KR100222318B1 - Autoclaved lightweight concrete and production thereof - Google Patents

Abstract

In the present invention, when manufacturing lightweight insulation foam concrete used as a heat insulating floor material of the hot water underfloor structure, ALC Meal, which is a by-product generated in the production or construction process of ALC (Autoclaved Lightweight Concrete), is added as fine aggregate and a part of cement is used. The present invention relates to a method for manufacturing lightweight insulation foam concrete by replacing with a fly ash, which is a pozzolanic-based admixture, and the lightweight insulation foam concrete prepared in this way is characterized in that the insulation layer of the hot water underfloor structure There is an effect of improving the strength of the cracks due to the improvement of strength, dry shrinkage.

Description

[Name of invention]

Lightweight insulating foam concrete containing ALC Meal and its manufacturing method

Detailed description of the invention

[Field of Invention]

The present invention relates to a lightweight insulating foam concrete used as a heat insulation layer material of the hot water ondol floor structure. More specifically, the present invention adds ALC (Autolaved Lightweight Concrete) Meal as a fine aggregate to lightweight insulation foam concrete prepared by the preform method by mixing bubbles generated from a diluent mixture of foaming agent and water with cement mortar to increase the strength of the thermal insulation layer. The present invention relates to a lightweight insulating foam concrete which has been improved and improved the cracking phenomenon caused by dry shrinkage. Light-weight insulation foam concrete of the present invention can be mixed with fly ash (posh ash) -based admixture.

[Background of invention]

Lightweight insulation foam concrete is a material with low thermal conductivity, which is excellent in thermal insulation performance, which can improve energy efficiency by improving the thermal efficiency of buildings, and has an advantage in construction that can be press-fitted evenly into complex spaces. It is used a lot.

Although lightweight insulation foam concrete has suitable conditions as a hot water ondol floor structure material in terms of workability, light weight, and insulation performance, the research on this is insufficient and the construction of hot water underfloor structure applied to this depends on the skill of skilled workers. There is no specific standard in the formulation or construction method. In addition, various defects that frequently occur in the floor structure constructed with lightweight insulation foam concrete are pointed out by various problems such as damage to the residential environment and additional costs due to defect repair, as well as image loss to the contractor. have.

Therefore, the inventors of the present invention have developed a lightweight insulating foam concrete with improved performance by adding ALC Meal as fine aggregate and adding fly ash as a partial replacement material of cement to the lightweight insulating foam concrete used in the hot water underfloor structure.

Pipe buried hot water heating heating method has good heat storage effect and floor impact strength and is integrated with floor slab, which is not only good stability but also jointly applied for construction and materials. The structure is generally composed of a heat insulating layer, a heat storage layer, and a finishing layer. The structure of each structure is different depending on the construction company, and additional parts may be reflected in the design or excluded to improve performance.

The insulation layer, which is a structural element that requires lightweight insulation foam concrete among the hot water underfloor structures, has been mandated at the national level to save energy since the energy surge in 1973.The material mainly includes heat reflecting plates such as styropol and etiron and lightweight insulation plates. In addition, lightweight foamed concrete, which can be used in parallel, has been used, but in recent years, the use of lightweight insulating foamed concrete has been common in multi-unit housing due to rising labor costs and material supply shortages. However, the insulation layer of the hot water underfloor structure using lightweight insulation foam concrete as a material has defects due to the weak compressive strength, excessive dry shrinkage and absorption of the material, and the lack of homogeneity of the material. It is emerging as a matter of concern and measures are required.

[Purpose of invention]

An object of the present invention is to provide a lightweight insulating foam concrete with improved compressive strength of the insulating layer as concrete used as the insulating layer material of the floor structure.

Another object of the present invention is to provide a lightweight insulating foam concrete containing ALC Meal that can improve the cracking phenomenon caused by dry shrinkage.

These and other objects can all be achieved by the invention described below.

[Summary of invention]

Light-insulating foam concrete of the present invention is a mixture of ALC Meal so that the mixing ratio of cement to ALC Meal is in the range of 1: 0.1 ~ 1 while mixing the bubbles generated from the diluent mixture of the foaming agent and water and the cement mortar. Characterized in that it is prepared by mixing the step. The lightweight insulating foam concrete of the present invention may incorporate fly ash instead of a part of the ALC Meal.

