JPH07196350A - Hardened cement, protecting agent applied thereto and method for protecting hardened cement - Google Patents

Abstract

PURPOSE:To obtain a hardened cement capable of assuming the resistance to chemical corrosion, suppressing the elution of an alkali from a cement, consequently improving the durability of the cement, moderating the pollution due to the elution of the alkali and further preventing water stopping properties from deteriorating. CONSTITUTION:This hardened cement is constituted by comprising a protecting agent containing a sequestering agent, an orthophosphoric acid-based compound or a mixture thereof in colloidal silica prepared by removing Na ions of water glass with an ion exchange resin in a hardened cement or coating the surface of the hardened cement with the protecting agent. The protecting agent is a tacky and water absorbing synthetic resin or a hardenable liquid. Furthermore, this method for protecting is constituted by pressing and permeating the protecting agent into a cement structure in the ground and coating the back side of the structure with the protecting agent.

Description

Detailed Description of the Invention

[0001] The present invention relates to a hardened cement material which is widely used, for example, a wave-dissipating block, a soil retaining block, or a cast material in the sea, a protective agent applied to the cement, and a protective method using the protective agent. In particular, the present invention relates to a hardened cement product that has improved durability, mitigates pollution caused by alkali elution, and prevents deterioration of water blocking performance, and a protective agent and protective method applied to the hardened cement product.

[0002]

2. Description of the Related Art A hardened product of cement undergoes physical and chemical alterations and changes over time due to various natural forces or artificial actions. That is, although it has been proved that many hardened cement products, such as concrete, have excellent durability, in recent years, cases in which they have insufficient durability are increasing. Further, while the alkali content eluted from the hardened cement material harms the environment, it also causes neutralization of the hardened cement material. Further, at the contact surface between the hardened cement and the water glass grout or colloidal silica grout, the alkali content of the cement dissolves the silica content in the grout to dissolve and deteriorate the gel. In particular, cement structures constructed in hot spring soil and corrosive soil are corroded by these soil components and are significantly deteriorated.

Various repairs and reinforcement measures have been conventionally taken against the above defects of the hardened cement product.
There is not enough satisfaction, and it is an issue that needs further study.

[0004]

Problems to be Solved by the Invention As described above, the hardened cement product is deteriorated with age due to various external actions,
The transformation progresses. The present invention, among these various external actions,
In particular, it forms a hardened cement product that is resistant to chemical erosion, and a hardened cement product that does not elute alkali. Furthermore, the present invention provides a protective agent or a protective method exhibiting the above-mentioned resistance.

The present inventor has found that a sequestering agent or a protective agent for an orthophosphoric acid-based compound selectively reacts with Ca ions in a cement component to form a passivated complex, and the Ca ions are strongly bound to the protective agent. Found to combine. Therefore,
The purpose of the present invention is to apply this fact to hardened cement products,
An object of the present invention is to provide a hardened cement material which is hardly altered physically or chemically, and a protective agent and a protective method applied thereto.

[0006]

In order to achieve the above-mentioned object, according to the hardened cement of the present invention, N of water glass is
It is characterized in that colloidal silica obtained by removing a ions with an ion exchange resin contains a protective agent containing a sequestering agent and / or an orthophosphoric acid compound in the hardened cement. (Invention A)

Further, in order to achieve the above-mentioned object, according to the hardened cement of the present invention, metal ions are added to colloidal silica obtained by removing Na ions of water glass with an ion exchange resin from the surface of the hardened cement. It is characterized in that a coating treatment is carried out with a protective agent containing a blocking agent and / or an orthophosphoric acid compound. (Invention B)

Furthermore, in order to achieve the above-mentioned object,
According to the protective agent applied to the cured cement of the present invention,
Colloidal silica obtained by removing Na ions of water glass with an ion exchange resin is used as a sequestering agent and / or
Or an adhesive liquid containing an orthophosphoric acid compound,
It is characterized by being made of a water-absorbent synthetic resin or a curable liquid. (Invention C)

Further, in order to achieve the above object, according to the method for protecting a hardened cement product of the present invention, a hardened cement product composed of a cement structure in the ground is added to Na of water glass.
A colloidal silica obtained by removing ions with an ion exchange resin is permeated with a sequestering agent and / or a protective agent containing an orthophosphoric acid compound under pressure.
Thereby, the back side of the structure is coated with the protective agent. (Invention D)

[0010]

DETAILED DESCRIPTION OF THE INVENTION The present invention is described in detail below.

