JPS5964582A - Reformation of cementitious material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for improving the modification of cementitious materials by soaking a specific modifier under full pressure from the surface of hardened cementitious material.

Hardened materials such as concrete, mortar, and cement are widely used as inorganic materials in civil engineering, architecture, and other fields, but regardless of their shape, these cementitious materials generally contain countless fine particles that connect two surfaces. Because the hole exists, 2
As time passes, the outer layers of clothing that are comfortable to wear, especially outdoors, gradually deteriorate. When this deterioration becomes noticeable, cracks will eventually appear in the cement-based materials, which can cause problems in structures such as reinforced concrete.

Rust occurs in the internal reinforcing steel, which is often the cause of serious problems.

Conventionally, a method for preventing such surface layer deterioration of cement-based materials is to impregnate the surface of the cement-based materials with a polymerizable 7-mer of /fEi quality.

A method of polymerizing by applying heat, radiation, etc., or a method of impregnating an organic polymer from the surface of a cementitious material and then removing the solvent have been proposed. Since the modified cementitious material surface obtained by the method of A method to prevent surface deterioration has been adopted.
be. For example, a method using inorganic impregnation is 2%.
Publication No. 53-19609 proposes a method of impregnating silica sol with a specific molar ratio, but the impregnation depth is generally shallow, except for certain cement-based materials, and a sufficient reforming effect cannot be expected. many. Also, as another example,
In Japanese Unexamined Patent Publication No. 55-78764.

A method has been proposed in which the material is impregnated with a silicate bath solution and then further coated with cement paste.

In this method, since the impregnation depth of the silicate aqueous liquid is not sufficient, the t1
However, it increases the number of times of construction, and although cement paste 1αC3 has fi+'+ ease that is normally considered optional by those skilled in the art, Further material costs are required for this purpose, and there are problems in implementation.

Yet another example is the Tokuko Sho 54. In Japanese Patent No. 4571, a modification method is also proposed in which alkyl silicate is impregnated from the surface of a cement material under reduced pressure and then subjected to a hydrolysis process. It requires a hydrolysis step after impregnation, the process is complicated, and there are still difficulties in implementation.

The present inventors conducted detailed research on a method for modifying the surface layer of cement materials using an inorganic impregnating agent, and found that a silicate aqueous solution, particularly a lithium silicate bath solution, or a naphthalene sulfonic acid soda formaldehyde butyrate was further added to this solution. When a small amount of added liquid is impregnated under pressure from the surface layer of cement-based materials, the impregnation depth increases several times compared to normal-pressure impregnation, and it also improves long-term strength and neutralization of cement-based materials. We have found that it is possible to completely prevent this from occurring. An object of the present invention is to provide a method for forming a modified layer on a hardened cementitious material, which has excellent strength and significantly improved frost damage resistance, weather resistance, heat resistance, and fire resistance. . of the present invention.

A method for modifying a cementitious material is to modify the cementitious material from its surface.10. /MmO (where 1M represents an alkali metal atom or a substituted or unsubstituted ammonium cation group) is 1 to 50, and Si
It is characterized by being impregnated under pressure with an aqueous alkali silicate solution containing 1 to 50% by weight of O,'i and then dry kneading.

Cement materials to which the method of the present invention is applied include cement paste hardened products, mortar hardened products, concrete hardened products, light weight equalized concrete hardened products such as ALC, calcium acid plates, etc., and cement binders used once a month. These cured products may have any shape, and may have surface deterioration due to long-term use. For example, precast concrete), &,,
A La board, concrete structure wall surface.

A suitable example is a mortar wall surface. Also, highly carbonated cement products, dry-out, and freezing.

Concrete 1 that was insufficiently hardened due to lignin contamination, etc.
・Surface 2 Also applicable to concrete surfaces that have deteriorated due to fire.

The aqueous alkali silicate solution used in the present invention is:

It is a stable liquid in which an alkali silicate is dissolved in water or a dissolved alkali silicate and dispersed colloidal fine particles coexist.

Instead of water as the liquid medium, an alkali silicate bath solution using a mixed solvent of water and a water-soluble organic solvent as the medium can also be used. The silicon used may be alkali metal silicates such as lithium silicate, aluminum silicate, sodium silicate, cesium silicate, or substituted metal silicates (2 or 4th).

