JPH04260674A - Production of lightweight cured product - Google Patents

Abstract

PURPOSE:To make blend of hydraulic powder, lightweight aggregate and water extremely smooth, enabling uniform disperse and remarkably decrease excess kneading water used for the purpose of only providing fluidity and solve the problem such as lowering of strength of lightweight cured article by excessive water addition, dimensional shrinkage after curing, fine crack of cured product and retardation of curing time. CONSTITUTION:Production of lightweight cured article characterized by adding lightweight aggregate, foaming agent and water, stirring the mixture to generate countless foam, uniformly dispersing and blending lightweight aggregate, water and foaming agent and adding and blending hydraulic powder, uniformly dispersing and ending each components and curing the blend.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] This invention relates to a method for producing a lightweight cured product that can be cast on-site or molded in a factory, and can also be applied to various fillers.
More specifically, the present invention relates to a manufacturing method for obtaining a lightweight cured product with uniform distribution of lightweight aggregate, small dimensional shrinkage after curing, and high strength.

0002

BACKGROUND OF THE INVENTION Various lightweight cured products have already been developed and widely used. For example, lightweight aerated concrete (AL) is made by foaming activated aluminum powder.
C), lightweight concrete that is solidified with air bubbles created by a foaming agent, or lightweight hardened material that is solidified by kneading lightweight aggregate and hydraulic powder with water. The lightweight aggregates used here include inorganic materials such as perlite, natural pumice, artificial lightweight aggregate (ALA), etc., and organic materials such as pre-expanded particles of synthetic resin foam, typified by expanded polystyrene, or foam molding. These include crushed particles such as those obtained by crushing bodies. In the case of inorganic lightweight aggregates, they are generally porous and have a high water absorption capacity.In order to have fluidity for on-site construction and filling into molds, it is necessary to use hydraulic materials such as cement. An unnecessarily large amount of water is required when kneading with powder. If such a large amount of water is used, the strength of the cured product will be significantly reduced, leading to problems such as dimensional shrinkage and cracking after curing, and a delay in curing time. On the other hand, in the case of organic lightweight aggregate, the amount of water can be reduced considerably as it has almost no water absorption per se, but this time it has poor affinity with hydraulic powder and the difference in specific gravity is extremely large. , it is difficult to produce a lightweight cured product with uniform distribution of aggregates due to the problem of lifting. As a method for improving the uniform distribution of foamed synthetic resin particles, Japanese Patent Application Laid-open Nos. 118716-1982 and 1983-
There is a proposal, as in No. 79118, to improve the uniform mixability of aggregates by using aggregates whose surfaces are pre-coated with organic and inorganic substances such as foamed polystyrene particles. In this method, the affinity with hydraulic powder is improved and the specific gravity of the aggregate itself is increased, so the kneading properties are certainly improved and a lightweight cured product with uniform aggregate distribution can be obtained. Since one step of pre-treatment of aggregate is essential, it is also a negative economic factor. Also, JP-A-4
No. 7-35061 points out that the miscibility with cement can be improved by using pulverized styrene foam moldings that are once molded into particles. However, any of these methods still requires a large amount of kneading water, which has an adverse effect on strength and shrinkage. Considering fluidity, the ratio of the weight of water added to the weight of hydraulic powder such as cement is 50.
At present, it is difficult to reduce the content to below 40 wt%. If the hydraulic powder is cement, A
There is a method of improving the fluidity of aggregate, water, and cement by using E agent, water reducer (non-AE), AE water reducer, etc., and as a result, reducing the mixing water, but the viscosity during mixing There are practical problems because control management is difficult, the strength decreases because it hardens with very fine air bubbles mixed in, and the water reduction effect cannot be expected to be large.

