occur.

In addition, latency may occur when concrete is poured to construct a concrete structure. Here, "latance" refers to "a layer of a fragile substance formed on the surface of concrete by floating fine particles inside with bleeding after concrete is poured" (JIS A0203: 2019). When latency occurs, not only the aesthetics are impaired, but also the strength and weather resistance may be significantly impaired in the part.

The above problem due to latency can be avoided, for example, by removing the latency before (or possibly after) the concrete is cured and then splicing the concrete. However, reliably removing such latency on-site requires a high degree of skill from the operator, and takes time and cost.

For this reason, in the general construction field, the existence of latency is allowed to some extent, and the removal work may not be performed or the work may be completed by a simple work.

However, even if the strength and durability that are the essential functions of the concrete structure are obtained, the presence of latency impairs the texture or aesthetic expression peculiar to the exposed surface of the concrete structure, and the satisfaction with the construction quality. May also decrease. In particular, since the latency portion is fragile, cracks are likely to occur, volume changes due to rainwater infiltration, wetting / drying, etc. cannot be ignored, and fine particles tend to fall off / peel off.

The present invention relates to a surface treatment method for an exposed concrete surface that achieves maintenance and improvement of weather resistance and strength without impairing the unique aesthetic expression of the surface of exposed concrete, and a method for improving the strength of exposed concrete.

In order to solve the above problems, the surface treatment method for an exposed concrete surface according to the present invention contains silicic acid in a concrete structure having an exposed surface and a latency existing on the entire surface or a part of the exposed surface. It is characterized in that the treatment agent is infiltrated to form an insoluble crystallized layer in which the concrete structure and the latency are integrated.

As a preferred embodiment, such a surface treatment method according to the present invention includes a treatment agent containing silicic acid, which is a clear coat agent containing an inorganic pigment.

In such a surface treatment method according to the present invention, as a preferred embodiment, the treatment agent containing silicic acid is impregnated into the exposed surface of the concrete structure in a wet color state after demolding and the latency in an undried state. Including things.

In such a surface treatment method according to the present invention, as a preferred embodiment, the exposed surface of the concrete structure and the latency are pretreated before the treatment agent containing silicic acid is infiltrated. Include.

In such a surface treatment method according to the present invention, as a preferred embodiment, the pretreatment is at least one selected from a cleaning treatment, a polishing treatment, a repair treatment, a drying treatment, a blow treatment, a chemical treatment, a coloring treatment, and a color clear treatment. Includes one that is.

In such a surface treatment method according to the present invention, as a preferred embodiment, the volatilization of water from the concrete structure and the latency is suppressed by the insoluble crystallized layer in which the concrete structure and the latency are integrated. Including what is.

Further, in the method for improving the strength of exposed concrete according to the present invention, a treatment agent containing silicic acid is impregnated into a concrete structure having an exposed surface and a latency existing on the entire surface or a part of the exposed surface. It is characterized in that crack generation in the concrete structure and / or the latency is suppressed by forming an insoluble crystallized layer in which the concrete structure and the latency are integrated.

Here, as a typical specific example of the "exposed concrete surface", the exposed concrete surface as it is exposed immediately after the formwork is removed after the concrete is poured (at this time, the entire surface or a part of the exposed surface of the concrete structure). There can be latency on the surface of the concrete). It should be noted that this "exposed concrete surface" includes a case where the concrete is in a wet color state immediately after demolding, and also includes a case where the concrete is in a dry concrete color after being solidified and dried after being demolded. Then, there may be formwork marks, joints, plastic cone marks (P-con marks), and these blindfold marks.

Further, as another specific example of the "exposed concrete surface" in the present invention, there can be mentioned a "exposed concrete surface" several weeks to several decades after demolding. For example, for "exposed concrete surface" whose surface characteristics have changed or deteriorated due to exposure to the surrounding environment for several weeks to several decades after demolding, and to this "exposed concrete surface whose surface characteristics have changed or deteriorated". It includes exposed concrete surfaces that have undergone some pretreatment (for example, repair treatment such as cleaning treatment, polishing treatment, repair treatment, drying treatment, blow treatment, chemical treatment, coloring treatment, color clear treatment, etc.).

