JP2501591B2 - Mortar concrete curing sealant - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mortar-concrete curing sealant, and more particularly, to a crack due to drying that occurs after casting or molding of mortar-concrete until curing. The present invention relates to an encapsulant for curing mortar and concrete for preventing the occurrence of dust.

[Prior art and its problems] Conventionally, if mortar and concrete are subjected to strong drying between the setting and the setting and hardening, cracking due to the plastic sticking linkage occurs.

Especially rich mixed concrete with little breathing, for example concrete with slump value Sl of 5 cm or less,
Highly fluidized concrete, and without breathing,
For example, ultra-hard concrete with an Sl of 1 cm or less or mortar / concrete with a high-performance water-reducing agent has a very strong tendency.For example, concrete with a high-performance water-reducing agent and a water-cement ratio of about 35% by weight is non-breathing. Then, at the same time as the driving, the concrete begins to dry, the concrete surface becomes hard like a shell, and a crack enters within tens of minutes. This crack is a large one with a width of 2 to 6 mm, and at the same time, if you cheek, it will be several tens of cm to several meters.
It grows to a length of 10 cm and reaches a considerable depth of more than 10 cm.

Also, in the case of humor pipes and steel mortar / concrete lining pipes where the finish on the inner surface is life for concrete products, etc., minute cracks are generated when the wind passes during steaming until steam curing after molding. In many cases, it grows due to the tensile stress due to the temperature gradient that occurs when it is taken out of the curing tank to the outside, or due to the drying that is received during curing in the stockyard, and it becomes impossible to ship as a product.

In order to prevent these cracks, measures may be taken to prevent the evaporation of water in the concrete immediately after placing or molding the concrete or at an appropriate time, for example, by pouring water. It is conceivable to directly contact the concrete surface with vinyl, polyethylene sheet or curing mat. However, these methods
If the casting area is large, careful finishing is required, or if it is a deformed shape such as a Hume tube, it is difficult to take and the work becomes complicated.

Therefore, as an alternative curing method, a method using a chemical moisture absorbent or a film curing method using polymer emulsion (concrete engineering handbook Asakura Shoten P166-17
0, Japanese Patent Publication No. 62-116).

The method of using a chemical hygroscopic agent is to sprinkle a highly hygroscopic and deliquescent chemical such as calcium chloride or sodium silicate on the concrete surface, and use this deliquescent property to prevent water from evaporating and to solidify the concrete surface. It is expected to prevent evaporation of water by accelerating curing, but it is not practical at all.

The film curing by polymer emulsion is said to be highly effective, and it is this type that is generally called a sealing agent and is commercially available.

However, in the polymer emulsion, the water in the emulsion evaporates when the film is formed. At this time, because of the formation of pinholes, ultra-hard concrete or a high-performance water reducing agent with no breathing was used. It has no effect on viscous concrete.

The present inventors have added a high-performance water-reducing agent, which is particularly prone to cracking, as a result of intensive studies on non-breathing and highly viscous concrete, and an initial curing method in which cracks do not enter in the Hume pipe and steel pipe lining, The present invention has been completed based on the finding that it is possible to reduce or prevent the occurrence of cracks by using a specific solution as a sealing agent.

[Means for solving problems]

That is, the present invention is a mortar-concrete curing sealant comprising triethanolamine and / or glycerin, and further using one or more of polyvinyl alcohol, an alginic acid aqueous solution, and a polymer emulsion.

 Hereinafter, the present invention will be described in detail.

The triethanolamine and / or glycerin (hereinafter referred to as “trieta” etc.) in the present invention is well known in the art as a quick setting agent for cement. The idea of using a cement quick-setting agent to quickly harden the concrete surface and prevent the evaporation of water is also recognized in the method using the above-mentioned chemical moisture absorbent, and calcium chloride and sodium silicate that have been conventionally studied as chemical moisture absorbents. In addition to having deliquescent properties, is also known as a setting accelerator and a quick setting agent for cement. Prominent quick-setting agents such as calcium carbonate and sodium silicate, which are used in sprayed concrete such as sodium carbonate and sodium aluminate, have no effect, and only the trieta of the present invention exhibits the effect. That is, even with the same quick-setting agent, the former is due to the acceleration of hydration of calcium silicate, and the latter Trieta, etc. is a quick-setting agent due to the acceleration of hydration of calcium aluminate. Since the tissues are completely different, it is considered that there is a difference in the effect of preventing water evaporation.

Triethanolamine and glycerin are usually viscous liquids, and commercially available industrial products are used.

The trieta may be applied or sprayed as it is, but from the viewpoint of efficiency, spraying with an air gun or the like is better, and in this case, a concentration of about 30 to 70% by volume is preferable. The amount of trieta may be sprayed or applied in an amount of at most 500 g, preferably about 30 to 300 g, per 1 m ^{2 of} mortar / concrete surface.

Less than 30g, the effect of preventing cracks is small, 500g
If it exceeds, it is not economically preferable.