As described above, the present invention uses colloidal silica obtained by removing Na ions of water glass with an ion exchange resin, a sequestering agent, orthophosphoric acid compound,
Alternatively, a cement hardened product (Invention A) formed by containing a protective agent containing a mixture of these in hardened cement, or formed by coating the surface of the hardened cement with the protective agent. Cement hardened product (Invention B), further comprising an adhesive liquid, a water-absorbent resin or a curable liquid containing the sequestering agent, the orthophosphoric acid compound, or a mixture thereof in the colloidal silica, A protective agent (invention C) applied to the hardened cement product, and further a method for protecting a hardened cement product (invention D), which comprises injecting the protective agent into a hardened cement product composed of a cement structure in the ground. Specifically, it is as follows.

[Invention A] The protective agent is contained in a cured product by being press-fitted into the cured cement and permeating.
For example, a hardened cement material existing in hot spring soil or corrosive ground, such as a concrete structure such as a tunnel, is drilled from this surface to the back surface, and the above-mentioned protection is applied to the soil boundary surface through this hole. The agent is pressed and infiltrated to coat the protective agent on the back side of the concrete structure.

Furthermore, the above-mentioned protective agent is press-fitted and infiltrated into a deteriorated concrete structure having a crack to prevent the corrosion of the concrete structure from progressing, and the protective agent is applied to a joint of a hardened cement material. The joint is filled with a protective agent by press-penetrating the agent.

[Invention B] In order to coat the surface of the hardened cement with the protective agent, the inner surface of the mold is coated with the protective agent or covered by spraying or the like, and then the cement is driven into the mold, It is performed by curing.

Further, as the above-mentioned coating treatment method, a base material such as a non-woven fabric or a water-swelling resin is impregnated with the protective agent, and the impregnated base material is coated with an adhesive or the like on the surface of the hardened cement. A method of adhering is used, and means such as immersing the hardened cement in a protective agent, directly applying the protective agent on the surface of the hardened cement, or spraying is also adopted. To be done.

[Invention C] The protective agent applied to the hardened cement product is a colloidal silica containing a sequestering agent, an orthophosphoric acid compound, or a mixture thereof, respectively, an adhesive liquid and a water-absorbing synthetic resin. Alternatively, it is a curable liquid.

The protective agent composed of the adhesive liquid is a substance having an adhesive force, for example, polyvinyl alcohol aqueous solution, CM.
C aqueous solution, obtained by mixing with a methyl cellulose aqueous solution and the like, the protective agent consisting of the water-absorbing synthetic resin is obtained by mixing with Na-CMC, Ca-CMC, water-absorbing urethane resin, etc. Further, the protective agent formed by curing is a substance having a curing power, for example, a mixture of water glass and a reactant, a mixture of colloidal silica and a reactant,
It can be obtained by mixing with a curable resin, cement, etc. and uniformly dissolving or dispersing. The protective agent made of the water-absorbent synthetic resin described above is used by being pressed into concrete joints and filled.

In the present invention, a protective agent according to the present invention is previously injected into a leaking concrete structure,
After stopping the water, inject urethane resin and water-swellable rubber,
It is also possible to take measures such as filling cracks. Also,
After filling the cracks of large concrete with cement,
It is also possible to press-fit the protective agent according to the present invention to completely stop the water.

[Invention D] A cement structure (concrete structure) in the ground is drilled from the surface, and the protective agent is press-fitted and infiltrated through the hole, so that the protective agent is bound to the soil on the back side of the structure. The surface is penetrated, so that the back surface is covered and protected with the protective agent. In particular, concrete structures constructed in hot spring soil and corrosive soil are corroded by these soil components and are severely deteriorated, but this deterioration can be prevented by implementing the protection method by press-fit infiltration described above. It

Furthermore, the above-mentioned protection method has the following embodiments. For example, by injecting the protective agent into a deteriorating cement structure having cracks through the cracks, the progress of corrosion of the structure is prevented. In addition, the joint is filled with the protective agent by press-fitting and infiltrating the joint into the joint of the hardened cement material.

As the sequestering agent, condensed polyphosphates such as tetrapolyphosphate, hexametaphosphate, tripolyphosphate, pyrophosphate, acidic hexametaphosphate and acidic pyrophosphate, ethylenediaminetetraacetic acid, nitrilotriacetic acid, Examples thereof include gluconic acid, tartaric acid and salts thereof, and condensed phosphates are preferred for practical use. Examples of orthophosphoric acid compounds include phosphoric acid, phosphates, acidic phosphates and the like.

