KR20030086955A - Manufacturing technology of autoclave lightweight concrete use of extensibility lightweight for manufacture of bulyon sandwitch pannel - Google Patents

Abstract

PURPOSE: Sandwich panels, substituted for the conventional expanded styrene foam, for outer and inner walls of construction are provided, which has nonflammability, no emission of toxic gas and heat insulation by using lightweight foam concrete and expansive lightweight aggregate. CONSTITUTION: The lightweight foam concrete is produced by the following steps of: foaming a mixed liquid obtained by mixing lauryl alkyl ether sulfate-based synthetic foaming agent diluted 40times by water with liquid admixture containing calcium nitrite more than 45pts.wt. and aluminum sulfate more than 5pts.wt as main components under air pressure of 8-10atm; preparing cement slurry containing aggregate by adding 70-85L of lightweight aggregate, vermiculite, to cement slurry(240-320kg cement + 96-192L water) and mixing thoroughly; stirring the mixture slowly and adding 650-800L of prepared foam; pouring the mixture to a mold; curing for 24-48hrs.

Description

Manufacturing technology of autoclave lightweight concrete use of extensibility lightweight for manufacture of bulyon sandwitch pannel}

The invention lauryl the surfactant mainly composed of an alkyl benzene sulfonate in water to 40: After dilution in the ratio of the first density generated by the air pressure to a pressure of about 8 to 10 kg / cm ² 40 to 50 kg / cm ² Non-flammable lightweight foamed concrete using lightweight aggregate with bubbles of air and continuous voids. More specifically, it is a lauryl alkyl benzene sulfonate-based material that is a swelling vermiculite formed with a void by heating natural vermiculite at a high temperature and a surfactant. Air pressure about 8 to 10 kg / cm ² to adjust the density of the resulting air bubbles to about 40 to 50 kg / cm ² , and the resulting bubbles, cement slurry and expanded vermiculite is mixed to burn in case of fire The present invention relates to a non-flammable lightweight foamed concrete sandwich panel considering the building exterior wall finishing and insulation without burning and emitting toxic gases.

Until now, the construction sandwich panel is composed of the outer steel sheet and the inner styrofoam or urethane foam. Internal styrofoam or urethane foam has been used as the most popular material for sandwich panel because of its insulation and light weight. However, due to the nature of the material, it is easily ignited by fire, and moreover, many toxic gases are generated due to toxic gas. Due to the characteristics of these materials, the Ministry of Construction and Transportation revised the Fire Evacuation Regulations in March 2003 to restrict the use of non-combustible and toxic gases to the components of sandwich panel for exterior walls. Accordingly, various materials have been developed, but have a light weight and incombustibility, and the composition of materials that can be compared with conventional styrofoam foam or urethane foam in terms of economy is only long. Inorganic non-combustible materials that can be compared with conventional styrofoam or urethane foam include rock wool or asbestos, but these materials are restricted to use due to carcinogenic substances. Due to the disadvantage that it can not be evenly distributed on the sandwich panel. In addition, in the case of the foamed glass foamed at a high temperature, the glass is expensive because it requires a high temperature heat treatment to foam the glass, the resulting foamed glass is not easily used for construction because there is a property that is easily destroyed. In the case of other expandable minerals such as vermiculite and ferrite, natural minerals are heated at a high temperature and heat-treated, so they are expensive and cannot be used alone. Therefore, there is an urgent need for a new material that is the most economical, lightweight, incombustible, and free of toxic gases.

Therefore, the present invention has been made to solve the problems of the prior art as described above, the object of the present invention is a specific gravity of 0.3 to 0.5, and does not burn even in the fire, as a material without the release of toxic gas surfactant It is a substitute material for foamed styrene foam that is easily burned in case of fire and emits toxic gas. The present invention provides a technique for manufacturing a building sandwich panel which is non-combustible and emits no toxic gas even in a fire.

