JPH0450183A - Formed cement product and production thereof - Google Patents

Abstract

PURPOSE:To obtain a formed cement product excellent in weather resistance, surface smoothness and decorativeness by adding an aqueous solution of sodium silicate to cement, kneading, forming and hardening the resultant mixture. CONSTITUTION:An aqueous solution of sodium silicate expressed by the formula R2O.nSiO2.mH2O (R is alkali metal or alkaline earth metal; 2.0<=n<=3.2; 0.4<=m<=4.0) in an amount of 10-100 pts.wt. based on the weight of cement is added thereto in kneading cement and the resultant mixture is kneaded, formed and hardened to afford the objective formed product. The strength of the formed cement product after burning can be improved in producing a cement decorative material according to the aforementioned method for producing the formed product. Furthermore, the surface of the formed cement product can be simply smoothed and water absorption can be cut off. Thereby, decoration excellent in weather resistance can be readily applied with an organic, inorganic coating or glaze. Even if the coating thickness is small, the objective cement decorative material excellent in surface properties can be obtained in a few steps.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides cement with a dense and smooth surface for use as a cement decoration material for building materials such as interior materials, exterior materials, floor materials, roofing materials, counters, etc. The present invention relates to a molded body and a method for manufacturing the same.

[Conventional technology]

Conventionally, organic paints or inorganic paints have been applied to the surface of cement molded bodies to decorate the surface of cement molded bodies, to prevent cement from efflorescence and neutralization, to make the surface smooth and glossy, to prevent liquid penetration, etc. It has been practiced to apply a glaze or a glaze.

However, when applying paint to cement molded bodies, it is difficult to apply paint due to the water absorbency of the cement material itself, and complicated processes such as applying sealer treatment multiple times before painting are required, and repeated painting is also required. In addition, it has heat resistance, weather resistance,
It has the disadvantage of poor chemical resistance.

Additionally, when applying a glaze to a cement molded body, it is necessary to sinter it at a temperature of 600 to 1200°C after applying the glaze to the cement molded body, and as a result, the cement base material deteriorates due to firing and its strength decreases. Therefore, in order to recover from this decrease in strength, it is necessary to rehydrate the cement base material using an autoclave or the like after firing, which has the disadvantage of complicating the treatment process. Moreover, since the surface of the cement base material is rough, there are problems with the surface smoothness and aesthetic appearance of the finished product.

In order to compensate for such defects in appearance, JP-A-57-100991 discloses that a water glass aqueous solution is applied to the cement base material and an enamel glaze is applied on the applied layer. Even in cases where a small amount of water glass solution is applied to smooth the surface, the strength of the cement base material inevitably decreases after firing. It has the disadvantage that it requires treatment and the treatment process is complicated.

Furthermore, instead of surface treatment of the compact, a method of adding water glass and a hardening agent to alumina cement, kneading it, and heating and molding this kneaded product to obtain a cement compact with an improved surface condition has also been disclosed. It is disclosed in Publication No. 1988-71562. However, since hardening agents such as sodium silicofluoride are difficult to mix with cements, excessive water must be added for uniform mixing. For this reason, after molding, a large number of pores are likely to be generated inside and on the surface of the cement molded body due to evaporation of the excessively added water, resulting in a drawback that this leads to a decrease in the strength of the cement molded body.

[Issues that Hikari is trying to solve]

The problem to be solved by the present invention is to overcome the drawbacks of the above-mentioned prior art, to achieve excellent weather resistance, smoothness of the surface,
The object of the present invention is to find a cement molded article that has a surface condition with excellent decorative properties and does not cause deterioration of the cement base material, and a method for obtaining the same.

[Means to solve the problem]

The present invention impregnates a cement molded body with sodium silicate or adds an aqueous sodium silicate solution during cement kneading,
A cement molded body by kneading, molding, and hardening, and a method for producing the same.

The sodium silicate used in the present invention has the general formula RxO・nSi
02・m Hs OCR is an alkali metal or alkaline earth metal (the same applies hereinafter), 2.0≦η≦3.2゜0.
4≦m≦4.0] All sodium silicate can be used, but from the viewpoint of ease of impregnation and kneading, and strength after firing, the preferred one is 5iOi/R2O molar ratio 2.
．． Examples include those having a value of 0 to 3.5.

Furthermore, materials suitable for impregnation are SiOh/Rt○ molar ratios of 2.0 to 2.0, from the viewpoint of ensuring viscosity that allows the sodium silicate aqueous solution to easily penetrate into the pores in the cement by capillary action.
3.5 and a viscosity of 150 Cp or less.

In addition, from the viewpoint of the formability of cement mortar and the surface condition of the molded product, SiO
/ Rx O molar ratio 2.0-3.5 and viscosity 250c
It is used in the form of a solution with p or less. The concentration and amount of sodium silicate added at the time of cement mixing is 10 to 100 parts by weight based on the weight of cement, preferably depending on the ease of mixing of cement mortar, the degree of air bubble mixing, the fluidity of cement mortar during molding, etc. Concentration 10-70% from the point of
, 80 parts by weight or less based on cement.

[Effect]

The present invention utilizes the property of sodium silicate itself to cause a crosslinking reaction between the silica component in the cement and the silica component in the sodium silicate to fill the voids between cement particles.