0003

[Problems to be Solved by the Invention] In all of the above conventional techniques, the amount of water in the formulation is still large, and the purpose is only to provide fluidity during compounding, on-site casting, and casting. Currently, it is necessary to add more kneading water than necessary. As a result, uniform distribution of aggregate is not obtained, the strength after curing is low, dimensional shrinkage after curing is large and causes cracking, and curing time is delayed. The current situation is that this has become a negative factor, such as the necessity to do so. Therefore, how to reduce the amount of water is an issue for future lightweight cured products. In addition, if the lightweight aggregate is pre-expanded particles or crushed particles of synthetic resin foam, such as expanded polystyrene,
There are methods of pre-coating the surface of pre-expanded particles with an organic or inorganic material or crushing them to make the surface open-celled to increase the kneadability with hydraulic powder and water. The number of processing steps increases, which is not economically advantageous, and even with this method, the amount of water required for mixing to obtain fluidity is still large, and the current situation is that it includes the above-mentioned negative factors. Therefore, the problem in this field is how to achieve uniform mixing using untreated aggregate and reduce the amount of kneading water.

0004

[Means for solving the problem] This invention has been made in view of the above circumstances, and the means thereof are as follows:
Light aggregate, foaming agent and water are added and stirred to generate countless air bubbles. After the lightweight aggregate, water and foaming agent are uniformly dispersed, hydraulic powder is added and mixed to separate each component. The process involves uniformly dispersing and mixing, and then curing. In a more preferred embodiment, the lightweight aggregate is pre-expanded particles of expanded polystyrene or crushed particles of expanded polystyrene, and the average particle diameter of the pre-expanded expanded polystyrene particles or crushed expanded polystyrene particles is at least 10 mm. or less, preferably 2 mm or less. Further, the foaming agent is a water-soluble polymer, and further, the water-soluble polymer is polyvinyl alcohol, and the dissolution concentration in water is 0.5.
~25%, preferably 1~10%. In addition, the foaming agent is first dissolved or dispersed in water, then lightweight aggregate is added and stirred to form countless bubbles. The fibrous material is added during mixing, and after the lightweight aggregate, water, and foaming agent have been uniformly dispersed, aggregates other than the hydraulic powder and lightweight aggregate are added. , and the hydraulic powder is cement or calcined gypsum.

[0005]

[Function] The lightweight aggregate used in the above means generally includes organic and inorganic aggregates. Examples of organic materials include synthetic resin foams such as foamed polystyrene, foamed polyethylene, composite resin foams of polystyrene and polyethylene, foamed polyprene, foamed AS resins, various foamed styrene resins, and foamed vinyl chloride resins. It is not limited. The shape may be pre-expanded particles of these synthetic resins or crushed particles of foamed molded products. Examples of inorganic materials include, but are not limited to, perlite, permicrite, natural pumice, coal, artificial lightweight aggregate (ALA), whitebait balloons, glass balloons, slag, and obsidian. Specific examples of foaming agents include water-soluble polymers, polymer emulsions, and surfactants, but other foaming agents can also be dissolved or dispersed in water and can be used to create lightweight bones. When mixed with materials and stirred, countless air bubbles are generated,
Any material may be used as long as it has the property of significantly reducing the number of air bubbles when kneaded with the hydraulic powder. As the hydraulic powder, Portland cement, calcined gypsum, and a mixture of the two are generally used, and are preferable from the viewpoint of properties and cost, but other types of cements and various types of gypsum may also be used.

