JPH05213647A - Self-leveling cement composition - Google Patents

Abstract

PURPOSE:To improve crack resistance by incorporating a silicone oil into cement in a specified weight ratio. CONSTITUTION:From 0.001 to 2 pts.wt. of a crack preventive agent of the silicone oil such as dimethylpolysiloxane, 0.1-3.0 pts.wt. of a dispersant such as a melamine-formalin condensate, a sulfonate, etc., 0.005-1 pts.wt. of a cellulosic water-retention agent, 10-200 pts.wt. of an aggregate such as fly ash and other additives, as required, are added to 100 pts.wt. of the base material such as blast-furnace cement, an appropriate amt. of water is further added, the mixture is kneaded by a mortar mixer, etc., for a specified time, and a slurry self-leveling cement composition is obtained. The slurry is pured into an evaluation test vessel having a 60-by-600mm arched bottom plate 15mm in depth and allowed to let stand for 28 days to form a cement composition cured body which is not cracked and from which the aggregate is never separated.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a self-leveling cement composition.

[0002]

2. Description of the Related Art Conventionally, when a self-leveling cement composition is used, cracking may occur due to shrinkage of the cement slurry during setting and hardening, or drying shrinkage. In particular, cracks often occur when there is a large amount of unevenness on the floor surface or when there is a weak point in strength such as a corner of a column. For this reason, when applying the self-leveling cement composition, it may be necessary to carry out repairs in advance so that there is no large unevenness, and to install a reinforcing material in the part that is a weak point in terms of strength. is there. As a measure to prevent shrinkage and drying shrinkage during setting and hardening of cement slurry, a known expansive admixture for cement such as lime type or calcium aluminate type as a shrinkage reducing agent, or other material that causes expansion (hydrofluoric acid type II anhydrous gypsum) Etc.) is used, but the effect of suppressing shrinkage remarkably differs depending on the addition amount, small amount has little effect, and addition of a large amount causes expansion cracks due to excessive expansion, and smoothness is impaired. There is a risk of Further, since the expansion expression of these expansive admixtures differs depending on the curing temperature, it is very difficult to set an addition amount that exerts a shrinkage suppression effect in a wide temperature range and does not cause expansion cracks or the like. .. As a measure to suppress drying shrinkage during construction, the room is closed to prevent air from flowing in and out, and a curing sheet is used to prevent drying.

[0003]

The performance required as a self-leveling cement composition is that it has appropriate viscosity and fluidity and is excellent in self-leveling property.
Appropriate fluidity retention time and setting time; excellent expansion and shrinkage during and after hardening and hardening of cement slurry, and excellent dimensional accuracy. In order to improve the performance of the above, the shrinkage suppression measures by adding the expansive admixture as described above are incomplete in the contraction suppression effect depending on the expansion amount of the admixture, or the smoothness is impaired due to excessive expansion. And the occurrence of problems such as expansion cracks are unfavorable because the performance most important as a self-leveling material is impaired. Also,
As a measure for suppressing the drying shrinkage at the time of construction shown above, it is uneconomical since labor other than pouring is required at the time of construction. Therefore, the present inventors consider that it is necessary to provide the self-leveling cement composition with a property of being excellent in crack resistance without deteriorating the properties of and.

Therefore, the object of the present invention is to provide excellent fluidity,
An object of the present invention is to provide a self-leveling cement composition that exhibits good strength and is excellent in crack resistance.

[0005]

The object of imparting the performance of being excellent in crack resistance to a self-leveling cement composition can be achieved by incorporating silicone oil into the cement as a base material.

That is, the self-leveling cement composition of the present invention is characterized by containing 0.001 to 2 parts by weight of silicone oil per 100 parts by weight of cement.

[0007]

In the self-leveling cement composition of the present invention, the cement used as a base material is ordinary Portland cement, early-strength Portland cement, ultra-early-strength Portland cement, sulfate-resistant Portland cement, white Portland cement and blast furnace cement, fly ash. Cement, silica cement or the like can be used. In particular, it is desirable to use blast furnace cement in order to obtain a self-leveling cement composition having a relatively small change in length and excellent fluidity. Silicone oil contained is 0.00
It is in the range of 1 to 2 parts by weight, preferably 0.005 to 1 part by weight. By adding a dispersant, a coagulation modifier, a viscosity modifier, a water retention agent, a defoaming agent, an expansive admixture, a plaster, an aggregate, etc., it can be used as a self-leveling cement composition.

The self-leveling cement composition of the present invention has excellent dimensional accuracy in addition to excellent crack resistance (length change from 28 days to -0.03 to + 0.03%). ). In addition, no separation of aggregates, subsidence, or cracking is observed even when there is a large level of unevenness in the floor surface and there is a large difference in height between the cast floors and when there is a weak point in strength such as the corners of columns. Further, it has extremely excellent performance such as high smoothness and excellent appearance of the surface.

