JP5406026B2 - Concrete protective colloid sol - Google Patents

Description

  The present invention relates to a concrete protective material. This protective material is an outer coating penetration type product, and is a kind of colloidal sol type concrete protective material.

  Currently, there are many methods that employ a material that is applied to the concrete surface layer to protect the concrete structure.

The purpose of protecting the concrete structure is achieved by injecting or applying a penetrating material mainly composed of sodium silicate into waterproofing and repairing parts. However, the main component of this material (water-proof coating material) is sodium metasilicate, which has a high reaction rate in concrete, low permeability, generates film-like substances on the surface, and is easily damaged by abrasion. Exists.

  To solve the above problems, an alkali metal silicate aqueous solution is improved. For example, according to published patent application, two kinds of sodium silicate, potassium silicate, and lithium silicate in alkali metal silicate are arbitrarily selected and combined, and water is mixed according to a molar ratio of 1: 1. Produces a metal silicate aqueous solution (hereinafter referred to as a mixed aqueous solution). Further, sodium hydroxide is added, and by adjusting the amount of sodium hydroxide added, the mixed aqueous solution adjusts the rate of gelation in the concrete.

  After this mixed aqueous solution is applied to the surface of the concrete structure, the material gels into the voids in the concrete, closes the voids, and prevents moisture from entering the concrete. This improved mixed aqueous solution plays a major role in slowing the gelation rate of the mixed aqueous solution by adjusting the gelation rate and allowing the mixed aqueous solution to penetrate deeply into the concrete. However, the quality of the reaction-generated gel-crystal is a decisive factor for waterproofing the concrete structure in the case of the penetration protection of the permeation crystal type protective material in the comprehensive protection of the concrete structure.

  Since the material is a mixed aqueous solution of alkali metal silicate, the quality of the reaction-generated gel is defective due to the nature of the solution, and the problem to be solved remains.

Unresolved issues with mixed aqueous solutions to achieve effective protection of concrete structures:
1. The gel formed in the concrete pores is unstable.
When the generated gel comes into contact with water again, it returns to the state of an aqueous solution. The gel undergoes a change of gel → aqueous solution → gel due to the action of water. In other words, it has reversibility. Therefore, the gel produced by the mixed aqueous solution in the concrete is unstable and has a low protective effect. This is extremely disadvantageous for the protection of concrete structures in the natural environment.

2. The mechanical performance of the gel itself formed in the concrete pores is not good.
The gel in which the mixed aqueous solution was formed in the pores of the concrete was formed by a direct reaction without a solid structure. Therefore, the mechanical performance is not good because the gel does not support the solid skeletal structure. And the resistance to penetration of water is not good. Furthermore, the resistance to deformation of concrete is weak. Therefore, it is disadvantageous for the protection of concrete structures.

3. The pore structure of the gel formed in the concrete pores is not good.
Since the gel has no solid skeleton, the pore structure of the gel layer is not good. The pore diameter is large and the degree of dispersion of the pores is small. Therefore, the specific surface area of the gel layer is small, and the surface adsorption capacity is also small. Therefore, the gel layer has a weak adsorbing ability to atmospheric water (humidity) and a corrosive medium, and the ability to protect concrete is lowered.

4). The protection of the mixed aqueous solution on the concrete is insufficient.
Protecting the concrete structure of the mixed aqueous solution only by fixing calcium ions (Ca2 +) of calcium hydroxide (Ca (OH) 2), which is one of the components that are easily eroded into the concrete by gel. To do. However, calcium hydroxide (Ca (OH) 2) is only part of the erodible component from the viewpoint of full protection of concrete structures. There are still components in concrete that are eroded by similar corrosive media.

  For example, hydrated calcium aluminate (4CaO ・ Al2O3 ・ 19H2O) and calcium sulfoaluminate (3CaO ・ Al2O3 ・ 3CaSO4 ・ 32H2O) in the cement mineral C3A (3CaO ・ SiO2) in concrete are sulfates. Easily eroded and may cause explosive destruction of concrete; CSH (3CaO · 2SiO2 · 3H2O) is a carbonizable substance, is susceptible to corrosion by carbon dioxide, and may cause neutralization and destruction of concrete There is. Since the mixed aqueous solution cannot protect against other components that are easily eroded by the corrosive medium in the concrete, the corrosive medium erodes other unprotected and easily eroded components in the concrete and corrodes the concrete. there is a possibility. Therefore, this alone is incomplete in terms of the resistance of the concrete structure to the corrosion medium erosion in the mixed aqueous solution.