Water absorption of the cement material can be relatively easily stopped by simple operations such as cement mixing and impregnation that do not require excessive water, and the sodium silicate that has entered the surface and inside of the cement molded body can be By filling the pores inside the cement and the pinholes on the surface, the surface becomes smooth and the strength is improved by 30 to 50% compared to untreated cement molded bodies.

In addition, when this cement molded body is fired, the sodium silicate acts as a flux material, and the soda silicate fills and binds the cracks caused by the dehydration reaction of the cement, thereby preventing a sudden decrease in the strength of the cement molded body after firing. It can be prevented.

〔Example〕

Example 1 5 kg of Portland cement, 10 kg of silica sand,
3Q x 33c of cement mortar consisting of 3.5kg of water
The molded product was poured into a tile-shaped formwork of 1.5 m and cured for 28 days in a constant temperature and humidity chamber of 2 Ot and 80% R)I, and then S+
Oz/Naz O molar ratio 2.1. J with viscosity 110cp
IS K140g standard No. 1 water glass solution, 510a
/Na, ○ Molar ratio 2.4-2.5° Viscosity 80-100c
p JIS K140g standard No. 2 water glass aqueous solution, S
l 02 /Naz O molar ratio 2.7. Viscosity 130Cp
water glass aqueous solution, 52Oz/Nas○ molar ratio 3.05
Samples A, B, C, and D were immersed in a JIS K140g standard No. 3 water glass aqueous solution with a viscosity of ~3.15° (viscosity 130 CJ) for 24 hours each, and then dried in a dryer at 60°C for a day and night. Water absorption rate, before and after firing The results of measuring the bending strength are shown in Table 1.

The bending strength was determined from each sample at a length of 30 cI11. Radius 5cm,
Thickness 2. The three-point bending strength was measured using a universal strength testing machine made by Shimabara Seisakusho after cutting a 0cm plate with a span of 20cm.

(Hereinafter, this page margin) Samples A, B, C, and D in Table 1 have much higher bending strength after firing than the untreated cement molded body, and have low water absorption. In addition, the surface has almost no unevenness, making it easy to apply organic or inorganic paints.

Cracks also occur when this sample is glazed.

No defects were observed, and the surface was smooth and beautiful.

Furthermore, the amount of paint used is 30~30% less than when painting an untreated sample.
b Example 2 5 kg of Portland cement, 10 kg of silica sand,
A cement mortar consisting of 1.8 kg of water, various types of water glass (same composition of water glass as in Example 1) aqueous solution (concentration: 301% H, 7 kg) was poured into a 30 x 30 cm tile-shaped formwork, and molded into a molded product. days, 2O℃, 80
Table 2 shows the results of measuring the water absorption rate and bending strength before and after firing using the same method as in Example 1 for Samples E, F, G, and H that were cured in a constant temperature and humidity chamber at %RH.

Table 2 was beautiful. The amount of paint used was also 30~b compared to the painting of the non-additive sample.Example 3: 5 kg of Portland cement, 10 kg of silica sand,
Cement mortar consisting of 3.5 kg of an aqueous solution (concentration of 30%) of various types of water glass (same composition of water glass as in Example 1) was poured into a 30 x 30 cm tile-shaped mold and molded, and the molded product was kept at 20°C for 28 days. , 80%R) Water absorption rate for samples I, J, and L cured in a constant temperature and humidity chamber.

The bending strength before and after firing was measured by the same method as in Example 1, and the results are shown in Table 3.

Samples E, F, G, and H in Table 3 have a higher bending strength after firing than the water glass-free sample and the water glass-impregnated sample of Example 1, and have a lower water absorption. In addition, the surface has almost no unevenness, making it easy to apply organic or inorganic paints. Furthermore, when this sample was glazed, there were no cracks or chips, and it was smooth.

Samples I, J, and L have a higher bending strength after firing than the water glass-free sample and the water glass-impregnated sample on the actual flow side 1, and have a lower water absorption. In addition, the surface has no unevenness and can be easily coated with organic or inorganic paint. Furthermore,
Even when this sample was glazed, no cracks or chips were observed, and the surface was smooth and beautiful. The amount of paint used was also 30-b compared to the coating of a sample without additives. [Effects of the Invention] (1) In the production of cement decorative materials, the strength of cement molded bodies after firing can be improved.

(2) The surface of the cement molded body can be easily smoothed and water absorption can be prevented, resulting in excellent weather resistance. It can also be easily decorated with organic paints, inorganic paints, or glazes, and the surface quality can be improved even when the coating thickness is thin. A cement decoration material with good quality can be obtained with fewer steps.

Claims (1)

[Claims] 1. General formula R_2O・nSiO_2・mH_2O (R is an alkali metal or alkaline earth metal, 2.0≦n≦
3.2, 0.4≦m≦4.0) A cement molded body impregnated with sodium silicate. 2. General formula R_2O-nSiO_2・mH_2O (R is an alkali metal or alkaline earth metal, 2.0≦n≦
3.2, 0.4≦m≦4.0)) When kneading the cement, apply an aqueous solution of sodium silicate to
A method for producing a cement molded body by adding 100 parts by weight, kneading, molding, and hardening.