KR20060118073A - Refractory and adiabatic cement mortar composition - Google Patents

Abstract

Provided is a cement mortar composition, which imparts high strength and excellent durability to a concrete structure, prevents a concrete structure from being overheated and exfoliated upon a fire accident, and shows improved refractory and heat insulation property. The cement mortar composition comprises cement, sand, an inorganic oxide, a polymer, mineral substances and organic polymeric fiber. The cement mortar composition comprises, per 100 parts by weight of the cement, 200-350 parts by weight of sand, 5-15 parts by weight of the inorganic oxide, 3-20 parts by weight of the polymer, 1-10 parts by weight of the mineral substances and 0.2-0.8 parts by weight of the organic polymeric fiber. The inorganic oxide is at least one selected from the group consisting of silica fume, alumina, titania and zirconia.

Description

Cement mortar composition for improving fire resistance and thermal insulation performance {REFRACTORY AND ADIABATIC®CEMENT MORTAR COMPOSITION}

1 is a graph showing a time heating temperature curve prescribed by the Ministry of Construction of the Ministry of Transportation of Germany,

2 is a photograph showing the results of the fire resistance test for the cement mortar compositions of Example 1 and Comparative Example 3,

3 is a graph showing the thermal insulation performance test results for the cement mortar compositions of Example 1 and Comparative Example 4.

[Technical Field]

The present invention relates to a cement mortar composition, and more particularly, to a cement mortar composition having high strength and high durability, and excellent fire and heat insulating performance.

[Private Technology]

As concrete structures deteriorate over time, cracks and breakages occur due to natural deterioration and external conditions. This degrades the durability of the structure, which in turn causes the structure to be destroyed. In addition, the structure may collapse due to the explosion or peeling of the concrete structure in the fire or the structural fire resistance is sharply reduced due to the decrease in strength due to the thermal stress of the concrete.

As such, there is a need to develop a cement mortar composition that improves the fire resistance and insulation performance required for repairing structures due to deterioration of building structures, tunnels, and underground concrete structures, preventing thermal explosion and peeling due to fire, and thermal insulation performance.

Republic of Korea Patent Publication No. 2003-0047069 discloses the application of organic fibers in the production of high-performance concrete. However, the organic polymer fibers have an effect on preventing the thermal expansion of concrete, but in case of fire, the heat continuously stresses the structure, thereby degrading the original physical properties of the concrete, thereby preventing the load drop of the concrete structure due to thermal stress in the fire. There is a problem that does not have an effect on.

In addition, U. S. Patent No. 5749961 discloses a method of preventing thermal expansion and peeling of concrete by incorporating organic polymer fibers for fire resistance of an ultra high strength concrete composition. However, this also has an effect on improving the fire resistance, but there is a limit in controlling both fire resistance and heat insulation due to the decrease in strength due to thermal stress.

Korean Patent Laid-Open Publication No. 2004-0053069 discloses a composition of polymer cement mortar using coal ash. However, the polymer cement mortar composition is excellent in high strength and durability, but is suitable as a repair material, but there is a problem in that the thermal explosion, peeling, and thermal insulation effects due to fire are inferior.

As described above, the mortar composition having excellent physical and chemical properties, such as durability, freeze-melting resistance, waterproofness, chemical resistance, etc., while having an insulation effect that reduces fire performance and thermal stress on the explosion and peeling of concrete due to fire, is optimal. The technology has never been so far.

It is an object of the present invention to provide a cement mortar composition having excellent cross-sectional protective fire and thermal insulation performance.

In order to achieve the above object, the present invention provides a cement mortar composition comprising cement, sand, inorganic oxides, polymers, minerals and organic polymer fibers.

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

The present invention relates to a cement mortar composition which can be applied to new and existing concrete structures and has improved cross-sectional protection fire resistance and thermal insulation performance, and improves the high strength and high durability of the cement mortar composition by incorporating a polymer and an inorganic oxide into the mortar composition. In addition, by further mixing the organic polymer fibers and minerals, it was possible to improve the fire resistance and heat insulation that can reduce the explosion, peeling, etc. due to fire.

More specifically, the cement mortar composition according to the present invention includes cement, sand, inorganic oxides, polymers, minerals and organic polymer fibers.

The cement mortar composition is preferably included in the sand 200 to 350 parts by weight, more preferably 200 to 250 parts by weight based on 100 parts by weight of cement. When the sand content in the cement mortar composition is out of the above range, there is a fear that the strength during use or the workability during construction decreases.

In addition, the inorganic oxide may be one or more selected from the group consisting of silica fume, alumina, titania, zirconia, and more preferably silica fume.