5. The gel layer itself has no resistance to freezing and thawing.
Freezing and thawing destruction can be suppressed by the mixed aqueous solution keeping the concrete inside in a certain dry state. However, since the gel layer absorbs water by capillary action due to the porosity of the gel layer and the gel itself after freezing is frozen when it is below freezing, the concrete gel layer is destroyed by freezing and thawing. Therefore, the protective effect on concrete is lost.

  That is, the mixed aqueous solution can prevent freezing and thawing destruction occurring in the concrete, but cannot prevent freezing and thawing destruction of the concrete gel layer itself. However, since the freeze-thaw failure of concrete generally extends from the surface to the inner surface, it can be said that the inhibitory effect on the freeze-thaw failure of the mixed aqueous solution is low.

The content of the invention

  The present invention provides a concrete protective colloid sol for the purpose of protecting concrete more effectively and improving the durability of concrete structures against the above-mentioned problems related to the protection of mixed aqueous solutions to concrete structures. Researched and developed.

Concrete protective colloidal sol is present invention is composed of potassium and water sodium silicic acid and silicic acid. The feature is that the aforementioned sodium silicate and potassium silicate are ultrafine solid particles having a diameter of 1 to 100 nm. The weight ratio of sodium silicate and potassium silicate is 3.2 to 4.2: 1, and the weight ratio of the total amount of ultrafine solid particles in the colloidal sol to the total amount of water is 26 to 30:74 to 70. The component ratio of sodium silicate and potassium silicate in the colloidal sol is as follows.

Sodium silicate Weight ratio SiO2: Na2O = 3.20-3.40 : 1
Molar ratio SiO2: Na2O = 3.30-3.50 : 1
Potassium silicate Weight ratio SiO2: K2O = 2.10-2.30 : 1
Molar ratio SiO2: K2O = 3.20-3.25 : 1
The physicochemical indicators of the concrete protective colloid sol of the present invention are as follows.
・ Solubility: 350g / 100g (20 ℃)
Boiling point: 100 ° C
Density: 1.13 ± 0.03 / 20 ° C (g / ml)
・ Viscosity: 1-5CPS / 20 ℃
・ PH value: 11.4
-Solid particle diameter: 1 to 100 nm

Advantages of the concrete protective colloid sol of the present invention The concrete structure is eroded by various corrosive media due to external factors, or the workability of the concrete structure caused by deterioration of the performance of the structure itself, the decrease in safety and durability The concrete protective colloid sol of the present invention has a total isolation layer (isolating the corrosion medium and water erosion in the concrete external environment) and a local isolation layer (concrete concrete) against the concrete structure. Produces a double isolation protective layer that protects components that are susceptible to erosion inside. Based on that, organic properties of colloidal sol and gel are organically combined to work on the whole and prevent the invasion and erosion of corrosive media, realizing long-term, stable and effective protection to concrete structures. To do. In addition, it improves the durability of the concrete structure, extends the actual service life, and reduces maintenance costs.

The concrete protective colloidal sol of the present invention fundamentally changed the properties of "solution" type materials. That is, with improved ion form of the solution in a colloidal sol ultrafine solid particles are highly dispersed. That is, the ions, which are the main component that chemically reacts with the hydrate in the pores of the concrete, were changed to ultrafine solid particles.

  The present invention introduces nanotechnology and makes sodium silicate and potassium silicate into ultrafine solid particles having a diameter of 1 to 100 nm. The component ratio is as follows.