Sandwich panel for building has characteristics required as building material such as impact strength resistance over a certain standard for its use. However, lightweight foamed concrete is a kind of lightweight concrete made by mixing a large amount of bubbles and lightweight aggregate in cement slurry, making it lighter than ordinary concrete of the same volume.In the state of slurry before hardening, excellent fluidity, lightness, filling and self-leveling properties After curing, it is a material having various useful properties such as independence, light weight and sound absorption.

Research on the use of such properties of lightweight foam concrete has already achieved considerable results in advanced countries, as well as non-structural concrete for indirect effects such as insulation and sound insulation, as well as for filling voids, soft ground reinforcement and steep slopes. It is also receiving great attention as a light weight soil material such as vertical fillet and earth pressure relief on the back of the structure. However, despite the many useful properties, lightweight foamed concrete has fundamental disadvantages such as instability of materials when the unit volume weight is lowered, high volume reduction rate after curing, and large dry shrinkage strain caused by not using aggregate. Even in developed countries, its application has been limited until now.

In particular, the weakness according to such material properties is becoming a more serious problem in Korea where lightweight foam concrete is mainly used as the filling and insulation of the ondol floor. Most of the lightweight foam concrete used for ondol floors in Korea is constructed by on-site casting method. In general, unit volume weight is 400 ~ 700 ㎏ / ㎥, and the thickness of casting is about 4 to 8 ㎝. However, at this level of unit volume weight and pour thickness, the instability of the material becomes very high, so that high volume reduction rate and large dry shrinkage deformation are likely to occur during curing. In addition, on-site mixing based on the operator's experience increases the quality fluctuation factor, which causes the quality of lightweight foam concrete, which requires sophisticated compounding design, to be further deteriorated. Therefore, in order to solve this problem and use it as a sandwich panel material, it is considered that research on the development of the optimum lightweight foam concrete considering domestic conditions must be done. Up to now, not only these problems have been overlooked in subsequent works but also the recognition that lightweight foam concrete is buried under the ondol plastering mortar has no need for special technology. As a result, construction companies have been in trouble and subcontracting has been prevalent, and quality has been continuously deteriorated. However, the development of technology to solve this problem has rarely been made since the introduction of lightweight foam concrete in the mid-80s. After all, domestic light foam concrete technology is very underdeveloped in view of the possibility and importance of the material itself. However, this patent technology is not a lightweight foam concrete for ondol by on-site mixing, but quality control of all materials is performed in the factory, the use of raw materials, materials, and constant process control in production, etc. Through the production of finished products in the factory will be able to supplement the above problems. In other words, under this background, the patented technology significantly improves the performance of existing lightweight foam concrete to ensure the fluidity and stability of the foam slurry even at low unit volume weight, to reduce the appearance of roughness after hardening, volume reduction and dry shrinkage deformation. To make it

① Use of modified LAES (Linear Alkyl Ether Sulfate) foaming agent (hereinafter referred to as "synthetic foaming agent").

② Minimization of volume reduction and dry shrinkage deformation Use of liquid admixture for cement expansion (hereinafter referred to as "liquid admixture") mainly composed of aluminum sulfate and polyethylene glycol.

③ Development of a standard formulation design program using new foaming agents and admixtures.

④ Use of lightweight aggregate to reinforce incombustible performance and to increase impact strength of lightweight foamed concrete.

It is intended to secure manufacturing technology of lightweight foam concrete for light weight sandwich panel with incombustibility and heat insulation.

end. Basic configuration

In order to achieve the above object, the present invention mixes the ratio of the synthetic foaming agent and water in the ratio of 1:40 ("diluent"). Then, the foaming agent and the liquid bubble admixture are mixed in a ratio of 1: 1, and these mixed liquids are pressurized in the range of about 8 to 10 atmospheres of air pressure to generate a fine bubble group. Meanwhile, cement in the range of about 240 kg to 320 kg per cubic meter of water: cement ratio is about 40 wt% to 60wt% to make cement slurry, and then a certain proportion of lightweight aggregate is added. The resulting bubbles are mixed well and evenly to the specific gravity required for the cement slurry mixed with light aggregate. Mixed foamed concrete is poured into a mold of the specified size for the panel. The manufacturing process is shown below.

