JPH06127996A - Production of waterproof concrete - Google Patents

Abstract

PURPOSE:To improve durability by pulverizing an aq. emulsion contg. PP and asphalt or a mixture formed by adding a fluidizing agent and/or high- performance water-reducing agent thereto and adding this power to concrete. CONSTITUTION:The aq. emulsion of 2 to 20wt.% concn. of PP is prepd. by mixing the PP, such as atactic PP, 0.5 to 10 pt.wt. asphalt per 1 pt.wt. PP, a dispersant, such as PVA, having 70 to 98% rate of saponification and water. The aq. emulsion prepd. by adding 10 to 300wt.% fluidizing agent, such as polyalkylene glycol or acrylate and/or high-performance water-reducing agent, such as modified methyrol melamine, to the above emulsion or further to the PP is dried at 150 to 300 deg.C by a spray drying system, etc., and the power is produced by adding an tntiblocking agent thereto. The powder of the amt. to make 2 to 2kg per 1m<3> concrete is kneaded with cement, aggregate, various intimate mixtures and water, by which the waterproof concrete having the excellent durability is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing waterproof concrete, and more particularly to a method for producing concrete which is excellent in waterproofness and other characteristics and has good workability in placing.

[0002]

2. Description of the Related Art Attempts have been made to add various admixtures during the production of concrete for the purpose of improving waterproofness and other properties of concrete. For example, a waterproofing agent is added for the purpose of improving waterproofness and watertightness, and in addition to these characteristics, a water reducing agent is added for the purpose of reducing drying shrinkage at the time of hardening of concrete and suppressing cracks. Further, an AE agent has been added for the purpose of improving durability against repeated freeze-thawing in cold regions and cold seasons. These admixtures are usually water-based liquids, and the addition of these admixtures has the drawback of decreasing the strength of concrete. To compensate for this, reduce the amount of water for concrete mixing,
Alternatively, it is dealt with by increasing the mixing ratio of cement.

Further, a water-based fluidizing agent has been added for the purpose of improving the efficiency of concrete pouring work. In this case as well, the strength of the concrete is lowered, so that the proportion of cement is increased to compensate for this, and the sand ratio is increased to prevent the separation of concrete.

Most of the concrete admixtures, which are water-based liquids as described above, become unusable when frozen in cold weather.
As measures against this, there are some which are mixed with an ethylene glycol-based or alcohol-based antifreezing agent, but the antifreezing agent often impairs the stability of the admixture. In addition, these concrete admixtures are stored in drums, gallons, plastic cans, etc., and empty containers after use are difficult to clean, so their recycling is expensive, and they are disposed of as landfill as industrial waste. However, due to recent industrial waste problems, there is a strong demand to control the amount of waste generated.

[0005]

In view of the above situation, an object of the present invention is to provide a concrete having good waterproofness with good workability without lowering the strength of the concrete or separating the concrete during production. It is to provide a manufacturing method.

[0006]

According to the present invention, there is provided a method for producing waterproof concrete, characterized in that an aqueous emulsion containing asphalt and polypropylene is powdered and the powder is added to concrete. Furthermore, according to the present invention, a waterproof concrete characterized by mixing an aqueous emulsion containing asphalt and polypropylene with a superplasticizer or a superplasticizer, powderizing the mixture, and adding the powder to concrete. A method is provided.

A typical example of an aqueous emulsion containing asphalt and polypropylene is described in Japanese Patent Publication No. 54-11328 previously filed by the present applicant. That is, the preferred aqueous emulsion is an aqueous emulsion containing substantially atactic polypropylene and 0.5 to 10 parts by weight of asphalt per 1 part by weight of the polypropylene as important components. In addition to atactic polypropylene, isotactic polypropylene can be used, but atactic polypropylene is preferred because it is easy to prepare an aqueous emulsion. This aqueous emulsion is prepared by uniformly kneading atactic polypropylene and a dispersant (0.03 to 0.5 parts by weight per 1 part by weight of polypropylene) to form a slurry or paste, and adding a required amount of water thereto and mixing. Furthermore, it can be prepared by mixing with the hot-melt asphalt, or by first mixing the hot-melt asphalt and then mixing with water. At relatively high temperatures, polypropylene, asphalt,
It is also possible to employ a method in which a dispersant and a small amount of water are kneaded at once, and then a large amount of water is added.

