JP4616930B1 - Protecting concrete structures - Google Patents

Abstract

[PROBLEMS] To make water glass gelled and watertight, and at the same time, prevent neutralization, and water glass flows out of the surface layer of a concrete structure by rain water or the like before gelation. A method of protecting a concrete structure capable of preventing the above is provided.
An alkaline solution modifier obtained by mixing a water glass solution and a gelling agent is applied to the surface of a concrete structure 5 to form a modified layer 6 and voids formed in the concrete structure 5 3 is impregnated, and the upper layer cement 7 is further applied or dispersed before the modifier is gelled in the modified layer 6, so that the water glass and the cement are made faster on the surface of the concrete structure 5. The silicic acid gel formed by reacting the gelling agent contained in the modifier impregnated in the voids with water glass and water glass is gelled at a low speed to form a water-impermeable film 8. The gap 3 is watertight.
[Selection] Figure 1

Description

  The present invention relates to a method for protecting a concrete structure suitable for improving waterproofness by watertightening a void formed in a surface layer of a concrete structure made of cement, mortar, or the like.

  Concrete structures composed of cement, mortar, and the like often deteriorate over time. In particular, the deterioration of the concrete structure with time is based on the influence of the surrounding environment such as salt damage caused by seawater, various acidic substances such as carbon dioxide in the atmosphere, and other freeze-thaw substances. As a result, fine defects and gaps are generated in the concrete structure, the strength, durability, waterproof performance and the like are reduced, and water leakage, neutralization, and the like occur. Therefore, in order to prevent the deterioration of the concrete structure due to these effects over time, a method of applying a protective material to the surface and impregnating the protective material over the void formed in the surface layer portion to achieve water-tightness Has been used in the past.

  Incidentally, as an example of this protective material, there is one using an inorganic material typified by silicic acid or the like in addition to the organic material. And as this silicic-acid type modifier, there exists alkali silicates (henceforth water glass), such as sodium silicate, and this invention belongs to this type | system | group. Sodium silicate has a high viscosity.

  However, such water glass exhibits a high alkalinity with a pH of about 11-12 and does not cure as it is. When this water glass is exposed to the atmosphere, its water evaporates and loses its fluidity from the surface, but although it takes a very long time, it eventually solidifies into a hardened body that appears glassy. It becomes a smooth state. However, the initial solidified product has a property that when it comes into contact with water, it contains water and becomes liquid again and returns to the original water glass.

  On the other hand, the gelled product in which water glass and gelling agent are mixed has different properties depending on the type of gelling agent in the atmosphere (concrete surface). Otherwise, those that do not shrink become dry and the consolidated strength disappears.

  For this reason, after the surface layer portion of the concrete structure is impregnated, the modifier remaining on the surface is removed by water spraying or water application. And after removing a modifier and surface-drying, when performing a top coat, the method of apply | coating a coating material etc. and forming a film layer is taken.

  That is, the modifier to be impregnated in the surface layer portion of the concrete structure (first step of the present invention described later) and the coating layer (second step of the present invention described later) to be applied as an overcoating are handled as separate constructions. ing.

  In addition, a cement mortar is applied to the defect portion of the concrete structure after impregnating the surface layer with a modifier, washing with water and surface-drying.

When water glass is applied to the surface of the concrete structure, the water glass impregnates the voids in the surface layer portion. This impregnated water glass reacts with the calcium hydroxide in the concrete structure to cause a very slow reaction but an insoluble calcium silicate gel (Ca ₂ SiO ₃ .nH ₂ O). Is generated. The calcium silicate gel makes it watertight by filling the voids in the concrete structure. By the way, the reaction described above is limited to a case where a cement composition such as CaO effective for gelation remains in a concrete structure and has the ability to react with water glass to form calcium silicate gel. .

  Patent Document 1 discloses a technique in which a solution containing a silica component containing an alkali silicate salt is applied to the surface of concrete or mortar or injected from the surface.

  Non-Patent Document 1 discloses a composition in which a curing agent (gelator of the present invention) is added to water glass and a curing agent for water glass itself is blended. The specific compound of the curing agent is unknown.

  On the other hand, the water glass modifier has the following problems 1) to 3) in view of the degree of deterioration with time of the concrete structure and the actual construction.

