JP2002080254A - Cement mortar composition for continuous footing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance workability of mortar composition for continuous footing capable of coating thinly within 5 mm thick, without generating interface separation or crack and especially less prone to cause efflorescent phenomenon. SOLUTION: In the cement mortar composition for continuous footing mixed with cement, fine aggregate and water dispersive synthetic resin, which is made from a mixture of ethylene-vinyl acetate copolymer or acrylic resin or mixture of both, the cement mortar composition is mixed with the water dispersive synthetic resin of 15-40 pts.wt. to the cement of 100 pts.wt. The cement mortar for continuous footing which can be applied thinly within 5 mm thick, without generating interface separation or crack less prone to cause efflorescent phenomenon, can be formed by mixing a lot of prescribed water dispersive synthetic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ready-mixed material for mortar coating a foundation surface of a building, and to a cement mortar composition for a cloth foundation used by adding and kneading water at the time of use.

[0002]

2. Description of the Related Art In general, in a house or other foundation work, a foundation consisting of a foundation slab and a foundation is constructed in order to transmit a load of a building to the ground and safely support a structure.

[0003] There are various types of such foundations depending on the conditions such as the size of the building and the ground. In particular, those having a structure in which a series of pillars and walls are supported by a long foundation such as a belt,
It is called cloth foundation or continuous foundation.

[0004] Normally, a cloth foundation is made of reinforced concrete as a base material of a foundation slab, and its surface is covered with cement mortar to prepare the surface neatly, or is covered with a plate material (board) for surface mounting and the like, and is constructed with a good appearance. Have been.

[0005] When the surface of the cloth base is covered with cement mortar, plastering cement mortar is applied to a predetermined thickness by plastering work. In this case, the rough surface of the base material is smoothed in advance. They adjust the so-called groundwork and apply a finishing mortar.

A mortar composition called polymer cement, which is well known as a plastering mortar material, is prepared by mixing a cement resin mortar with a synthetic resin emulsion (which may be a water-dispersible synthetic resin powder) or rubber latex to retain water. It is a cement mortar that elongates and improves adhesion to the substrate. The synthetic resin emulsion of the ingredients is
An acrylic resin or a vinyl acetate-ethylene copolymer resin is used, and its compounding ratio in the mortar is usually 5 to 10% by weight as a resin solid content weight ratio (hereinafter referred to as polymer / cement ratio) with respect to 100 parts by weight of cement. Parts is sufficient, and in the case of mortar used for fabric foundation,
It was about 5 parts by weight.

[0007]

However, the above-mentioned conventional mortar for fabric foundation has a thickness of 10 to 15 m on the surface of the base.
If it is not applied thickly to about m, there is a problem that it is easy to crack.

[0008] Such cracks (also called cracks) are usually caused by cracks generated from the inside of the foundation up to the surface or due to a difference in expansion / shrinkage ratio between the surface layer and the underlayer. This is considered to be caused by the occurrence of stress at the interface of the layers due to the difference in temperature and the degree of drying, resulting in interfacial separation and cracking.

It is preferable that the mortar to be troweled on the surface of the fabric base is formed as thin as possible in order to improve construction efficiency. However, when the mortar is thinly applied to a thickness of 5 mm or less and dried, there is a problem that a state in which white powder is blown out on the surface of the fabric base, that is, a so-called efflorescence phenomenon easily occurs.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to apply a mortar composition for a cloth foundation to a thickness of 5 mm or less so that workability is good, and furthermore, interfacial peeling and cracking occur. Instead, it should be one in which the phenomenon of efflorescence is unlikely to occur.

[0011]

In order to solve the above problems, the present invention provides a cement mortar composition for a cloth base, comprising cement, fine aggregate and a water dispersible synthetic resin. The synthetic resin is composed of an ethylene-vinyl acetate copolymer or an acrylic resin or a mixture of both, and the water-dispersible synthetic resin (solid content) is compounded in an amount of 15 to 40 parts by weight based on 100 parts by weight of the cement. This is a characteristic cement mortar composition for fabric foundation.

[0012] The cement mortar composition for a fabric foundation constructed as described above has a thickness of 5 mm or less because a predetermined water-dispersible synthetic resin is blended in a large amount of 15 to 40 parts by weight in solid content. The coating can be applied thinly, and no interfacial peeling or cracking occurs, and the efflorescence phenomenon hardly occurs.

In the cement mortar composition for fabric foundation described above, it is preferable that the fine aggregate has a particle size of 3 mm or less, because the work efficiency of troweling is improved, and the uniform thickness is 5 mm or less. It is also preferable for thin coating.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The cement used in the present invention may be any cement that can be used for plastering work, and can be used by adjusting the color tone and selecting a well-known cement according to the demands of a consumer. For example, portland cement, white cement, color cement and the like are specific examples of the cement used in the present invention.

The fine aggregate used in the present invention does not have a very large particle size as the aggregate. For example, sand, perlite or vermiculite having a particle size of 3 mm or less can be used. Fine aggregate having a particle size of 3 mm or less improves the work efficiency of trowel coating of mortar to which this is added,
The mortar can be applied to a thin and uniform layer having a thickness of 5 mm or less.

