JPH07277855A - Lightweight concrete - Google Patents

Abstract

PURPOSE:To provide a high quality concrete balanced with the strength, being made to be lighter weight and less water absorption ratio, becoming high strength, being superior in water resistance, being small dry shrinkage and not degrading the strength and incombustibility and being superior in the flow property of the concrete. CONSTITUTION:The lightweight concrete is formed by kneading lightweight concrete aggregate molded integrally by hardening at least plural synthetic resin foamed bodies with a hydraulic binder, with water and the hydraulic binder. Also it is the lightweight concrete which is formed by kneading the lightweight concrete aggregate prepared by integrally hardening plural pieces synthetic resin foamed bodies with a hydraulic binder, water, the hydraulic binder and a synthetic resin foamed body. The above-mentioned synthetic resin foamed body is beads in the range of 0.1-1.5mm average particle size and produced by foaming polystyrene and is in the range of 0.05-0.2 true specific gravity. Also the above-mentioned hydraulic binder is cement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to lightweight concrete containing lightweight concrete aggregate.

[0002]

2. Description of the Related Art Lightweight concrete has come to be used in various fields.
As shown in SA5002, artificial lightweight aggregates such as expanded shale, expanded clay, expanded slate, and fired fly ash, natural lightweight aggregates such as volcanic gravel and its processed products, by-product lightweight aggregates such as expanded slag, and These products are classified as by-product lightweight aggregates.

Further, recently, synthetic resin foam beads are mixed as they are to obtain lightweight concrete. For example, as shown in Japanese Patent Publication No. 54-11814, synthetic resin foam beads and synthetic resin moldings are used. For example, lightweight concrete is obtained by mixing a granular material obtained by crushing with a hydraulic binder such as cement bonded.

[0004]

[Problems to be Solved by the Invention] However, JIS
The lightweight concrete using the lightweight aggregate shown in Fig. 2 has a problem that it has poor water-tightness and freeze-thaw resistance due to the large number of voids in the aggregate, and also has a high water absorption rate, resulting in a large drying shrinkage rate. . Furthermore, since the water absorption rate is high and the water absorption amount is large, the overall weight increases and the weight reduction decreases,
There is a problem that the heat insulating property is also lowered. Furthermore, since there are few aggregates having uniform bubbles, and the strength as an aggregate is generally low, it is necessary to increase the specific gravity in order to obtain a certain strength, and it is difficult to reduce the weight of concrete. There is a point. Furthermore, when concrete is prepared by mixing a lightweight aggregate such as described above and a hydraulic binder such as cement, it is difficult to control the water-cement ratio due to its high water absorption rate, which results in variations in fluidity and strength performance. Is likely to occur.

Further, in the case of lightweight concrete in which the synthetic resin foam beads are mixed as they are, since the synthetic resin foam beads have a strong water repellency and an extremely low specific gravity, they lack affinity for the cement paste and the cement is hardened. In addition, the synthetic resin foam beads float up, which makes it difficult to obtain uniform concrete. Furthermore, in the case of lightweight concrete using lightweight aggregate in which a hydraulic binder is bonded to the surface of synthetic resin foam beads, etc., a uniform thickness is obtained on the surface of the synthetic resin foam beads of this lightweight aggregate. It is difficult to coat the hydraulic binder, and therefore, the specific gravity and strength of the lightweight aggregate tend to vary, and as a result, the quality of the lightweight concrete using the same deteriorates.

In view of the above circumstances, the present applicants proposed a lightweight concrete aggregate useful at the same time as the present application. Since this lightweight concrete aggregate is still new, a lightweight concrete using the same has not been proposed, and it is decided to propose it in the present application.

[0007]

According to a first aspect of the present invention, there is provided a lightweight concrete aggregate in which a plurality of synthetic resin foams are solidified with a hydraulic binder to form a single unit, and a water-soluble concrete aggregate. It is a lightweight concrete formed by kneading and a hydraulic binder.