Silicone oil used as an anti-cracking agent is 0.0 with respect to 100 parts by weight of cement as a base material.
It is contained in the range of 01 to 2 parts by weight, preferably 0.005 to 1 part by weight. If the content of silicone oil is less than 0.001 part by weight, there is no effect of preventing cracking,
Further, if it exceeds 2 parts by weight, it causes a decrease in strength, which is not preferable. As the silicone oil, dimethylpolysiloxane oil, methylphenylpolysiloxane oil, methylalkylpolysiloxane oil, methylaralkylpolysiloxane oil, methylvinylpolysiloxane oil and other methyl-based silicone oils, propyl-based silicone oils and the like can be used. Further, alkali metal compounds of these silicone oils can also be used. The silicone oil used here is a suitable inorganic fine powder.
It is preferable to use a substance in which (calcium carbonate, slaked lime, Portland cement, gypsum, etc.) is adsorbed as a carrier, or to use as a water-soluble emulsion by using an appropriate solvent, since it is easy to mix with the base material.

In the self-leveling cement composition of the present invention, a dispersant or a coagulation modifier is used in order to improve the fluidity of the slurry, delay the coagulation and maintain the pot life. Desirably, the dispersant is melamine formalin condensate sulfonate, lignin sulfonate,
Known substances such as β-naphthalene formalin condensate sulfonate can be used. Also, a plurality of these dispersants can be used in combination. In particular, melamine formalin condensate sulfonate is preferable because it can maintain the pot life without causing a significant delay in setting or a decrease in strength development.
The content of the dispersant is 0.1 to 3 with respect to 100 parts by weight of the base material.
It is in the range of 0 parts by weight, preferably in the range of 0.5 to 2.0 parts by weight.

It is desirable that the self-leveling cement composition of the present invention contains a water retention agent so that volume contraction, cracking, flexure and the like due to drying do not occur when the slurry is set, and these water retention agents are viscosity modifiers. It also acts as a separator and is effective in preventing aggregate separation and floating water generation. As the water retention agent, known ones such as cellulose type, vinyl type and acrylic type can be used. Also, a plurality of these water retention agents can be used in combination. The content of the water retention agent is in the range of 0.005 to 1 part by weight, preferably 0.1 to 0.5 part by weight, based on 100 parts by weight of the base material.

[0012] The self-leveling cement composition of the present invention may contain a known defoaming agent in order to prevent air bubbles from being mixed in during slurry kneading.

When used as a self-leveling cement composition, various sands such as river sand and crushed sand as well as fly ash, blast furnace slag, calcium carbonate and the like can be used as aggregates to be contained. The content is in the range of 10 to 200 parts by weight, preferably 50, with respect to 100 parts by weight of the substrate.
Within the range of 150 parts by weight.

[0014]

EXAMPLES The present invention will be further described below with reference to examples. Examples The materials used in the examples are as shown in Table 1.

[0015]

[Table 1]

Table 2 shows the material composition in the examples. The cement composition of the present invention is shown in Experiment Nos. 1 to 4, and the comparative product is shown in Experiment Nos. 5 to 8.

[0017]

[Table 2]

[0018]

[Table 3]

[0019]

[Table 4]

[0020]

[Table 5]

In the above experiment, a mortar mixer was used for kneading, and kneading was performed for 3 minutes. The flow test is the Housing and Urban Development Corporation method (a pipe with an inner diameter of 5 cm and a height of 5 cm is placed on a glass plate to fill the slurry, the pipe is pulled up to spread the slurry in a circular shape on the glass plate, and the diameter is measured) It was measured based on. The length change is based on the test method for length change of mortar and concrete (JIS A 112
It was measured based on 9). The compressive strength test was measured based on the physical test method for cement (JIS R 5201).

As an evaluation method for the self-leveling cement composition of the present invention, in addition to flow value, length change and compressive strength, an evaluation test assuming pouring on a floor with a large unevenness
By (Test A), the occurrence of cracks and aggregate separation was observed. In addition, the occurrence of cracks and the appearance of the surface were observed by an evaluation test (Test B) that envisages pouring into a floor that has weak points in strength such as corners and openings of columns. The outline of the test A is shown in FIG. 1, and the outline of the test B is shown in FIG. The casting thickness of the self-leveling cement composition was 15 mm in both tests A and B. Test A Crack: The surface of the hardened body of the cement composition at 28 days of age was observed. Aggregate separation: The cured product was cut and the cross section was observed. Test B Crack: The surface of the hardened body of the cement composition at 28 days of age was observed. Aesthetic: The surface of the hardened body of the cement composition at 28 days of age was observed. ○ = Beautiful, △ = Slightly wrinkled, × =
Many wrinkles occur.

[0023]

As is clear from the experimental results shown in Tables 3 to 5, when the self-leveling cement composition of the present invention has a large difference in casting thickness (Test A).
Or pouring into a place where there are weak points in terms of strength
In (Test B), no cracks were generated. Particularly, at 30 ° C., comparatively large cracks were generated in all of the comparative products in the test B, and the superiority of the product of the present invention was remarkably exhibited.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of test A in an example.
(a) is a plan view and (b) is a sectional view.

FIG. 2 is a diagram showing an outline of test B in an example.
(a) is a plan view and (b) is a sectional view.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication C04B 24:30 C 2102-4G 24:38 D 2102-4G 24:00 2102-4G 22:14 B 2102-4G 14:02) Z 2102-4G (72) Inventor Atsuo Kameoka 2-4 Daisaku, Sakura City, Chiba Prefecture Central Research Laboratory, Onoda Cement Co., Ltd.

Claims (1)

[Claims] 1. A self-leveling cement composition, which comprises 0.001-2 parts by weight of silicone oil per 100 parts by weight of cement.