  1) As a result of the progress of deterioration over time, the surface layer portion of the concrete structure deteriorates (neutralizes) and the effective cement composition is reduced or almost disappeared. There is no ability to gel, and even if the voids are impregnated with these water glasses, the expected calcium silicate gel cannot be produced, so that it cannot be watertight.

  2) Even when an effective cement composition remains to react with water glass to form calcium silicate gel, the reaction itself is very slow and takes a long time. For this reason, for example, when the outdoor concrete structure is impregnated with water glass by rainwater before the reaction is completed, the water glass itself dilutes and flows out at the surface and its surroundings, which is completely effective. There are many cases that cannot be demonstrated. Also, the water glass component that has flowed out can cause water pollution.

As described above, in order to add a gelling ability to the water glass itself, the concrete structure having deteriorated is already known in which a hardening agent for the water glass itself is blended. The modifier added with the gelation ability fills the cavity when impregnated in the surface layer of the concrete structure to produce an insoluble silicate gel (SiO ₂ · nH ₂ O), thereby enabling water-tightening. To do.

  If an alkaline gelling agent is used as the gelling agent, neutralization can be enhanced. However, the thin modified layer remaining on the surface of the concrete structure causes the following problems.

  (A) The modified protective material made of water glass does not necessarily have high strength of the gel itself, and may deteriorate again over time.

  (B) Even if the protective material itself has a gelling ability, if it takes a long time to actually gel, it is necessary to prevent the concrete structure from being washed by rainwater or the like before gelation in the outdoor construction. There arises a problem that water glass flows out of the surface layer. On the other hand, when it does not flow out, the surface becomes dry and shrinks to form a cracked glass, or when it does not shrink, the strength is lost in the dried state.

  Further, when overcoating is performed, the following problems also occur.

  (C) The modifier layer remaining on the surface of the concrete structure needs to be removed by washing with water.

  (D) When the paint is used as the top coat after surface drying in (c), the adhesive strength with the concrete is not necessarily strong, and after a while, the water enters the adhesive surface for some reason and the paint peels off. End up.

  (E) Although the cement mortar is applied to the deficient portion of the concrete structure after washing with water in (c) and surface-drying, the adhesion of cement cannot be further enhanced on the concrete surface.

  If these problems can be solved together, the effect as a protective material can be further enhanced.

JP 2006-183446 A

Japan Society of Civil Engineers “Concrete Library 119 Surface Protection Method Design and Construction Guidelines (Draft) Japan Society of Civil Engineers (April 26, 2005)

  From the problems of the background art described above, the modifier to be impregnated in the concrete surface layer portion needs to solve the following problems.

  (1) The ability to automatically gel the water glass to be applied to the concrete structure is added, and preferably the gelation time can be adjusted.

  (2) A gelling agent that adds gelling ability to water glass should not inhibit the concrete structure.

  (3) In addition, the gelling agent should be able to retain alkali components including water glass for a long time.

  (4) It is necessary to form a water-impermeable film on the surface so as not to flow out of the surface layer of the concrete structure due to rain water or the like before gelation.

  An object of this invention is to provide the protection method of the concrete structure which can satisfy | fill these conditions (1)-(4). That is, the present invention is effective for gelling remaining in the concrete structure, in other words, without being influenced by the degree of deterioration of the concrete structure over time or the deterioration or neutralization due to the influence of the surrounding environment. Without being controlled by the presence or amount of the cement composition that acts, it is possible to reliably gel the water glass and make it watertight, and at the same time, prevent neutralization later, before further gelation An object of the present invention is to provide a method for protecting a concrete structure capable of preventing water glass from flowing out of the surface layer of the concrete structure due to rain water or the like.

  In order to solve the above-described problems, the present inventor applied an alkaline solution modifier having a gelling ability in which water glass and a gelling agent are mixed to the surface of the concrete structure to form a modified layer. A first step of forming and impregnating the void formed in the concrete structure, gelling it at a low speed to make the void watertight, and a modifier for the surface of the modified layer. By combining or spreading a cement for overcoating before gelation, the surface layer of the modified layer is gelled at a higher speed to combine with the second step to form a strong and highly adhesive impermeable film. Thus, the present inventors have invented a method for protecting a concrete structure capable of gelling water glass and water-tightening voids while preventing the modifier from flowing out due to rainwater or the like.