The lightweight insulating foam concrete of the present invention can improve the compressive strength of the insulating layer when used as the insulating layer material of the floor structure, and has the effect of improving the cracking phenomenon by dry shrinkage.

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

[Detailed Description of Embodiments of the Present Invention]

In general, the shrinkage form of the cement hardened body is represented by three types of shrinkage by hardening shrinkage, dry shrinkage, and carbonation. Hardening shrinkage refers to shrinkage due to the reduction of the absolute volume of cement and water when the hydration reaction proceeds without supply of water, and this hydration reaction is called a volume reduction reaction. In addition, the volume change is caused by the carbonation of cement hydrate. In this case, shrinkage occurs because the crystallization decomposes when carbonation is applied to the crystal of lime hydroxide corresponding to the internal humidity. Therefore, the degree of carbonation shrinkage varies according to relative humidity and lasts for a long time. In addition, when curing concrete in the air, concrete causes shrinkage due to evaporation of moisture. Such shrinkage due to the outflow and evaporation of gel water is called dry shrinkage.

In general, the change in the length of lightweight foam concrete is caused by excessive drying shrinkage, which is the main cause of cracking of lightweight insulation concrete, which causes the shrinkage of cement paste, the properties and content of aggregates, water cement ratio, The degree of hydration, autoclave curing, miscible materials, etc. will be affected. Influence factors related to the scope of the present invention are the properties and content of aggregate.

The effect of aggregate properties or content on the shrinkage of concrete can be explained by two mechanisms. In general, dry shrinkage of aggregates used in concrete is much smaller than shrinkage of paste, so the shrinkage of concrete decreases with increasing aggregate mixing rate, and the shrinkage depends on the modulus of elasticity. Increasing decreases the drying shrinkage of concrete. The effect of aggregate stiffness and mixing on the shrinkage of the concrete was studied by Pickett, who examined the effect of a single, non-shrinkable aggregate particle on the shrinkage of the concrete. Under the assumption that

Where Sc is the amount of shrinkage of the concrete, Sp is the amount of shrinkage of the paste, Va is the volume fraction of the aggregate, and n is the relative amount of the elastic property of the aggregate with respect to the elastic property of the concrete.

Drying shrinkage in the various cement hydrate is the same in the following table, according to the experiment dryness shrinkage of lightweight cellular concrete is to be improved to some extent by, but generally the relatively large pieces to the 40 ~ 80 × 10 ^-4 added in a range of specific gravity 0.4 to 1.0 It is known that you can.

TABLE 1

When concrete is used in real structures, shrinkage is largely constrained, and this sphere effect creates tensile stress in concrete and cracks occur when this stress exceeds the tensile strength of concrete.

Cracks due to dry shrinkage may occur due to differences in the drying speed between the surface and the interior of the concrete member. Part of the surface contraction is constrained because the contraction within the member is less than the contraction of the surface part. Due to this restraint effect, the compressive stress inside the concrete member is in equilibrium with the surface portion, and thus the tensile stress is generated. This tensile stress is maximum at the surface and if it exceeds the tensile strength of the concrete, cracking occurs.

Cracked concrete is weaker and more permeable than crack-free concrete, and is more susceptible to chemical erosion and the East Sea.

Based on the theoretical considerations on the mechanism of dry shrinkage, the following can be assumed as a way to reduce the occurrence of cracks in lightweight insulation foam concrete.

First, shrinkage can be reduced by reducing the amount of cement as much as possible. In this case, since there is a limit in reducing the amount of unit cement, it is possible to expect a crack reduction effect through the use of a substitute material that can replace cement.

Secondly, the shrinkage of aggregates generally used in concrete is much smaller than the shrinkage of pastes. Therefore, the dry shrinkage can be reduced by adding the aggregate exhibiting a smaller dry shrinkage rate to the dry shrinkage of the cement paste in the lightweight insulating foam concrete. In this case, the foam stability of lightweight insulation foam concrete is not impaired, and the material that can overcome the risk of material separation due to specific gravity difference is added to the aggregate of lightweight insulation foam concrete so as not to impair the performance of lightweight insulation foam concrete. The effect of reducing shrinkage can be improved.

Accordingly, in the present invention, by selecting ALC Meal and fly ash as a material having applicability to lightweight insulating foam concrete based on the above assumptions, the performance improvement of the lightweight insulating foam concrete has been sought.

