JP2003055018A - Polymer cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer cement based injection material free from cracking at a construction surface just after the construction is finished and when several months passed after the construction is finished and having stable adhesion ability to a rock lump. SOLUTION: This polymer cement composition contains cement, at least one polymer selected from among a polyacrylate resin, a styrene-butadiene synthetic rubber and an acrylic VeoVa (R)-vinyl acetate copolymer and an organic shrinkage reducing agent having a surface active function.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention particularly relates to the formation of rock masses by injecting into the cracks or gaps of rock masses scattered on the slopes of mountainous areas and coastal areas to solidify them and to integrate the rock masses. The present invention relates to a polymer cement composition which can be suitably used as a rock crack injection material for preventing collapse and the like.

[0002]

2. Description of the Related Art Rock masses scattered on the slopes of mountainous areas and coastal areas may have cracks and gaps, and if left unattended, the rock masses will collapse during rainfall or earthquakes. There is a risk, and it is desired to effectively prevent such collapse of rock mass.

Therefore, conventionally, in order to prevent such collapse of rock mass, there is known a method of injecting a polymer cement type injection material into cracks of rock mass and gaps between rock masses. And
As this type of polymer cement-based injecting material, one using an ethylene vinyl acetate resin-based polymer dispersion is known.

[0004]

However, since the polymer itself is poor in water resistance, the polymer cement injecting material using the ethylene vinyl acetate resin-based polymer dispersion has a poor water resistance even after being sufficiently dried. There is a problem that the polymer is redissolved when contacted with. Further, since the viscosity of the polymer itself is high, the amount of kneading water has to be increased in order to ensure the predetermined workability and pouring property, and as a result, the denseness of the cured body structure is impaired, and the strength is reduced and There is a problem of causing a decrease. Further, there is a problem that the ethylene vinyl acetate resin-based polymer itself has a functional group in the molecular structure that delays the hydration reaction of the cement, which hinders the hardening and strength development of the polymer-cement-based injection material.

On the other hand, as a polymer cement-based injecting material other than the above, one using a polyacrylic ester resin-based, styrene-butadiene synthetic rubber-based, ethylene vinyl acetate-based, or vinyl acetate-vaoba acrylic copolymer-based polymer dispersion There is. Cement-based injecting materials using polymer dispersions such as polyacrylic acid ester resin have excellent water resistance and the molecular structure of the polymer does not hinder the strength development of the cement, thus causing the above-mentioned problems. There is no fear.

However, when the polyacrylic ester resin polymer dispersion is used, the resin exhibits skin peeling at the initial stage of curing due to its excellent strength development property, and the resin is rapidly dried due to direct sunlight or excessive ventilation. In the case of receiving the above-mentioned problem, there is a problem that so-called plastic cracks are formed on the surface of the cured product before the complete curing.

Further, it is difficult to completely suppress the drying shrinkage of the cement in any of the above-mentioned polymer cement type injection materials, and it is considered that the drying shrinkage of the cement is caused after 2-3 weeks to 1-2 months. Occurrence of cracks may also be seen. If cracks are generated due to such drying shrinkage, the adhesive action of the rock mass is reduced, and the original function of the injection material may be reduced.

In view of the above problems of the prior art, the present invention is a polymer cement having a stable rock mass adhering ability, which does not cause cracks on the construction surface immediately after construction and even after several months after construction. An object is to provide a system injection material.

[0009]

The present invention has been made to solve the above problems, and the means for solving the problems are cement, polyacrylic ester resin system, styrene butadiene synthetic rubber system, or There is provided a polymer cement composition comprising at least one polymer selected from vinyl acetate vinyl acetate copolymers and an organic shrinkage reducing agent having a surface active action.

According to such a polymer cement composition,
Polyethylene glycol, polypropylene glycol, polyether, or their derivative compounds, which are the main components of the organic shrinkage-reducing agent, prevent the cement from drying and shrinking by exhibiting the original function and effect of the shrinkage-reducing agent. Furthermore, the shrinkage-reducing agent not only suppresses the drying shrinkage of cement, but also effectively prevents skinning due to the polyacrylate resin in the initial stage of the curing process due to its surface-active effect, so-called plastic in the initial curing process. An unexpected effect of suppressing the occurrence of cracks can be achieved.

Further, the present invention is the above-mentioned polymer cement composition, which further comprises a fiber material. When the fiber material is contained, the dry shrinkage stress can be dispersed also by the fiber material, and both the shrinkage reducing agent and the fiber material act synergistically, so that the dry shrinkage can be effectively performed. It is possible to suppress cracking.

The means of the present invention is that the polymer cement composition further comprises an expanding material. When the expansive material is contained, the reduction of the dry shrinkage becomes more remarkable, and the crack due to the dry shrinkage can be more effectively prevented.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The polymer cement composition according to the present invention will be described in more detail below.