First Process The results of intensive studies to realize the first process will be described.

  A modifier obtained by mixing a gelling agent with water glass is an alkaline solution. The gelling agent at the time of mixing is an absolute condition that a sufficient water glass component (unreacted water glass) still remains without completely gelling the water glass.

And even after the surface layer is impregnated to produce an insoluble silicate compound (SiO ₂ · nH ₂ O), the cement component (mainly Ca (OH) ₂ ) around the cavity and the water glass that remains very slowly but remains Can react to produce calcium silicate (CaSiO ₃ ) gel. These insoluble compounds are filled in and closely adhered to the cavities in the concrete structure to be watertight, and exhibit waterproofness.

Second Step In addition to the first step described above, the present invention also proceeds with a second step described below. In this second step, water glass is applied to the modified layer in which the modifier is applied to the surface of the concrete structure by further applying or spreading cement for overcoating before the modifier gels. By mixing the cement with contact, it is gelled at a high speed to form a water-impermeable film having a strong and high adhesion.

  That is, with the modifier functioning as a protective material in the first step maintaining the properties unique to water glass, by further applying or spreading cement as a top coat, both are brought into contact and mixed, for example, about Gelation is carried out with a gel time close to 20 seconds or less, and a gel-impermeable impermeable film is formed on the surface of the concrete structure to develop strength.

  In addition, the reaction between the modifier required in the first step and the cement added in the second step proceeds based on the contact mixing between the two. That is, the reaction proceeds at the contact surface between the modifier and the cement. As a result, the surface of the concrete structure will be covered with a water-impermeable film, so that the modifier can be prevented from leaching from the surface, and further, water pollution due to alkali leaching due to these can be prevented. It is also possible to do. The impermeable film is composed of two layers of a hardened gel by contact mixing of water glass and cement occurring on the surface of the concrete structure, and a hardened cement on the surface.

  As described above, by forming a water-impermeable film having a strong and high adhesion on the surface of the concrete structure, it is possible to prevent the modified layer as the protective material from flowing out due to rainwater or the like. A function as a protective material in the process can be sufficiently exhibited.

Configuration of the present invention The present invention is a method for protecting a concrete structure in which the first step and the second step described above are combined.

  According to a first aspect of the present invention, there is provided a method for protecting a concrete structure, wherein an alkaline solution type modifier mixed with a water glass solution and a gelling agent is applied to the surface of the concrete structure to form a modified layer and the concrete. The modified layer is impregnated with a void formed in a structure, and the surface of the modified layer is further coated or sprayed with cement for overcoating before the modifying agent gels. The water glass and the cement are gelled at a higher speed in the surface layer to form an impermeable film, and the gelling agent contained in the modifier impregnated in the voids is reacted with the water glass. The generated silicate gel is gelled at a low speed to make the voids watertight.

At the same time, the water glass component remaining in the modifier impregnated in the surface layer part reacts with the cement around the cavity (mainly Ca (OH) ₂ ) to produce an insoluble calcium silicate.

  That is, in the present invention having the above-described configuration, there is a difference in configuration in that the surface coating method and the surface impregnation method referred to in Non-Patent Document 1 that could not be realized at the same time are realized at the same time. It exists and exhibits remarkable effects that cannot be achieved with the prior art.

  The present invention is a protection method for preventing deterioration of a concrete structure, which has a self-gelling ability without being influenced by aging, in other words, the remaining amount of effective cement in the concrete structure. It has a first step of forming a modified layer by applying a quality agent, and a second step of applying or spraying cement for overcoating before gelation on the surface of the modified layer.

  From this first step, a modifier as a protective material is applied to the surface of the concrete structure, and the void formed in the surface layer portion of the concrete structure is impregnated to generate an insoluble silicate gel. Thus, watertightness can be achieved. Also, from the second step, before the protective material is gelled, by applying cement for overcoating, the water glass and cement of the modified layer are brought into contact and mixed to gel at a higher speed, and the gel hardened body and cement A water-impermeable film composed of two layers of the cured body can be formed. That is, the method for protecting a concrete structure according to the present invention is a very useful method for protecting a concrete structure that can exhibit the following three effects.

