JPH0450150A - Composition for mending concrete - Google Patents

Abstract

PURPOSE:To obtain a mending composition having improved workability and enabling mending of concrete within a moderate setting time in high adhesive strength without causing cracking by adding specific amounts of certain kinds of assistant substances to a mixture of cement and calcium aluminate powder. CONSTITUTION:The objective composition is produced by mixing 10-30 pts.wt. of a cement expanding material, 0.5-3.0 pts.wt. of melamine and 5-13 pts.wt. of an ethylene-vinyl acetate copolymer resin (EVA) to a mixture of 100 pts.wt. of cement and 15-35 pts.wt. of calcium aluminate powder. The expanding material is effective in preventing the cracking of cement in hardening process. When the amount of the material is smaller than the lower limit, the shrinkage after curing cannot be mended and when it exceeds the upper limit, an abnormal expansion may take place after hardening. Melamine has water-reducing effect, remarkably improves the troweling workability in mending and retards the setting of the concrete. There is no improvement on the workability at a melamine content lower than the lower limit and, when the content exceeds the upper limit, the kneaded mixture exhibits problems of sagging and trowel adhesion. The EVA improves the adhesivity to the substrate. Its effect becomes insufficient when the amount is less than the lower limit and the trowel separation becomes poor when the amount exceeds the upper limit.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a composition for repairing concrete, which uses a quick-hardening cement mixture containing calcium aluminate to repair defects, cracks, etc. in concrete products, structures, etc. The present invention relates to a repair composition.

[Prior Art] Repairs of defects, cracks, etc. that occur during the manufacturing process, construction process, or after construction of concrete products and structures are often performed.

As a material used for repair, for example, a repair material made by mixing ethylene/vinyl acetate copolymer resin with a cement mixture containing amorphous calcium aluminate, gypsum, and cement is known, and this repair material is actually used. In order to control coagulation, citric acid, K2CO
, then add sand and water if necessary and knead;
Techniques for repair work are known (Special Publication Act 1986-863).
Publication No.).

[Problems to be Solved by the Invention] The above-mentioned repair material can achieve the purpose of repair, but in addition to the repair material, a caking control agent must be prepared and mixed before use. During repair work, the workability was poor, such as the spread of cross-conducting mortar with a trowel, and the same work area had to be troweled several times.

[Means for Solving the Problems] Therefore, the inventors conducted various studies in order to obtain a composition that eliminates the above drawbacks while taking advantage of the quick hardening properties of a cement mixture of cement and calcium aluminate powder.
The present invention was completed based on the discovery that a composition obtained by mixing specific amounts of several types of auxiliary substances with the above formulation is optimal as a repair material.

That is, the present invention provides a cement mixture consisting of 100 parts by weight of cement and 15 to 35 parts by weight of calcium aluminate powder, and 10 to 30 parts by weight of a cement expanding agent, 0.5 to 3.0 parts by weight of melamine, and ethylene/acetic acid. This is a concrete repair composition prepared by mixing 5 to 13 parts by weight of a vinyl copolymer resin.

In relation to the prior art, the present invention is an improved repair composition in which cement, calcium aluminate powder, and ethylene-vinyl acetate copolymer resin are each mixed in specific proportions, and a cement expanding agent and melamine are also mixed in specific proportions. be.

(Raw materials for blending) Cement Examples of the cement in the cement blend of the present invention include commonly used ordinary/early strength/moderate heat Portland cement, and mixed cement blended with silica, fly ash, and the like.

(Calcium aluminate powder) Calcium aluminate powder is alumina cement or CaO・Al2O3,12Ca04Aj203.2
In addition to CaO・Al2O3, 3CaO・Aj20x, calcium aluminate powder containing an appropriate amount of 11ca (17A120.・CaFz) is used in some cases.The fineness of the powder is 1000cm27g or more in Blaine value, preferably 3000 to 7000cIo2/g. .

Any commercially available expandable admixture may be used as the cement expansion material for the upper plate of im 2, and is not particularly limited. Preferably, C
Examples include a5O,.CaO type, specifically "Asano Dibucal" manufactured by Nippon Cement Co., Ltd.

After repair work, this cement expanding material appropriately expands the repair member during the hardening process of the cement composition, compensates for shrinkage strain during hardening of the cement, and prevents cracks.

MelamineMelamine is usually sold commercially in powder form. You can use this as is. Melamine has a water-reducing effect when mixed with cement, and the present invention not only has this effect, but also has the effect of significantly improving troweling work during repair work and delaying setting. has.

As for ethylene/vinyl acetate co-density A resin (EVA ethylene/vinyl acetate copolymer resin fEVA), both commercially available powder and emulsion forms can be used. When using powdered EVA, all other materials are powdered, so
This is preferable because a repair composition with sufficient quality control can be manufactured in a factory, etc. However, if an emulsion composition must be used, it may be necessary to use an emulsion composition at the construction site due to the condensation time as it contains water. Must be mixed with other materials.

(Blending ratio) In the cement mixture serving as the base material, the composition suitable for the present invention is based on 100 parts by weight of cement.
The composition includes 15 to 35 parts by weight of calcium aluminate powder.

