KR101477108B1 - Lightweight Concrete Composition With High Insulation Effect - Google Patents

Abstract

The present invention relates to a lightweight concrete composition excellent in heat insulation effect. The lightweight concrete composition of the present invention comprises a lightweight aggregate having a heat storage capacity of 4 J / g or more, wherein the lightweight aggregate is impregnated with a phase change material having a phase change temperature range of 18 to 35 DEG C of 1 wt% to 7 wt% Acrylic resin, epoxy resin, polyurethane, ethylene vinyl acetate, and polyester.

Description

[0001] Lightweight Concrete Composition with High Insulation Effect [

The present invention relates to a lightweight concrete composition excellent in heat insulation effect.

Concrete is a generic term for materials that consist of a certain form using binders such as water, aggregate, and cement. The materials can be subdivided according to the characteristics of the material. Aggregates are classified into coarse aggregate and fine aggregate. Particles with a particle size of less than 5 mm are classified as fine aggregate, and those with a particle size of 5 mm or more are classified as coarse aggregate. Also, the aggregate can be divided into crushed aggregate, lightweight aggregate and recycled aggregate depending on the type. Lightweight aggregate is a kind of coarse aggregate of coarse aggregate, and it is said that the weight of aggregate of concrete or mortar is lighter than that of ordinary aggregate. Lightweight aggregates include natural lightweight aggregates, artificial lightweight aggregates, and industrial byproducts.

As a method of producing lightweight concrete, there is known a method of using lightweight aggregate and lightening air by blowing a binder such as fine aggregate and cement of 5 mm or less. This series of lightweighting work has been developed and used for economical reasons for securing an internal space by reducing the size of a column by reducing the weight of a building, or for reducing heat insulation, interlayer noise, and soundproofing.

However, it is known that the insulation performance of lightweight concrete is not excellent. This is very difficult to use as a thermal insulation material because it has the highest thermal conductivity of binder and aggregate, which are the largest volume of materials used in lightweight concrete. In general, the conductivity is 1.41 Kcal / mhr ℃ for concrete and 0.4 ~ 0.5 Kcal / mhr ℃ for sand and gravel. Lightweight concrete is also reported to be 0.45 Kcal / mhr ° C. In addition, it has been reported that foamed concrete, which is a kind of lightweight concrete, has a thermal conductivity of 0.35 Kcal / mhr ° C.

Therefore, the present inventors have considered using a phase change material in a lightweight concrete having a heat insulating effect. The phase change material is generally a wax composed of hydrogenated carbon. In Korean Patent No. 844942, a phase change material is applied to a regenerative floor system to provide heat storage floor material capable of storing heat generated during heating. In Korean Patent Laid-Open No. 10-2012-0019497, And encapsulates it. The patent discloses a method of reducing energy by attaching a microcapsule to the surface of a civil engineering building material to adjust the temperature.

Korean Patent No. 1090526 also discloses a mortar composition comprising a phase change material. The above patent discloses a method of directly introducing a phase change material, paraffin wax, into a mortar. This method may adversely affect the compressive strength. When the phase-change material reaches the melting point, it may be eluted on the surface of the mortar There are disadvantages.

Korean Patent No. 101001351 discloses a lightweight wall having a phase-shifting substance concentrated on the surface and a method of manufacturing the wall, but it is difficult to apply to a slab or the like due to the use of a panel and its use may be limited for various applications due to the risk of separation .

The present invention has been made in order to solve the above problems of the prior art, and it is an object of the present invention to provide a lightweight aggregate which absorbs a phase change material suitable for a lightweight concrete and replace the existing lightweight aggregate with concrete, And the present invention was completed.

The present invention aims at providing a lightweight concrete composition which can satisfy the physical properties of concrete required in the construction of a lightweight concrete by impregnating a lightweight aggregate constituting a lightweight cone creek material with a phase change material, do.

An object of the present invention is to provide a lightweight aggregate having a heat storage capacity of 4 J / g or more, wherein the lightweight aggregate is impregnated with 1% by weight or more and 7% by weight or less of a phase change material having a phase change temperature range of 18 to 35 DEG C, And is coated with one kind of polymer selected from the group consisting of epoxy resins, polyurethane, ethylene vinyl acetate and polyesters.

Preferably, the concrete composition comprises 25 to 55% by weight of the lightweight aggregate, 15 to 25% by weight of a binder, 5 to 15% by weight of water and 25 to 35% by weight of sand, based on the weight of the total composition.

Preferably, the phase change material is paraffin wax.

The polymer coating has a thickness of 0.1 to 1 mm.