According to a second aspect of the present invention, a lightweight concrete aggregate in which a plurality of synthetic resin foams are solidified with a hydraulic binder and integrated together, water, a hydraulic binder and a synthetic resin foam are kneaded. The purpose is to form a lightweight concrete.

The means of claim 3 is that the synthetic resin foam is beads.

The means of claim 4 is that the average diameter of the synthetic resin foam is in the range of 0.1 to 1.5 mm.

According to a fifth aspect of the present invention, the synthetic resin foam is formed by foaming polystyrene.

According to a sixth aspect of the present invention, the true specific gravity of the synthetic resin foam is in the range of 0.05 to 0.2.

The means of claim 7 is that the hydraulic binder is cement.

The means of claim 8 is that the ratio of the water-bonding agent to the hydraulic binder of the lightweight concrete aggregate is 30% or less.

The means of claim 9 is that the true specific gravity of the lightweight concrete aggregate is 0.8 or more.

According to a tenth aspect of the present invention, the overall shape of the lightweight concrete aggregate is substantially spherical.

The means of claim 11 is that the synthetic resin foam is exposed on the outer peripheral surface of the lightweight concrete aggregate.

[0018]

According to the lightweight concrete according to the means of claim 1, as compared with a case where one synthetic resin foam as a lightweight concrete aggregate is coated with a hydraulic binder such as cement, the hydraulic binder is Since the thickness of the coating on the synthetic resin foam is kept substantially uniform and the variations in specific gravity and strength are small, a lightweight concrete product with balanced strength can be obtained.

According to the lightweight concrete of the second aspect of the present invention, a lightweight concrete aggregate, a plurality of synthetic resin foams are solidified with a hydraulic binder to form an integral body, water, a hydraulic binder and a synthetic resin foam. Since it is a lightweight concrete formed by kneading, it is possible to obtain a lightweight concrete having a balanced strength and further reduce the weight.

According to the lightweight concrete according to the means of claim 3, since the synthetic resin foam is a bead, that is, spherical or nearly spherical, both weight and volume can be easily measured, and dispersion of the measurement can be suppressed. Also, because it is an aggregate with good strength and high stress dispersion,
A good quality concrete product can be obtained.

According to the means of claim 4, since the synthetic resin foam has an average diameter in the range of 0.1 to 1.5 mm, it is possible to obtain a stable aggregate having a small variation in specific gravity and strength. As a result, good lightweight concrete products can be obtained. If it is 0.1 mm or less, the fluidity of the mixture is lowered, and the amount of the synthetic resin foam cannot be increased, which makes it difficult to reduce the weight. Further, if it is 1.5 mm or more, the density of the aggregate tends to vary, and the aggregate itself becomes large, which is not preferable.

According to the means of the fifth aspect, since the synthetic resin foam is polystyrene, the strength of the property is high and the cost is low. As a result, the lightweight concrete product is also strong and inexpensive. Things are obtained. Also, since the closed cells have low water absorption, the water absorption rate of the lightweight concrete also becomes low.

According to the means of the above-mentioned claim 6, when the true specific gravity of the synthetic resin foam is in the range of 0.05 to 0.2, the strength is appropriately maintained, so that the original shape of the synthetic resin foam is kneaded. Since it is difficult to deform and the aggregate strength does not decrease, the lightweight concrete product using this also becomes of good quality.

According to the means of claim 7, since cement is used as the hydraulic binder, the strength is increased,
It has excellent water resistance. Mixing blast furnace slag into cement further improves performance and makes it more desirable.

According to the means of claim 8, since the water-bonding ratio of the hydraulic binder of the lightweight concrete aggregate is 30% or less, the water absorption rate and the expansion rate due to the water absorption are small, and the strength is high. The light-weight concrete using this has the same effect under the influence, and the drying shrinkage rate becomes small.

According to the means of claim 9, since the total specific gravity of the lightweight concrete aggregate is 0.8 or more, the strength,
Since the non-combustibility does not decrease, the lightweight concrete using this is also affected by it and has the same effect.