Examples include ammonium silicate. i myself. Examples of non-convertible ammonium include:

NH,, 0 days *NH,, (OH,), NH,, (
OHs)s ('Os)ItC)H)xN+ (Ot'
LOIη4N.

(a, H, oe), NH, (c, day.), N day m, (
CsHs) ('-@OH)υHv, (CsH++)
(e, H, OH) IN etc. are mentioned. If desired, two or more types of these lucaris can be used in combination. Particularly preferred silicate alp y') is
It is lithium silicate.

When the aqueous solution of alkali silicate has a molar ratio of SiO,/M,O of 1 or less, it can be used to prepare the solution. The aged cement-based cured product is not modified, IIIli aqueous, ll+M
1. Power; However, when an aqueous silicate aqueous solution having a molar ratio of 50 or more is used, the content of colloidal silica in the solution becomes high, and the impregnation depth from the surface of the cement thread ilide is shallow, which is not preferable.

Furthermore, in the present invention, an aqueous alkali silicate solution containing Si
o, 8 and h1 is 1 to 50% by weight. siO, the modified cement material that Arisho borrowed once a month with an alkaline silicate water bath solution of 19c or less had low strength.
Alkaline silicate water bath solutions containing 50% or more of Sin have poor stability, and in some cases, buildup and gelation may occur. 1. A cement-based cured product having a modified layer with constant quality cannot be obtained. % preferred content Ir15
~6fJ%.

The above-mentioned alkali silicate water bath solution n + used in the present invention
A SiOs/λ4.0 molar ratio of 1 to about 4 can be easily obtained by dissolving in aqueous alkali silicate, or by adding caustic alkali to a colloidal silica dispersion and heating if necessary. It will be done.

As the SiO,/M, 0 molar ratio increases by 4 or more, the alkaline silicate aqueous solution becomes a liquid in which colloidal silica is dispersed and coexists. It can be easily obtained by adding alkali IJ and subjecting it to a heat treatment if necessary, or by dealkalizing it from an alkali silicate water bath by a cation exchange method or the like, and then stabilizing it by adding an alkali if necessary. When the S i O,/M, 0 molar ratio is 4 or more, especially 7 or more, colloidal silica coexists dispersed in the silica 1β alkali aqueous solution. , particles having a particle size of 50 mμ or less, particularly 20 mμ or less are preferred.

Particularly preferred is an aqueous lithium silicate solution with a molar ratio of about 2 to 7.

A more preferable alkaline silicate water bath solution used in the present invention is a solution to which 0.01 to 5mM 9 (iA) of naphthalene sulfonate and soda bormaldehyde condensate is added. The soda formaldehyde condensate is easily available as a commercial product with a degree of bipolymerization of about 2 to 100.The naphthalene sulfonic acid soda formaldehyde condensate added above allows the alkali silicate bath solution to penetrate from the surface of the cement-based compound. However, if the above addition rate is less than 0.1% by weight, it has almost no effect, and if the above addition rate is 5% by weight or more, the stability of the aqueous alkali silicate solution, especially A decrease in long-term stability often occurs. Particularly preferred loading rates are O, IJ 5 to 1 wt.

The alkaline silicate water bath solution used in the present invention further includes two as long as the object of the present invention is achieved.

Optional ingredients such as tinting agents, stabilizers, viscosity modifiers, etc. can be added as required.
may be included.

The method of the present invention includes the step of impregnating the entire surface of the 7-mention-based material under pressure with the alkaline silicate water bath solution.

This pressurized impregnation process can be easily carried out by placing a high quality NQ silica alkaline water bath solution into a pressure-resistant container, immersing the cement material to be treated therein, and then pressurizing the solution. . However, if it cannot be treated in a container, such as on the walls of concrete buildings, cement
This can be carried out by bringing an aqueous alkali silicate solution into contact with the surface of the silicate and applying pressure from a pressure generator to the solution. In such a pressurized impregnation method, an open pressure-resistant funnel-shaped device having an internal volume large enough to store an aqueous alkali silicate solution is pressed against the surface of the cement material, and then a pressurized alkali silicate water bath solution is poured into the funnel. This can be easily done by maintaining the above pressurized state for a sufficient period of time without pressure leakage. The pressure increases the impregnation depth of the alkaline silicate bath solution, but it is usually 20-30 kg/cr.
Pressurization of 1 or more can be easily carried out and the impregnation depth can be increased significantly for a short period of time. It is an unexpected effect that the conventional normal pressure impregnation method has an immersion depth of 2 to 3 ff11%, but it can be increased to several times or even more depth by applying a pressure of several k17/cnl. be. In some cases, by applying reduced pressure to the surface of the ment-based material before applying the pressure, it may be possible to more effectively increase the immersion depth by applying pressure.