  First, it becomes possible to form a water-impermeable film having high adhesion on the surface of the concrete structure. As a result, it is possible to continue the function of impregnating the modifier into the gap to achieve water-tightness for a long period of time.

  Second, from the surface of the water-impermeable film, it becomes possible to suppress alkali leaching caused by the water glass contained in the modified layer, and prevent water pollution caused by the outflow of rainwater or the like. In addition, the concrete structure itself can be strengthened.

  Third, it is particularly effective when repairing and strengthening the surface of a structure having a crack or joint larger than the void of a concrete structure or a defective portion by forming a strong coin body.

It is a figure for demonstrating the protection method of the concrete structure to which this invention is applied. It is an enlarged view which shows the impermeable film formed on the concrete structure surface.

  Hereinafter, a concrete structure protecting method will be described in detail as an embodiment of the present invention.

  The present invention relates to the deterioration of concrete structures that have deteriorated due to the formation of voids in the surface layer due to the influence of the surrounding environment such as salt damage caused by aging and seawater, or acidic substances such as carbon dioxide in the atmosphere, freezing and thawing. This is a method for protecting a concrete structure capable of improving waterproofness by watertightening the gap. In addition, the present invention is a method for protecting a concrete structure, which is also intended to prevent the deterioration of the concrete structure afterwards by applying in advance to a concrete structure that has not yet deteriorated.

  The modifier used in the method for protecting a concrete structure to which the present invention is applied is configured by mixing a gelling agent and water glass.

  In addition, the void | space here is what the concrete structure itself formed with the porous material hold | maintains, and includes what kind of physical cracks, a defect, and a crack which can be made to impregnate a water | moisture content, It is a concept that includes cavities.

Water glass is an alkali silicate, typically sodium silicate, potassium silicate, or the like, or a mixture thereof. Incidentally, the molar ratio in the alkali silicate is desirably 2.5-4. Sodium silicate has a large viscosity. Water glass exhibits high alkalinity with a pH of about 11-12 and is not cured as it is. The amount of water glass used is not particularly limited, but preferably corresponds to a viscosity of 2 to 5 mPa · s in view of impregnation, and is 4 to 25% by weight in terms of SiO _2. .

  Further, the modifier to which the present invention is applied may further contain a retarder, a gelation accelerator, a dispersant, a strength increasing agent, a surfactant or the like as an additive, or ultrafine bubbles.

  The gelation accelerator is a compound for adding gelation ability to an alkaline solution obtained by mixing with water glass, and is not particularly limited as long as it does not inhibit the concrete structure. Typical examples include sodium aluminate, sodium bicarbonate, phosphoric acid and its acid salt, glyoxal, ethylene carbonate, and the like.

  The gelation time of the modifier in the first step of the present invention is not particularly limited, but it takes 0.5 hours to several tens of hours in consideration of workability and reactivity with the cement in the second step. However, it is preferably 1 to 24 hours.

  It should be noted that a sufficient water glass component still remains in the first step modifier.

  Although the modifier having such conditions is inorganic (sodium aluminate, sodium bicarbonate, etc.) depending on the type of gelling agent, it is possible to adjust the long gelation time and control the gelation ability. It becomes possible.

  In addition, by gelling the modifier impregnated in the voids in the surface layer of the concrete structure, it is possible to adhere and fill the modifier gelled in these voids over a long period of time, improving water tightness It becomes possible to make it.

  For example, as shown in FIG. 1A, the modifier having such performance is injected or applied to the concrete structure 5 that has deteriorated with time. The deterioration of the concrete structure 5 with time is based on the influence of the surrounding environment, such as salt damage caused by seawater, various acidic substances such as carbon dioxide in the atmosphere, and other freeze-thaw substances. The voids 3 that have been formed will progress from the surface 5a toward the inside of the structure. By the way, this concrete structure 5 is all structures that use cement, such as concrete, mortar, cement paste, secondary cement products (precast material), etc. Examples include piers of railways and their ancillary parts, tunnels (including underground space structures such as electricity, communications, gas, etc.), embankments, retaining walls, slopes, etc.