Among fine aggregates, the sand is preferably river sand, and the standard particle size (JASS 15) of plaster sand is preferably type B, more preferably type C, and the particle size distribution is narrow. Are preferred. For example, silica sand produced in China having a particle size of about 20 to 100 mesh is particularly preferable.

Perlite is obtained by pulverizing perlite or obsidian, heating it to about 1000 ° C., and expanding it. It is a lightweight aggregate having a unit weight of about 0.02 to 0.5 kg /. There is an irregular shape in the perlite system and a spherical shape in the obsidian system.

Vermiculite is obtained by adjusting the particle size of vermiculite (expandable mica) and expanding it by heating to about 1000 ° C. The unit weight per unit volume is 0.1 to 0.4 kg / l.
It is a granular or flaky particle.

The water-dispersible synthetic resin used in the present invention is a powder or an aqueous emulsion of a synthetic resin having a smaller particle diameter than the fine aggregate, and the liquid one is a liquid obtained by emulsion polymerization or a concentrated liquid thereof. The powder is an ethylene-vinyl acetate copolymer powder or an acrylic resin powder formed by drying the powder, or a mixed powder containing both powders.

Among them, ethylene-vinyl acetate copolymer (hereinafter abbreviated as EVA) is a thermoplastic polymer in which ethylene and vinyl acetate are randomly copolymerized,
The larger the copolymerization ratio of vinyl acetate is, the more flexible it is. The powdery one is produced by drying the EVA emulsion in the emulsion polymerization step, and the ethylene content is 60%.
Less than a redispersible synthetic resin emulsion powder. Commercially available EVA powders include those manufactured by Elotex AG: El
OTEX 1080.

The acrylic resin is formed, for example, by copolymerizing a monomer composition containing at least a (meth) acrylate ester in an aqueous medium in the presence of a water-soluble oligomer to form a nucleus. In the presence, an emulsion obtained by emulsion polymerization of an ethylenically unsaturated carboxylic acid and a (meth) acrylic acid ester to form at least a surface layer on the nucleus can be used, or it can be dried and redispersible. Certain acrylic emulsion powders can also be employed.

The amount of water to be mixed when kneading the cement mortar composition for fabric foundation is about 5 to 6 liters per 20 kg of the powder cement mortar material. Needless to say, it may be changed appropriately according to the situation.

In order to trowel the cloth mortar according to the embodiment of the present invention on the cloth base, the surface of the cloth base prepared by cutting with a sander or the like so as to have no steps is previously brushed. After "water squeezing", etc., "ironing" is performed with a thickness of about 1 mm or less. Then, in a dry state, the cement mortar composition for fabric foundation is re-applied for about 1 mm.
Apply to a thickness of ~ 2 mm and brush immediately afterwards.

In this manner, the cement mortar composition for a cloth foundation can be uniformly applied to a thickness of 5 mm or less and even after drying, no interface peeling or cracking occurs on the surface of the cloth foundation.
In particular, the phenomenon of efflorescence does not occur.

[0025]

EXAMPLES AND COMPARATIVE EXAMPLES [Example 1] Materials and compounding ratio (% =% by weight) of the cement mortar composition of Example 1
Is shown below. Portland cement 9.08% White cement 14.52% Silica sand 59.9% F4 silica sand (28 mesh passing 52%) / G5 silica sand (35 mesh passing 39.8%) / F6 silica sand (100 mesh passing 30.9%) Sepiolite (4%) Sepiolite (Omi Mining Co., Ltd .: Miraclay) 1.81% Ethylene-vinyl acetate copolymer powder (Elotex AG: Elotex 1080) 4.54% (to 100 parts by weight of cement with Is 19.2 parts by weight.) Efflorescence inhibitor (potassium stearate) 0.09% Water-soluble cellulose ether (manufactured by Shin-Etsu Polymer: Metroose) 0.03% cellulose fiber 0.09% white Pigment 3.63% [Comparative Examples 1 and 2] Materials and compounding ratios of cement mortar compositions of Comparative Examples 1 and 2 Showed weight parts) shown in Table 1 below.

[0026]

[Table 1]

Example 1, Comparative Example 1 and Comparative Example 2
Was mixed with water in the ratio shown in Table 1 to produce a kneaded cement mortar for fabric foundation, and the following tests a, b, and c were performed for the physical properties thereof, and the properties of the mortar for fabric basis were evaluated. .

(A) Crack resistance test A mortar for a base material of a test sample having the following composition was prepared in a cylindrical mold, and the mortar was poured into the mold to have a shape shown in FIG.
A base material of a test specimen having a size of 5 cm, a height of 4 cm, and a steel ring outer diameter of 7 cm) was formed.