Sodium silicate Weight ratio SiO2: Na2O = 3.20-3.40 : 1
Molar ratio SiO2: Na2O = 3.30-3.50 : 1
Potassium silicate Weight ratio SiO2: K2O = 2.10-2.30 : 1
Molar ratio SiO2: K2O = 3.20-3.25 : 1

Ultrafine solid particles of sodium silicate and potassium silicate are dispersed in water as a dispersion medium in a weight ratio of 3.2 to 4.2: 1 and mixed with water. Thereby, sodium silicate and potassium silicate ultrafine solid particles highly dispersed in water, the colloidal sol. In the colloidal sol, the weight ratio of the total amount of ultrafine solid particles to the total amount of water is 26-30: 74-70 .

Specific Example: An example of producing a 200 kg concrete protective colloid sol will be described.
1. An ultrafine solid particle raw material of sodium silicate and potassium silicate having a diameter of 1 to 100 nm is made into a mixture of 26 to 30 kg according to the weight ratio of sodium silicate to potassium silicate, 3.2 to 4.2: 1.
Sodium silicate: Potassium silicate = 19.81-24.23: 5.0-7.14 (Unit: kg)
2.1. 70-74 kg of water is added to the mixture.
3.2. Is sufficiently stirred at room temperature and pressure for about 1 hour.
4). The mixed liquid after stirring is filtered through a 3 μm molecular sieve to obtain 100 kg of double concentrated particle colloid.
5.4. Respect, Dilution with magnification of water, can be obtained concrete protective colloidal sol of 200 kg.

Physical chemical indicator of the concrete protective colloidal sol obtained here is as follows.
・ Solubility: 350g / 100g (20 ℃)
Boiling point: 100 ° C
Density: 1.13 ± 0.03 / 20 ° C (g / ml)
・ Viscosity: 1-5CPS / 20 ℃
・ PH value: 11.4
-Solid particle diameter: 1 to 100 nm

Features of this concrete protective colloid sol:
1. The feature of this concrete protective colloid sol is the introduction of nanotechnology, and the dispersion degree of the raw material particles is increased to the nano level with a particle diameter of 1-100 nm. Since nanotechnology has changed the molecular and atomic structure of the raw materials, ultrafine particles have surface and body effects. Its surface and body effects further give ultrafine particles new chemical and physical properties that are different from those of raw materials. Accordingly, ultrafine solid particles have properties such as extremely large specific surface area, excellent chemical reaction activity, low melting point, and strong magnetism.

2. A colloidal sol type concrete protective material is obtained by dispersing ultrafine solid particles having a diameter of 1 to 100 nm in a dispersion medium of water. This colloidal material has properties such as diffusion, Brownian motion, precipitation, and electrokinetic phenomena. Ultra fine solid particles in the colloidal sol suitable for molecular motion theory, with relative stability and high dispersibility kinetics.

  3. The gel formed by the reaction of the colloidal sol and the cement hydrate is a rigid gel of a three-dimensional network skeleton composed by connecting rigid mass points by chemical bonds. The structure is very stable and does not show bidirectionality even when heated by adding water after dehydration and drying. Therefore, it becomes an irreversible gel. Rigid gels have a solid geometrical nature because they have a certain geometric profile. That is, it has a certain strength, elasticity, yield value and the like.

  The advantages of applying the above-mentioned concrete protective colloid sol to the surface of a concrete structure are as follows.

1. The reaction of the concrete protective colloid sol inside the concrete shows a very good chemical reaction activity.
The ratio of the number of atoms and the total number of atoms on the surface of the ultrafine particles of this protective material increases rapidly as the particle diameter decreases, and the surface effect of ultrafine particles occurs. At the same time, since the number of atoms on the surface of the ultrafine particles has increased, the number of atoms contained in the particles decreases. Therefore, the energy level interval in the energy band is increased, further affecting the electron motion, and the ultrafine particles have a body effect. The surface effect and body effect are very advantageous for the formation of a gel protective layer because the concrete protective colloid sol has excellent chemical reaction activity.

2. The reaction inside the concrete of the concrete protective colloid sol is delayed.
The compounding technique of the concrete protective colloid sol can delay the time for the material to react with the hydrated product inside the concrete than the penetration time of the material. Therefore, the material can reach the maximum penetration depth inside the concrete, which is advantageous for increasing the thickness of the concrete gel protective layer.