According to the means of the tenth aspect, since the overall shape of the lightweight concrete aggregate is spherical, the flowability of the concrete is improved when the aggregate is used.

According to the means of the eleventh aspect, since the synthetic resin foam is exposed from the outer peripheral surface of the lightweight concrete aggregate, when this is used as an aggregate, the water absorption rate becomes small, and the water at the time of kneading is reduced. The cement ratio is easy to control and the quality is stable.

[0029]

Embodiments of the present invention will be described below. As shown in FIGS. 1 and 2, the lightweight concrete of this example includes at least a plurality of synthetic resin foams which are solidified with a hydraulic binder to form a lightweight concrete aggregate, water and a hydraulic binder. It is formed by kneading.

The synthetic resin foam may be a crushed product obtained by crushing a synthetic resin foam or a modified product.
The beads formed into spherical or substantially spherical beads have less weighing error and less variation in specific gravity of the individual lightweight concrete aggregates, and a product of stable quality can be obtained. Also, for concrete products using this, if stress is applied, it can be dispersed if it is beads, and a concrete product with high strength can be obtained, but in the case of crushed products or irregular shapes, stress concentration It is desirable to use beads as much as possible, since it will cause damage and weaken the strength.

The light-weight concrete aggregate is obtained by hardening a plurality of such synthetic resin foams by solidifying them with a hydraulic binder such as cement, removing the water content, and hardening. When the shape of the concrete product is as close to a spherical shape as possible, the stress can be dispersed and a concrete product having high strength can be obtained. The size of the lightweight concrete aggregate is preferably selected from those having a diameter in the range of 3 to 45 mm, which is similar to the commonly used aggregate mixed in concrete, but is particularly limited to this range. It is not something that will be done.

When only one synthetic resin foam is coated with a hydraulic binder such as cement to cover its outer periphery and hardened, it is difficult to adjust the coating thickness of the hydraulic binder, and as a result,
It is difficult to obtain a uniform aggregate because variations in specific gravity and strength are likely to occur, but when a plurality of hydraulic binders are used for hardening in the present invention, the coating thickness of each synthetic resin foam is almost even. As a result, it is possible to obtain a uniform aggregate without variations in specific gravity and strength. Further, also in the manufacturing method thereof, the manufacturing can be easily performed as compared with the case of coating individual synthetic resin foams. The specific number varies depending on the product depending on the diameter of the lightweight concrete aggregate and the average diameter of the synthetic resin foam. For example, the diameter of the lightweight concrete aggregate is 10 mm, and the average diameter of the synthetic resin foam. When is 0.7 mm, the number is about 50 to 250.

The synthetic resin foam, whether it is a crushed product, an irregular shape or a bead, has an average diameter of 0.1 to 2.
0 mm, preferably 0.1 to 1.5 mm,
If the thickness is less than 0.1 mm, the mixture becomes too small and the fluidity of the mixture is reduced, and the amount of the synthetic resin foam cannot be increased, which makes it difficult to reduce the weight. Also, if it is 2.0 mm or more, 1
This is because the number that can enter one aggregate is extremely limited and the strength becomes weak. In this case, the average diameter of the crushed product and the irregular shape is expressed as the average value of the maximum length and the minimum length.

The synthetic resin used as the raw material of the synthetic resin foam is polystyrene, polypropylene, polyethylene,
Acrylic nitric polystyrene, polystyrene-polyethylene copolymer, polyvinylidene chloride, etc.
Among them, when polystyrene is used, the strength is high,
It is the most desirable because it is cheap.

The true specific gravity of the synthetic resin foam, that is, the specific gravity before kneading with the hydraulic binder is 0.05 to 0.2.
The range of is good. If it is 0.05 or less, the strength becomes small, and the shape is deformed at the time of kneading with a hydraulic binder to reduce the strength as an aggregate. Even though the cost is high, its strength is almost unchanged and it becomes uneconomical,
Those within the above range are suitable. It is not appropriate to describe this in terms of the expansion ratio because it depends on the type of raw material and the like, but it is in the range of about 5 to 20 times.