Examples of the dispersant include anionic activators such as sodium oleate and sodium stearate, nonionic activators such as polyoxyethylene alkylphenol ether, polyvinyl alcohol, carboxymethyl cellulose (and its sodium salt), and polyacryl. Examples include acids and hydrophilic polymers such as polyacrylic acid amide. A preferred dispersant is polyvinyl alcohol having a saponification degree of 70 to 98%. Further, the asphalt may be natural asphalt or petroleum asphalt. The concentration of polypropylene in the obtained aqueous emulsion is preferably 2 to 20% by weight.

The above polypropylene / asphalt aqueous emulsion is pulverized as it is or after adding a fluidizing agent and / or a superplasticizer to it. As the fluidizing agent, naphthalene-based, melamine-based, polycarboxylic acid-based, acrylic acid ester-based polyalkylene glycol, and other commonly used fluidizing agents can be used. Further, as a high-performance water reducing agent, the same components as the above-mentioned fluidizing agent are used as a main component, and a modified methylolmelamine-based, ligninsulfonic acid-based or polycarboxylic acid-based additive for reducing slump loss is added to this. A commonly used high-performance water reducing agent can be used. The blending amount of the superplasticizer and / or the superplasticizer is preferably 10 to 300% by weight based on polypropylene in the aqueous emulsion.

As a method for pulverizing the aqueous emulsion, a spray dry method is preferable. The spray dry may be either a nozzle spray method or an atomizer method, but the nozzle method is preferable from the viewpoint of productivity. Solid content concentration in powdered aqueous emulsion is about 30% by weight
It is preferable for it to be the following, because the particle size of the powder is uniform and the particle size is small. However, if the concentration is too low, the energy cost for pulverization increases, which is disadvantageous. At the time of spray drying, the temperature of the hot air applied for drying is 1 at the jet outlet.
It is about 50 to 300 ° C, preferably about 230 ° C.
If the temperature is too high, the powder tends to be heat-sealed, and conversely, if the temperature is too low, water remains in the powder and causes blocking.

Since the produced powder generally has hygroscopicity, it is quickly filled in a highly moisture-proof bag. Various anti-blocking agents can be used in combination to prevent blocking of the powder. Examples of the anti-blocking agent include talc, silicon powder, and paraffin powder.

Various methods are available for mixing the powder prepared as described above into concrete. That is, cement, sand, gravel, water, A
E When adding the water-reducing agent, any of these materials can be mixed in advance. According to this method, the powder dissolves in water and mixes with concrete within a normal batcher kneading time. In addition, when a ready-mixed concrete truck (truck agitator vehicle) is loaded with normal ready-mixed concrete and arrives at the construction site, this powder is put in from the upper hopper of the truck agitator, and the agitator is agitated at high speed for about 1 minute. The powder is dissolved in water and mixed with concrete. When mixing powder containing a fluidizing agent into concrete, the fluidizing effect duration of the fluidizing agent is 30 to 6
Since it takes about 0 minutes, the method of mixing at the concrete construction site as described above is preferable.

The concrete pouring method is not particularly different from the ordinary concrete pouring method in the case of concrete in which asphalt and powder containing polypropylene are mixed. When asphalt, polypropylene and a powder containing superplasticizer are mixed, the workability of concrete is significantly improved.Therefore, the compaction work with a vibrator and the concrete filling work with tapping and poking, which are performed during concrete pouring, are eliminated or significantly omitted. can do.

The concrete used may be conventional concrete consisting of cement, water and aggregate.
As the cement, ordinary commercially available ones such as ordinary Portland cement, early-strength cement, moderate heat cement, blast furnace cement and fly ash cement are used, and some of them are fly ash, granulated slag powder, siliceous mixture material. May be replaced with. polypropylene,
The amount of asphalt and powder containing a superplasticizer and / or a superplasticizer as required is 1 m of concrete.
^It is about 2 to 5 kg per ³ and particularly preferably about 3 kg.

[0015]

The concrete produced by the method of the present invention generally possesses the following characteristics. (B) The strength of concrete does not decrease due to the addition of powder. (B) The waterproofness and watertightness are remarkably improved, and no new waterproofing treatment is required. (C) The concrete becomes excellent in acid resistance, alkali resistance and salt resistance and durability is improved. (D) The resistance of concrete to frost damage due to repeated freezing and thawing increases remarkably. (E) Suppress the white flower phenomenon and prevent concrete from becoming dirty. (F) The thermal conductivity of concrete is reduced, and the effect of suppressing dew condensation is also exerted. (G) The drying shrinkage rate of concrete is reduced and cracking is prevented.