Silica fume (dry silica) is an industrial by-product from electric arc furnaces used in the manufacture of silicon metals or silicon alloys and contains more than 80% of amorphous silica (SiO ₂ ). It is composed of very fine spherical particles (average particle diameter of 0.1 to 0.2 mu m) and has a specific surface area of 150000 to 250000 cm ² / g. Since such silica fume contains a large amount of silica, it is possible to cause a pozzolanic reaction very effectively. This can have a positive effect on the long-term strength of concrete. It is also very fine compared to the particles of cement, so it is filled between cement paste and aggregate, showing excellent water resistance, chemical resistance and freeze-melting resistance.

The inorganic oxide is preferably included in 5 to 15 parts by weight, more preferably 5 to 10 parts by weight with respect to 100 parts by weight of cement. When the content of silica fume is less than 5 parts by weight, there is a concern that the function as a repair mortar may be deteriorated due to a decrease in strength and a decrease in durability, and when it exceeds 15 parts by weight, not only workability is deteriorated but also curing may be delayed. have.

The polymer usable in the present invention is not particularly limited, but any polymer can be used as long as it is a reemulsifying powder resin (or also referred to as a powder emulsion), and more preferably a polyvinyl resin can be used. Ethylene-vinylacetate (EVA) or polyvinyl acetate is used.

The polymer is uniformly filled in the fine pores in the cement cured product, and the workability, air embrittlement, and the like due to the hydrophilic colloidal properties of polymer particles, entrained air bubbles, surfactants contained in the polymer-dispersion, and the polymer-dispersion itself Improved bleeding and resistance to material separation improve the tensile strength and toughness in the state that cement mortar is not hardened because the aggregate is strongly bonded as the cement hydrate and polymer film are finally mixed together. It can improve the freeze-melting resistance and the like.

The polymer is preferably included in 3 to 20 parts by weight, more preferably 7 to 15 parts by weight based on 100 parts by weight of cement. When the content of the polymer is less than 3 parts by weight, the function of the repair mortar may be deteriorated due to the decrease in strength and durability, and when the amount is more than 20 parts by weight, the workability may be degraded and the curing may be delayed.

In addition, the mineral material may be one or more selected from the group consisting of pearlite, vermiculite and diatomaceous earth, more preferably pearlite.

When the pearlite ore is pulverized to 8 to 12 mesh or less and rapidly heated at a high temperature of 1,000 ° C. or more, volatiles contained in the pearlite gasify and expand in the softened particles to form internal pores. What is formed on the surface of the particles is ejected outward, expanding about 10-20 times the original volume of pearlite. At this time, the airtight small air bubbles become expanded pearlite having a shape surrounded by a glassy film. Because of this, expanded pearlite has a light specific gravity and is a myriad of porous materials connected by point contact between powders, so that the solid thermal conductivity of the pearlite itself is very small, and the pores between the pearlite particles are filled with fine particles to prevent convection and the color of the pearlite particles is white. It also has excellent thermal insulation. The pearlite usable in the present invention preferably has a specific gravity of 0.10 to 0.35. When the specific gravity of pearlite is 0.10 or less, there is a concern that a decrease in strength and durability in the composition may occur. There is a risk of decrease.

The pearlite is preferably contained in an amount of 1 to 10 parts by weight, more preferably 2 to 6 parts by weight, based on 100 parts by weight of sand. If the content of pearlite is less than 1 part by weight, the thermal conductivity of the composition is increased and the thermal insulation performance is reduced, so that the thermal insulation effect on the thermal stress may be reduced in case of fire, which is not preferable, and the content of the pearlite is 10 weight. When the portion is exceeded, the hardness and strength of the pearlite is small, which may result in a decrease in strength and a decrease in durability in the cement mortar composition, which is not preferable.

Examples of the organic polymer fibers include all organic polymer fibers having a melting point of 300 ° C. or lower, specifically polyolefin fibers including polyethylene, polypropylene, and the like; Polyamide fiber including nylon; Polyacrylic fibers; Polyester fibers; And one or more selected from the group consisting of polyvinyl alcohol fibers, and more preferably polyolefin fibers, and most preferably polypropylene fibers (hereinafter referred to as 'PP').

Since these organic polymer fibers are not thermally conductive, they have their own fire resistance, and also, when the concrete rises to 300 ° C. or higher due to fire, it melts to form voids in the cement. Therefore, heat and gas can move through these voids to prevent the explosion of concrete due to fire.

In particular, the polypropylene fiber is a mesh-type specific gravity 0.91, the melting point is 160 ℃ to 170 ℃, the ignition point is 590 ℃. In addition, the tensile modulus of elasticity is as high as 3,500 to 7,700 kg / cm 2. Generally, when 0.9kg of fiber per 1m 3, more than 6 million fibers are distributed within 1m 3. In addition, it is inexpensive, durable, and controls the tensile stress and cracking caused by restraint when mortar and concrete shrink, increasing toughness and resistance to impact, abrasion and fatigue, It has the effect of reducing the concrete thermal explosion by low melting point.