  A 1st process is performed with respect to the surface 5a of the concrete structure 5 in which such a temporal deterioration generate | occur | produced. That is, the roller 2 in which the modifier to which the present invention is immersed is caused to travel on the surface 5 a of the concrete structure 5. As a result, the modifier soaked in the roller 2 can be applied to the surface 5a, and the modifier 3 can be impregnated in the gap 3 as shown in FIG. Become. In addition, application | coating here may be the method of apply | coating a modifier using brush, and the method of spraying a modifier other than the case where this roller 2 is used. This spraying includes concepts such as spraying and spraying. Incidentally, in this application method, one or more of the various methods described above may be combined in accordance with the purpose, and the number of application may be performed once or twice or more.

  Moreover, when performing application | coating twice or more, you may make it pinch | interpose water application in the middle. However, after applying the final finish, if the water is applied or washed with water, the modified layer on the surface of the concrete structure, that is, the water glass component is lost. For this reason, avoid applying water or washing after the final finish.

  In addition, when it is not possible to apply the modifier directly to the surface 5a due to the shape of the concrete structure 5 or surrounding conditions, or when it is desired to inject the modifier deeper than the surface 5a. Alternatively, an injection hole may be drilled using a drilling machine (not shown), and the modifier may be injected into the injection hole. As a result of applying the modifier on the surface 5a, the modifier is thinly laminated on the surface 5a. Hereinafter, a layer in which the modifier is laminated on the surface 5 a is referred to as a modified layer 6.

  Next, as shown in FIG. 1 (b), the process proceeds to the second step, and a cement 7 for overcoating is further applied or spread on the surface of the modified layer 6. In the second step, the cement 7 for overcoating is applied or dispersed before the modifying agent contained in the modifying layer 6 gels, that is, the modifying agent still retains the function as water glass. To do under. In this second step, the top coating cement 7 is applied or sprayed once in principle, but the cement may be applied several times to the surface of the formed water-impermeable film to increase the strength. it can.

  The top coating cement 7 that is applied in the second step is not particularly limited, and can be used to gel water glass. Typically, ordinary cement, early-strength Portland cement, blast furnace cement are used. Can be mentioned. The method of using the cement 7 for overcoating is not particularly limited. For example, water is added to the cement and then applied or sprayed as a cement paste (including cement milk) and further as a cement powder without adding water. May be. Furthermore, a plastering method may be used at the missing part.

  In the process of the second step, a dispersant, a water reducing agent, a curing accelerator, a retarder, a waterproofing agent, a surfactant, a polymer (a material such as nylon), etc. may be used as necessary. It may be.

  By the way, in such a 2nd process, the cement 7 for overcoating is further included in the modified layer 6 by apply | coating or spraying the cement 7 for overcoating with respect to the surface of the modified layer 6. It will react with the water glass. At this point, the modified layer 6 in the first step disappears and a water-impermeable film 8 is formed. It is desirable that the modified layer 6 is in a wet state when the cement 7 is applied. This reaction proceeds at the contact surface between the modified layer 6 and the cement 7 for overcoating. As a result, the water glass contained in the surface layer of the modified layer 6 reacts with the cement 7 for overcoating to produce a strong gel. When the modified layer 6 and the cement are gelled at high speed, the surface of the concrete structure can be made into a gel hardened body. As a result, as shown in FIG. 2, a water-impermeable film 8 can be formed. This water-impermeable film 8 is a gel cured body formed by the reaction on the contact surface described above, and has a property of preventing permeation of water. For this reason, even if rainwater or the like adheres due to rain, it can be prevented from penetrating the water-impermeable film 8, and the modifier coated with the water-impermeable film 8 flows from the surface 5a due to the rainwater. Can be prevented. Moreover, it is possible to prevent water pollution caused by elution of alkali caused by the water glass contained in the modified layer 6.

  In this manner, the water glass component and the cement in the modified layer 6 are gelled at high speed to form the water-impermeable film 8 by the cement 7 for overcoating, or thereafter, the lower layer of the water-impermeable film 8 and the void 3 are impregnated. The modified modifier gels with time and becomes a silicate gel. The gel-like insoluble silicic acid gel is filled in the gap 3, thereby making it possible to achieve water-tightness. Since the water-impermeable film 8 is only formed on the surface layer of the concrete structure 5, the water glass contained in the modifier impregnated in the lower layer of the gel hardened body and in the voids is used as a cement for coating. No reaction with 7. For this reason, the water glass contained in the lower layer of the gel hardened body and the modifier impregnated in the voids also reacts with the gelling agent component contained in the lower layer modifier of the gel hardened body. Is possible.