The method of the present invention requires following the above-mentioned pressure impregnation treatment and drying the pressure impregnated cementitious material. Drying may be done by either natural drying or forced drying, but natural drying is preferable. Upon drying, the alkali silicate causes an irreversible hardening reaction within the impregnated layer of the cementitious material and binds to the contacting tissue.

A modified layer is formed. In particular, lithium silicate has properties significantly different from other alkali silicates, and after drying, the lithium component is bathed out as an alkali #1. < , a favorable modified layer is formed. Modification by the method of the present invention is a material that is easily permeable to an aqueous alkali silicate solution according to 4Li [4] of the applied cementitious material.For example, lightweight concrete such as A TJ 0 is modified throughout the material, In addition, in the case of a material that is relatively difficult to penetrate, such as ordinary concrete, the surface layer of the material is modified. However, in the case of modification of one surface layer, the modified layer is formed in a significantly deeper region that could not be achieved by conventional methods.

Since the cementitious material modified by the method of the present invention is prevented from being carbonated for many years, there is no need to provide a cement paste coating to prevent carbonation. Furthermore, since the water permeation prevention properties of the modified layer are extremely excellent, weathering can be completely prevented. Freeze damage does not occur, especially in cold regions.

In addition, 1) the surface of the cement material modified by the method of the present invention has good adhesion with ordinary paints, coating materials, etc., , Cement-tMj side yarn #valley drawing paint or coating material can also be used for decorative coating.

The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the technical scope of the present invention is not limited thereto.

Example 1 Ordinary Portland cement - m - 297 weight part Sand with a diameter of 5 or less - 759 Sand between 5 and 25 diameters - 1.1065 water
0. ++ 178A, Tfl liquid --- 29.7 After making a concrete specimen according to the above distribution.

A cylindrical specimen with a diameter of 10 cln and a length of 20 tyn was prepared by curing in water for one week and then curing in humid air for three weeks.

Separately, 810g/Lt, O molar ratio 3. s,
slo, #degree 10% silica r1λ lithium water rg*
was placed in a pressure-resistant container, and the concrete specimen was immersed in it so that its entire surface was submerged under the liquid surface for 60 minutes.
After maintaining the pressure at a reduced pressure of 1 g, a pressure impregnation process was carried out by immediately introducing 1 okg/cJ of cable gas into the +i1 container and maintaining the same pressure for 60 minutes. Immediately after the above treatment, the concrete specimen was taken out, a part of it was split, and the depth of the part covered with the lithium silicate aqueous solution from the surface was measured to determine the impregnation depth, which was 30 leaps; p)tsu/hi. In addition, the above-mentioned split specimen was
The device was left in a room at 3℃ and 60% relative humidity for one week to air dry, and the compressive strength was measured, and the result was 510k.
y/crl f showed. When the above example was changed to (AJ) and two different tests (B) and (C) were conducted in the same manner by changing the pressure impregnation conditions, the results shown in Table 1 were obtained.

Example 2 Silicon in Example IVrC [instead of IJ tium water bath solution,
The same test as in Example 1 was conducted, except that a solution containing naphthalene sulfone soda formaldehyde condensate having an average degree of polymerization of 10 was added to the vaginal fluid in an amount of 0.1% by weight of the vaginal fluid, and the results shown in Table 1 were obtained. .

Comparative example 1 Compensation? The same test as in Example 1 was conducted, except that the impregnation was carried out by brushing at normal pressure without the vacuum and pressure impregnation in step 11, and the results shown in Table 1 were obtained.