3. The reaction of the concrete protective colloid sol inside the concrete shows consistency.
According properties such as kinetic relative stability and high dispersion with colloidal sol, the material can generate mass equivalent of a chemical reaction within the concrete. It is advantageous for the production of a gel protective layer having an equivalent mass.

4). Advantages of gel protective layer produced by concrete protective colloid sol:
The concrete protective colloid sol is composed of polydisperse phase particles having a diameter of 1 to 100 nm. Among them, particles of different diameters have different roles when reacting with hydrates inside the pores of concrete to form a gel. Large particles mainly form a rigid three-dimensional network skeleton in the chemical reaction process, give the gel layer a certain geometric outline, and show solid mechanical properties, that is, certain strength, elasticity, yield value, etc. . Medium and small particles adhere between the three-dimensional network skeleton and the pore wall, fill the voids, and extend the three-dimensional network skeleton into the pores, thereby reducing the large porosity in the concrete and the gel layer. Make it dense. The reaction-generated CSH gel wraps the surface of each particle and the pore wall with chemical bonds, and adheres each particle to the pore wall, thereby forming a gel layer with irreversible and solid mechanical properties with a very stable structure To do. By organically combining particles with different diameters from CSH gel and pore walls of concrete, the gel layer has a good pore structure and large pore dispersion. Therefore, the specific surface area is large, and the surface adsorption ability is excellent.

5. The gel protective layer produced by the concrete protective colloid sol has the advantage of double isolation protection.
5.1 Gel forms a total isolation protective layer against concrete.
The concrete protective colloid sol of the present invention reacts in the pores and fine cracks of the concrete, and the produced gel closes the pores and fine cracks to improve the density of the concrete. Effectively prevents gas or liquid water in the external environment from entering the concrete. Form an overall isolation layer against the concrete. Since the gel present in the pores and microcracks is a rigid network material composed of ultrafine gel pores, it has a very large specific surface area and exhibits a very strong adsorption ability.

  When the gel is in a dry state, when moisture from the external environment enters the pores, the moisture is adsorbed to the gel layer and works so that a pore water film is not formed in the pores inside the gel layer. Therefore, the path through which the corrosive medium moves into the pore water film and prevents diffusion and enters the concrete is blocked. As the amount of moisture absorbed by the gel layer increases, the concrete pores are sealed by the gel when a sufficient amount is reached to seal the gel pores. Therefore, it is possible to completely prevent moisture in the external environment from entering from the concrete surface.

  When liquid (body) water in the external environment enters the concrete pores, the gel layer adsorbs liquid water and slightly expands, and then seals the gel pores. Accordingly, it is possible to completely prevent the liquid (body) water in the external environment from entering the subsequent liquid water. It completely prevents liquid water from continuing to enter the concrete surface.

The gel formed after the reaction of the concrete protective colloid sol has solid mechanical properties. It is integrated with the pore inner wall of the concrete by chemical bonding and exists stably in the pore of the concrete. Therefore, the gel layer has a high water pressure resistance ratio and can show the reliability of the gel isolation layer of concrete.

  Since the concrete protective colloid sol can effectively and effectively prevent moisture or liquid water from entering the concrete, the inside of the concrete gel layer can always be kept dry even in different water environments. It becomes impossible for the corrosive medium to enter the concrete using moisture or liquid water as a medium. Furthermore, there is no water-solid-liquid interface condition, which is an essential condition for causing a corrosion reaction. Therefore, one of the necessary conditions for the corrosion reaction of concrete was destroyed. From the standpoint of isolating and protecting the entire concrete, it can be said that protection to concrete is possible.