In addition, not only the "exposed concrete surface" that is inevitably generated by traces of the formwork, for example, when the concrete is poured and removed, but also the decorative / decorative treatment is visually or tactilely equivalent to the exposed concrete surface. It also includes concrete surfaces with similar designs, aesthetic expressions, textures, etc.

In the exposed concrete surface finishing method according to the present invention, a treatment agent containing silicic acid is applied to the exposed surface of the concrete structure to the latency existing on the surface of the concrete structure and the inside of the concrete structure. Since it penetrates into the latency to form an insoluble crystallized layer integrated with the concrete structure, the weather resistance and strength of the concrete surface are not impaired without impairing the unique aesthetic expression of the exposed concrete surface. Can be suppressed.

In the present invention, a treatment agent containing silicic acid is infiltrated into microcracks of latency caused by drying shrinkage by utilizing a capillary phenomenon, and recombination, densification, and integration are performed. Since the impregnated coating film reacts with the calcium content in the concrete and crystallizes, there is no need for subsequent recoating, and the concrete surface layer is protected for a long period of time.

That is, in the present invention as described above, the resolubility latency that appears on the surface of the exposed concrete of the concrete structure is changed to an insolubilized crystallization layer to suppress aging deterioration and make it maintenance-free.

In addition, for example, after demolding, a treatment agent containing silicic acid is applied while the concrete is still in a wet color, and the latency adhering to the surface layer is incorporated and integrated, so that the micro generated by the drying shrinkage of the latency. The occurrence of cracks can be suppressed.

Further, in the present invention, so-called film curing (that is, a film is attached to the surface of the structure after demolding to suppress the splash of water from the surface of the structure and the generation of surface cracks due to drying shrinkage occurs. Instead of the reduced curing treatment), shrinkage cracks in the concrete structure can be suppressed.

Therefore, in the exposed concrete surface finishing method according to the present invention, the penetrant containing silicate is permeated into the voids or cracks existing in the surface layer or the inside of the surface layer or the exposed concrete surface of the latency and the exposed concrete surface and the peripheral portion thereof. In the permeation region of, the strength of the latency and the concrete structure can be improved by forming an insoluble crystallization region based on the reaction between the inorganic penetrant and the latency and the components in the concrete structure.

That is, the penetrant adopted in the present invention permeates into the inside of the concrete structure through voids or cracks on the surface of the concrete structure, and is based on the reaction with the components in the cement-based material constituting the structure. A strong insoluble crystallized region is formed that is in close contact with or integrated with the cement-based material.

Since the insoluble crystallized region has a moisturizing property, it promotes the hydration reaction of the cement material and shortens the curing time. Further, since the insoluble crystallized region prevents the elution of the alkaline component, the neutralization of the concrete structure is suppressed and the durability is improved.

Since the penetrant adopted in the present invention has low viscosity and has almost the same permeability as water, it can be quickly applied to the deep part of the minute microcracks of the latency and the concrete structure and the peripheral part thereof. And it can be surely penetrated. From this, it is possible to improve the strength and impart waterproofness not only to the latency but also to the deep part of the structure in which the inorganic penetrant has penetrated.

The penetrant adopted in the present invention does not cause whitening or the like even after insoluble crystallization and drying. For this reason, cracks and the like are not visually noticeable due to the filling with the inorganic penetrant. From this, it is possible to improve the aesthetic appearance of the surface of the exposed concrete.

In addition, the surface of the exposed concrete of the latency and concrete structures is made hydrophilic, densified, hardened and imparted antifouling properties.

Hereinafter, the present invention will be described in more detail based on preferred embodiments.
<Surface treatment method for exposed concrete surface>
In the surface treatment method for an exposed concrete surface according to the present invention, a treatment agent containing silicic acid is impregnated into a concrete structure having an exposed surface and a latency existing on the entire surface or a part of the exposed surface, and the concrete is treated. It is characterized by forming an insoluble crystallized layer in which the structure and the latency are integrated.

