JP6476007B2 - Control method of water leakage from concrete by adding silicates - Google Patents

Description

For example, in a concrete water tank, the present invention is a method for suppressing leakage of water from cracks and gaps between joints, and by reacting with carbon dioxide from the atmosphere, the calcium carbonate is precipitated and the concrete components are stored in the water. The present invention relates to a method for suppressing outflow.
Furthermore, the present invention is not limited to water storage tanks, and is intended to suppress leakage of water from concrete pipes and pipes covered with concrete or cement milk, to suppress leakage of concrete floor slabs and roofs, and carbonation from those concrete surfaces. It can also be used to suppress neutralization by gas permeation and to suppress steel corrosion.

By storing water in the hollow of the concrete foundation pile and circulating this water, it is possible to collect underground heat from the surrounding ground where the foundation pile is located. Since 1992, this underground heat exchange pile has been used for snow melting and air conditioning, but this method produces a pile that leaks water.

Furthermore, calcium ions emerge from the concrete of the foundation pile into the water over time, and this reacts with carbon dioxide from free carbon dioxide in the atmosphere or groundwater, forming calcium carbonate and depositing on pipes and heat exchangers. Led to blockage.
Because of such troubles of water leakage and calcium carbonate precipitation, a heat exchanger such as a U-tube is often inserted into the water stored in the hole for indirect heat exchange. However, if a heat exchanger such as a U tube is inserted into the water storage, the construction cost increases and the heat collecting ability is reduced.

  Then, in order to suppress calcium carbonate precipitation and water leakage, resin coating was applied to the concrete inner wall. However, this also increases the construction cost. Furthermore, since the weak substance layer slime covers the surface of the concrete inner wall due to bleeding during production, the adhesion between the concrete wall and the resin coating is poor, and the reliability of long-term adhesion in water remains doubtful. The calcium ion after 1 and 2 years of water storage in an example in which the pile bottom of a concrete pile actually coated with epoxy coating was sealed with a steel plate and buried in the ground was 90 to 95 mg / liter. Then, deposition of calcium carbonate was confirmed on the ball tap ball at the water injection point opened to the atmosphere.

  In the heat exchanging pile method, where the inner wall is damaged by the excavating machine, the inner wall is damaged by the excavating machine using the intermediate excavation method that digs the inside of the wall of the foundation pile and embeds the pile. This method cannot be applied. It is also difficult to paint the inner surface of the pile wall after excavation. And this digging method cannot avoid water leakage from the cement milk at the bottom of the pile. Therefore, in this digging method, water is stored at a high groundwater level where it is guaranteed that no leakage occurs, a U tube is inserted, and ground heat is collected in the U tube by circulation of the heat medium liquid. That is, it cannot be used in areas with low groundwater.

  In such concrete water storage, in addition to heat exchange piles, there are water storage tanks for fire prevention and disaster prevention, and concrete water storage tanks for midnight power water storage systems. Here too, leakage of water and leakage of concrete components into the water storage becomes a problem, and resin coating is applied to the concrete inner wall in order to suppress calcium carbonate precipitation and water leakage from fine cracks. However, this also increases the construction cost. The calcium ion in the case of the heat storage tank is about 60 mg / liter, and no trouble has occurred, but the calcium component outflow from the concrete is not completely prevented.

  In addition, concrete sewer pipes have a problem of water leakage. Furthermore, on the roofs and floor slabs of buildings, a waterproof sheet is laid on the concrete and then covered with concrete or the like. However, there are still many cases where water leakage occurs and repairs are made.

By the way, when surface impregnating materials such as sodium silicate are applied to cracks in concrete, the mortar surface and cracks are filled and densified with CSH crystals that react with calcium hydroxide. Has been.
The silicate surface impregnated material applied on the surface is filled and densified with CSH gel (xCaO · SiO ₂ · zH ₂ O) in which calcium hydroxide in concrete reacts with water.

  Therefore, the application of a silicate surface impregnating material is widely used as a waterproof measure for concrete structures. The Japanese Society of Civil Engineers has already designed the “Surface Protection Method Design and Construction Guidelines (draft)” established in 2005 to design concrete methods to improve concrete surfaces, repair cracks, or suppress various types of deterioration by silicate surface impregnation methods. In addition, technical guidelines for construction and maintenance after construction and various test methods for performance evaluation have been established.