5.2 Gel forms a local isolation protective layer against erodible components.
The concrete protective colloid sol chemically reacts with calcium hydroxide (Ca (OH) 2) in the pores of concrete and fine cracks, and then CSH gel is formed. Gel protects dissolved and free calcium hydroxide (Ca (OH) 2) in the pores of the concrete as a component of the gel. At the same time, the CSH gel generated after the reaction wraps the surface of each particle and the pore wall by chemical bonding, and the wrapping action forms a protective film on the surface of the substance containing the aluminum compound that is easily eroded on the pore wall. Since the reaction of the protective film continues with time, the film becomes thicker and denser, and a protective film such as a shell is formed on the surface of the substance containing the aluminum compound. In this situation, even if the corrosive medium enters the concrete pores from the outside, or there is a corrosive medium decomposed from other additive components inside the concrete, calcium hydroxide (Ca (OH) 2) The protective film on the surface of the aluminum compound eliminates the target of erosion reaction, and the conditions for the erosion reaction to proceed are not uniform. Accordingly, the protective film forms a local isolation layer for the erodible components inside the concrete. The local isolation layer inside the concrete eliminates another requirement for the corrosion reaction of the concrete, and the concrete is protected by local isolation of the erodible components inside the concrete.

The concrete structure is separated from the external corrosive medium and water by separating the concrete protective colloidal sol from the water, and the local protection of the components that are easily eroded into the concrete .
1． It cannot penetrate into concrete using moisture and liquid water as a medium .
2． There is no target that can corrode inside the concrete .
3． Because the concrete interior dries and there is no condition to satisfy the erosion reaction, the possibility of erosion destruction to the concrete structure is greatly reduced. Alternatively, the corrosion medium significantly reduces the rate of erosion of the concrete structure.

  Therefore, the concrete structure can maintain the original alkalinity (pH> 11.5), and the comprehensive protection ability against the corrosive medium is enhanced, and the durability of the concrete structure is improved.

6). The gel layer itself produced by the concrete protective colloidal sol is resistant to freeze-thaw failure.
The gel layer in which the concrete protective colloid sol is generated inside the concrete is a porous material formed of gel pores by forming a three-dimensional network skeleton by the rigid points of the gel. Gel increases the density of concrete and changes large pores into fine pores and gel pores. After increasing the density of the concrete with gel, when water infiltrates into the concrete, the gel layer adsorbs the initial water, the three-dimensional network skeleton expands into a dense wet gel, and then penetrates Block external water paths. Since the inside of the concrete is always kept dry by the protection of the gel layer, water saturation, which is a necessary condition for freeze-thaw destruction, cannot be established.

  On the other hand, the gel generated by reaction inside the pores of the concrete is a porous gel layer composed of gel pores. Since the porous gel greatly reduces the diameter of the pores of the concrete, when water enters the gel pores, it can be physically adsorbed on the pore wall surface of the gel pores only in the form of water molecules. The diameter of the pores of the concrete is greatly reduced to the diameter of the gel pores, and the freezing point of the water adsorbed in the gel layer is also greatly reduced to become an antifreeze water layer.

  The concrete protective colloid sol forms a gel layer inside the concrete, thereby eliminating the freezing conditions inside the concrete layer and the gel layer and effectively preventing the destruction of the concrete structure due to freezing and thawing.

Claims (4)

Sodium silicic acid, consists of potassium silicate and water, sodium and potassium silicate the silicate is a ultrafine solid particles of a diameter of 1 to 100 nm, the weight ratio of sodium and potassium silicate the silicate A concrete protective colloidal sol characterized in that the weight ratio of the total amount of ultrafine solid particles to the total amount of water in the colloidal sol is 26-30: 74-70.
The weight ratio of the sodium silicate is SiO2: Na2O = 3.20-3.40 : 1,
The molar ratio is SiO2: Na2O = 3.30-3.50 : 1
The concrete protective colloid sol according to claim 1, wherein The weight ratio of the potassium silicate is SiO2: K2O = 2.10-2.30 : 1,
The molar ratio is SiO2: K2O = 3.20-3.25 : 1
The concrete protective colloid sol according to claim 1, wherein The main physicochemical indicators of the colloidal sol are:
・ Solubility: 350g / 100g (20 ℃)
Boiling point: 100 ° C
Density: 1.13 ± 0.03 / 20 ° C (g / ml)
・ Viscosity: 1-5CPS / 20 ℃
・ PH value: 11.4
-Solid particle diameter: 1 to 100 nm
The concrete protective colloid sol according to claim 1, wherein