JPS5945626B2 - Cement-based self-leveling flooring - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cement-based self-leveling flooring material that prevents the occurrence of laitance on the surface of the flooring material.

In recent years, attention has been paid to self-leveling flooring materials that form a horizontal surface with excellent surface accuracy through the natural flow of the kneaded material by simply pouring a highly fluid aqueous mixture onto an uneven floor surface such as a concrete slab.

Self-leveling flooring has excellent initial fluidity when mixed with water and poured onto an uneven floor surface, does not cause solid-liquid separation during curing, forms a uniform horizontal surface, and has low volumetric shrinkage during curing. (Even after hardening, it must be mechanically stable against repeated drying and wetting, and be workable, workable, and economical. To date, Portland cement, magnesia cement, etc. Various types of self-leveling flooring materials are known, such as cement-based self-leveling flooring materials using water-conserving materials such as gypsum plaster, and gypsum-based self-leveling flooring materials using gypsum plaster as a water-conserving material.

However, although conventional self-leveling flooring materials are relatively good at preventing solid-liquid separation during curing and maintaining early strength, workability, and workability, they do not sufficiently prevent cracks on the surface of the flooring material after curing. I can't.

Therefore, the applicant has developed a cement-based self-leveling flooring material that prevents the occurrence of cracks by incorporating cement as a main component and a lime-based expansive material, an admixture, etc. No. 56-84358).

By the way, when self-leveling flooring is installed on-site, the fluidity of the self-leveling flooring requires a high melting point, so the amount of water added during kneading tends to be excessive.As a result, after curing, laitance occurs on the surface of the flooring, causing plastic particles to form on the surface of the flooring. When pasting tiles, vinyl sheets, carpets, etc., there is a phenomenon that leads to poor adhesion.

This is because the amount of water to be added is often determined visually at the construction site, and since the amount of water varies widely, there may be cases where the amount of water is excessive in some areas.

The present invention provides a cement-based self-leveling flooring material that can prevent the occurrence of cracks on the surface of the flooring material after hardening and also suppress the occurrence of laitance even when an excessive amount of water is added. The basic composition of the material is 100 parts by weight of cement, 6 to 20 parts by weight of a lime-based expansive agent, 0.5 to 3 parts by weight of a water reducing agent made of a sulfonated modified resin of a melamine formaldehyde condensate, and 6 to 6 parts of an admixture made of fly ash. 25 parts by weight, water retention agent 0
．． 04 to 0.2 parts by weight and 80 to 1,800 parts by weight of sand, and 0.05 to 2 parts by weight of polyethylene oxide.
It is characterized in that it is blended in parts by weight.

The present invention will be explained in detail below based on examples.

A slurry made by adding and kneading various amounts of water to a cement-based self-leveling flooring material with the composition shown in Table 1 is poured onto a concrete slab to form a smooth surface, and after curing for 7 days, the surface In addition to visually determining the presence or absence of laitance, a steel attachment (4C) is coated with epoxy resin on the surface.
rIL×4CrrL) was attached, and the surface adhesion strength was measured using a Kenken-type tensile tester.

Surface adhesion strength is an indicator of adhesion when adhering finishing materials such as carpets and vinyl sheets to plastic tights on flooring materials using an adhesive. If this value is small, the There is a risk that the finishing material will peel off, and empirically, a strength of 6 kg/criJfi is required.

In addition, when measuring the surface adhesive strength, it was also observed which parts were broken.

Note that the flow and coagulation of the slurry were measured using conventional methods.

The results are shown in Table 2.

As is clear from Table 2, the amount of water added to 100 parts by weight of cement is 7.
When the amount reaches 5 parts by weight, laitance occurs on the surface and the surface adhesive strength decreases significantly (see sample AI).

This tendency is observed when the amount of polyethylene oxide added is 0.03
The same applies to parts by weight (sample 116.I [reference)]
.

However, the amount of polyethylene oxide added to cement is 1
When the amount of water is 0.05 parts by weight to 100 parts by weight, no laitance occurs even if the amount of water added is 75 parts by weight to 100 parts by weight of cement, and the surface adhesion strength is 6.0 parts by weight, which is the practically required level. kg/cyst or more (see sample A III).