[0006] By adding the above-mentioned lightweight aggregate, a foaming agent, and water and stirring, countless air bubbles are generated, and the lightweight aggregate, water, and foaming agent are uniformly dispersed. These bubbles are formed by a highly viscous film that retains water, and are microscopic bubbles filled with countless air. The lightweight aggregate exhibits a uniformly dispersed state with these countless microbubbles, forming what can be described as a white mousse state. Usually, if you give a good agitation and stir well;
In this mousse state, the volume increases due to the presence of countless air bubbles, and easily increases from 1.2 times or more to 2 times or more, or even 3 times or more, the apparent volume of the lightweight aggregate. If the fine air bubbles contained in this mousse are left as they are for a long time, they will eventually turn into coarse air bubbles or burst and disappear. In this invention, the light aggregate and the foaming agent form a mousse with countless microbubbles, and if hydraulic powder is gradually added and mixed while stirring,
The hydraulic powder can be uniformly dispersed and can be kneaded extremely smoothly. As the amount of hydraulic powder added increases, the number of air bubbles in the mousse decreases significantly and the viscosity increases. Then, with a predetermined amount of hydraulic powder added,
The components are uniformly and well-dispersed and mixed, then poured on-site or placed in a mold and allowed to harden.

[0007] In this way, by adopting a method of mixing hydraulic powder and lightweight aggregate using countless microbubbles, the mixability is increased, and the mixing water that has been used only for the purpose of imparting fluidity is improved. It becomes possible to significantly reduce the amount of According to this invention, the water/cement ratio described below is 50
Since it is extremely easy to achieve a content of 40 wt% or less, a highly homogeneous, high-strength, lightweight cured product can be industrially advantageously produced.

[0008] In the above, when pre-expanded particles of expanded polystyrene or crushed particles of expanded polystyrene are used as the lightweight aggregate, the affinity with water and hydraulic powder is increased, and the uniform distribution of the crushed particles is improved. A lightweight cured product with low dimensional shrinkage and high strength after curing can be obtained. The average particle size of these pre-expanded polystyrene particles or pulverized particles of expanded polystyrene is preferably 10 mm or less, more preferably 2 mm or less. The finer the bubbles, the finer the bubbles generated when stirring with the foaming agent, and if the diameter is 2 mm or less, it will be easier to form a good mousse, and the water reduction effect will be greater, and if it is possible to uniformly distribute these crushed particles. After curing, the lightweight cured product has a strong strength. In addition, since lightweight aggregates such as expanded polystyrene improve their kneading ability with hydraulic substances, surface treatment with an appropriate treatment agent will further improve the properties of the lightweight cured product of this invention. preferred. Furthermore, if the foaming agent is a water-soluble polymer such as polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, or an acrylic superabsorbent polymer, it can be mixed with lightweight aggregate and stirred to form a highly viscous polymer with water-retentive properties. A film is formed, which facilitates uniform kneading with the hydraulic powder. In addition, when the water-soluble polymer is polyvinyl alcohol, its concentration in water is 0.5 to 2.
5%, preferably in the range of 1 to 10%. If it is less than 0.5%, the foaming ability will decrease and it will be less than 25%.
This is because not only does the manufacturing cost increase, but also the viscosity increases significantly when kneading with the hydraulic powder, resulting in a poor water reduction effect and the necessary reduction due to the bursting of countless bubbles. Furthermore, if it takes some time to dissolve or disperse the foaming agent in water, it is possible to dissolve or disperse the foaming agent in water first, then add lightweight aggregate and stir. It is desirable to foam the air bubbles. A specific example is powdered polyvinyl alcohol. Furthermore,
If a fibrous material is added before or during the dispersion mixing of each component, it may lead to cracks during curing of the lightweight cured product and improvement in the tensile and bending strength of the product, resulting in lower strength of the cured product. It will become even stronger. Specific examples of fibrous materials include inorganic fibers such as asbestos, rock wool, and glass fibers, and synthetic resin fibers such as polyester, nylon, and polypropylene, but they are not limited to those that have similar effects. Furthermore, after the lightweight aggregate, water and foaming agent are uniformly dispersed, aggregates other than the hydraulic powder and the lightweight aggregate, such as
When silica sand, CaO, Ca(OH)2, sand, gravel, clay sand, etc. are added, it is possible to further improve the strength of the lightweight cured product and reduce the product cost. Moreover, it is of course possible to add additives other than those mentioned above that are generally added to such cured products.