The lightweight concrete composition of the present invention can ensure high thermal insulation properties as compared with conventional lightweight concrete. Also, the lightweight concrete composition of the present invention can achieve energy saving by heat storage, thereby accumulating heat supplied from the inside and the outside during the summer and winter, thereby helping to create a cool environment in the summer and a warm environment in the winter. Also, the lightweight concrete composition of the present invention can reduce the weight of the concrete by reducing the unit weight of the concrete, and can achieve energy saving effect by heat insulation.

FIG. 1 shows a result of analysis of heat storage capacity by differential scanning calorimetry (DSC) of lightweight aggregate of the present invention.

Unless defined otherwise, all technical terms used in the present invention have the following definitions and are consistent with the meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Also, preferred methods or samples are described in this specification, but similar or equivalent ones are also included in the scope of the present invention. The contents of all publications referred to herein are incorporated herein by reference.

The term " about " is used herein to refer to a reference quantity, a level, a value, a number, a frequency, a percent, a dimension, a size, a quantity, a weight, or a length of 30, 25, 20, 25, 10, 9, 8, 7, Level, value, number, frequency, percent, dimension, size, quantity, weight or length of a variable, such as 4, 3, 2 or 1%.

Throughout this specification, the words " comprises " and " comprising ", unless the context requires otherwise, include the steps or components, or groups of steps or elements, Steps, or groups of elements are not excluded.

Hereinafter, the present invention will be described in more detail.

The lightweight concrete composition of the present invention may comprise 25 to 55% by weight of lightweight aggregate, 15 to 25% by weight of binder, 5 to 15% by weight of water and 25 to 35% by weight of sand, based on the weight of the total composition.

The lightweight aggregate preferably has a thermal storage capacity of 4 J / g or more. If it is 4 J / g or less, the heat storage amount is too low to be practical. The higher the heat storage capacity, the better, but it is theoretically difficult to exceed 30 J / g even if all the phase change materials are impregnated in lightweight aggregate. When the impregnation amount is high and the heat storage capacity is 30 J / g, the strength of the lightweight aggregate becomes low and it becomes unusable in many cases.

For this purpose, the lightweight aggregate is impregnated with a phase change material having a phase change temperature range of 18 to 35 占 폚 in an amount of 1 wt% to 10 wt% based on the weight of the lightweight aggregate, and is mixed with acrylic, epoxy resin, polyurethane, ethylene vinyl acetate and polyester It is preferable to coat them with one type of polymer selected from the group consisting of

The lightweight aggregate may be any of natural lightweight aggregate and artificial lightweight aggregate. In order to prevent decrease in the compressive strength of the lightweight concrete, the water absorption rate of the lightweight aggregate is preferably 10 wt% or less, more preferably 1 wt% to 7 wt%, based on the weight of the lightweight aggregate. If the content is less than 1 wt%, the heat storage ability is too small to perform, and if it is 7 wt% or more, the heat storage ability is excellent, but the light aggregate can easily be destroyed.

As the natural lightweight aggregate, volcanic power, pumice stone, lava stone and the like can be used, and pumice stone can be preferably used. Artificial lightweight aggregates are clay and shale fired at high temperature, expanded clay and expanded shale homogeneously expanded and fired when fired. As industrial byproducts, expanded slag made by quenching coal ash or slag can be used.

The following describes the amount of lightweight aggregate that will not adversely affect the production of concrete, the amount of phase change material impregnated and the amount of water used for insulation.

The phase change material impregnated in the lightweight aggregate may be a compound of C _n H _{2n + 2} alone or in combination. In the above, n is 10 to 25, but is not limited thereto. The phase change material may preferably be a paraffin wax, and the phase change material preferably has a phase change temperature range of 18 캜 to 35 캜 and a melting point of 20 to 40 캜. In the present invention, the melting point of the preferred phase change material is selected to suit the lightweight concrete composition by introducing the advantages of the phase change material.

In order to impregnate the lightweight aggregate with the phase change material, the phase change material is first heated. Next, after the lightweight aggregate is heated to a temperature higher than the heating temperature of the phase change material, the phase change material is impregnated with the phase change material to absorb the phase change material into the lightweight aggregate.

The heating temperature of the phase change material is preferably at least the melting point of the phase change material, particularly preferably 30 to 60 ° C. The heating temperature of the phase change material can be set in consideration of the melting point, the boiling point, and the thermal decomposition temperature of the phase change material, because evaporation or thermal decomposition of paraffin may occur when the heating temperature is 60 ° C or higher.