When the amount of polyethylene oxide added is 0.2 parts by weight per 100 parts by weight of cement, even if 85 parts by weight of water is added to 100 parts by weight of cement to make soft wire,
No laitance is generated, a satisfactory surface adhesive strength is obtained, and no breakage occurs on the bonded surface during the surface adhesive strength test.

However, as the amount of polyethylene oxide added increases, the setting time becomes longer and fractures occur in the flooring material itself, resulting in a decrease in the strength of the flooring material itself and weaker adhesive strength.

(Refer to sample boiling ■～■) If the amount of polyethylene oxide added is 2.5 parts by weight per 100 parts by weight of cement, the completion time will exceed 24 hours, and the required surface adhesive strength will not be achieved. Therefore, it is not suitable for practical use (see sample boiling ■).

Therefore, the amount of polyethylene oxide added is 10% of cement.
0.05 to 2 parts by weight is suitable for 0 parts by weight.

There are various types of polyethylene oxide, ranging from low to high polymerization degrees, but those with a molecular weight of less than 2.5 million have little laitance prevention effect, and require a large amount to be added to achieve a sufficient effect. It's the economy.

Furthermore, if the molecular weight exceeds 6 million, the dissolution rate in water will be extremely slow, so it will be necessary to take a long kneading time, resulting in a decrease in construction efficiency.

Therefore, polyethylene oxide having a molecular weight of 2.5 million to 6 million is suitable for use in self-leveling flooring.

Next, as a cement-based self-leveling flooring material to which the above-mentioned polyethylene oxide is added and mixed, from the viewpoint of preventing cracking, 6 to 20 parts of lime-based expansive material is added to 100 parts by weight of the lime-based expansive material.
Parts by weight, 0.5 to 3 parts by weight of a water reducing agent made of a sulfonated modified resin of a melamine formaldehyde condensate, 6 to 25 parts by weight of an admixture of fly ash, 0.04 to 0.04 parts by weight of a water retention agent.
0.2 parts by weight and 80 to 180 parts by weight of acid are preferred.

In the composition of the self-leveling flooring material, as well as ordinary Portland cement, early-strength Portland cement, ultra-rapid hardening cement, white cement or colored cement with added pigments are used as the cement.

Colored cement or a mixture of these cements with calcium chloride, hemihydrate, anhydrite, etc. is used to accelerate hardening.

As the lime-based expansive material, Onoda Expan is used, and the amount used is 6 to 20 parts by weight per 100 parts by weight of cement. If it is less than 6 parts by weight, the drying shrinkage of the hardened product becomes large and the shrinkage reduction effect appears. (Also, if it exceeds 20 parts by weight, the dimensional stability will deteriorate due to expansion action, and the strength development will also be significantly reduced. If it is added in excess, it may expand and collapse. There is.

Various water reducing agents are known, but among these, sulfonated modified resins of melamine formaldehyde condensates are particularly suitable; if the amount added is less than 0.5 parts by weight, it is difficult to obtain the desired fluidity. The amount of water required for this process is undesirable because it increases breathing, reduces strength, and causes drying shrinkage, and when it exceeds 3 parts by weight, it is unsuitable because separation of the material occurs.

The optimum amount is 1.0-1.5 parts by weight.

As an admixture, fly ash has a powder degree of 2500 to 40.
00crrt/Y (Brain) is preferable, and the amount added is 6 to 25 parts by weight per 100 parts by weight of cement.
The amount is preferably 8 to 15 parts by weight, and if it is less than 6 parts by weight, fluidity decreases and drying shrinkage increases.

Moreover, if it exceeds 25 parts by weight, the strength will be significantly reduced.

Finely divided silica and blast furnace slag powder are also commonly used as admixtures, but when used in the present invention, finely divided silica is not preferred because it significantly impairs fluidity.

Blast furnace slag powder increases fluidity, but on the other hand, drying shrinkage becomes significant, resulting in poor dimensional stability and reduced strength of the cured product, which is not preferred.

The water retention agent plays an important role in keeping water floating in the slurry, and methyl cellulose, hydroxypropyl methyl cellulose, glyoxal-added hydroxypropyl methyl cellulose, etc. are used in the present invention. Preference is given to using hydroxypropyl methylcellulose.

