JPH0474780A - Ceramic product prevented from base-silica reaction and method for preventing base-silica reaction - Google Patents

Abstract

PURPOSE:To obtain the title product stabilized for a long period of time by bringing ozone-contg. water into contact with the reactive silica component in a base-silica-reactive ceramic product to prevent base-silica reaction. CONSTITUTION:Ozone is brought into contact, in the presence of water, with a water-absorptive ceramic product containing silicic acid and/or silicate component(s) reactive with basic component(s) to modify the reactive site of the reactive silica component, thus obtaining the objective ceramic product prevented from base-silica reaction. The present method can effectively be applied to ceramic products advanced in base-silica reaction; that is, a base-silica reaction product developed on the surface of a ceramic product containing silicic acid and/or silicate component(s) reactive with basic component(s) is removed, and ozone-contg. water is penetrated into the part(s) where said reaction product was developed.

Description

[Detailed Description of the Invention] Field of Application The present invention relates to ceramic products that suppress base-silica reactions in ceramic products containing silica components that are reactive with basic components; and ceramic products that have undergone base-silica reactions. The present invention relates to a method for inhibiting the progress of this reaction in a product. The present invention is extremely useful for improving the quality of ceramic products that may suffer from cracks, breakage, and surface contamination due to base-silica reactions.

Prior Art and Problems Base-silica-reactive ceramic products, typified by ceramic products, form alkali-silica-reactive silica components during sintering and firing. The reactive ceramic reacts with an alkali component (for example, by reacting with an alkali component contained in seawater or with an alkali component contained in the cement mortar that is the base to which the ceramic product is attached) and produces an alkali-silica reaction product. Form. There has been a major problem in the formation of cracks and fractures due to the expansion of the alkali-silica reaction product and the formation of surface contamination due to its surface precipitation. Traditionally, to alleviate this problem,
(a) reducing the amount of reactive silica components in the raw material;
and (b) it was necessary to make ceramic products non-water absorbent by high temperature firing. However, method (a) above is difficult to use because the raw materials are somewhat expensive and the quality of the raw materials to be supplied is uncertain. The above method (b) is disadvantageous from the viewpoint of thermal economy and furnace, and tends to limit the raw materials.

Hitherto, simple means for improving the reactivity of such base-silica-reactive ceramic products have remained unresolved. The main purpose of the present invention is to provide a means to easily solve the above problems.

Means for Solving the Problems The present inventor unexpectedly brought into contact the reactive warp component in the above-mentioned base-silica reactive ceramic product with ozone-containing water (sometimes referred to as 03 water below C). It has been found that by doing so, the surface structure of the silica component is modified and stabilized over a long period of time, and its reactivity is suppressed.

According to the invention, therefore, a water-absorbing mineral ceramic product containing silica and/or silicate components that are reactive with basic components is contacted with ozone in the presence of water to destroy the reactive sites of the reactive silica components. The modified ceramic product is provided which suppresses the base-silica reaction.

The present invention can also be advantageously applied to suppressing the progress of the base-silica reaction in ceramic products where j=the reaction progresses. Therefore, according to the present invention, monobase-silica reaction products that appear on the surface of a ceramic product containing a silicic acid component and/or a silicate component that are reactive with basic components are removed, and the reaction products of the ceramic product are removed. There is also provided a method for inhibiting the progress of the base-silica reaction in ceramic products, which is characterized by infiltrating ozone-containing water into the portion where the material has appeared.

Detailed Description of the Invention (1) Examples of Base-Silica Reactive Ceramics Ceramic products to which the present invention is advantageously applied are typically ceramic products, stoneware products, and most porcelain products. The 24-hour immersion water absorption rate of the water-absorbing ceramic product is approximately 0.
．． 2% or more, usually about 0. X or more and typically about 1
% or more. As the basic component of the ceramic product, an alkali component is particularly involved in the base-soldering reaction. Reactive silica components include opal, cristobalite, tritumite, volcanic glass, and minerals such as ball shafts.
And there are synthetic materials that form a corresponding surface or glass structure. Generally, igneous rock materials, glass powder, etc. are also exemplified. Note that silicates or other inorganic raw materials that become reactive with alkali and silica upon firing are also included.

(2) Ozone Ozone used in the present invention can advantageously be obtained from an ozone generator using silent discharge or electrolysis. For example, ozone can be obtained inexpensively by silently discharging oxygen or dry air with alternating current voltage.

use. 3. The concentration (% by weight) of the water (which may be ozone-containing water, such as an aqueous solution of ozone or a supersaturated aqueous solution or ozone-containing water vapor) is generally about 0.02% or more;
It ranges from about 0.02 to 3%, usually about 0.05
The dust concentration is approximately 2%, and in the case of ozone-containing water vapor, the concentration is even higher. Note that the above ozone supersaturated aqueous solution is obtained by introducing ozone or an ozone-containing gas into water under pressure. The ozone-containing water vapor mentioned above is obtained by mixing ozone or an ozone-containing gas with, for example, saturated water vapor, and the ozone concentration relative to water is, for example, about 20.
High concentrations of ~30% are also possible. When contact treatment is performed with o3 water, infiltration into o3 water (for example, 05 to 2%
2) For several tens of minutes at a concentration, or you can spray O3 water. In addition, a supersaturated aqueous solution of o3
When using ozone-containing steam, it is generally preferable to seal the container for contact treatment. Alternatively, the ceramic article to be contacted is placed in a container, and (a) ozone-containing water vapor is continuously introduced, or (b) water is added to immerse or wet the material and then ozone or water vapor is introduced into the container. Continuous introduction of ozone-containing gas is also a preferred treatment method.