The lightweight aggregate is preferably heated before being impregnated with the phase change material. In particular, it is preferable that the heating is performed at about 10 to 20 DEG C higher than the heating temperature of the phase change material. This is to enlarge the micro pores of the lightweight aggregate so that the phase change material can be well absorbed between the micro pores of the lightweight aggregate.

The lightweight aggregate in which the phase change material is absorbed may pass through the perforated belt where the temperature is maintained at a temperature equal to or higher than the melting point of the phase change material so that the amount of the phase change material remaining on the surface is minimized. If the phase change material remains on the surface of the lightweight aggregate in large amount, the bond between the polymers may be loosened during the polymer coating. Also, when the concrete composition is manufactured, the bonding strength with the binder such as cement is lowered, and the compressive strength of the final concrete can be reduced.

The lightweight aggregate impregnated with the phase change material may be coated with a polymer. The polymer may be a mixture of one or more selected from the group consisting of acrylic, epoxy resin, polyurethane, ethylene vinyl acetate, and polyester. This is because, when the phase change material is mixed into the concrete, the compressive strength is lowered. In addition, it can suppress the movement of the capillary water of the lightweight aggregate due to the pressure generated when the concrete is poured, so that the pouring can be smoothly carried out even at high pressure transportation.

In general, the polymer may be in the form of a resin or an emulsion. In particular, a resin containing a surfactant is most preferable because it has a high drying and curing rate and a small amount of usage. The non-ionic surfactant is preferably a non-ionic surfactant, an anionic surfactant, a cationic surfactant or an amphoteric surfactant. Particularly, a non-ionic surfactant is preferred for the emulsion, Can be more preferably used. The amount of the surfactant is preferably 10% by weight or less based on the weight of the polymer. If the amount of the surfactant is more than 10% by weight, it is likely to be melted and deteriorated in water resistance, and may be eluted even after being made into concrete.

The thickness of the polymer coating is preferably about 0.1 to 1 mm. When the thickness of the coating is less than 0.1 mm, the coating tends to be broken when it is made of concrete. When the thickness exceeds 1 mm, the aggregate tends to clump together when the aggregate is produced, It is not.

In the polymer coating process, the coating temperature is preferably lower than the melting point of the phase change material. When the coating temperature is higher than the melting point of the phase change material, the phase change material and the polymer to be coated may be mixed with each other to deteriorate the mechanical properties of the coating material. Therefore, the polymer can be coated after the lightweight aggregate impregnated with the phase change material is cooled for a certain period of time.

The lightweight concrete composition may include 25 to 55% by weight of the lightweight aggregate impregnated with the phase change material and coated with the polymer. In order to reduce the weight of the concrete, it is more preferable that the lightweight aggregate is 35 wt% or more. When the weight of the lightweight aggregate is less than 25% by weight, it is impossible to reduce the weight of the concrete. When the weight of the lightweight aggregate exceeds 55% by weight, mechanical properties such as compressive strength are deteriorated.

The lightweight concrete composition may include 15 to 25% by weight of a binder. Preferably, about 20% by weight of binder may be used. When the amount of the binder is less than 15% by weight, the mechanical properties are deteriorated and it is difficult to use. When the amount of the binder is 25% by weight or more, it is difficult to reduce the weight of the concrete.

The binder may be at least one selected from the group consisting of portland cement, slag cement, fly ash cement, mixed cement, ultralong speed cement, and cold rolled cement. In addition, it is possible to mix slag fine powder and fly ash with the cement. When slag fine powder and fly ash are used, it is advantageous in terms of economic and resource recycling, securing workability of lightweight concrete and securing low water / binder ratio Light weight is advantageous in the same volume.

The lightweight concrete composition may contain 5 to 15% by weight of water. And more preferably 12% by weight or less in order to reduce the compressive strength and prevent the durability from deteriorating. When the amount of water used is less than 5% by weight, the hydration reaction of the binder does not occur or the workability is bad and it is difficult to use. When 15% by weight or more is used, the compressive strength is remarkably low and collapses.

In addition, the weight of the lightweight concrete composition may include 25 to 35% by weight of sand. And more preferably 30% by weight or less for reducing the unit weight of the lightweight aggregate. When the weight of the sand is 25 wt% or less, there is a limit in securing workability and a rough surface. When the weight of the sand is more than 35 wt%, the density of the sand is increased and it is difficult to reduce the weight.

Hereinafter, the present invention will be described in detail with reference to Examples. However, the present invention is not intended to limit the scope of the present invention, And the scope of the claims of the present invention.