Cement, lime, gypsum and the like can be used as the hydraulic binder for solidifying a plurality of synthetic resin foams or the hydraulic binder used for concrete. Of these, cement is strong and water resistant. It is most desirable because it has excellent properties and is relatively inexpensive. As cement, other than Portland cement such as normal Portland cement and early strength Portland cement, blast furnace cement,
Silica cement, fly ash cement, etc. can be used, and it is preferable to use them depending on the application.

When the water-to-water ratio (W / C) of the hydraulic binder of the lightweight concrete aggregate to water is 30% or more, the water absorption rate is high, the expansion rate due to water absorption is high, and the strength is low. Since it is not preferable, the performance is preferably as small as 30% or less.

If the solidified specific gravity of the lightweight concrete aggregate is 0.8 or less, the mixing ratio of the synthetic resin foam increases correspondingly, so that both strength and nonflammability decrease, which is not preferable. 0.8 or more, particularly preferably 1.0 to 1.5. When the hydraulic binder is cement, the specific gravity when solidified is about 1.9 to 2.2, so it is most preferable when the synthetic resin foam having a specific gravity of 0.1 is used. The mixing volume ratio of the synthetic resin foam is in the range of about 20 to 60%.

The outer shape of the solidified lightweight concrete aggregate can be made into various shapes depending on the manufacturing method, but by making it as spherical as possible, it was solidified for use in lightweight concrete products. In this case, when stress is applied to the lightweight concrete product, the stress is dispersed, so that a lightweight concrete product having high strength can be obtained. However, since a large amount of hydraulic binder such as cement is exposed on the outer peripheral surface of the lightweight concrete aggregate, it is easy to be compatible with the hydraulic binder such as cement used for lightweight concrete products, so it is integrally bonded. .
Therefore, it is not particularly limited to the spherical shape.

When a part of the synthetic resin foam is exposed from the outer peripheral surface of the lightweight concrete aggregate as shown in FIG. 1, when the lightweight concrete product is manufactured, the water absorption rate when mixed with cement or the like is used. Is preferred, and the water-cement ratio during kneading is easy to control, and the quality is stable, which is particularly preferable.

Materials that can be mixed with lightweight concrete include lightweight concrete aggregates detailed above, hydraulic binders such as water and cement, artificial lightweight aggregates, gravel, sand, synthetic resin foams, fibers, By appropriately selecting and mixing various admixtures and the like, it is possible to obtain an optimal lightweight concrete that matches the purpose of use.

Next, specific examples of the present invention will be described. First, as shown in [Table 1], the composition of the lightweight concrete aggregate used in this lightweight concrete was set as four samples of Examples 1 to 4 having different water cement ratios (W / C). These are all ordinary portland cements as hydraulic binders, so that the volume is 1 m ³ .
It is a mixture of water, high-performance AE water reducing agent and synthetic resin foam beads. The synthetic resin foam beads are made by foaming polystyrene and have an average diameter of 0.7 mm and a true specific gravity of 0.
1 was used. The mixture mixed under such conditions was formed into a spherical shape having an average diameter of about 10 mm and solidified.

[0043]

[Table 1]

The results of the performance tests of Examples 1 to 4 thus prepared are shown in [Table 2].

[0045]

[Table 2] [Test Method] (1) Water absorption rate is according to JIS A 1135. (2) Compressive strength is according to JIS R5201. (3) The expansion coefficient due to water absorption is according to JIS A 1129. (4) Freeze-thaw resistance is according to ASTM C 666 A method (in water). Regarding (2), (3), and (4) above, concrete molded products with the same composition as the lightweight concrete aggregate were prepared and tested.

From this [Table 2], the water cement ratio (W /
In Examples 1 and 2 in which C) is 25% and 30%, the water absorption rate is small at about 8 and about 9, the compressive strength is large at 320 and 280, and the expansion rate due to water absorption is 0.01 and 0.02. It was found to be superior to any of Examples 3 and 4 which were small and had a water-cement ratio (W / C) of more than 30%. The comparative example is a commercially available expanded shale artificial lightweight aggregate (trade name: Asanolite), but it was found that Examples 1 to 4 were superior in water absorption.