The organic polymer fibers are preferably contained in 0.2 to 0.8 parts by weight, more preferably 0.3 to 0.5 parts by weight based on 100 parts by weight of cement. When the content of the organic polymer fiber is less than 0.2 parts by weight, the effect of reducing the explosion in the mortar composition in the fire is lowered, which is not preferable because of difficulty in preventing the explosion. If the content exceeds 0.8 parts by weight, the workability is lowered and after curing It is not preferable because there is a possibility that the durability may be reduced due to agglomeration of fibers.

The composition of the present invention is water in addition to the above components; High fluidizing agents; Antifoaming agents capable of reducing excessive air entrained by surfactants and dispersants contained in the polymer; And at least one compound selected from the group consisting of shrinkage reducing agents to reduce shrinkage occurring upon drying of the mortar composition. In addition, a powder type high fluidizing agent may be used as the high fluidizing agent, and more preferably, a polycarboxylic acid type high softening agent may be used.

In addition, the antifoaming agent may be used one or more selected from the group consisting of silicone-based and hydrocarbon polyglycol-based antifoaming agents, preferably both neutral or alkaline silicone-based and hydrocarbon polyglycol-based antifoaming agents. As the shrinkage reducing agent, one or more selected from the group consisting of lower alcohol alkylene oxide adducts and ether type nonionic surfactants can be used.

The cement mortar composition of the present invention can improve fire resistance and insulation performance as well as prevention and repair of concrete cracks, breakages and fires caused by deterioration of concrete such as tunnels, shotcrete structures and sandwich structures. Can be. In addition, the cement mortar composition according to the present invention satisfies all properties such as high strength, high durability, adhesion, crack resistance, fire resistance, heat insulation, and at the same time, excellent in economics and construction properties, and exhibits improved fire and insulation performance.

Hereinafter, preferred examples and comparative examples of the present invention are described. However, the following examples are only preferred embodiments of the present invention and the present invention is not limited to the following examples.

<Example 1>

Usually 603 kg (100 parts by weight) of Portland cement and 1286.4 kg (200 parts by weight) of sand, 67 kg (10 parts by weight) of silica fume, 46.9 kg (7 parts by weight) of ethylene vinyl acetate (EVA) as a polymer, 53.6 kg of pearlite (sand) 4 parts by weight per 100 parts by weight) and 3 kg (0.5 part by weight) of polypropylene fiber (length 19 mm, thickness 2.1 Deniar) are mixed as organic polymer fibers, and then mixed with 268 kg of mixed water and an appropriate amount of high fluidizing agent Cement mortar composition was prepared.

Comparative Example 1

A cement mortar composition was prepared in the same manner as in Example 1, except that 670 kg of cement was used without adding ethylene vinyl acetate and silica fume.

Comparative Example 2

A cement mortar composition was prepared in the same manner as in Example 1, except that ethylene vinyl acetate was not added.

Comparative Example 3

A cement mortar composition was prepared in the same manner as in Example 1, except that no polypropylene fiber was added.

<Comparative Example 4>

A cement mortar composition was prepared in the same manner as in Example 1, except that 1340 kg of sand was used without adding pearlite.

Table 1 shows the compounding ratio of the components of the cement mortar composition according to Example 1 and Comparative Examples 1 to 4.

division usage  Cement (kg / ㎥) Sand (kg / ㎥) Silica fume (kg / ㎥) Pearlite (kg / ㎥) Ethylene Vinyl Acetate (kg / ㎥) Polypropylene Fiber (kg / ㎥) Mixed water (kg / ㎥) Example 1 603 1286.4 67 53.6 46.9 3 268 Comparative Example 1 670 1286.4 - 53.6 - 3 268 Comparative Example 2 603 1286.4 67 53.6 - 3 268 Comparative Example 3 603 1286.4 67 53.6 46.9 - 268 Comparative Example 4 603 1340 67 - 46.9 3 268

Test Example 1 Compressive Strength Test

In order to compare the compressive strength characteristics of Example 1 and Comparative Examples 1 and 2, a compressive strength test was conducted. The test method was carried out by the specimen preparation and strength measurement method specified in the Korean Industrial Standard KS F 2403, 2405, 2476 and the results are shown in Table 2 below.

Test Example 2 Flexural Strength Test

In order to compare the flexural strength characteristics of Example 1 and Comparative Examples 1 and 2, a flexural strength test was conducted. The test method was carried out by the specimen preparation and strength measurement method specified in the Korean Industrial Standard KS F 2476 and ASTM C 348 and the results are shown in Table 2 below.