ALC (Autoclaved Lighrweight Concrete) is a kind of foam concrete that is light weight by dispersing countless bubbles in concrete by foaming agent independently. It has excellent performance in phosphor light weight, heat insulation, fire resistance and workability. ALC produces sludge by mixing lime, siliceous raw material, foaming agent, and admixture with water as main raw materials, and then, through vapor curing process in autoclave at high temperature and high pressure (180 ℃, 10kg / ㎠) Tobermorite) is produced by the process of making crystals.

In general, ALC is produced by crushing and combining raw materials, preparing reinforcing materials, mixing, placing, preliminary curing, demolding and cutting, and curing, and by-products are inevitably generated by the cutting process. In addition, by-products are inevitably generated in the field construction process even though they are standardized ready-made products. By-products generated during the production process may be partially recycled and re-introduced into the production process, but the amount of by-products recycled is very small because the quality or quantity of the by-products may affect the quality of the finished product. .

As the use of ALC as a softening material is becoming more common, the amount of by-products is increasing as ALC production and usage are increasing.However, the treatment of by-products is emerging as a new problem because it is classified as industrial waste due to the characteristics of products into which cement is injected. Although there is a difference in the amount of by-products produced or re-bridges depending on the producers, most of the by-products are landfilled or deposited except for a small part of the re-introduction into the production process.

Therefore, by processing these by-products generated during ALC production in the form of Meal, we obtain ALC Meal with relatively even particle size distribution. Although there are not many examples of recycling this as a building material, the possibility of using it as aggregate for concrete has been raised. . Existing studies on the physical properties and mechanical properties of concrete using ALC Meal as fine aggregates are known to be sufficient for application as fine aggregates for lightweight insulating foam concrete under the condition that there are almost none of them.

In general, lightweight foam concrete is a lightweight material that has excellent insulation and sound insulation, but has a weak strength, high absorption rate, and a large length change rate due to dry shrinkage. ALC is also a lightweight, porous material that has excellent insulation and sound insulation properties, and may exhibit strength enough to be used as a structural member, depending on the degree of control of the mixing and production processes. In particular, due to the characteristics of the process undergoing a high-pressure steam curing process, the length change rate is smaller than the specific gravity or strength. Therefore, ALC Meal, a by-product of ALC production, can be expected to have some of these physical and mechanical properties.

Addition of ALC Meal to the fine aggregate of lightweight foamed concrete resulted in the improvement of compressive strength of lightweight foamed concrete.In particular, the addition of ALC Meal reduced the amount of unit cement and the relatively small length change rate compared to the lightweight insulating foamed concrete. ALC Meal shows the restraint effect of dry shrinkage.

Fly ash is melted when incineration of non-powdered coal at high temperature of 1,400 ~ 1,500 ℃ in thermal power plant, etc., and it is collected from the flue gas of combustion boiler by electric and mechanical folding device. It has the same properties as volcanic ash and is very fine powder. It is a state. Its main component is silica sand and its spherical shape is spherical, and it is also called artificial pozzolan or modern volcanic ash because it has the same characteristics as natural pozzolan, and itself is not hydrophobic, but silica component is calcium hydroxide and calcium hydroxide, which is a hydration product of lime and cement. Reacts slowly to produce a stable water-soluble compound and to cure. As the main component is such as _{SiO 2, Al 2 O 3,} Fe 2 O 3, it is also contained trace amounts of K, P, B, Co, Mo, Mg.

The idea for the use of fly ash concrete originated in the United States in 1914, and recently, it was only used as a cement admixture for high-corrosive mass concrete such as dams and other repair structures. As research results and usage results on chemical properties have increased, the scope of use and its uses have gradually expanded.

Light-weight insulation foam concrete of the present invention is the foaming agent used to manufacture a conventional lightweight insulation foam concrete is added to the bubble generator to generate a bubble, the foam is mixed with the cement mortar, The mixture is prepared by mixing ALC Meal so that the mixing ratio of cement to ALC Meal is in the range of 1: 0.1-1. Light-weight insulation foam concrete of the present invention can be mixed with the fly ash ALC Meal instead of a part of the ALC Meal.