Table 1 [From the results shown in Table 1, it is recognized that the pressure impregnation treatment can achieve a significant increase in impregnation depth and strength compared to the normal pressure impregnation treatment.

Example tell ・4j'i ・t%Saga 10Crnx 10
crnx 10 crn lightweight concrete ALC (manufactured by Nippon Iton Kogyo ■), surface 1 Deya Kishin 510x /Li,
It was immersed in a lithium silicate water bath solution with an IJ molar ratio of 5.5, Sin, and a concentration of 209, and was subjected to pressure impregnation treatment for 10 minutes with 5 kg/ad of soil, then taken out and kept in a room at 23°C and a relative humidity of 60% for one week. Dry. The compressive strength of this sample was measured to be 53 ky/cl. Further, when phenolphthalene was applied to the fractured cross section of the above sample to develop color and observed, it was found that the lithium silicate water bath solution had permeated the entire interior of the ATJ (3).

Furthermore, for the sample dried after the pressure impregnation treatment, a glass tube with a diameter of 31 Jm and a length of 350 mm was fixed upright on the surface of the sample via a layering agent, and water was injected to a height of 300 va, and the water level after 24 hours was When measured, it showed a decrease of only 4 degrees, indicating that it had excellent water permeation prevention properties.

Furthermore, the sample dried after the pressure impregnation treatment in 1111 was immersed in water for 1 hour, maintained at -2υ'C for 16 hours, and taken out and held in water for 4 hours at j'l'# for a total of 1 cycle. The freeze-thaw test was repeated for 20 cycles, but no abnormalities were observed.

As a comparison, the water permeability of ALO was measured in the same manner as above except that the pressure impregnation treatment with the lithium silicate water bath solution was not performed, and a decrease in the water column of 62 vyrb was observed. However, when the freeze-thaw test was repeated in the same manner as above, collapse occurred after one cycle.

Example 4 A test specimen was taken from a concrete floor whose surface had deteriorated and worn out 20 years after it was placed, and a wide-mouthed portion with a diameter of 200 mm was placed on the surface.
ym's pressure-resistant iron funnel-shaped device was attached via adhesive so that its wide rim was firmly attached to the concrete surface. Then, through a pressure-tight conduit into the funnel with
O,/Li1O molar ratio 3.58i0. A lithium silicate water bath solution with a concentration of 10x was injected and pressure impregnated from the co/crete surface at 5 kg/ffl for 10 minutes, and then the solution was removed and the equipment was removed.

Natural drying was performed by leaving it as it was for one week.

The compressive strength, l1lI'I abrasion resistance, and impregnation depth of the lithium silicate aqueous solution were measured for the sample after drying, and the results shown in Table 2 were obtained. The impregnation depth and compressive strength were measured in the same manner as described above.

Surface 1 abrasion resistance was measured by the method described in -G.

First, a test piece with a square shape of 100 vvrb on a side and a thickness of 15 was taken from the sample after drying, and abraded at 500 rotations on a seedling bundle of 50 log-F using a taper abrasion tester't JIJ and an abrasion wheel ■122. All operations, weight loss due to wear? 11.

Example 5 Addition of phthalenesulfonic acid soda formaldehyde condensate [Additionally, the same procedure as in Example 4 was performed except that a liquid was used, and the results shown in Table 2 were obtained.

Soft Ratio Examples 3 and 4 The same procedure as in Example 4 was carried out except that the pressure impregnation treatment was not performed, and the measurement results are shown in Table 2 as Ratio Soft Example 3.

Furthermore, the same procedure as in Example 4 was carried out except that instead of the pressure impregnation treatment, the normal pressure impregnation treatment was carried out by brush coating, and the results shown in Table 2 were obtained.

From the above examples and comparative examples, it is possible to apply the pressure impregnation treatment method of the present invention to walls etc. without using the sowing method, and moreover, it can bring about significant improvement effects (#4) One.

Table 2

Claims (1)

[Claims] The cementitious material has a molar ratio of SiO, z 0 (however, 1M represents an alkali metal atom or a substituted or unsubstituted ammonium cation group) from its surface of 1 to 50, and a total of 1 to 50 of SiO. A method for modifying a cementitious material, which comprises performing pressure impregnation treatment with an alkaline silicate water bath solution containing % by weight, and then drying the material.