JPS5825061B2 - Cement-based self-leveling flooring - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to cementitious self-leveling flooring compositions.

In recent years, attention has been paid to cement-based self-leveling flooring materials that form a horizontal surface with excellent surface accuracy due to the natural flow of the kneaded material by simply pouring a water-based kneaded material with good fluidity onto an uneven floor surface such as a concrete slab.

Cement-based self-leveling flooring is made by mixing this with water.
It has excellent initial fluidity when poured onto uneven surfaces, does not cause solid-liquid separation during curing, and forms a uniform horizontal surface.There is no volumetric shrinkage during curing, and even after curing, it can be repeatedly wet and dry. However, mechanical stability, workability, construction efficiency, and economic efficiency are essential requirements, and to date, Portland cement has been mixed with aggregates such as sand, fly ash, and rapidly cooled blast furnace slag. Various cement-based self-leveling flooring compositions have been proposed, in which cement, various water-reducing agents, water-retaining agents, etc. are added. A method of pouring it into the system is being implemented.

However, according to these methods, even though solid-liquid separation does not occur during curing, early strength is achieved, and workability and workability are relatively good, cracks that occur on the flat surface after curing occur. cannot be prevented.

In an effort to prevent this drawback, the present inventors added an expansive agent to a cementitious self-leveling flooring composition, thereby preventing the flow value of the cementitious self-leveling flooring slurry from decreasing and causing cracks in the hardened flooring. We conducted various experiments in an attempt to prevent this from happening.

The results show that cement and sand mixtures can be used as water reducing agents, especially sulfonated modified resins of melamine formaldehyde condensates (Melment F-10, manufactured by Showa Denko @), water retention agents, fly ash and lime-based expansive agents (Onoda Expan, Onoda Cement (manufactured by)) is blended in a specific proportion, the flow value of contaminants with water improves,
It has been found that a cement-based self-leveling flooring material that does not generate cracks can be obtained because the change in length of the cured product is also small.

Next, the results of various experiments will be explained.

The blending ratios of the cement-based self-leveling flooring materials used in the experiment are shown in Table 1 below.

Measure the flow value, solidification completion time, compressive strength, bending strength, and length change of the hardened floor body for the sample of the mixture of cement self-leveling flooring material and water listed in Table 1.
The results shown in Table 2 were obtained.

From Table 2 above, comparing Samples 1 to ■, Sample ■ is much better than Samples I and ■ in terms of flow value, and Sample ■ is the best in terms of compressive strength and bending strength, and Samples ■ and I are the worst in that order. However, in terms of length change, sample ■ is far superior to samples ■ and ■, and sample I has a long completion time, while samples ■ and ■ are almost the same. It is recognized that ■ has excellent properties as a cement-based self-leveling flooring material.

Next, when the expanding material of sample ■ (lime-based Onoda Expan) was changed to an expanding material (C8A-based Denka C8A) (sample ■
), it can be seen that sample (2) is much superior to sample (2) in terms of flow value, compressive strength, bending strength, length change and termination time.

The present invention is based on the above-mentioned experimental results, and based on 100 parts by weight of cement, 6 to 20 parts by weight of a lime-based expansive agent and 0.5 to 3 parts by weight of a water reducing agent made of a sulfonated modified resin of a melamine formaldehyde condensate. , a cement-based self-leveling flooring material containing 6 to 25 parts by weight of an admixture consisting of fly ash, 0.04 to 0.2 parts by weight of a water retention agent, and 80 to 180 parts by weight of sand, and when used. To 100 parts by weight of cement in this cement-based self-leveling flooring material, 45 to 68 parts by weight of water are added and kneaded.

In the present invention, the cement used is not only ordinary Portland cement, but also early-strength Portland cement,
Ultra-early and strong Portland cement, ultra-fast hardening cement, white cement, or colored cement with added pigments are used.

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. It is undesirable because the length change will be too large, and if it exceeds 20 parts by weight, the dimensional stability will deteriorate due to the expansion effect, and the strength development will also be significantly reduced, and if it is added in excess, it may expand and collapse. be.

Various water reducing agents are known, but among these, sulfonated modified resin of melamine formaldehyde condensate (Melment F-10) is particularly suitable; if the amount added is less than 0.5 parts by weight, This is undesirable because the amount of water required to obtain the fluidity increases, resulting in increased breathing, reduced strength, and drying shrinkage.
Moreover, if it exceeds 3 parts by weight, separation of the wood powder will occur, which is inappropriate.

The optimum amount is 1.0-1.5 parts by weight.

As an admixture, fly ash has a powder degree of 2500 to 40.
00crit/9 (Blaine) 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, 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 eliminating floating water in the slurry, and methyl cellulose, hydroxypropyl methyl cellulose, glyoxal-added hydroxypropyl methyl cellulose, etc. are used. Preference is given to using methylcellulose.

Among the above water retention agents, the viscosity of a 2% aqueous solution (pH 8) at 20°C measured by a B-type viscometer is 2,400 to 15,00.
Up to 0 cps 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 was prepared by o,io
It is preferable to use 0.14 parts by weight.

If the amount of methylcellulose or methylcellulose derivative used is less than 0.04 parts by weight, a large amount of breathing will occur and laitance will occur on the floor surface.

In addition, if it exceeds 0.2 parts by weight, not only will the strength decrease, but it will also cause damage to the floor surface with a diameter of 2 to 10 mrft and a depth of 2 to 5 m.
Vt bubble marks are created, which reduces the smoothness of the surface.

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, hanging sand, etc. can be used, but the particle size should be 5 mrlt or less, especially 2.5 m in particle size.
m or less is preferable, and in the case of silica sand, L2mm
The following are optimal, and by using them, the most excellent 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 water utilization 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. This is undesirable because it increases the strength, decreases strength, and increases drying shrinkage.

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 urns to 30 urns on a concrete slab, for example, only by its own fluidity.

Furthermore, the dimensional stability (change in length) after curing is superior to that of cement mortar coated trowel, and no cracks were observed in the hardened flooring material, and the strength was You can demonstrate your strength.

Therefore, the present cement-based self-leveling flooring can be used for outdoor finishes such as parking lots, balconies, dirt floors, etc., as well as indoor floor finishes for water seepage areas.

EXAMPLE The cement-based self-leveling flooring material of Test No. (3) in Table 1 used in the above-mentioned experimental example was poured on a concrete slab with an uneven surface of 1.5 mvt and a width of about 88 m2 according to the following procedure.

That is, first, the concrete slab surface is cleaned and then the level is determined, then a primer is applied to the slab surface, and after drying, a cement-based self-leveling flooring material with the composition shown in sample number ■ in Table 1 is applied using a band mixer. The slurry obtained by kneading was transferred to a mortar pump and poured onto the concrete slab surface at a discharge speed of 2 m'/h over 30 minutes.

The average thickness of the slurry was 10 mm.

The finish flatness after curing is very good at around 1/1000,
No cracks were observed, and the P-tile could be attached approximately 20 days after installation.

Claims (1)

[Claims] 1 6 to 20 parts of lime-based expansive agent per 100 parts by weight of cement
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.
A cement-based self-leveling flooring material containing 0.2 parts by weight and 80 to 180 parts by weight of sand.