I. Formulation Design

The mixing ratio of each material is determined by the formula according to the specific gravity required and the required physical properties of the panel. Information on deriving the compound design is given in Annex-1.

Hereinafter, specific embodiments of the present invention will be described by way of example, and the scope of the present invention is not limited by the embodiments described below.

Example 1

In Example 1, when a compounding quantity of 1 cubic meter is blended, 1 liter of the synthetic foaming agent is diluted with 40 liters of water, and 1 liter of the liquid admixture is mixed again. The mixture is foamed by air pressure of about 8 to 10 atmospheres. Meanwhile, about 240 kg to 320 kg of cement is mixed with 96 to 192 liters of water and stirred at about 150 revolutions. At this time, the lightweight aggregate is added to the cement slurry in a volume ratio of 70 to 85 liters and mixed sufficiently. While slowly mixing the cement slurry containing the sufficiently mixed lightweight aggregate at about 30 revolutions, the amount of foamed foam is added to about 650 to 800 liters and stirred. Mix for about 3 to 5 minutes and pour into a mold of a certain standard. After pouring into the mold, it is cured for about 24 to 48 hours.

Example 2

In Example 2, about 10 kg to 32 kg in the amount of cement in Example 1 was replaced with light dolomite. After proceeding to the same process as in Example 1 and poured into a mold to cure for about 6 hours to 10 hours.

In order to determine the performance of the present invention as described above, the applicant of the present invention carried out the experiment on the product of the present invention as described above.

① Experiment plan

In order to understand the characteristics of lightweight foamed concrete according to the present technology, various experiments on lightweight foamed concrete were conducted under the conditions shown in Table 1.

② material used

The foaming agent used the synthetic foaming agent. In addition, general industrial aluminum sulfate and sodium nitrite were used as the ettringite generating material and the crude material of the liquid admixture, and the general physical properties are shown in Table 2.

The cement used for the test was OPC and its properties are shown in Table 3 and Table 4.

③ Manufacturing Process of Lightweight Aerated Concrete for Experiment

One batch of materials are mixed according to the following procedure to produce experimental lightweight foam concrete.

㉠ Determination of material requirements for each experimental model using the blend design program

㉡ Synthetic foaming agent is diluted by mixing with water in the ratio of 1:40 by volume.

㉢ 1: A foaming agent is generated by injecting a diluent of foaming agent diluted to 40 and air of 8 to 10 atm into a proper amount of foamer per unit time.

시멘트 Put cement and water in the mixer and mix for 5 minutes at 150 rpm.

㉤ If the admixture is applied, add the admixture to the dilution liquid of subparagraph 한다 and mix it for 1 additional minute.

(3) Stop the mixer and inject bubbles into the mixer as required.

㉦ In case of adding lightweight aggregate, insert it in Paragraph 1 before adding bubble.

㉧ After mixing for 3 minutes at 150 rpm, finish the mixing.

④ Experiment method

단위 The unit volume weight and compressive strength of the resulting lightweight foamed concrete are tested according to KS F 2459 (Test Method of Apparent Specific Gravity, Water Content, Water Absorption and Compressive Strength of Foamed Concrete).

㉡ Flowability test is based on ASTM C-109 (flow test method for cement mortar)

㉢ Defoaming rate and flow are tested according to KS F 4039 (foamed concrete for field casting).

la. Results and Discussion

① Result of XRD and electron microscope analysis at 7 days of age

XRD (X-Ray Diffraction) at 7 days of lightweight foam concrete (hereinafter referred to as "test lightweight foam concrete") by the present technology and lightweight foam concrete (hereinafter referred to as "reference lightweight foam concrete") using existing animal foaming agent ) The analysis results are shown in Figure 2 and Figure 3. The analysis conditions of XRD were Cu target, 30Kv, 30mA, and the scan range was analyzed in the range of 5 ~ 55 °.

In Figure 2, the reference lightweight foam concrete shows only calcium silicate hydrate at 7 days of age, and the test lightweight foam concrete in Figure 3 shows the formation of calcium silicate hydrate and ettringite.