[0009]

[Example] Examples of the present invention will be described below.
The invention is not limited to this embodiment.

<Example 1> In advance, 160 parts by weight of water was weighed and placed in each of seven containers, and powdered polyvinyl alcohol (hereinafter referred to as PVA, manufactured by Nippon Gosei Co., Ltd., Gohsenol GH20M) was added as a foaming agent. ,0,0.8,1.6,8.0
, 16, 40, and 80 parts by weight were added and mixed by stirring, and the respective PVA solution concentrations were 0, 0.5, 1.
0,5.0,10.0,25.0,50.0wt%
Seven types of foaming agent aqueous solutions were prepared in advance. and,
These are expanded polystyrene pre-expanded particles (manufactured by Kanebuchi Kagaku Kogyo Co., Ltd., Kanepal 40 times pre-expanded particles, average particle size = 0).
．． 76 mm) without any surface treatment was added and mixed by stirring. When stirring is continued, only the PVA-containing mixture generates countless microscopic bubbles, resulting in a white mousse (m
ousse) state, and the apparent volume of the mixture has increased approximately twice. When 360 parts by weight of ordinary Portland cement is gradually added to these while stirring and mixing is continued, the mousse begins to burst and disappear innumerable microbubbles, and eventually each component is mixed extremely uniformly to obtain a viscous fluid. When the mixture did not contain PVA, no mousse was generated, and the viscosity of the mixture was dry, and it was necessary to add more water to achieve the appropriate viscosity. Water/cement ratio (%) of this formulation (weight of water added/weight of Portland cement) x 1
00 is all 44wt%. This is 4cm x 4
Pour into a cm x 16 cm test piece creation mold,
It was pressed and filled. Next, after curing this at room temperature for 28 days, the strength was measured and the results are as follows. Items that do not contain PVA...Bending strength 5.8 kg/c
m2, compressive strength 8.2 kg/cm2 PVA concentration 5wt%...bending strength 20.6 kg/c
m2, compressive strength 38.7 kg/cm2 Other products containing PVA generally showed high strength, but the one with a very high dissolved PVA concentration of 50.0 wt% had too high a viscosity during mixing. It was unsuitable for casting.

<Comparative Example> In the formulation of Example 1, the formulation without PVA would be dry, so in order to increase fluidity, water was added to increase the weight ratio of water to Portland cement to be 55 wt%. The strength when 198 parts by weight was added was 9.6 kg/cm2 in bending strength and 16.5 kg in compressive strength.
/cm2. In addition, a non-dispersion phenomenon in which the pre-expanded particles floated slightly upward during curing was observed from the fractured surface of the test piece.

<Example 2> When a lightweight cured product was produced in the same manner as in Example 1, the relationship between the weight of water added and the amount of the other components mixed and the evaluation of fluidity are shown in Table 1. . However, EPS refers to the above-mentioned Example 1.
The same as the expanded polystyrene pre-expanded particles,
Blend No. In Examples 2 and 6, pulverized foamed polystyrene moldings were used as described in the notes at the bottom of Table 1. Cement also refers to ordinary Portland cement.

[0013]

[Table 1]

[0014] The results of each test and the observation of the dispersion state of lightweight aggregate when a heavy weight cured product was produced based on the above conditions were as follows.
Table 2].

[0015]

[Table 2]

[0016] From the experiment and test results shown in [Table 1] and [Table 2] above, polyvinyl alcohol (PVA)
is used as a foaming agent, and by stirring and mixing the aqueous solution with lightweight aggregate, a mousse is formed, and by stirring and mixing this with cement, the amount of water added can be reduced to obtain the same fluidity. As a result, it has been found that uniform dispersibility and strength can be improved.