If the proportion of calcium aluminate powder is less than 15 parts by weight, rapid hardening will not be sufficient, and if it exceeds 35 parts by weight, it will tend to set rapidly and it will be difficult to ensure sufficient setting time for melamine, so both are preferable. do not have.

The blending amount of the cement expanding agent is 10 to 30 parts by weight based on the above cement mixture. If the amount is less than 10 parts by weight, the mixing amount is too small to compensate for the shrinkage of the cross-wire composition after curing, and there is a risk that cracks may occur, especially at the interface with the base concrete. Further, a blend exceeding 30 parts by weight is not preferable since abnormal expansion may occur after curing.

Melamine is added in an amount of 0.5 to 3.0 parts by weight, preferably 1.0 to 21 parts by weight, based on the cement mixture. If the mixing amount is less than 0.5 part by weight, no improvement in workability can be obtained and there is no mixing effect. On the other hand, if the blending amount exceeds 3.0 parts by weight, it is not preferable because when repair work is performed in the vertical direction, the interfering material will be stuck, a smooth surface will not be obtained, and the trowel separation will be poor.) .

EVA is mixed to increase the adhesion strength with the base concrete, and the amount of EVA added is 5% to the cement mixture.
~13 parts by weight, preferably 7 to II parts by weight. If the amount is less than 5 parts by weight, the mixing effect will be small, and if the amount exceeds 13 parts by weight, it will be difficult to separate the trowel and work efficiency will be reduced, which is not preferable.

The method for producing a repair composition using each of the above-mentioned materials is that when powdered EVA is used, each material is put into a conventional mixer according to its respective proportions, and if thoroughly mixed, the composition becomes powdery. You can get things.

When using an EVA emulsion, it must be mixed at the construction site; for example, other materials other than EVA are mixed in advance in a mixer, the EVA emulsion is added to the mixture, and then water is added. Just knead it.

(Construction) When applying the repair composition of the present invention, the state of the repair,
It varies depending on the difficulty, but as a guide, the ratio of sand to the composition is 100 to 300% by weight, and the proportion of water to the powder is 18 to 300% by weight.
If 25% by weight is mixed and kneaded, a mixed material having suitable workability and setting time (quick hardening) can be obtained, and repair work is easy and repairs with high adhesive strength can be obtained.

[Function] The concrete repair composition of the present invention contains cement, calcium aluminate powder, and ethylene-vinyl acetate copolymer resin in specific proportions to the conventional repair composition. It is a mixture of an expanding material and melamine at a certain ratio, and as mentioned above, the workability is improved by adding melamine, but its performance as a repair material depends on the integrated effect of the balance of the amounts of each composition. This is thought to be due to

[Example] The following materials were used in the following examples and comparative examples.

Base material: A base material was prepared by mixing 200 parts by weight of sand with 100 parts by weight of cement. The amount of water was 20% of the water/powder ratio.

Cement: “Early strength Portland cement” manufactured by Nippon Cement Co., Ltd. Sand: rNP silica sand, NP-8OJ calcium aluminate powder manufactured by Nippon Plaster Co., Ltd. U alumina cement J cement manufactured by Nippon Cement Co., Ltd. Expanding material: “Asano Zipcal” manufactured by Nippon Cement Co., Ltd. Melamine: "Melment F-10J EVA" manufactured by Showa Denko Co., Ltd. "Movinyl Powder" manufactured by Hoechst Gosei Co., Ltd. Also, each measurement item is shown below.

Workability: 300 x 300 x 60mm as shown in Figure-1
Repair mortar was applied to the chipped corners of concrete slabs for sidewalks, and trowel separation and trowel extension were determined.

Cracks: The concrete specimens used in the workability test were exposed outdoors for three months and visually observed for cracks.

Condensation time: As shown in Figure 2, inner diameter 50III11, height 40++
V+ PVC pipe was filled with repair mortar. From that point on, the Vicat needle was lowered periodically, and the time until the needle stopped sticking was measured.

Adhesive strength: Surface mortar removed by sandblasting 3
Mortar was applied to a sidewalk concrete slab measuring 0 x 300 x 60 mm to a thickness of 5+++a+.

Examples 1 to 3, Comparative Examples 1 to 8 Each of the formulations shown in Table 1 was cured for 28 days in a hot air box at 20°C and 80% RH or higher, and the adhesion strength was determined using a Kenken type adhesion tester. Each of the above measurement items was tested using mortar.

The results are shown in Table 1.

[Effects of the Invention] The concrete repair composition of the present invention contains cement, calcium aluminate powder, and ethylene/vinyl acetate copolymer in specific proportions to the conventional repair compositions, and Furthermore, by mixing a certain proportion of a cement expanding material and melamine, workability is greatly improved, and repairs with no cracks and high adhesive strength can be performed with an appropriate setting time.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a sidewalk concrete slab used as a concrete test specimen, and Figure 2 is a perspective view of a formwork for mortar setting tests.

Claims (1)

[Claims] (1) For a cement mixture consisting of 100 parts by weight of cement and 15 to 35 parts by weight of calcium aluminate powder,
Cement expansion agent 10-30 parts by weight, melamine 0.5-3
．． 0 parts by weight and 5 to 1 parts of ethylene/vinyl acetate copolymer resin
A concrete repair composition prepared by mixing 3 parts by weight.