As the polymer used in the present invention, at least one selected from the group consisting of polyacrylic acid ester resin, styrene-butadiene synthetic rubber, and vinyl acetate vinyl acrylate copolymer can be used. The usage form of the polymer is not limited. Therefore, for example, the one that is in the dispersion state is mixed at the site immediately before construction, or the polymer is mixed in advance as a re-emulsifying powder with cement or the like, and the dispersion is added when kneading by adding water. It can be used in any form such as a state.

The blending ratio of the polymer is 100% cement.
The amount is preferably 3 to 30 parts by weight with respect to parts by weight. If the amount is less than 3 parts by weight, the effect of improving the adhesion strength with the rock mass and suppressing the increase in viscosity is insufficient.
Even if the amount is more than 0 parts by weight, no further effect can be obtained and the cost is rather increased.

As the shrinkage-reducing agent, use should be made of alcohol-based, lower alcohol alkylene oxide-derivative-based, glycol-based, glycol ether / amino alcohol derivative-based, polyether-based organic compounds having a surface-active action. You can These shrinkage reducing agents exhibit the effect of preventing the unreacted water from escaping and suppressing the dry shrinkage of the cement hydrate. Furthermore, although it has not been clarified what kind of action it causes, it exerts an effect of preventing skin peeling of the polymer. Therefore, by adding the shrinkage reducing agent, it becomes possible to effectively prevent the shrinkage phenomenon and the occurrence of cracks due to both the cement and the polymer. The content of the shrinkage reducing agent is preferably 0.3 to 6 parts by weight with respect to 100 parts by weight of cement. If it is less than 0.3 parts by weight, the improvement effect is insufficient, and if it is more than 6 parts by weight, no further improvement effect is obtained and the cost is rather increased.

Further, as the fiber material in the present invention,
Polyvinyl alcohol (vinylon) fibers, polyamide fibers, polyester fibers, polypropylene fibers, polyacrylonitrile fibers, aramid fibers, carbon fibers, alkali-resistant glass fibers and the like can be used. When such fibrous material is included in the rock crack injecting agent,
It is possible to disperse the shrinkage stress and suppress the occurrence of cracks. Among them, polyvinyl alcohol fibers, polyamide fibers, polyacrylonitrile fibers, and alkali-resistant glass fibers can be used more preferably because they have extremely excellent adhesiveness due to chemical bonding with cement hydrate.

Cement 1 is used as the mixing ratio of the fiber material.
It is preferable that the amount is 0.1 to 1 part by weight with respect to 00 parts by weight. If the amount is less than 0.1 part by weight, the effect of suppressing cracking is insufficient, and if the amount is more than 1 part by weight, no further effect is obtained and the cost is rather increased.

As the cement, various Portland cements such as normal Portland cement, early strength Portland cement, super early strength Portland cement, sulfate resistant Portland cement, moderate heat Portland cement, low heat Portland cement, blast furnace cement and fly ash. It is possible to use various mixed cements such as cement and silica cement, or cement in which admixtures such as blast furnace slag fine powder, fly ash, silica fume, and limestone powder are added to the Portland cement.

Further, it is preferable to add fine aggregate to the polymer cement composition of the present invention within a range that does not impair the effects of the above-mentioned respective components. Examples of the fine aggregate include river sand, mountain sand, sea sand, Crushed sand, limestone sand, cold water stone, etc. can be used. The mixing ratio of the fine aggregate is 100% of the cement.
The amount is preferably in the range of 30 to 300 parts by weight with respect to parts by weight. If it is out of this range, the workability of the injection material at the time of freshness is deteriorated or the physical properties after curing are significantly changed, and it becomes difficult to obtain a good injection material.

Further, the polymer cement composition in water /
The cement ratio is preferably 20 to 45% in consideration of strength development, and it is preferable to add a fluidizing agent in order to secure fluidity as an injecting agent at the water / cement ratio. As the fluidizing agent, one or more selected from lignin sulfonate, naphthalene sulfonate, melamine sulfonate, and polycarboxylate can be used. The fluidizing agent is preferably added in an amount of 0.3 to 3.0 parts by weight with respect to 100 parts by weight of the cement. If it is less than 0.3 parts by weight, workability during injection cannot be sufficiently improved, while if it is added in excess of 3.0 parts by weight, no further effect can be obtained, and conversely. High cost.

If desired, other chemical admixtures such as a thickener, a defoaming agent and a metallic aluminum-based foaming agent may be added to the polymer cement composition of the present invention.

The polymer cement composition according to the present invention can be injected into the cracks of rock masses or the spaces between rock masses by the injection method similar to the conventionally known method. That is, first, the joint material is filled while leaving the injection port in the peripheral portion of the crack of the rock mass and the gap between the rock masses. Then, the polymer cement composition according to the present invention is injected from the injection port, and cracks and gaps are entirely filled with the injection material and solidified.