In general, fly ash in concrete using fly ash improves the workability of the concrete by reducing the unit quantity, and it is known that when used by replacing it with cement, it reduces the heat of hydration and significantly improves the long-term strength of concrete. . Fly ash is used in the range of 10% to 100% by weight of cement. In addition, the use of fly ash significantly improves the water-tightness of concrete at long-term age, and in particular, it is known that the dry shrinkage of concrete can be reduced by substituting a part of cement with fly ash. It is shown.

By incorporating ALC Meal and Fly Ash into the manufacturing process of lightweight insulation foam concrete, the compressive strength improvement effect of lightweight insulation foam concrete was improved.

The invention will be further illustrated by the following examples, which are intended to illustrate the invention and are not intended to limit the protection scope of the invention.

Example 1

The diluent mixture of the foaming agent and water was introduced into the bubble generator to produce bubbles, and the produced bubbles were mixed with the cement mortar. While stirring the mixture, ALC Meal and a small amount of fly ash were mixed so that the mixing ratio of cement to ALC Meal was 1: 0.5. The ALC MEAL used at this time was used to pass the # 8 standard body (2.38㎜) in order to secure the particle size as fine aggregate. The foam ratio of the lightweight insulating foam concrete prepared here was 65%, and measured in the physical properties are shown in Table 1 below.

Example 2

A lightweight insulating foam concrete was prepared in the same manner as in Example 1 except that the mixing ratio of cement to ALC Meal was 1: 1. The bubble ratio in this example was 65%, and the physical properties thereof are shown in Table 1 below.

Comparative Example 1

The conventional lightweight insulating foam concrete was prepared by a preform method in which a diluent mixed with a foaming agent and water was added to a bubble generator to produce bubbles, and the produced bubbles were mixed with a cement mortar. The foam ratio of the lightweight insulating foam concrete prepared here was 65%, and measured in the physical properties are shown in Table 1 below.

Physical property measurement:

Average of apparent specific gravity: measured according to KS F 2459.

Average of compressed phase: measured by KS F 2460.

Average of length change rate (× 10 ): It was measured by KS F 2424.

As can be seen through the above examples, the lightweight insulation foam concrete of the present invention is increasing the side weight with the increase of the ALC Meal addition rate, which is ALC Meal having a greater specific gravity than the apparent weight of the lightweight insulation concrete According to the addition of the expected results, but this is not a level that would impair the lightness of the lightweight insulating foam concrete of the present invention. In addition, it can be seen that the compressive strength improves with the addition of ALC Meal. However, when the ALC Meal addition rate is 100%, the compressive strength is slightly lower than that of 50%. It can be said that the results indicate that there is an appropriate level, the decrease in the rate of change in length according to the increase of the ALC Meal addition rate, which can be referred to as the drying shrinkage effect of the aforementioned ALC Meal.

Simple modifications and variations of the present invention can be readily used by those skilled in the art, and all such variations or modifications can be considered to be included within the scope of the present invention.

Claims (8)

In manufacturing the lightweight insulation foam concrete constituting the thermal insulation layer of the hot water underfloor structure, by adding a diluent mixed with a foaming agent and water into a bubble generator to produce bubbles, and mixing the produced bubbles with a cement mortar, the mixture Method for producing lightweight insulating foamed concrete with increased compressive strength and improved cracking caused by dry shrinkage by mixing ALC Meal so that mixing ratio of cement to ALC Meal is in the range of 1: 0.1 ~ 1 while stirring . The method of claim 1, wherein the particle diameter of the ALC Meal is 3mm or less. The method of claim 1, wherein a fly ash is used in place of a part of the ALC Meal. The method of claim 3, wherein the use amount of fly ash is 10% to 100% of the amount of cement used. The compressive strength is increased and dried, characterized by containing ALC Meal in the mixture of cement and ALC Meal in the mixture of air bubbles and cement mortar generated from the mixture of foaming agent and water in the range of 1: 0.1 ~ 1. Lightweight insulation foam concrete with improved shrinkage due to shrinkage. [6] The lightweight insulating foam concrete according to claim 5, wherein the particle size of the ALC Meal is 3 mm or less. 6. The lightweight insulating foam concrete according to claim 5, wherein fly ash is incorporated in place of a portion of the ALC Meal. 8. The lightweight insulating foam concrete according to claim 7, wherein the fly ash is used in an amount of 10% to 100% of the amount of cement used.