The ratio of triethanolamine to glycerin is not particularly limited, but 80 to 20 parts by weight of glycerin is preferable to 20 to 80 parts by weight of triethanolamine.

When the sealing agent of the present invention is sprayed or applied to the surface of the mortar / concrete, the mortar / concrete with little or no breathing is carried out as soon as possible in such a manner that casting, surface finishing and spraying proceed simultaneously, and breathing is performed. For mortar / concrete, which contains a lot of mortar, it is good after breathing has taken place, and for Himum pipes and steel pipe linings, it is good to do it immediately after centrifugal force molding is completed. The solution or aqueous solution such as Trieta penetrates into the mortar and concrete and at the same time forms a hardened layer of several mm at the same time to prevent evaporation of water and prevent cracking.

Further, polyvinyl alcohol, alginic acid aqueous solution, polymer emulsion and the like (hereinafter referred to as PVA and the like) can be used in combination with trieta and the like. That is, a completely saponified product of polyvinyl alcohol and an arbitrary partially saponified product or modified product thereof, alginic acid and its sodium, potassium, calcium salt, ethylene vinyl acetate emulsion, vinylidene chloride-
Examples of the vinyl chloride copolymer emulsion include, but are not limited to, any emulsion that forms a water-impermeable (wet) continuous film.

Among these, polyvinyl alcohol and alginic acid usually have a small film-forming ability and are not used as a sealing agent, and ethylene vinyl acetate or vinylidene chloride-vinyl chloride emulsion is used.

However, a small film forming ability such as polyvinyl alcohol and alginic acid, which does not have a crack prevention effect, aside from ethylene vinyl acetate or vinylidene chloride-vinyl chloride-based generally commercially available sealing agents, is as described above. As described above, no effect is shown in the case of non-breathing and highly viscous concrete with high performance water-reducing agent, which is particularly prone to cracking, but when used in combination with the trieta etc. of the present invention, a synergistic effect is obtained. It is something to demonstrate.

These combined use may be carried out by spraying with a trieta etc. or may be carried out in advance, and a mixed solution of both may be prepared and sprayed. When viewed only for PVA and the like, the amount of spray is 5 to 500 g per m ^{2 of the} concrete surface in terms of solid content, and if the amount of spray of trieta is within the above range, 10 g or more is preferable, and more preferably 50 g. More than 50
Although it is about 0 g, if it is less than 5 g, the effect of preventing water evaporation is small, and if it exceeds 500 g, it is not economically preferable.

The trieta etc. used in the present invention may be those for general industry, and the same applies to polyvinyl alcohol and alginic acid,
Polymer emulsions are not limited to those commercially available for sealing agents, but may be any of water-based paints and adhesives, and basically any polymer emulsion can be used.

As the cement in the mortar concrete using the sealing agent of the present invention, various portland cement, mixed cement, expansion cement, cement containing calcium aluminate, or soluble aluminum such as blast furnace slag fine powder cement. The cement contained, or the cement which has calcium aluminate as a main component is mentioned.

〔Example〕

 Hereinafter, the effects of the present invention will be described in detail in Examples.

Example 1 Normal Portland cement, citric acid as reagent, FM2.93
Using natural river sand and high performance water reducing agent, the weight ratio is 10
We made mortar with 0: 0.15: 150: 1, W / C of 30% and flow value of 280 ~ 300mm, and packed about 5.5kg in a 15cm × 30cm × 6cm depth iron plate formwork. Immediately on top,
Furthermore, spray PVA etc. with a normal paint air gun and
The amount of evaporated water was measured 24 hours after being left in a room at 5 ° C and RC50%, and at the same time, the sum of the gaps at both ends in the major axis direction was measured because the mold can be scratched if the weight loss is large and there is shrinkage.

The results are shown in Table-1. The materials used are shown below.

[Materials used]

Ordinary cement: manufactured by Andes Cement Co., Ltd. Sand: River sand from Himekawa, Niigata Water reducing agent: Dai-ichi Kogyo KK, trade name “Cellflow 110P” powder Trieta etc. A: triethanolamine, industrial Kishida Chemical Co., Ltd. 50% by volume B: Industrial glycerin manufactured by Kishida Chemical Co., Ltd.
50% by volume PVA, etc. C: Polyvinyl alcohol, manufactured by Denki Kagaku Kogyo Co., Ltd., trade name "Denka Poval F-17" 4% by weight
Aqueous solution 〃 D: Polyvinyl alcohol, manufactured by Denki Kagaku Kogyo Co., Ltd., trade name "Dencapobar B-17" (partially saponified product), 6 wt% aqueous solution PVA, etc. E: Alginic acid, industrial Kishida Chemical Co., Ltd.
Made, 50% by volume 〃 F: Ethylene Vinyl Acetate Emulsion Denki Kagaku Kogyo Co., Ltd., trade name "Dencatex # 50", adjusted to a solid content of 30% by weight 〃 G: Vinylidene chloride-vinyl chloride emulsion, Asahi Kasei Kogyo ( Co., Ltd., trade name "Saran Latex" (solid content 50% by weight) When the combination of Trieta etc. and PVA etc. is used in combination, the former is applied and then the latter is applied.