In these cases, it may generally be preferable to rinse the treated ceramic product with water after contact treatment;
No need to wash with water. In addition, in order to alleviate the effect of 03, it is also desirable to use a small amount (for example, an equivalent of 2/3 or less of the ozone equivalent of 03 water) of a reducing compound (for example, sulfite or nitrite). This is one aspect.

(3) Specific Examples 1 to 2 As a representative example of a ceramic product to which the present invention is applied, a stoneware tile base having a water absorption rate of 5% was prepared as follows. That is, 63 parts by weight of a mixture of raw talc and pottery stone (63 parts by weight) and 30 parts by weight of a mixture of feldspar and betalite (5 parts by weight) are mixed, and a slurry is formed by using a whole mill to form a cotton layer until the particle size of the feldspar is about 2 microns or more.

This is mixed with slurry clay 71, and then dehydrated and milled to produce clay. This clay was pressurized with a press pressure of 300 kg/sq.
m). This molded body was fired at a maximum temperature of 1150° C. for 36 hours to obtain a stone tile base. The 24-hour immersion water absorption rate of the tile base was 55.

In Example 1 (Example), this tile base was sealed in an excessive amount of 21 ozone water, immersed for 24 hours, and then washed with running water. In Example 2 (comparative example), a tile base that was washed with running water without being treated with ozonated water was used as it was.

A box-shaped container with an inner frame size of a little over 1 m x a little over 1 m was placed horizontally, and a foundation mortar consisting of 1 liter of Portland cement and 5 parts of sea sand in a weight ratio of 5 cm was poured into the container and allowed to harden by hydration. A mortar for adhesion consisting of Portland cement and water was placed thereon to a thickness of 5 mm, and 10XIO of the above tile base samples were adhered thereon at joint intervals. In order to accelerate the alkali-silica reaction, the sample was kept in an environmental test chamber at a temperature of 40° C. and a relative humidity of 95%. In Example I according to the invention, no cracks or contamination of the tile substrate and grout surfaces were visually detected. In Example 2, which is a comparative example, about 96 to 10 circular alkaline reaction products (water glass) with a diameter of about 0.5 to 2 cm were detected on the surface of the substrate and in the joint area. It was done.

The above circular reaction product is caused by the alkaline component in the mortar (especially the base mortar) penetrating into the tile base, causing an alkaline-lika reaction, and the reaction product appearing on the surface and sides of the tile base. It is something.

(4) Reference Examples 3 to 4 The alkali-silica reactivity of the above-mentioned stone tile bases was tested by the mortar bar method in accordance with JIS A330g Appendix 8. The tile base was pulverized to a particle size specified by the JIS, and portland cement and water were mixed to prepare a mortar bar specimen. Example 3:
The pulverized product was sealed in 15 tons of ozone water, immersed for 24 hours, and washed with water. In Example 4, the untreated pulverized product was used.

Other procedures were carried out in accordance with the provisions of Appendix 8 of JIS^5308. The results are shown in the table below.

Example 4 (untreated product) 0.80 1,17
1,21 1.24 Thus, Example 4 was very harmful, and Example 3 demonstrated that the alkali-silica reaction was sufficiently suppressed.

Actions and Effects Base-silica reactions (especially alkali-silica reactions) in ceramics in which base components and reactive silica components coexist are extremely harmful to the durability and contamination of the ceramics, or are essentially unresolved. was in a state of Although the effect of the present invention has not been fully elucidated, by bringing ozone into contact with the reactive ceramic in the presence of water, the glass structure, which is the reactive site of the silica component, is modified into a hydrogel-like substance. , it is thought that the reactivity is effectively suppressed to achieve the effect. For example, the reactive shearing force component typically has a =Si-0 reaction site, but in this case, ozone-containing water acts to modify it into a long-term stable Mi-S1-OH structure, and its It is thought that reactivity is also sufficiently suppressed. However, the present invention is not limited to such representative theory.

The modified ceramic product and base reaction suppression method according to the present invention are extremely useful for long-term stabilization and contamination prevention of reactive silica component-containing ceramics that come into contact with base components (particularly alkaline components). Note that the ozone-containing water used ultimately becomes water, so there is no harm or adverse effect.

Claims (2)

[Claims] (1) A water-absorbing ceramic product containing a silicic acid component and/or a silicate component that is reactive with a basic component is brought into contact with ozone in the presence of water to modify the reactive sites of the reactive silica component. , the ceramic product that suppresses the base-silica reaction. (2) Remove the base-silica reaction product appearing on the surface of the ceramic product containing the silicic acid component and/or silicate component that is reactive with the basic component, and remove the base-silica reaction product appearing on the surface of the ceramic product, and A method for suppressing a base-silica reaction in a ceramic product, the method comprising impregnating ozone-containing water.