In a preferred embodiment of the present invention, a treatment agent containing silicic acid is applied to a concrete structure having an exposed surface and a latency existing on the entire surface or a part of the exposed surface. A part of this penetrant is absorbed by the latency and reacts with the components in the latency (mainly the calcium component) to form an insoluble crystallized layer. Then, the remaining part of the penetrant penetrates the latency and further penetrates into the voids or cracks existing in the surface layer or the inside of the exposed surface of the concrete structure and the peripheral portion thereof, and the components in the structure (mainly). Reacts with the calcium component) to form an insoluble crystallized region in the structure. As a result, an insoluble crystallized layer in which the concrete structure and the latency are integrated is formed. The formation of the insoluble crystallized region can be easily carried out at room temperature, and preferably, it can be carried out by leaving it for 30 to 60 minutes under a temperature condition of, for example, 15 ° C to 25 ° C.

In this insoluble crystallized region, for example, an insoluble crystal containing calcium silicate formed by the following reaction is filled in cracks or voids of a cement-based structure and permeates into a cement-based material at the periphery thereof. As a result of being formed in the state, the insoluble crystal and the concrete material of the concrete structure can be integrated or composited.

SiO ₂ + Ca (OH) ₂ → CaSiO ₃ + H ₂ O
SiO ₂ + Ca (OH) ₂ + Mg (OH) ₂ → MgCaSiO ₄ + 2H ₂ O

By generating this insoluble crystallization region, the mechanical properties (tensile strength and bending strength) caused by the above-mentioned voids, which are weak points of concrete, can be dramatically improved.

Thereby, the mechanical strength (compressive strength, tensile strength, bending strength and strength) of the concrete structure, particularly the deteriorated concrete structure, can be improved to a satisfactory level.

Furthermore, since the insoluble crystallized region is composed of a crystal structure having fine gaps in the form of ultrafine particles (quasi-nano to nano-level ultrafine particles), gaseous water is applied from the latency surface to the inside of the concrete structure. It is possible to form a region that suppresses the permeation of liquid water while allowing permeation. As a result, a water impermeable region (that is, a waterproof region) can be formed from the surface to the inside of the concrete structure, so that the concrete structure can be imparted with waterproofness. Since the insoluble crystallization region has a moisturizing property, it promotes the hydration reaction of the cement material and shortens the curing time. Further, since the elution of the alkaline component is prevented, the neutralization of the cement-based structure is suppressed and the durability is improved.

Since this insoluble crystallized region is a crystal structure having fine gaps in the form of ultrafine particles (quasi-nano to nano-level ultrafine particles), it has the effect of instantly diffusing and evaporating attached water droplets. Have. Therefore, the adhesion or formation of water droplets on the surface is suppressed. That is, unlike the conventional concrete structure without this insoluble crystallization region, the generation of dew condensation and the generation of mold are suppressed.

In order to obtain the above effects, the silicate-containing penetrant in the present invention contains at least one silicate selected from an alkali metal and an alkaline earth metal as a main component and contains water. The preferred component of the silicate in this case is a silicate of potassium, calcium, magnesium, sodium and lithium, and preferably a component made from a natural silicic acid material can be appropriately used. For example, as a natural silicic acid material, silica stone fine powder containing α-quartz as a main component, silica fume which is an industrial by-product, fly ash, etc. can be used, and as a contained silicate, potassium silicate, etc. can be used. It is desirable to contain sodium silicate, lithium silicate or a mixture thereof.

The silicate-containing penetrant in the present invention is used in the form of an aqueous solution or a suspension (slurry), and the solvent in this case is preferably water or an aqueous medium.

The compounding ratio (solid content) of the silicate in the penetrant is preferably 10 to 40% by mass, more preferably 12 to 30% by mass, and particularly preferably 14 to 25% by mass.

Further, the penetrant may contain a predetermined amount of an inorganic pigment such as an extender pigment, if necessary. Preferably, in the case of a clear coating agent containing 20% by mass or less, preferably 5 to 15% by mass of an inorganic pigment, light coloring can be applied without impairing the texture of the exposed surface, and discoloration chalking or the like can be applied. It is also possible to suppress the influence of ultraviolet rays and maintain the aesthetic appearance for a long period of time (for example, 20 years or more).

Further, the penetrant in the present invention is essentially an inorganic composition and does not contain a resin-based component as a main component, but if necessary, additional properties such as dispersion performance and leveling properties can be obtained. A predetermined amount of resin component can be appropriately contained for improvement, and an antifungal agent or the like can be blended.