The joint material used herein is higher than the polymer cement composition by adjusting the composition of the polymer cement composition, specifically, by kneading the polymer dispersion and the kneading water in a reduced amount. A joint material prepared into a slurry having a viscosity can be preferably used.

In this way, the cracks and gaps of the rock mass are almost completely filled with the polymer cement composition, and the entire rock mass is integrated by solidifying the injection material. . In addition, as described above, the polymer cement composition according to the present invention effectively suppresses not only the drying shrinkage of the cement but also the burrs and plastic cracks caused by the polymer dispersion. Therefore, a strong adhesive state between the filled injection material (hardened body) and the rock mass is maintained for a long period of time, and the effect of preventing the rock mass from collapsing is more permanently maintained.

[0026]

EXAMPLES Using the cement materials shown below, the polymer cement compositions of Examples 1 to 3 and Comparative Examples 1 to 3 were prepared with the formulations shown in Table 1. (Material) Cement: Ordinary Portland cement, Sumitomo Osaka Cement Co., Ltd. Superplasticizer: Melanin-based superplasticizer, made by Nippon Sika Co., Ltd.,
Sikament FF86 / 100 Shrinkage reducing agent: NOF Corporation, Sudox E-40 Fiber material: Vinylon fiber, Kuraray Co., Ltd., RF-S6
02 (6 mm) Aggregate: Quartz sand N40 and Quartz sand N60 (weight ratio 3: 2)

[0027]

[Table 1]

(Test 1) Formwork using a concrete plate (inside dimension: frontage 90 cm x depth 30 cm x thickness 10 cm)
Was prepared, and the polymer cement compositions of the above Examples and Comparative Examples were filled on the assumption that the cracks of rock mass were simulated, and accelerated tests were carried out at 5, 20 and 35 ° C. The results are shown in Table 2.

[0029]

[Table 2]

As shown in Table 2, PAE system and SB
In Examples 1 and 2 in which the R-type polymer dispersion was added, cracks did not occur at any temperature, while in Comparative Examples 1 and 2 in which the PAE- and SBR-type polymer dispersions were added, shrinkage was observed. Since no reducing agent was added, cracking occurred at any temperature.

(Test 2) Regarding the polymer cement compositions of the above Examples and Comparative Examples, JIS R 5201 was used.
A setting test and bending and compressive strength tests were performed according to the "physical test method for cement". The results are shown in Table 3.

[0032]

[Table 3]

As shown in Table 3, it is clear that the comparative example 1 using the EVA type polymer dispersion takes twice or more the setting time as compared with the other polymer dispersions. Also, from the tests of compressive strength and bending strength, it is clear that Comparative Example 1 using EVA-based polymer dispersion is inferior in strength development.

(Test 3) Using the polymer cement compositions of Example 1 and Comparative Example 2 in which a PAE-based polymer dispersion was used, test samples were prepared according to JIS A 1171 "Testing method for polymer cement mortar". Then, in accordance with JIS A 1129 "Method for testing length change of mortar and concrete", dry shrinkage was measured with the next day of casting as the base length. The results are shown in Table 4.

[0035]

[Table 4]

As shown in Table 4, according to the polymer cement composition of Example 1 containing the shrinkage-reducing material, 8 to 13
It can be seen that the dry shrinkage of cement during the week is reduced to about 1/2 of that of the comparative example, and the shrinkage at the initial stage of hardening (1 to 3 days) is also effectively reduced.

[0037]

As described above, according to the polymer cement composition of the present invention, both plastic cracking and drying shrinkage can be effectively suppressed, and even immediately after the construction and after several months have passed. It is possible to form a stable adhesive layer without causing cracks on the applied surface.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // (C04B 28/02 C04B 24:26 C 24:26 FG 16:06 Z 16:06) 111: 70 111: 70 (72) Inventor Takahiro Yamamoto 7-55, Minami Enkajima, Taisho-ku, Osaka City Sumitomo Osaka Cement Co., Ltd. Cement Concrete Research Institute (72) Inventor Hisamu 1 Sakura, Tsukuba City, Ibaraki Prefecture 17 Showbond Construction Co., Ltd. In the Repair Engineering Research Institute (72) Inventor Kenichi Dowaki 1-17 Sakura, Tsukuba City, Ibaraki Prefecture F-17 Term at the Showbond Construction Co., Ltd. Repair Engineering Research Laboratory (reference) 2D040 AA06 AB01 AB05 AB16 AC01 CA01 CA03 CA04 CA05 CA10 CB03 4G012 PA04 PA23 PA24

Claims (3)

[Claims] 1. A shrinkage-reducing agent of cement, and at least one polymer selected from a polyacrylic acid ester resin system, a styrene-butadiene synthetic rubber system, or a vinyl acetate vinyl acrylate copolymer system, and an organic system having a surface-active action. A polymer cement composition comprising: 2. The polymer cement composition according to claim 1, further comprising a fiber material. 3. The polymer cement composition according to claim 1, further comprising an expansive material.