Next, an example of manufacturing a lightweight concrete product using the above lightweight concrete aggregate will be described based on [Table 3] and [Table 4].

[0048]

[Table 3] A: Normal concrete W / C (water cement ratio) = 55
% B: Lightweight concrete of the present invention using lightweight concrete aggregate W / C = 55% C: Concrete using expanded shale artificial lightweight aggregate W
/ C = 55% D: lightweight concrete aggregate and lightweight concrete of the embodiment of the present invention using foam beads as synthetic resin foam
W / C = 30%

First, as shown in [Table 3], four samples A to D having different formulations were prepared. Among these, B and D are those using the lightweight concrete aggregate used for the lightweight concrete of the present invention. The lightweight concrete aggregate used had the composition of Example 2 in [Table 1] above. B is a mixture of ordinary Portland cement, water, lightweight concrete aggregate and sand in the proportions shown in [Table 3]. D is a high-performance AE water reducing agent in addition to ordinary Portland cement, water, synthetic resin foam beads (true specific gravity 0.1, average diameter 0.7 mm) and the lightweight concrete aggregate of Example 1 of [Table 1] above. They are mixed in the proportions shown in Table 3]. [Table 4] shows the performance test results of the four lightweight concrete products A to D (see FIG. 2) thus prepared.

[0050]

[Table 4] [Test Method] (1) The water absorption rate was based on JIS A 1110. (2) Compressive strength is according to JIS A 1108. (3) Drying shrinkage is according to JIS A 1129. (4) Freeze-thaw resistance is according to ASTM C 666 A method (in water).

From this [Table 4], the following was found. The test specimens B and D of the examples of the present invention using the lightweight concrete aggregate have a weight B which is higher than that of the ordinary concrete A.
Despite being reduced by about 20% and D by about 45%, there is no decrease in water absorption rate, compressive strength, and dry shrinkage rate, and good performance is shown in terms of freeze-thaw resistance. on the other hand,
Specimen C using the expanded lightweight shale artificial aggregate has a weight reduction of about 20% compared to ordinary concrete A, but has a high water absorption rate and extremely low freeze-thaw resistance. From the above, it was found that the lightweight concrete of the present invention using the lightweight concrete aggregate is particularly excellent in lightness, watertightness, and freeze-thaw resistance.

[0052]

As is apparent from the above description, the lightweight concrete of the present invention is a lightweight concrete bone in which at least a plurality of synthetic resin foams having almost no water absorption are solidified with a hydraulic binder. Since it is formed by kneading a material, water and a hydraulic binder, the synthetic resin foam contained in the lightweight concrete aggregate reduces the weight accordingly. In addition, if synthetic resin foam beads are also kneaded together with these materials, a lightweight concrete product with an extra weight can be obtained.

Further, the lightweight concrete aggregate has a water content for each synthetic resin foam as compared with the case where one synthetic resin foam is coated with a hydraulic binder such as cement as a lightweight concrete aggregate. Since the coating thickness of the hard binder is almost even, compared to the conventional case where individual synthetic resin foams are coated, variations in specific gravity and strength are small, and a uniform lightweight concrete product can be obtained. .

Further, since the lightweight concrete aggregate having a lower water absorption rate than the conventional artificial light weight aggregate is used, the product itself also has a low water absorption rate and is a concrete having high freeze-thaw resistance.

Further, unlike the case of lightweight concrete in which the synthetic resin foam beads are mixed as it is, it has a good affinity with cement paste and the like, and does not float up until the hydraulic binder such as cement hardens, and is uniform. Lightweight concrete products can be obtained.

According to the lightweight concrete of claim 2, in the lightweight concrete of claim 1, further weight saving and heat insulation effect can be achieved.