In the surface treatment method according to the present invention, the treatment agent containing silicic acid can be impregnated into the exposed surface of the concrete structure in a wet color state after demolding and the latency in an undried state. That is, the treatment method according to the present invention can be applied to the surface treatment of the exposed surface of a new concrete structure that has not been substantially exposed to wind and rain after demolding.

Further, the surface treatment method according to the present invention can be applied to the surface treatment of the exposed surface of a concrete structure exposed to wind and rain after demolding, for example, several weeks to several decades. That is, the treatment method according to the present invention can be applied to the surface treatment of the exposed surface of a concrete structure whose surface characteristics have changed or deteriorated due to exposure to the surrounding environment after demolding. At this time, before applying the above-mentioned silicate-containing penetrant to the "exposed concrete surface whose surface characteristics have changed or deteriorated", if necessary, pretreatment (for example, cleaning treatment, polishing treatment, repair) Repair treatments such as treatment, drying treatment, blow treatment, chemical treatment, coloring treatment, and color clear treatment) can be appropriately performed. In particular, the present invention is extremely effective for deteriorated concrete structures in which voids are enlarged due to acid rain or elution of calcium components in concrete due to chloride ions.

<Method of improving the strength of exposed concrete>
In the method for improving the strength of exposed concrete according to the present invention, a treatment agent containing silicic acid is impregnated into a concrete structure having an exposed surface and a latency existing on the entire surface or a part of the exposed surface to make the concrete structure. It is characterized in that crack generation in the concrete structure and / or the latency is suppressed by forming an insoluble crystallized layer in which the body and the latency are integrated.

<Specific example>
The method for treating the surface of the exposed concrete surface and the method for improving the strength of the exposed concrete according to the present invention are preferably performed by performing the following steps (A1) to (A3) or the following steps (B1) to (B7). Can be carried out. In addition, depending on the size and form of the concrete structure to which the present invention is applied, the installation environment, the installation period, the specific situation, etc., the implementation order may be changed as necessary, or one or more steps may be performed. May be omitted, the same process may be performed multiple times, the content of each process may be changed as appropriate, or another process may be added.

(A1) "Investigation step": The concrete structure after demolding, in particular, the appearance of the exposed surface is visually observed or observed using a measuring device or the like to investigate the concrete structure.

(A2) "Permeation step of the treatment agent": The treatment agent containing silicic acid is infiltrated into the exposed surface of the concrete structure in a wet color state after demolding and the latency in an undried state. Alternatively, the concrete structure is left to stand or dried after being demolded to allow the treated agent containing silicic acid to permeate the exposed surface of the concrete structure having a dry concrete color and the latency in an undried state.

That is, the treatment agent containing silicic acid is infiltrated into the voids or cracks present in the surface layer or the inside of the exposed surface of the exposed surface of the concrete structure after demolding or after drying, and the peripheral portion thereof, and the latency. This step can be performed by applying, spraying, or pressure-injecting an inorganic penetrant containing a predetermined silicate using, for example, a brush, a roller, or the like. At this time, the content, concentration, viscosity, etc. of the inorganic penetrant containing a predetermined silicate are adjusted according to the content and size of cracks, the type of concrete material, the deterioration state, temperature, humidity, etc. be able to. For example, the inorganic penetrant can be diluted with water. This "penetration step of the inorganic penetrant" can be performed a plurality of times over the entire cement-based structure or for a part of the concrete structure.

(A3) "Surface treatment step": A surface treatment can be applied to the concrete structure in which the predetermined insoluble crystallization region is formed, if necessary. Preferred surface treatments include, for example, coloring treatment, waterproof treatment, chemical resistance treatment, surface hardness improving treatment, abrasion resistance treatment and the like.

(B1) "Investigation step": The concrete structure after demolding, particularly the appearance of the exposed surface, is observed visually or by using a measuring device or the like to investigate the concrete structure. Understand the size and depth of cracks, deterioration of concrete materials, etc.

(B2) "Step of removing unhealthy parts": When there are unhealthy parts on the outer peripheral surface of the concrete structure or the inner surface of cracks and voids in which sufficient strength recovery cannot be substantially expected due to excessive deterioration. It is preferable to remove the portion thereof. Further, the surface texture adjusting treatment of cracks, for example, polishing treatment, V-cut treatment, U-cut treatment and the like can be performed as necessary.