The hardened cement product according to the present invention includes concrete structures, various mortars, various blocks, lightweight concrete, foam mortar, foam blocks for vegetation, cement-based injecting materials, back-filling materials, and seawater and groundwater. , Industrial wastewater, slag, rainwater, water glass injection chemicals, silica sol chemicals, ultrafine silica grout (silica sol grout using silica sol obtained by removing alkali from water glass using ion exchange resin), etc. It is a hardened cement product. Specific examples include a wide range of hardened cement such as wave-dissipating blocks, fish reefs, revetment blocks, cement structures such as quay walls, cement structures that come into contact with acid soil and corrosive soil, and cast concrete in seawater or water. .

Since alkali from cement is not preferable for vegetation, conventionally, vegetation is applied to a hardened cement product, vegetation is performed by contacting a hardened cement product, or vegetation is performed by mixing cement and soil. However, vegetation is possible by using the hardened cement product according to the present invention.

[0024]

In the present invention described above, the sequestering agent, orthophosphoric acid compound, or a mixture thereof contained in the protective agent reacts with Ca ions in the cement component to form a passivating complex. , Ca ions are strongly bound to the protective agent.

Furthermore, since the colloidal silica contained in the protective agent does not contain alkali itself, it is easy to form a film on contact with the concrete surface. That is,
Colloidal silica forms a silica gel film on the surface of concrete and is fixed for a long period of time. Therefore, the sequestering agent contained in the gel film, orthophosphoric acid-based compound, or a mixture thereof is also stably fixed on the concrete surface for a long period of time, without elution into groundwater, Reacts selectively with calcium ions over a long period of time. Therefore, the alkali in the concrete is effectively blocked without elution to the outside, and harmful ions from the outside are also prevented from penetrating into the concrete.

The hardened product of cement is generally deteriorated or neutralized by gradually eluting alkali and Ca ions. In addition, colloidal silica generally exhibits a pH in the vicinity of a neutralization region, but on the contact surface with a hardened cement, it is weakened by alkali or Ca ions eluted from the hardened cement after gelation, or of silica. Elution occurs and the strength and water permeability are reduced. However, when the colloidal silica contains a sequestering agent and / or an orthophosphoric acid-based agent, the above phenomenon is prevented and the strength at the contact surface with the cement hardened product is increased.

The reason for this is that the sequestering agent and / or the orthophosphoric acid compound are mainly Ca in the cement.
A calcium phosphate-based compound or a calcium silicate-based compound that is passive by masking ions
Furthermore, a compound in which the silica component of colloidal silica is bound to these compounds is formed, and a coating film is formed on the surface of the cement coagulation body of these chemical substances, and this coating film forms the cement of the chemical substances from the outside. It is presumed that it inhibits the invasion of the solidified body and also suppresses the elution of the alkaline component in the cement to form a strong and durable solidified body. Further, since the elution of alkali from the cement coagulation body is also suppressed, the colloidal silica-based grout itself is weakened at the interface with the colloidal silica-based grout that is in contact with the cement coagulation body, and further does not solidify. It is presumed that both grouts are firmly adhered to each other as a result.

In the protective agent according to the present invention, the sequestering agent masks mainly calcium ions in the cement to form a passive calcium phosphate-based compound or calcium phosphate silicate-based compound in the hardened cement product.
By coating the surface of the hardened material of the cement with such a protective agent, the present invention prevents the entry of chemical substances such as sulfate, carbon dioxide gas, acid, and seawater from the outside, and the alkali in the cement. It also suppresses the elution of components. As a result, it is speculated that a hardened cement product having excellent durability is obtained in the present invention.

Further, the orthophosphoric acid-based compound contained in the protective agent according to the present invention does not have a metal ion masking action by itself, but is converted into a condensed phosphoric acid-based compound by causing a condensation reaction by the cement component, and the metal ion It seems to behave like a blocking agent. In addition, it seems that a metal ion sequestering agent, especially a protective agent which is used in combination with a condensed phosphoric acid compound and an orthophosphoric acid compound, exhibits some synergistic effect therebetween.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.

1. Materials used (1) Cement hardened product Using cement milk with a ratio of 2.5 of Portland cement and water, a cement strong zone with a diameter of 5 cm and a height of 10 cm was created and cured in water for 10 days. did.

(2) Colloidal Silica The colloidal silica having the physical properties shown in Table 1 below, which was obtained by treating JIS No. 3 water glass with a hydrogen type cation exchange resin, was used.

[0033]

[Table 1]

In Table 1, the viscosity of colloidal silica is
Although it is 14 cps (25 ° C.), the viscosity of ordinary JIS No. 3 water glass is 100 to 250 cps (20 ° C.), and the viscosity of the colloidal silica used in the present invention is considerably low.