Regarding this technique, “surface protection method for improving the durability of concrete” according to Japanese Patent Application Laid-Open No. 2012-232828, “concrete surface modifier” according to Japanese Patent Application Laid-Open No. 2007-197308, and the like are known.
However, all of these conventional technologies are mostly applied, and there are only some injections into the concrete and surface coating methods, so that water is stored in the target concrete and a small amount of sodium silicate is added to it. There is no implementation example.

Supra of the Japan Society of Civil Engineers "surface protection method design and construction guidelines (draft)" nor "a colorless, almost transparent stock solution, without dilution, in the number of applications on the order of 1-2 times, applied about 200~300g / m ^2" and is there. Such application to concrete is difficult, and work on the ceiling is more difficult. This work is almost the same as the work with resin coating, and does not significantly reduce costs.
"Surface protection method for improving the durability of concrete" according to Japanese Patent Application Laid-Open No. 2012-232828 "Concrete surface modifier" according to JP 2007-197308 A

  Thus, there is a problem in various fields as described above regarding water leakage from the concrete surface. The problem to be solved by the present invention is this problem, and provides a method for preventing leakage of concrete and adding concrete components to water by adding silicates into water.

  By the way, the present invention is not a method of applying a surface impregnating material such as sodium silicate to cracks or gaps in concrete, but a method of adding a slight amount of sodium silicate of 3% or less of the stored water weight in water. In actuality, when 0.5% is added, about 10 days after the addition of sodium silicate after completion of the concrete product and storing water, the surface of the concrete facing the surface, cracks in the surface, and pores on the surface will contain calcium hydroxide. Swelled with CSH crystals that reacted with the surface, voids on the surface disappeared, and the surface was also coated.

  By storing low-concentration sodium silicate for several days instead of applying it at a high concentration, the sodium silicate moves freely in the water, and flows into the water leakage area in a concentrated manner. It reacts with calcium hydroxide at the leaked concrete part, and water leakage is eliminated by swelling of the gel-like C-S-H crystals. Even if the water leakage is further deeper than the gel crystal swell, it is in the form of a gel, so that the sodium silicate water flows there to form the swelling of the gel C-S-H crystal, thereby improving the water shielding performance.

Since the conventional object was difficult to store for a long period of time, a high-concentration surface impregnation material almost undiluted was applied. However, the diluted low-concentration sodium silicate or the like is effective because it flows in many places where water leaks.
For example, if the specimens for compressive strength of hollow concrete are stacked in two stages and filled with water containing 0.5% sodium silicate up to the upper surface of the two stages, the water leaks from the first and second joints at first. To do. However, if the water leakage state continues with the water full, there will be no water leakage after a few days.

If the gap between cracks is large, the flow of water leaks and the resulting CSH crystal flows out and the crack does not fill up. In this case, if fine fiber scraps, etc., which have a specific gravity close to that of the stored water, are mixed into the water together with the silicate, the fiber scraps are introduced into the flow of the water leak. As a result, the water leaks to the clogged area and becomes clogged, and the flow rate of the leaked water decreases. Thereafter, CSH crystals are deposited around the fiber waste. Thus, water leakage can be suppressed at a practical level.
On the other hand, not only water leakage but also CSH crystals generated on the concrete surface and surface pores prevent new calcium from coming out of the concrete surface into the water storage tank.

  When water leaks in an existing concrete water tank, the water is once drained, the water leakage point is discovered, and repaired with resin. Even with such repairs, water leakage can be prevented by injecting a surface impregnating material such as sodium silicate while the water is still stored. Anything that reacts with calcium hydroxide in the water slowly settles, so if there is a possibility of clogging when it flows into the pipeline, it can be easily removed because it is a precipitate. Compared to the conventional method, sodium silicate itself is cheaper and does not require a coating operation, so it is much cheaper and easier.

For concrete drainage channels and underground fume pipes, stop the flow at the end of the flow and fill it with water. Then fill the hole.
Even in concrete floor slabs and rooftop concrete roofs, the drainage channel is closed and water is stored, and if sodium silicate is added, it reacts at the holes in the leaking part and swells to fill the holes.

For concrete drainage channels and underground fume pipes, if the surface impregnating material such as sodium silicate is introduced in a state where the flow at the end of the flow is stopped and the water is full, it reacts at the hole in the water leakage part. Then it swells and fills the hole.
Even with concrete floor slabs and rooftop concrete roofs, the drainage channel is closed and water is stored, and if surface impregnating material such as sodium silicate is introduced, the diluted water flows into the holes of the water leakage part, Sodium silicate reacts and swells to fill the pores.