[0017]

Effects of the Invention As is clear from the above explanation, the method for producing a lightweight cured product of the present invention uses a foaming agent when producing a lightweight cured product using lightweight aggregate, water, and hydraulic powder. First, a countless number of bubbles are generated by stirring and mixing lightweight aggregate, a foaming agent, and water. Then, hydraulic powder is added and mixed to uniformly disperse and mix each component, and then hardened. This is how it was done. As mentioned above, this makes the mixing of hydraulic powder, lightweight aggregate, and water extremely smooth.
In addition, uniform dispersion becomes possible, and the amount of extra kneading water, which was conventionally used only for the purpose of imparting fluidity, can be significantly reduced. As a result, the problems that were observed in conventional lightweight cured products, such as a decrease in the strength of lightweight cured products due to excessive water addition, dimensional shrinkage after curing, minute cracks in the cured products, and delayed curing time, are eliminated. can do.

Furthermore, when the lightweight aggregate is pre-expanded particles of expanded polystyrene or crushed particles of expanded polystyrene, the affinity with water and hydraulic powder is increased;
It becomes easier to uniformly disperse the pulverized particles, and a lightweight cured product with low dimensional shrinkage and high strength after curing can be obtained. Further, when the average particle diameter of the pulverized particles is made fine, at least 10 mm or less, preferably 2 mm or less, the water reduction hardening is large, the pulverized particles are more easily dispersed uniformly, and the strength is improved. Furthermore, when the foaming agent is a water-soluble polymer, uniform kneading with the hydraulic powder can be facilitated. Furthermore, when the water-soluble polymer is polyvinyl alcohol and its concentration is 0.5 to 2.5%, preferably 1 to 10%, the water reduction effect is further improved,
Another advantage is that countless bubbles can be easily generated. Also, if it takes some time to dissolve or disperse in water, such as when using a non-liquid foaming agent such as powdered polyvinyl alcohol, dissolve or disperse the foaming agent in water first. By this, uniform dispersion mixing of each component can be better obtained. Furthermore, by adding a fibrous material before or during the dispersion mixing of each component, it is possible to prevent cracks during curing of the lightweight cured product, improve the tensile and bending strength of the product, and improve the strength of the cured product. becomes even stronger. Furthermore, when aggregates other than lightweight aggregates are also used, the strength of the lightweight cured product can be further improved and the product cost can be reduced. Furthermore, when cement or gypsum is used as the hydraulic powder, it is useful in terms of properties and cost.

Claims (9)

[Claims] Claim 1: Lightweight aggregate, foaming agent and water are added and stirred to generate countless air bubbles. After the lightweight aggregate, water and foaming agent are uniformly dispersed, hydraulic powder is added and mixed. A method for producing a lightweight cured product, which comprises uniformly dispersing and mixing each component, and then curing. 2. The method for producing a lightweight cured product according to claim 1, wherein the lightweight aggregate is pre-expanded particles of expanded polystyrene or crushed particles of expanded polystyrene. 3. The method for producing a lightweight cured product according to claim 2, wherein the average particle diameter of the pre-expanded particles of expanded polystyrene or the crushed particles of expanded polystyrene is at least 10 mm or less, preferably 2 mm or less. 4. The method for producing a lightweight cured product according to claim 1, wherein the foaming agent is a water-soluble polymer. 5. The water-soluble polymer is polyvinyl alcohol, and the solubility concentration in water is 0.5 to 25.
%, preferably 1 to 10%. 6. The production of a lightweight cured product according to claim 1, wherein the foaming agent is first dissolved or dispersed in water, and then lightweight aggregate is added and stirred to form numerous bubbles. Law. 7. The method for producing a lightweight cured product according to claim 1, wherein a fibrous material is added before or during uniform dispersion mixing of each component. 8. The method for producing a lightweight cured product according to claim 1, characterized in that after the lightweight aggregate, water and foaming agent are uniformly dispersed, an aggregate other than the hydraulic powder and the lightweight aggregate is added. . 9. The method for producing a lightweight cured product according to claim 1, wherein the hydraulic powder is cement or gypsum.