(3) Hardener As hardeners for colloidal silica, various ones such as inorganic salts can be mentioned, but potassium chloride and sodium hydrogensulfate (both are first-class reagents) were used.

(4) Sequestering Agents The following three sequestering agents were used among various sequestering agents. (B) sodium hexametaphosphate ((NaPO _{3) 6)} (b) sodium acid pyrophosphate _{(Na 2 H 2 P 2 O} 7) ( c) sodium citrate _{(C 6 H 5 O 7 Na} 3 · 2H 2
O)

[0037] (5) phosphoric acid over sodium orthophosphate drugs reagent primary (NaH ₂ PO ₄ · 2H
₂ O) was used.

2. Immersion test of hardened cement product Solidified product of hardened cement product (diameter 5 cm, height 10 cm)
With a sequestering agent or orthophosphoric acid-based agent 4
After sealing and immersing it in 00 ml of colloidal silica-based grout homogel and leaving it in a thermostatic chamber at 20 ± 2 ° C for one month, take out the cement hardened sample and wash it with water, and then seal it again in 400 ml of water. After curing, the pH of the curing water after 3 months was measured. As a control, the specimen was sealed and immersed in water and a 0.1% sulfuric acid aqueous solution instead of homogel, and then newly sealed and cured in water. (Control (1), Control (2)
And )

3. PH of Colloidal Silica-based Grout and Curing Water Table 2 collectively shows the composition of various colloidal silica-based grouts and the pH value of the curing water measured according to the test method.

In Table 2, the colloidal silica-based grout is mixed with colloidal silica and an aqueous solution in which a curing agent (potassium chloride and sodium hydrogen sulfate) is dissolved in predetermined water. At this time, the sequestering agent or the orthophosphoric acid-based agent may be added to the colloidal silica solution or the curing agent aqueous solution to be uniformly dispersed and dissolved, or may be divided into both solutions and added and dissolved. Good.

[0041]

[Table 2]

In Table 2, the control (1) was immersed in water (implemented).
In No. 9), the pH of the curing water is about 12, and even when immersed in the 0.1% sulfuric acid aqueous solution of the control (2) (implementation No. 10), the pH of the solution is about 12.
It has risen to 11. PH of curing water in a system that does not contain any sequestering agent or orthophosphoric acid chemical (implementation No. 1)
Has risen to 11.

On the other hand, in the practice Nos. 2 to 7 in which the sequestering agent and the orthophosphoric acid-based agent were contained in the colloidal silica-based grout, the pH of the curing water was in the range of 7.9 to 8.5. In practice, the pH of the curing water is slightly higher at 9.4 in the practice No. 8 with a small amount of addition, but a certain degree of effect can be seen in comparison with the practice No. 1 without addition.

The low pH of the curing water supports the fact that the alkali is little eluted from the hardened cement product, and it is clear that the hardened cement product itself is prevented from being neutralized.

The appearance of the test cement body is control (1) (implementation No.
9), Control (2) (Execution No. 10), and Except for No. 1 which does not use sequestering agents or orthophosphoric acid agents
In Nos. 2 to 7, the surface was clearly white. Even in Example No. 8 in which the amount of the sequestering agent or the orthophosphoric acid-based agent added was small, it was slightly whitish but slightly white.

4. Component Examination As described above, since the surface of the cement specimen according to the present invention was slightly white, the surface of the cement specimen and the immersed colloidal silica homogel were examined by component analysis.

As a representative system, the execution No. 2 in Table 2 and the execution No. 1 as a control (without sequestering agent or orthophosphoric acid-based agent) were applied to the surface of the homogel and the cement specimen immediately before curing in water. The scraped product was dried at 105 ° C. for 5 hours and then the components were analyzed. The results are shown in Table 3.

[0048]

[Table 3]

In Table 3, the sample A'contains about 20 times more Ca and about 5 times more P than A. This result shows that sodium hexametaphosphate binds with Ca ions eluted from the cement specimen to form an insoluble film on the surface, which prevents the elution of Ca ions and prevents the invasion of ions from the outside. Has demonstrated. In the case of the control sample B, no insoluble film was formed on the cement specimen, so that Ca and Na ₂ O, which are the components eluted from the cement, were greater in the homogel than in A, and conversely, in Ca in B ′, Na
_{The amount of 2} O is small, and the tendency of neutralization due to the elution of alkaline components from cement can be clearly seen.