  That is, according to the present invention, the water glass is mixed with the solution containing the gelling agent component to form the modifier, so that the gelling agent component contained in the modifier reacts with the water glass. Thus, the silicate gel can be spontaneously generated. By previously mixing the gelling agent component with water glass, it becomes possible to automatically add gelling ability to the water glass to be applied to the concrete structure. Further, the gelation time can be adjusted by adjusting the mixing ratio of the water glass and the gelling agent component.

  In particular, when the voids 3 are deeply developed, the modifier hardens before reaching the depth of the voids 3 and becomes a gel unless the time until gelation is delayed to some extent. In such a case, by adjusting the gelling time to be delayed, the modifier is infiltrated deep into the gap 3 and then adjusted to be cured. On the other hand, when the gap 3 extends only shallowly, the modifier permeates relatively early without slowing down the gelation time. As a result, the modifier flows out of the gap 3 before gelling. For this reason, when the space | gap 3 has progressed only shallowly, after filling a modifier to every corner of the shallow space | gap 3, it can be said that it is desirable to gelatinize this as early as possible. Thus, in the present invention, it is possible to adjust the gelation time of the modifier according to the depth of the gap 3.

  Moreover, in the present invention, even when the time for gelation of the modifier is long, as described above, the six surfaces of the concrete structure react with the cement and are coated with the water-impermeable film 8 made of a hardened gel hardened body. Therefore, emphasis can be placed on watertightness without worrying about runoff due to rainwater. Moreover, since this gelatinizer component is alkaline, it can hold | maintain the alkaline component including water glass for a long period of time. For this reason, by applying this concrete modifier to a concrete structure that has been deteriorated and neutralized, it is possible to maintain the alkalinity of the concrete structure.

Next, an embodiment of a concrete protecting method to which the present invention is applied will be described. The material of the specimen used in the experiment is JIS No. 3 water glass, sodium aluminate (Al ₂ O ₃ content 160 g / l), sodium bicarbonate (reagent product) as the gelling agent in the first step, Ordinary cement was used as the cement.

  Table 1 shows the measurement results of gel time, pH, and viscosity for a combination of a predetermined amount of water glass, sodium aluminate, and sodium bicarbonate.

  As shown in Table 1, in Invention Examples 1 to 4, when a gelling agent solution was mixed with water glass, a transparent liquid was obtained and gelled. It can also be seen that the gel time can be adjusted by changing the amount of the gelling agent. In the case of Invention Example 3 where the amount of the gelling agent was small, the ability to include all the water in the blended solution was weak, but it was confirmed that the gel could be reliably generated and precipitated.

  Moreover, it turns out that all the modifiers of this invention exhibit pH 12 or more alkalinity, and can also prevent subsequent neutralization.

  The specimen of the concrete structure used for the experiment is a mortar surface that was cut about 10 cm deep from the surface of the mortar that was constructed outdoors about one year before the experiment, and the foreign matter adhering to the surface was removed with high-pressure water. .

  In the example of the present invention, in order to confirm the degree of deterioration of the specimen, it was cut from the surface layer in the depth direction every 1 cm and crushed into small pieces. In the experiment, after immersion for 3 days at a ratio of 3 parts of the specimen to 1 part of water by weight ratio, the curing water was taken out and the degree of deterioration was determined using pH. The pH measurement results are shown in Table 2.

  Inventive Example 5, which was measured from the experimental results shown in Table 2, is within one year after construction, so the pH is slightly lower within 2 cm from the surface layer, but shows a high pH in a region deeper than 2 cm. It was confirmed that sufficient effective cement remained.

  In Example 3, the mortar of the specimen was molded from the surface into a size corresponding to each test, and a modifier (protective material) to which the present invention was applied was applied with a brush and sufficiently impregnated. Next, the protective material was brushed for the second time. As the protective material used in this experiment, Invention Examples 2 and 4 described above were used. Table 3 shows combinations of protective materials (Invention Examples 2 and 4) impregnated for each specimen (Invention Examples 6 to 7, Comparative Example 2).