Manufacturing example  One

Paraffin wax was used as a phase change material and lightweight aggregate manufactured by Dols Co. of China was used as a lightweight aggregate. The paraffin wax and the lightweight aggregate were prepared in a weight ratio of 4: 6. The lightweight aggregate was heated to 60 占 폚 and impregnated with the paraffin wax heated to 40 占 폚. Thereafter, the mixture was allowed to stand for about 10 minutes so that the phase-change material was sufficiently absorbed. Next, the lightweight aggregate impregnated with the phase change material was passed through a vibrating belt (vibration number 3600 rpm, output 0.15Hp W x L = 1 x 2 m, temperature 40 ° C) to remove the phase change material on the surface of the shirting surface. Next, DER-331 (epoxy base) of Dow Chemical Co., Ltd. and Anquamin 401 of Air Products Co., Ltd. as a polymer substance were mixed at a weight ratio of 2: 1, and then 5 wt% of the lightweight aggregate was sprayed on the surface of the lightweight aggregate 0.1 to 1 mm. After the coating was completed, a cylindrical rotary stirrer was operated for 30 minutes until the polymer was completely cured, so that the lightweight aggregate was stirred to prevent the aggregates from sticking together. The final lightweight aggregate has a water absorption of about 1.0 wt% of the aggregate weight. The heat storage capacity of the lightweight aggregate was 4 J / g as measured by differential scanning calorimetry (DSC) as shown in Fig.

Example  1 to 3, Comparative Example  One

Lightweight concrete compositions were prepared according to the composition ratios shown in Table 1 below using the lightweight aggregate impregnated with the phase change material prepared in Preparation Example 1. The lightweight aggregate was lightweight aggregate impregnated with phase change material and coated on the surface with epoxy. Also, sand was used in general and cement was used as binder. In case of water, tap water was used and chemical admixture for concrete was not used for comparison.

* However, the aggregate of Comparative Example 1 is ordinary aggregate, not lightweight aggregate.

Unit (wt%) cement sand Lightweight aggregate water Example 1 20 30 38 12 Example 2 21 30 37 12 Example 3 22 30 36 12 Comparative Example 1 25 30 38 ^* 12

Test Example  One

The concrete was poured using the lightweight concrete composition prepared in Examples 1 to 3 and Comparative Example 1, and then the slump value, the unit volume mass, the compressive strength and the thermal conductivity with time were measured.

Concrete tests were conducted according to the KSF 2560 "Chemical admixture for concrete" test method. In addition, the thermal conductivity of a 30 × 30 × 5 cm lightweight concrete plate is exposed to a heat source at 50 ° to 60 ° C. in a plane, and the temperature change is observed 10 to 20 minutes after a 1 cm side exposed to a heat source to measure the thermal conductivity. Surface contact type thermal conductivity measuring device. The measurement results are shown in Table 2 below.

slump Unit volume mass Compressive strength Thermal conductivity 3 days 7 days 28th cm Kg / m ³ MPa w / mk Example 1 20 1,830 20 25 31 1.1 Example 2 20 1,877 17 27 35 1.2 Example 3 18 1,907 15 24 30 1.2 Comparative Example 1 20 2,388 17 26 34 2.03

The same or similar slump results were obtained with concrete using the same cement and sand gravel, and the compressive strength was slightly increased or the same result was obtained. However, in the case of the unit volume weight, the weight of each of Examples 1 to 3 is about 20% lower than that of Comparative Example 1, indicating that the weight is reduced as lightweight concrete. Also, the thermal conductivity of the lightweight concrete prepared with the composition of the present invention was measured to be about 40% lower than that of Comparative Example 1. It can be evaluated that the insulation effect is excellent when the lightweight heat insulating concrete is manufactured using the composition of the present invention.

The present invention has been described with reference to the preferred embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

Claims (4)

As lightweight concrete compositions,
A lightweight aggregate having a heat storage capacity of 4 J / g or more,
The lightweight aggregate has a phase change material having a phase change temperature range of 18 to 35 ° C impregnated in an amount of not less than 1% by weight and not more than 7% by weight, and is selected from the group consisting of acrylic, epoxy resin, polyurethane, ethylene vinyl acetate, Wherein the impregnation is performed by impregnating the phase change material heated to a temperature not lower than the melting point with a lightweight aggregate heated to a temperature 10 to 20 캜 higher than the heating temperature of the phase change material. The lightweight aggregate according to claim 1, wherein the concrete composition comprises 25 to 55% by weight of the lightweight aggregate, 15 to 25% by weight of binder, 5 to 15% by weight of water and 25 to 35% Concrete composition. The lightweight concrete composition of claim 1, wherein the phase change material is paraffin wax. The lightweight concrete composition according to claim 1, wherein the polymer coating has a thickness of 0.1 to 1 mm.

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