Among the above water retention agents, the viscosity of a 2% aqueous solution (H8) at 20°C measured by a B-type viscometer is 2400 to 30000 c.
Up to ps are suitable for use.

The amount added varies depending on the viscosity of each methylcellulose derivative, but is 0.04 to 100 parts by weight of cement.
0.2 parts by weight, especially 2% aqueous solution (pH 8)
Glyoxal-adducted hydroxypropyl methylcellulose with a viscosity of 15,000 cps at 0°C is
Preferably, 0.14 parts by weight is used.

Finally, as sand, artificial sand such as silica sand, crushed sand, crushed blast furnace slag sand, etc., and natural sand such as river sand, sea sand, mountain sand, etc. can be used, but the particle size of the sand is 5 mm or less, especially 2.5 mm or less. In the case of silica sand, it is best to use silica sand with a diameter of 1.2 mm or less, and if this is used, the best fluidity and other physical properties can be exhibited with the same amount of water.

The amount of sand used is 80 to 180 parts per 100 parts by weight of cement.
Parts by weight are particularly preferably 100 to 140 parts by weight.

If it is less than 80 parts by weight, the amount of cement will increase,
Cracks occur in the hardened product due to temperature stress caused by the heat of hydration of cement, and if the amount exceeds 180 parts by weight, the amount of sand is large, so the amount of water must be increased to obtain the specified amount of fluidity, which causes breathing. This is undesirable because it increases the strength, decreases strength, and increases drying shrinkage.

Note that when the self-leveling flooring material is kneaded with water to form a slurry, fine bubbles may be generated, so it is preferable to add a small amount of an antifoaming agent in advance.

The cement-based self-leveling flooring material of the present invention has fluidity for several hours after being kneaded, and can finish a smooth surface with a thickness of several mTt to 30 mm on, for example, a concrete slab only by its own fluidity.

Furthermore, the dimensional stability (change in length) after curing is superior to that of cement mortar coating and troweling, and no cracks were observed in the flooring material after curing, and variations in the amount of water measured at the construction site were avoided. There is no need to worry about laitance occurring even when it is softened to improve construction efficiency.

The flow value suitable for installing self-leveling flooring is 300.
~400 mm, but within this range, the larger the flow value, the higher the construction efficiency, so in on-site construction there is a tendency to increase the amount of added water as much as possible to make the mixture soft.

For this reason, in the past, the occurrence of laitance often caused a decrease in surface adhesive strength, but in the present invention, this problem does not occur even when it is softened, and plastic tiles,
It has great advantages in construction, such as being able to adhere well to finishing materials such as vinyl sheets and carpets.

Next, examples of the present invention will be shown.

Example 80 parts by weight of tap water was added to a self-leveling floor material prepared by mixing the raw materials shown in the table below and kneaded to form a slurry.

The flow value of the slurry at this time was 3857X7X.

This slurry is applied onto a concrete floor slab to an average thickness of 20 mm.
I poured it to form a smooth surface.

The finished state after curing was very good and there was no laitance.

Surface adhesion strength was measured 7 days after pouring and the average was 1.
It was 3.0 kg/cy4.

For comparison, 70 parts by weight of tap water was mixed with a composition obtained by removing the polyethylene oxide from the above self-leveling flooring material and kneaded.

The flow value of the slurry at this time was 360 mvt.

This slurry was poured onto a concrete floor slab to an average thickness of 20 mm in the same manner as above to form a smooth surface.

Occurrence of laitance was observed after curing. The surface adhesive strength was measured 7 days after pouring and found an average of 3.5 ky/ca.
Met.

Claims (1)

[Claims] 1 The basic composition of self-leveling flooring is cement 100.
6 to 20 parts by weight of a lime-based expansive material, 0.5 to 3 parts by weight of a water reducing agent made of a sulfonated modified resin of a melamine formaldehyde condensate, 6 to 25 parts by weight of an admixture made of fly ash, and 0 parts by weight of a water retention agent. A cement-based self-leveling flooring material comprising 0.04 to 0.2 parts by weight and 80 to 180 parts by weight of sand, and 0.05 to 2 parts by weight of polyethylene oxide having a molecular weight of 2.5 million to 6 million. .