Test Example 3 Durability Test

In order to compare the durability of Example 1 and Comparative Examples 1 and 2, the chlorine ion permeability test was performed.

The test method was measured permeability according to the method specified in ASTM C 1202 (chlorine ion permeation test method) and the results are shown in Table 2 below.

At this time, the evaluation criteria of permeability were very high permeability when the Coulombs value was 4000 or more, usually 2000 to 4000, low for 1000 to 2000, very low for 100 to 1000, and impermeable to 100 or less. .

division Age Example 1 Comparative Example 1 Comparative Example 2 Compressive strength (MPa) 7 days 389.3 251.7 312.3 28 days 453.5 320.1 390.8 Flexural strength (MPa) 7 days 4.5 2.8 4.1 28 days 6.1 3.4 5.5 Chlorine Ion Permeability (coulombs) 28 days 1852 5871 2847

As shown in Table 2, the mortar composition according to the present invention (Example 1) has superior mechanical properties such as compressive strength and flexural strength than the general mortars of Comparative Examples 1 and 2 and the high-strength repair cement mortar and the chlorine ion permeability. It is shown to be superior to the excellent durability composition.

Test Example 4 Fire Resistance Test

A fire resistance test was conducted to determine the effect of preventing the thermal explosion and peeling of the cement mortar composition of the present invention in the event of fire.

The fire resistance test was carried out by raising the temperature to 1200 ° C. according to the RABT curve of FIG. 1, which is a time heating temperature curve defined by the Ministry of Transport and Transportation. The experimental results are shown in FIG.

In Figure 2 a) is a fire resistance test results for the mortar composition of Example 1 is shown, b) is a fire resistance test results for the mortar composition of Comparative Example 3 is shown.

As a result of the experiment, the composition of Comparative Example 3 bursting with the sound from about 15 minutes after the start of the experiment, and partial peeling phenomenon and cracks occurred throughout the specimen. However, the composition of Example 1 in which the PP fiber was mixed did not cause any explosion and peeling during the experiment, which caused the fiber to melt and dissipate to the outside by melting the thermal stress and pore pressure of the composition due to fire. Because it did not occur

Test Example 5 Insulation Performance Test

Using the K-type thermocouple in the refractory furnace, Example 1 and Comparative Example 4, the temperature of the opposite side 10 cm away from the heat receiving portion of the fire was measured at the time when the RABT curve ends. The results are shown in FIG.

As a result, in Example 1, the temperature of the composition at the end of the RABT curve was 286 ° C, and in Comparative Example 4 was 563 ° C. From this, the composition of the present invention was confirmed that the thermal insulation performance is remarkably excellent due to the mixed pearlite.

By using the cement mortar composition of the present invention can not only ensure the high strength and high durability of the concrete structure, but also prevent the explosion and peeling of the concrete structure due to fire and increase the fire resistance and insulation properties of the concrete by the thermal stress on the concrete structure The reduction in performance can be minimized.

Claims (14)

Cement mortar composition comprising cement, sand, inorganic oxides, polymers, minerals and organic polymer fibers. The method of claim 1, The sand is a cement mortar composition containing 200 to 350 parts by weight based on 100 parts by weight of cement. The method of claim 1, The inorganic oxide is a cement mortar composition of at least one selected from the group consisting of silica fume, alumina, titania and zirconia. The method of claim 1, The inorganic oxide is a cement mortar composition is contained in 5 to 15 parts by weight based on 100 parts by weight of cement. The method of claim 1, The polymer is a cement mortar composition is a reemulsifying powder resin. The method of claim 1, Cement mortar composition of the polymer is a polyvinyl resin. The method of claim 1, The polymer is a mortar composition of 3 to 20 parts by weight based on 100 parts by weight of cement. The method of claim 1, The mineral material is a cement mortar composition of at least one selected from the group consisting of pearlite, vermiculite and diatomaceous earth. The method of claim 8, The pearlite is cement mortar composition having a specific gravity of 0.10 to 0.30. The method of claim 1, The mineral mortar composition is contained in 1 to 10 parts by weight with respect to 100 parts by weight of sand. The method of claim 1, The organic polymer fiber is a cement mortar composition having a melting point of less than 300 ℃. The method of claim 1, The organic polymer fibers are cement mortar composition of at least one selected from the group consisting of polyolefin fibers, polyamide fibers, polyacryl fibers, polyester fibers and polyvinyl alcohol fibers. The method of claim 1, The organic polymer fibers are cement mortar composition is contained in 0.2 to 0.8 parts by weight based on 100 parts by weight of cement. The method of claim 1, The mortar composition is a cement mortar composition further comprises one or more compounds selected from the group consisting of water, a high fluidizing agent, an antifoaming agent and a shrinkage reducing agent.

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