(B3) "Washing process": The concrete structure is washed. In particular, the scale, dust, dust, etc. that are clogged inside such as cracks are removed with a brush or air blow. If necessary, it can be washed with water or a detergent can be used.

(B4) "Repair treatment": If the size of cracks or voids is large, deep or penetrates, repair by filling or applying a repair agent such as cement paste, grout material, mortar, etc. be able to.

(B5) “Creation of Inorganic Penetrant Injection Hole”: If necessary, rapidly inject an inorganic penetrant containing a sufficient amount of a predetermined silicate into a deep region of a concrete structure, for example. For the purpose of the like, it is possible to create an injection hole for an inorganic penetrant in the concrete structure.

(B6) "Penetration step of inorganic penetrant": An inorganic penetrant containing a predetermined silicate is applied to the cement-based voids or cracks existing in the surface layer or inside of the cement-based structure and the peripheral portion thereof. Infiltrate the material. This step can be performed by applying, spraying, or pressure-injecting an inorganic penetrant containing a predetermined silicate using, for example, a brush, a roller, or the like. At this time, the content, concentration, viscosity, etc. of the inorganic penetrant containing a predetermined silicate are adjusted according to the content and size of cracks, the type of concrete material, the deterioration state, temperature, humidity, etc. be able to. For example, the inorganic penetrant can be diluted with water.

This makes it possible to optimize, adjust and optimize the permeability of the inorganic penetrant containing silicate. In addition, water can be applied to the outer surface of the concrete structure and the inside of cracks before applying the inorganic penetrant containing a predetermined silicate.

This "penetration step of the inorganic penetrant" can be performed a plurality of times over the entire concrete structure or a part of the concrete structure.

(B7) "Surface treatment step": A surface treatment can be applied to the concrete structure in which the predetermined insoluble crystallization region is formed, if necessary. Preferred surface treatments include, for example, coloring treatment, waterproof treatment, chemical resistance treatment, surface hardness improving treatment, abrasion resistance treatment and the like.

In the method for improving the strength of exposed concrete according to the present invention, a treatment agent containing silicic acid is impregnated into a concrete structure having an exposed surface and a latency existing on the entire surface or a part of the exposed surface to make the concrete structure. It is characterized in that crack generation in the concrete structure and / or the latency is suppressed by forming an insoluble crystallized layer in which the body and the latency are integrated.

In the present invention, the method for improving the strength of exposed concrete can be effective in one construction if the construction is appropriate, but in order to improve the surface layer modification of the concrete structure, this surface layer can be obtained. It is desirable to carry out the reforming process multiple times.

Claims (7)

A treatment agent containing silicic acid is impregnated into a concrete structure having an exposed surface and a latency existing on the entire surface or a part of the exposed surface, so that the concrete structure and the latency are integrated into an insoluble material. A surface treatment method for exposed concrete surfaces, which comprises forming a crystallized layer. The surface treatment method for an exposed concrete surface according to claim 1, wherein the treatment agent containing silicic acid is a clear coating agent containing an inorganic pigment. The surface treatment of the exposed concrete surface according to claim 1 or 2, wherein the treatment agent containing silicic acid is impregnated into the exposed surface of the concrete structure in a wet color state after demolding and the latency in an undried state. Method. The surface treatment method for an exposed concrete surface according to claim 1 or 2, wherein a pretreatment is performed on the exposed surface of the concrete structure and the latency before the treatment agent containing silicic acid is infiltrated. The surface of the exposed concrete surface according to claim 4, wherein the pretreatment is at least one selected from a cleaning treatment, a polishing treatment, a repair treatment, a drying treatment, a blow treatment, a chemical treatment, a coloring treatment, and a color clearing treatment. Processing method. The one according to any one of claims 1 to 5, wherein the insoluble crystallized layer in which the concrete structure and the latency are integrated suppresses the volatilization of water from the concrete structure and the latency. Surface treatment method for exposed concrete surface. A treatment agent containing silicic acid is impregnated into a concrete structure having an exposed surface and a latency existing on the entire surface or a part of the exposed surface, so that the concrete structure and the latency are integrated into an insoluble concrete structure. A method for improving the strength of exposed concrete, which comprises suppressing the generation of cracks in the concrete structure and / or the latency by forming a crystallized layer.