According to the lightweight concrete of claim 3, since the synthetic resin foam is beads, that is, spherical or nearly spherical, both weight and volume can be easily measured, and the dispersion of the measurement can be suppressed. Since the stress dispersion is good and the aggregate has high strength, a good quality lightweight concrete product can be obtained.

According to the lightweight concrete of claim 4, since the average diameter of the synthetic resin foam is in the range of 0.1 to 1.5 mm, it is possible to obtain a stable aggregate with a small variation in specific gravity and strength. As a result, good lightweight concrete products can be obtained.

According to the lightweight concrete of claim 5, since the synthetic resin foam is polystyrene, it has the following properties.
As a result of the strength being high and the cost being low, a lightweight concrete product is similarly strong and cheap. In addition, since the closed cells have low water absorption, the water absorption rate of the lightweight concrete also becomes low.

According to the lightweight concrete of claim 6, since the strength is appropriately maintained when the true specific gravity of the synthetic resin foam is in the range of 0.05 to 0.2, the original shape of the synthetic resin foam is kept at the time of kneading. Since it is difficult to deform and the aggregate strength does not decrease, the lightweight concrete product using this also becomes of good quality.

According to the lightweight concrete of claim 7, since cement is used as the hydraulic binder, the strength is increased and the water resistance is excellent. Mixing blast furnace slag into cement further improves performance and makes it more desirable.

According to the lightweight concrete of claim 8, the ratio of the water binder to the hydraulic binder of the lightweight concrete aggregate is 30.
% Or less, the water absorption rate is small, the expansion rate due to water absorption is small, and the strength is also strong, so that lightweight concrete using this is also affected by the same effect, and the same effect can be obtained. The drying shrinkage can also be reduced.

According to the lightweight concrete of claim 9, since the true specific gravity of the lightweight concrete aggregate is 0.8 or more,
Since the strength and non-combustibility do not decrease, the lightweight concrete using this is also affected by the same effect.

According to the lightweight concrete of claim 10,
Since the overall shape of the lightweight concrete aggregate is spherical, the fluidity of the concrete is further improved when this is used.

According to the lightweight concrete of claim 11,
Since the synthetic resin foam is exposed from the outer peripheral surface of the lightweight concrete aggregate, when this is used as an aggregate, the water absorption rate becomes small, and it is easy to manage the water-cement ratio during kneading.
Quality is stable.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of an example of a lightweight concrete aggregate used in the present invention.

FIG. 2 is a cross-sectional explanatory view of the embodiment of the lightweight concrete of the present invention.

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Claims (11)

[Claims] 1. A lightweight concrete aggregate formed by solidifying at least a plurality of synthetic resin foams with a hydraulic binder to form an integrated lightweight concrete aggregate, and water and a hydraulic binder. 2. A lightweight concrete formed by kneading a lightweight concrete aggregate in which a plurality of synthetic resin foams are solidified with a hydraulic binder to form an integral body, water, a hydraulic binder and a synthetic resin foam. 3. The synthetic resin foam is beads.
Or 2 lightweight concrete. 4. The lightweight concrete according to claim 1, 2 or 3, wherein the synthetic resin foam has an average diameter of 0.1 to 1.5 mm. 5. The lightweight concrete according to claim 1, wherein the synthetic resin foam is formed by foaming polystyrene. 6. The lightweight concrete according to claim 1, wherein the true specific gravity of the synthetic resin foam is in the range of 0.05 to 0.2. 7. The hydraulic binder is cement.
Or 2 lightweight concrete. 8. The lightweight concrete according to claim 1, wherein the ratio of the water binder to the hydraulic binder of the lightweight concrete aggregate is 30% or less. 9. The true specific gravity of the lightweight concrete aggregate is 0.8.
It is the above or more, The lightweight concrete of Claim 1 or 2. 10. The lightweight concrete according to claim 1, wherein the overall shape of the lightweight concrete aggregate is substantially spherical. 11. The lightweight concrete according to claim 1, wherein the synthetic resin foam is exposed on the outer peripheral surface of the lightweight concrete aggregate.