In general, ettringite is produced by the reaction of calcium aluminate (C ₃ A) in cement and gypsum added as a cement coagulant in the early stages of hydration in Portland cement, but this results in a phase transition to mono-sulfate. Ettlingite disappears. The XRD result after 7 days of age in the reference lightweight foam concrete is judged to be due to this cause, and in the case of the test lightweight foam concrete, it can be confirmed that enough ettringite is formed even at 7 days of age. On the other hand, the electron micrograph of 4,000 times magnification of the microstructure of light-weight foamed concrete at 7 days of age is shown in Figure 4, where it can be directly confirmed that the ettringite of the needle structure is formed.

② Analysis of electron micrographs at 28 days of age

Table 5 shows the results of analysis of cell structure and microscopic images of the reference lightweight foam concrete and test lightweight foam concrete at 28 days of age.

③ Relationship between unit volume weight and compressive strength

In Fig. 5, the compressive strength test results by unit volume weight of the test lightweight foamed concrete are shown in comparison with the standard lightweight foamed concrete. W / Cratio = 60% was fixed and the target light weight concrete was mixed with the target unit volume weight, respectively, to compare the test lightweight foam concrete in which the standard lightweight foam concrete and admixture were mixed at a ratio of 1: 1 compared to the foaming agent.

According to this result, the test foam concrete has higher compressive strength than the standard foam concrete of the same unit volume weight in the initial curing period, and it can be seen that the roughness of the admixture is sufficient to express the compressive strength at the initial curing period. However, as curing progresses, the compressive strength is mainly determined by the unit volume weight rather than the characteristics of the admixture, and when the unit volume weight is similar at 28 days of curing, the test lightweight foamed concrete is slightly larger than the standard lightweight foamed concrete.

Figure 6 shows the roughness, which is the characteristic of liquid admixtures, as a result of the test of the compressive strength by age of standard foam concrete and test foam concrete with 60% water cement ratio and 400kg / ㎥.

In the lightweight foam concrete for on-floor floors, the conditions for determining the required compressive strength exceeded 4.2kg / ㎠, which is the compressive strength that can resist the breakdown by subsequent work. Considering this in relation to Figure 6, which shows the characteristics of the liquid admixture, it can be seen that the present patented technology using the liquid admixture exhibits higher strength than that without using the admixture between 5 and 10 days. This fact can be said that even at a lower unit volume weight, the strength is expressed at the same time as when the admixture is not used. In this case, the same effect can be expected with a smaller amount of cement, thereby improving economic efficiency.

④ Change in water cement ratio, unit volume weight, and compressive strength

After testing the target unit volume weight of the lightweight foam concrete at 450kg / ㎥ and the specific gravity of the bubble at 45 ~ 55㎏ / ㎥, the relationship between the measured unit volume weight of the uncured lightweight foam concrete and the 14-day compressive strength was tested. Is shown in Figure 7.

According to this experiment, the test lightweight foamed concrete using liquid admixture shows the maximum strength at the water cement ratio of 60 to 70% and does not cause a sharp drop in strength unlike the standard foamed concrete at the water cement ratio of more than 80%.

Compared with standard foam concrete, test foam concrete has a relatively small difference between the unit volume weight after 3 minutes of mixing and the unit volume weight after 14 days of curing. It is considered to be a phenomenon caused by the presence of the cement paste structure in a stable state.

The moderate decrease in compressive strength even at water cement ratio of more than 70% is due to this reason, which is very helpful for improving economic efficiency. If the water cement ratio is high and the difference in compressive strength can fall within the allowable range, the amount of cement used can be significantly reduced.

The smaller the three-minute blended unit volume weight than the target unit volume weight, the greater the amount of light-weight foamed concrete produced than the actual intended production.The light-weight foamed concrete produced thus contains bubbles larger than the initially introduced bubbles. . These large bubbles are defoamered during the process of pouring and placing, resulting in volume reduction or deterioration of compressive strength due to uneven distribution of bubbles.