In Table 1, the amounts used (g / m ² ) are 100% weight% solution for trieta etc. and solid content for PVA etc.

The amount of water evaporation is the value obtained by subtracting the diluted water content of each of the sprayed aqueous solutions from the total weight reduction. In Table 1, Experiment Nos. 1 and 12 to 15 are comparative examples, and the others are examples.

In addition, the reason for adding the retarder (citric acid) to the mortar is
This is because the effect of suppressing the evaporation of water in the mortar is not affected by the curing speed and the effect is sufficiently understood. still,
The mortar is viscous and the breathing rate is 0%.

As shown in Table-1, it is shown that spraying more than 30 g / m ² of Trieta etc. rapidly exerts the effect of suppressing water evaporation and suppresses shrinkage, and the effect is remarkably promoted by the combined use of PVA etc. Is shown to be done.

Example 2 Using the concrete mix shown in Table-2, 3 m x 4 m outdoors
× Concrete with a thickness of 30 cm was poured, and triethanolamine aqueous solution (50% by volume) was sprayed on the concrete surface, and after triethanolamine aqueous solution was sprayed, ethylene vinyl acetate emulsion (35 wt% solids) solution was sprayed. Cracks were observed and the amount of water evaporation was measured for those that did and those that did not.

The outside temperature is 27 ° C, the wind speed is 0.8 m / s, the weather is fine, and the breathing rate of concrete is 0%.

The material used is the same as in Example 1, and the coarse aggregate is crushed stone from Himekawa, Niigata Prefecture.

Table 3 shows the measurement results of water evaporation, and Figures -1 to 3 show the generation of cracks. In Table 3, Experiment No. 33 is a comparative example. The crack of the comparative example entered within 1 to 2 hours after casting and before curing, and no new crack was generated thereafter, but the crack width increased (the cracks of the crack after 24 hours are shown in FIGS. 1 to 3). . On the other hand, in the Examples, only one crack was generated in Experiment No. 34 and no crack was observed in Experiment No. 35.

Example 3 Cement to sand weight ratio 1: 2, water, mortar with a cement ratio of 50% by weight, the cement was ordinary cement, alumina cement ("Denka Alumina No. 2" manufactured by Denki Kagaku Kogyo Co., Ltd.), and an inner diameter of 20 cm, Centrifugal force molding to a thickness of 10 mm in a steel tube with a length of 30 cm (centrifugal force molding conditions 3G-3 minutes, 15G-4 minutes, 35G-
After lining with water for 6 minutes, the water was well drained off, and cracks were observed with and without spraying the glycerin aqueous solution (50% by volume), the glycerin / polyvinyl alcohol, and the B-17 mixed aqueous solution.

The curing conditions are as follows: pre-curing for 4 hours in a room at 20 ° C RH65%, then raising it to 65 ° C at a rate of 20 ° C / hr, holding it for 4 hours, and allowing it to cool naturally the next day (after 24 hours) curing tank. It was taken out of the room and cured in a room at 20 ° C and RH 65% for 2 weeks. The cracks were observed 4 hours after the initial placement, 24 hours after steam curing, 20 ° C, and RH65.
% Indoor curing after 2 weeks. Further, the amount of water evaporated from the actual mortar lining was measured from the total weight before and after spraying various aqueous solutions after lining and the total weight 24 hours after steam curing. The results are shown in Table-4.

In Table 4, experiments Nos. 36 to 39 are ordinary cements, Nos. 40 to 42 are systems using alumina cement, and Nos. 36 and 40 are comparative examples.

In the comparative example of Table 4, innumerable fine hexagonal cracks were introduced during pre-curing and the crack width was growing after steam curing, but only on the surface. It is observed from the end that it grows to a depth of 2-5 mm after 2 weeks of room curing. In the examples of the present invention, no crack was observed at all, and the change in weight was extremely small, and it seems that the effect of alumina cement was more remarkable than that of ordinary cement.

〔The invention's effect〕

As described above, it is possible to reduce or completely prevent cracking due to drying before hardening of the mortar / concrete by using the curing sealant for mortar / concrete of the present invention, and in particular, for breathing that is easy to enter a crack. It has been shown to be extremely effective even for low or no concrete.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a crack generation situation on a concrete surface of Example 2 experiment No. 33. Similarly, Fig. 2 shows the concrete surface of Experiment No. 34, and Fig. 3 shows the concrete surface of Experiment No. 35. Here, the crack width is 0.1 to 0.3 mm, and the crack width is 1 to 5 mm.

Claims (2)

(57) [Claims] 1. A curing agent for mortar concrete, which comprises triethanolamine and / or glycerin. 2. A mortar comprising triethanolamine and / or glycerin and one or more of polyvinyl alcohol, alginic acid aqueous solution and polymer emulsion.
Sealant for curing concrete.