Further, the concrete mixed with the powder containing the superplasticizer is superfluidized and the workability is remarkably improved, and the compaction work by the vibrator and the concrete filling work by tapping or poking can be omitted or reduced. Greatly labor saving in the placement work. In addition, the amount of work to mix into concrete is small, and transportation and storage costs are low. Further, since the powder used in the present invention does not freeze, it can be advantageously used in cold regions and cold seasons, and can be stored in a paper bag or a plastic bag, so that the problem of waste disposal of empty containers after use can be significantly reduced.

[0017]

EXAMPLES The method of the present invention will be specifically described below with reference to examples. Examples 1 and 2, Comparative Example 1 Each of the following components Asphalt (petroleum-based straight asphalt) 1,000 parts by weight Polypropylene (atactic polypropylene having an average molecular weight of 20,000) 300 parts by weight Polyvinyl alcohol (saponification degree manufactured by Nippon Synthetic Chemical Industry) 88%) 150 parts by weight Water 300 parts by weight are kneaded in a kneader at an internal temperature of 90 ° C for 20 minutes, and then a large amount of water is added while the temperature is lowered to 50 ° C to obtain an aqueous emulsion having a solid content of 30%. (Example 1).

Further, in addition to the above-mentioned components, acrylic acid ester of polyalkylene glycol 45 is used as a fluidizing agent.
An aqueous emulsion containing 0 parts by weight (active ingredient amount) was similarly prepared (Example 2). For comparison, a powder containing only a superplasticizer was prepared (Comparative Example 1).

The aqueous emulsion was sprayed from a large number of nozzles and pulverized using a spray dryer in which hot air at 230 ° C. was used to dry it. The obtained powder is 100 μm
It had a particle size of around. The above powder was added at the time of pouring concrete to evaluate the characteristics of the obtained concrete. Table 1 shows the composition and properties of the concrete.

[0020]

[Table 1]

In Example 1, the watertightness was remarkably enhanced, and concrete having excellent waterproofness was formed. In Comparative Example 1, the elongation of the slump is large, but the concrete is separated,
Both strength and water absorption were inadequate. Further, in Example 2, the elongation of the slump was remarkably large, and a workable concrete that did not require a vibrator for concrete compaction, tapping, and poking was obtained, and no concrete separation was observed. Further, the water absorption of the concrete was remarkably reduced and the waterproof property was also good.

Example 3 The powder of Example 2 (asphalt / polypropylene /
Concrete for construction work was placed using a fluidizing agent). Concrete of a large truck agitator carried from a ready-mixed concrete plant (nominal strength 210 kgf / cm ² , slump 12 cm, air content 4.0%) 6 concrete test pieces were collected from 5.5 M ³ and air-dried on site. I got a cure.

The powder of Example 2 (3 kg / M ³ (total amount: 16.5 kg)) was put into the hopper of the track agitator, and the agitator was rotated at a high speed for 1 minute to mix.
When the concrete discharged from the truck agitator was sampled and the physical properties were measured, a slump of 25.5 cm,
The amount of air was 4.2%. Six concrete test pieces were collected and air-dried on site. After 3 weeks, using three test pieces each, JIS-A1404
Based on the above, a water absorption test after immersion for 24 hours was conducted. As a result, the water absorption ratio (= water absorption of concrete mixed with powder /
The water absorption of the concrete before mixing the powders) was 55%, which shows that the water absorption remarkably decreased due to the powder mixing.

Further, after 4 weeks, a compressive strength test was carried out based on JIS-A1108 using the remaining 3 test pieces, respectively. As a result, the compressive strength of the powder-mixed concrete was 246 kgf / cm ² , and the powder was The compressive strength of concrete before mixing was about the same as 243 kgf / cm ^2, and both of them achieved the nominal strength completely. On the other hand, when concrete mixed with powder was poured, the concrete was extremely fluid and the use of a vibrator was especially omitted when flowing into the formwork on the vertical surface. A few days later, the mold was removed from the mold, but no defective filling such as plywood and nests was found in the concrete.

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Claims (2)

[Claims] 1. A method for producing waterproof concrete, which comprises powderizing an aqueous emulsion containing asphalt and polypropylene and adding the powder to concrete. 2. A method for producing waterproof concrete, which comprises mixing an aqueous emulsion containing asphalt and polypropylene, a fluidizing agent and / or a superplasticizer, pulverizing the mixture, and adding the powder to concrete. .