  Next, in consideration of rainwater and the like on the outdoor concrete structure, water was sprayed on the surface of the specimen 3 days after application, and then cured indoors for 28 days. And after immersing the specimen A for 3 days at a ratio of 3 parts to 1 part of water in a weight ratio, the specimen A was cut from the surface of the specimen A every 1 cm in the depth direction and crushed into small pieces. The penetration depth was determined by taking out the curing water and measuring the pH. Table 3 shows the measurement results of the pH.

  From the results of Table 3, Examples 6 to 7 of the present invention all show a high value of about pH 12 or more from the surface to the fifth section. However, the effect of these pH values cannot be confirmed in relation to the penetration depth from the surface layer of the mortar, because the specimens before applying the modifier actually show almost the same pH. It was.

  The reason why the pH is low in the second section from the surface layer of Comparative Example 2 to 2 cm is that the used water glass does not have a spontaneous gelling ability, and thus has been poured into water. It can be said that this is the cause. On the other hand, the modifiers of Invention Examples 6 and 7 are gelled so that they do not flow into water and maintain a high pH of about 12 or more.

  Although not shown in the experiment, after applying the modifying agent to the specimen, the specimen was left as it was for 28 days without being sprayed with water. Although it was not shrunk, the strength was hardly expressed in the dried state, and in the case of Example 4 of the present invention, the gel shrunk to exhibit a glass shape. This difference is attributed to the different physical properties of the gel due to the difference in the reaction of the gelling agent.

  In order to confirm the water tightness (waterproofness) when the modifier was applied as a protective material to the specimen prepared in Example 2, a water permeability test was performed. In addition, the thing which did not apply | coat water glass for comparison was also confirmed.

  The water permeability test was performed in accordance with JASS8T-301 (quality and test method of siliceous coated waterproofing material) by processing the specimen into a predetermined shape. As the sample, Example 6 of the present invention was used as Example 8 of the present invention, Example 7 of the present invention was used as Example 9 of the present invention, and Comparative Example 3 was not treated with any protective material.

  When the above-mentioned water permeation test was performed on Examples 8 to 9 of the present invention and Comparative Example 3, the test results shown in Table 4 were obtained.

  According to the test results in Table 4, the inventive examples 8 and 9 to which the modifier was applied compared with those of Comparative Example 3 (no treatment) have a very small water permeability and water tightness (waterproofness). It was confirmed that it was excellent.

  This means that the modifier impregnated in the voids formed inside the concrete structure is densely packed and gelled, and the resulting silicate gel is in close contact with the voids. .

  As described above, in the first step in the method for protecting a concrete structure to which the present invention is applied, the surface layer portion of the concrete structure is impregnated with a protective material, gelled, and water-tightened, thereby the concrete structure. It prevents the deterioration of things.

  Hereinafter, specific examples related to the second step will be described.

  The purpose of the experiment is to observe the gel time and the state of the protective material applied to the surface of the concrete structure, where the protective material applied to the surface of the water structure has properties unique to water glass, and the top coating cement is applied and mixed. To do. The state having the properties specific to water glass here means a state before the modifier having spontaneous gelling ability is gelled.

  In the experiment, the specimen was molded into a length of 15 cm, a width of 3 cm, and a thickness of 2 cm.

A specific experiment flow is performed in the order of the first step and the second step. In the first step, a modifier as a protective material is applied with a brush to the entire periphery of the 8 cm long tip portion of the specimen. A material using Invention Example 2 as the protective material applied in the first step is referred to as Invention Example 10, and a material using Invention Example 4 as the protective material is referred to as Invention Example 11. Then, 3 minutes after application with the brush, a cement paste for overcoating is further applied to the entire surface with the brush, and after 20 seconds, it is put into a separately prepared water tank and sprinkled. Then, the adhesion and dropping state of the applied cement paste are observed.

  Comparative Examples 4 and 5 were obtained by applying a cement paste to the surface of the specimen 3 days after the inventive Examples 10 and 11 were gelled, and Comparative Example 6 was simply applied without applying a cement paste for overcoating. The same procedure was performed for an untreated sample (Comparative Example 4) that only wets the surface of the specimen C.

  From the results of Table 5, as a result of applying the protective material in the first step to the surface of the specimen and applying the cement paste for overcoating in the second step before the protective material gels, the protective material and the overcoat are obtained. In the contact mixing part with the cement paste for use, in any of the inventive examples 10 to 11, the gel time is 20 seconds or less, and both adhere to each other with a gel time close to an instant, and a gel hardened body is formed. It could be confirmed.