  Moreover, in a road surface snow melting device or the like, water leakage from a heat radiating pipe or a water supply pipe occurs due to a joint portion of pipe or corrosion. Many of these heat radiating pipes and water pipes are covered with concrete. Therefore, if sodium silicate is added to the circulating water from the pump chamber and operated, the sodium silicate flows from the leaked point of the pipe to the leaked part of the concrete around the pipe, where it swells and becomes porous. Fill.

In the present invention, only surface impregnation material such as sodium silicate is introduced into water, and water leakage in concrete storage tanks, concrete roofs and floor slabs is easy and inexpensive even if the location of water leakage cannot be specified. Solved.
At the same time, the pores on the concrete surface are filled, and the outflow of the concrete components into the water is suppressed. Therefore, precipitation of calcium carbonate in a heat exchanger or the like is eliminated without a resin film. At 1 cm from the concrete surface, the strength increases slightly. Moreover, it is suppressed that the calcium carbonate is formed on the concrete surface by the carbonic acid in the water from the atmosphere, and the corrosion of the reinforcing bars inside the concrete is prevented by the neutralization.

Addition of sodium silicate or the like raises the pH of the water tank to about 11. In applications where this is a problem, this water can be drained and replaced with fresh water. Since the component outflow from concrete is suppressed, the water quality does not change thereafter.
However, in heat storage tanks and heat exchanging piles, there are many cases in which troubles such as corrosion of the metal actually used do not occur just because a pump or the like does not carry out a durability test at high pH. Moreover, high pH water suppresses the reproduction of organisms. Accordingly, depending on the application, utilization with a high pH is excellent.

Embodiment of the water leak suppression method which concerns on this invention. Other embodiment of the water leak suppression method concerning the present invention.

  FIG. 1 is a cross-sectional view showing an embodiment in a heat exchange pile water storage system. Water is stored in the internal space of the concrete pile using the water injection hose 4, and after that, when the internal space is filled with water 1, a silicate surface impregnating material 5 such as sodium silicate is introduced from the container 6. When there is a slightly larger hole in the pile bottom or the like, a fine fiber waste mixture liquid 8 that slightly sinks in water is added.

  Accordingly, since the diluted silicate surface impregnating material 5 continuously concentrates and flows in the water leaking portion having cracks or gaps, even if the concentration is low, a gel-like CSH crystal that reacts with calcium hydroxide in the cracks is formed. As the water swells, water leakage is suppressed. After these reactions are completed and the water leakage is stopped, the water storage may be replaced when it is determined that the alkalinity is high and the heat exchanger or pipe material used is adversely affected.

  FIG. 2 shows an embodiment in which leakage of water is suppressed on the roof. The water distribution pipe 11 is covered with a padding 10 such as a rag, and the roof concrete 9 is covered with the water 1 flowing. Next, a silicate surface impregnating material 5 such as sodium silicate is sprayed and left for several days. Then, the silicate surface impregnating material 5 such as sodium silicate flows into the holes of the leaked portions with cracks and gaps, and the pores are filled with gel-like CSH crystals reacted with calcium hydroxide and water of the concrete. There is no leakage. Even if the leak location is not specified, it can be implemented at a very low cost. Even concrete floor slab bridges can be implemented in the same way.

DESCRIPTION OF SYMBOLS 1 Water 2 Concrete wall 3 Pile bottom steel plate 4 Water injection hose 5 Silicate surface impregnation material, such as sodium silicate 6 Container 7 Worker 8 Liquid waste mixture 9 Roof concrete
10 Stuffing etc.
11 Drainage pipe G Ground surface

Claims (3)

In a method to control cracks and other gaps generated in concrete tanks, heat exchange piles, pipes, roofs, or floor slabs, water is applied to the tanks, heat exchange piles, pipes, roofs, or floor slabs. By storing and adding sodium silicate as a concrete surface impregnating material into the water at a weight ratio of 3% or less , the concrete surface impregnating material flows into the cracks and other gaps and swells to suppress water leakage. In addition, a water leakage control method characterized by preventing calcium and other components from coming out of the concrete at the same time. In a method for suppressing leakage of water from resin or metal pipes covered with concrete or cement milk, by adding sodium silicate as a concrete surface impregnation material to the water flowing through the pipes, A method for suppressing leakage of water, comprising suppressing leakage of water by causing the concrete surface impregnated material to flow into and swell into cement milk. The water leakage suppressing method according to claim 1, wherein fine fiber waste is added to the concrete surface impregnated material to suppress water leakage from large cracks and gaps.