[Mortar for base material of test specimen] Portland cement 100 parts by weight No. 6 silica sand 50 parts by weight No. 7 silica sand 50 parts by weight Methyl cellulose 1 part by weight Sodium aluminate 1 part by weight Water 70 parts by weight Mortar of Example or Comparative Example , And kneaded by adding an amount of water shown in Table 1 to the cylindrical base material shown in FIG.
mm of mortar layer, and
After curing for 0 days, the state in which cracks occurred on the surface of the mortar layer during that time was examined. The results are shown in Table 2.

Reference numeral 1 in FIG. 1 denotes a base material of the specimen,
Reference numeral 2 denotes a mortar layer, and reference numeral 3 denotes a steel ring.

[0031]

[Table 2]

Large: cracks with a maximum width of 0.1 mm or more Small: racks with a maximum width of less than 0.1 mm () are cracks generated on the back and side surfaces of the substrate.

As is clear from the results in Table 2, cracks occurred in the mortar layer of Comparative Example 2 only by curing at room temperature, but no cracks occurred in the mortar layer in Example 1.

Next, the cured specimen is heated and cooled 10 times (one cycle is placed in a 50 ° C. atmosphere for 8 hours and then immersed in water at room temperature for 16 hours) to form a mortar layer. Observe the cracks that occur on the surface,
Table 3 shows the results.

[0035]

[Table 3]

As is clear from the results in Table 3, cracks occurred in both Comparative Example 1 and Comparative Example 2 due to the heating / cooling cycle, but only one very small crack occurred in Example 1. Was.

(B) Waterproof test The cement mortar of the example or the comparative example was applied to a slate plate to a thickness of about 2 mm, and the dried mortar was used as a test piece and a funnel fitted with a female pipette was adhered.
The water permeability was evaluated according to IS A6909 water permeability test method B. The results are shown in the graph of FIG.

Further, in order to examine the case where the thickness of the cement mortar was changed, a mortar of Comparative Example 1 was used as a test piece to apply 15 mm thick (Comparative Example 1-1) or 8 mm thick (Comparative Example 1-2). Or 3 m thick coating using the mortar of Example 1 (Example 1-1) or 2 m
An m-thick coating was applied (Example 1-2), and a waterproof test was performed under the same conditions as described above. The results are shown in the graph of FIG.

As is clear from the results of FIGS. 2 and 3,
The mortar of Example 1 was used in Comparative Examples 1 and 2 even when the coating thickness was small.
The mortar has a lower water permeability than that of the mortar, and has an excellent waterproofing effect. This indicates that no cracks (cracks) have occurred or only a very small number of cracks have occurred.

(C) Adhesion test The mortar of Example 1, Comparative Examples 1 and 2 was applied to a thickness of 3 mm on the surface of a 7 × 7 × 2 cm test piece of a rectangular plate and cured at room temperature for 4 weeks. Strength (N / mm
² ) was measured, and the results are shown in Table 4.

[0041]

[Table 4]

In the table, () indicates a fractured portion, which indicates A: fracture of the mortar layer, B: peeling of the interface between the mortar layer / base mortar, and C: fracture of the base mortar.

As is clear from the results shown in Table 4, the test pieces coated with the mortar of Comparative Examples 1 and 2 may break the mortar layer itself and peel off the interface between the mortar layer and the base material. Of 0.5 to 1.6 N / mm ²
It was a low strength.

On the other hand, in the test piece coated with the mortar of Example 1, the mortar layer itself was not destroyed, and the strength of the interfacial peeling between the mortar layer and the base material was 2.4 to 4.0.
The strength was as high as 3.4 N / mm ² .

[0045]

According to the present invention, as described above, a cement mortar composition for a fabric base containing a predetermined amount of a predetermined water-dispersible synthetic resin can be thinly applied to a thickness of 5 mm or less, and the interface There is an advantage that peeling and cracking do not occur and that no whitening phenomenon occurs.

In the above invention, if the fine aggregate and the water-dispersible synthetic resin have a fine particle diameter of 3 mm or less, in addition to the above-mentioned advantages, the work efficiency of the trowel coating is improved. In addition, a thin coating having a thickness of 5 mm or less can be performed more uniformly.

[Brief description of the drawings]

FIG. 1 is a perspective view of a test specimen.

FIG. 2 shows the results of a waterproof test of Examples and Comparative Examples,
Chart showing the relationship between water permeability and time

FIG. 3 shows the results of a waterproof test of an example and a comparative example,
Chart showing the relationship between water permeability and time

[Explanation of symbols]

 Reference Signs List 1 base material of specimen 2 mortar layer 3 steel ring

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C04B 24:26) C04B 24:26) F

Claims (2)

[Claims] 1. A cement mortar composition for a fabric base comprising a cement, a fine aggregate and a water-dispersible synthetic resin, wherein the water-dispersible synthetic resin comprises an ethylene-vinyl acetate copolymer or an acrylic resin or both. And a water-dispersible synthetic resin is blended in an amount of 15 to 40 parts by weight with respect to 100 parts by weight of the cement. 2. The cement mortar composition for a fabric base according to claim 1, wherein the fine aggregate has a particle size of 3 mm or less.