  However, this reaction occurs only in the contact mixing portion between the protective material and the cement paste for overcoating, and does not particularly occur on the surface of the concrete structure. This can be confirmed from the fact that the setting time of cement is 4.0 hours.

  Further, referring to the observation result of the state of the cement surface, the phenomenon is that the protective material applied in the first step is coated with the cement paste for overcoating applied in the second step, and the protective material is applied from the surface. It is suggested that the resulting alkali does not flow out due to rain water or the like, and is excellent from the viewpoint of preventing water pollution.

  On the other hand, since the protective material of the present invention (Invention Examples 2 and 4) does not adhere at all after 20 seconds after gelation, as in the case of no treatment (Comparative Example 6). It was confirmed that glass and cement did not react at all. This means that the properties unique to water glass are lost.

  In Example 6, the adhesion strength and the consolidation strength when the modifier as the protective material applied in the first step and the overcoat cement applied in the second step are contact-mixed are obtained by a bending strength test. It was.

  In the experiment, a specimen was molded into 4 × 4 × 16 cm, and a protective material was sufficiently applied on both sides. The applied protective material is that used in Examples 8 and 9 of the present invention, and is Examples 12 and 13 of the present invention, respectively. Three minutes after the application, a cement paste for overcoating was applied with a brush, and then immediately pressed in a state where both sides were in close contact with each other and cured. Then, after 28 days of wet curing, a bending strength test was conducted according to JIS R5201, and the results shown in Table 6 were obtained. For comparison, a bending strength test is similarly performed for Comparative Example 7 in which no protective material is applied in the first step.

  From the results in Table 6, the bending strength is significantly higher in Invention Examples 12 and 13 than in Comparative Example 7 (no treatment). This is because the adhesion and consolidation strength of the gel hardened body, which is manifested by the gelation by the reaction between the water glass component contained in the protective material and the cement, is greater than that of the hardened body of the cement alone. This is because the bending strength is also high.

  As described above, by applying the overcoat cement in the second step to the modifier in the first step, a strong water-impermeable film layer is formed on the surface of the concrete structure, and the effect of the protective material is improved for a long time. It can be seen that it can be held over the entire area. In addition, even when cracks, joints and defects that are larger than the gap are filled with this protective material, a strong water-impermeable film layer is formed on the surface, and the effect of the protective material is maintained over a long period of time. It becomes possible.

  After impregnating the surface layer portion of the first step with a protective material, a water permeability test was performed in order to confirm water tightness (water permeability) when a top coating cement was applied in the second step. In the experiment, the cement paste for the top coating in the second step was applied, and then wet-cured for 28 days. A water permeability test was performed in the same manner as in Example 4, and a water permeability coefficient was measured. The objects to be measured are those used in Examples 8 and 9 of the present invention in the first step, respectively, and cement paste for overcoating is applied in the second step, and these are newly set as Examples 14 and 15 of the present invention. As a comparative example, the above-described comparative example 3 is used.

From the results of Table 7, after applying the protective material in the first step, and applying the cement paste for overcoating in the second step to form a water-impermeable film having high adhesion, the water permeability coefficient is ^{Is on the} order of 10 ^{−8, which} is even better than the first step. As can be seen from Example 5 (Table 5) and Example 6 (Table 6), a strong, high-adhesion water-impermeable film produced by gelation of water glass and cement is applied to the surface of the concrete structure. This means that the watertightness can be further improved.

2 Roller 3 Cavity 5 Concrete structure 6 Modified layer 7 Cement for coating 8 Impervious film 9 Gel hardened body 10 Hardened body

Claims (1)

Applying an alkaline solution modifier mixed with a water glass solution and a gelling agent to the surface of the concrete structure to form a modified layer and impregnating the void formed in the concrete structure,
By applying or spreading a cement for overcoating on the surface of the modified layer before the modifying agent gels, the water glass component and the cement in the modified layer are gelled at a higher speed. Into a water-impermeable film,
Silica gel produced by reacting the gelling agent contained in the modifier impregnated in the voids and the water glass is gelled at low speed to make the voids watertight. Protecting concrete structures.

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