It was shown that the function of the technique that prevented large bubbles from foaming by properly adjusting the interfacial tension of the foaming agent was that the three-minute blending unit volume weight of the foamed concrete with the patented technology was higher than the standard foamed concrete. This function prevents large bubbles from entraining and keeps the overall bubble size and dispersion state uniformly. The actual bubbles are evenly distributed and cured.

⑤ Parcel rate

The defoaming rate problem of lightweight foamed concrete has been vaguely recognized until now, and it has been overlooked that this problem has a great influence on the quality of lightweight foamed concrete. In addition, since the cracks are generated by the defoaming in the panel manufacturing, the control of the defoaming rate is the biggest problem. Fig. 8 shows the difference in volume reduction due to the defoaming of the test lightweight foam concrete and the reference lightweight foam concrete using the synthetic foaming agent and the liquid admixture. In general, the volume change is much larger in the sample collected at the site in place than the sample made in the laboratory. If the water cement ratio is high and the unit volume weight is low, the vesicles may be formed up to 100 mm in the 200 mm high mold.

This is considered to be related to the phenomenon that the flow value increases as the bubble slurry contracted at high pressure during the feeding process is exposed to atmospheric pressure at the place of pouring.

Table 6 shows the settling depths of the standard lightweight foamed concrete and test lightweight foamed concrete in accordance with KS F 4039 in a compound design where the water cement ratio was fixed at 60% and the unit volume weight of the bubble slurry was 400, 500, and 600 kg / ㎥, respectively. The measured experimental value.

⑥ Cracking test

The most common method used to measure the amount of cracks generated by dry shrinkage of lightweight foamed concrete is to measure the change in length of the specimen by KS F 2460 (Test Method for the Change of Length of Foamed Concrete). However, this method has a problem that it is difficult to obtain good data because the specimens of lightweight foam concrete generally have a large deviation, and it takes a long time to measure another specimen. Therefore, in the development process of this technology, considering the characteristics that the occurrence time of cracks is more important than the amount of cracks due to the characteristics of lightweight foam concrete for panel, the H-shaped mold as shown in Fig. 9 is manufactured and the crack between the standard foam concrete and the test foam concrete Relative comparison of timing of occurrence was used.

As a result of this test, the standard lightweight foamed concrete began to have small cracks after 15 days of age and completely penetrated the neck at 23 days of age. However, in the case of test foam concrete, there was no cracking up to 35 days, and thus the crack reduction effect was confirmed.

Claims (6)

After diluting 1 liter of lauryl alkyl ether sulfate-based foaming agent in 40 liters of water, 1 liter of a liquid admixture mainly composed of aluminum sulfate and calcium nitrite is mixed again. The mixture is foamed by air pressure of about 8 to 10 atmospheres. Meanwhile, about 240 kg to 320 kg of cement is mixed with 96 to 192 liters of water and stirred at about 150 revolutions. Light weight aggregates are added to a 70 to 85 liter cement slurry in a volume ratio and mixed well. While slowly mixing the cement slurry containing the sufficiently mixed lightweight aggregate at about 30 revolutions, the amount of foamed foam is added to about 650 to 800 liters and stirred. Mix for about 3 to 5 minutes and pour into a mold of a certain standard. Manufacturing technology of lightweight foamed concrete for non-combustible insulation sandwich panels which are cured by pouring into a mold for about 24 to 48 hours The method of claim 1, Use of synthetic foaming agents containing at least about 60 parts by weight of lauryl alkyl ether sulfate The method of claim 1, Use of a basic stabilized liquid admixture consisting of components containing at least 45 parts by weight of an aqueous aluminum sulfate solution (at least 17 parts by weight of alumina) and at least 5 parts by weight of calcium nitrite The method of claim 1, As a lightweight aggregate, expanded vermiculite is used as a lightweight foam concrete for paneling using light foamed concrete in the range of about 70 to 85 liters per cubic meter of concrete. Apart from paragraph 1 Technology to change the curing time to about 6 to 10 hours by replacing about 10 kilograms to 32 kilograms of cement with light dolomite Apart from paragraph 1 Technology for manufacturing lightweight foamed concrete according to the mixing design formula of separately attached lightweight foamed concrete