5. Immersion of Cement Specimen in Sand Gel A sand gel (using Toyoura standard sand) was prepared with a compounding solution of colloidal silica-based grout shown in Table 2, and the cement specimen was immersed therein for about 1 year. System containing sequestering agent or orthophosphoric acid-based chemical (implementation No. 2 to 8)
Then, it was confirmed that the surface of the cement specimen was white and the sand was strongly bonded to the surface of the cement specimen at the interface with the solidified sand. Even in the sand gel of Example No. 8 in which the content of the sequestering agent was small, the effect was clear although it was weak.

In the sand gel of Example No. 1 containing no sequestering agent or orthophosphoric acid-based agent at all, the surface of the cement coagulation body was not whitish at all, and the boundary surface between the consolidated sand and the cement coagulation body was weak. Or, there was a phenomenon that it did not solidify sufficiently.

Such a phenomenon was observed not only in the colloidal silica-based grout but also in the case of the above-mentioned 5 in which the sequestering agent or the orthophosphoric acid-based agent was contained in the cement milk.

6. Consideration From the above results, by adding the sequestering agent or the orthophosphoric acid-based agent to the colloidal silica-based grout or the cement milk or both of them and mixing them uniformly, the surface of the cement coagulation body becomes whitish. . Then, the rise in pH of the curing water is suppressed. This is because Ca ions in the cement are mainly masked by the direct or indirect sequestering action of the sequestering agent or the orthophosphoric acid-based agent, and they are produced on the surface of the passive complex cement coagulation body.

Therefore, Ca from inside the cement solidified body is
That is, it prevents the elution of alkali and also prevents the intrusion of corrosive ions from the outside. Therefore, the corrosion and erosion of the cement solidified body can be prevented as much as possible. In addition, colloidal silica-based grout in contact with the cement coagulation body, because the alkali elution from the cement coagulation body is suppressed, the phenomenon of weakening or non-solidification at the interface disappears, leading to strong bonding and strengthening. .

[0055]

INDUSTRIAL APPLICABILITY As described above, the present invention contains a protective agent comprising colloidal silica and a sequestering agent and / or an orthophosphoric acid compound in a hardened cement, or in the hardened cement described above. By coating the protective agent, a hardened cement product that is particularly resistant to chemical erosion over a long period of time, or a hardened cement product that does not elute alkali over a long period of time, and exhibits such properties By obtaining a protective agent and further injecting this protective agent into a cement structure in the ground by press-fitting, a method for protecting a hardened cement product is obtained, in which the back side of the structure is coated with the protective agent. This is a useful invention.

Claims (11)

[Claims] 1. A hardened cement containing a protective agent containing a sequestering agent and / or an orthophosphoric acid compound in colloidal silica obtained by removing Na ions of water glass with an ion exchange resin. Hardened cement product. 2. The hardened cement product according to claim 1, wherein the protective agent is contained in the hardened cement by press-fitting and infiltrating the hardened cement with the protective agent. 3. A protective agent comprising the surface of the hardened cement, which comprises colloidal silica obtained by removing Na ions of water glass with an ion exchange resin and containing a sequestering agent and / or an orthophosphoric acid compound. A hardened cement product obtained by coating. 4. The surface of the hardened cement is coated with the protective agent by coating the inner surface of the mold with the protective agent and then driving the cement into the mold to cure the cement. Hardened cement. 5. The hardened cement product according to claim 3, wherein the surface of the hardened cement is coated with the protective agent by adhering a base material impregnated with the protective agent onto the surface of the hardened cement. 6. The hardened cement product according to claim 3, wherein the surface of the hardened cement is coated with the protective agent by immersing the hardened cement in the protective agent. 7. The surface of the hardened cement is coated with the protective agent by directly coating or spraying the protective agent on the surface of the hardened cement.
Hardened cement of. 8. A hardened cement product comprising a sticky liquid or a hardenable liquid in which a sequestering agent and / or an orthophosphoric acid compound is contained in colloidal silica obtained by removing Na ions of water glass with an ion exchange resin. Protectant applied to. 9. A hardened cement product comprising a cement structure in the ground, wherein colloidal silica obtained by removing Na ions of water glass by an ion exchange resin contains a sequestering agent and / or an orthophosphoric acid compound. A method for protecting a hardened cement material, which comprises infiltrating and infiltrating the resulting protective agent, thereby coating the back side of the structure with the protective agent. 10. The hardened cement product according to claim 9, wherein the progress of corrosion of the structure is prevented by press-fitting and infiltrating the deteriorating cement structure having cracks through the cracks. Protection method. 11. The method for protecting a cement hardened product according to claim 9, wherein the joint is filled with the protective agent by press-fitting and infiltrating the joint into the joint of the hardened cement.