KR101432750B1 - Mortar or concrete composition using fly ash and use thereof - Google Patents

Abstract

The present invention relates to a method for producing mortars having high compressive strength without the use of sand, which comprises 7.5 parts by weight of coal ash, 1.5-3.0 parts by weight of cement, 1.0-2.0 parts by weight of calcined stone, 1.0-2.0 parts by weight of calcium oxide (CaO) To 2.0 parts by weight of a thickener and 0.01 to 0.5 parts by weight of a thickener.

Description

[0001] Mortar or concrete compositions using coal ash and applications thereof [0002] Mortar or concrete compositions using fly ash and use thereof,

The present invention relates to a mortar or concrete composition and its use, and more particularly to a mortar or concrete composition using coal ash and its use.

Generally, mortars are used to build bricks and stones mainly because they are made of sand or cement mixed with sand or cement and hardened when water is removed. The cement mortar contains Portland cement mortar and natural cement mortar. The Portland cement mortar is prepared by mixing 3 parts by weight of sand and 1 part by weight of cement mixed with a proper amount of water, 2 parts by weight of sand and 1 part by weight of natural cement mortar, Cement in parts by weight is mixed. These cement mortars have a problem in that the cement is consumed in a large amount, the amount of sand used as aggregate is large, and the construction cost is increased, and the compressive strength of the mortar is not so high when dried.

Meanwhile, coal ash is a nonflammable substance remaining after coal combustion in a thermal power plant or the like, and is divided into coal fly ash, flooring material or bottom ash. The main components are silicon dioxide (SiO ₂ ), aluminum oxide (Al ₂ O _3), iron oxide (Fe ₂ O _3), calcium oxide (CaO) oxide, magnesium (MgO), sodium (Na ₂ O) oxide, potassium oxide (K ₂ O), titanium dioxide (TiO ₂₎ etc. to be. These coal ash is a typical industrial waste, and its use is not worth it, and almost all of it is landfilled, causing severe environmental pollution problems.

Accordingly, attempts have been made to recycle the coal ash. In this technique, an appropriate amount of water is added to 60 wt% of pulverized coal, 23 wt% of a curing mix, and 17 wt% of sand and agitated. Korean Patent Laid-Open Publication No. 2002-0065190 for bricks, 30-80 parts by weight of waste slug, 10-40 parts by weight of waste maggot, 5-20 parts by weight of coal ash, 15-20 parts by weight of cement and 20 parts by weight of water Korean Patent No. 237557 on mortar composition, a method of kneading portland cement, diatomaceous earth and magnesia cement with a coagulant in a coal ash, molding at a pressure of 1 kg / cm ² and curing the mixture at 65 ° C with steam Republic of Korea Patent Publication No. 86-001754 call, calcium oxide (CaO) and cement, potassium fluoride (KF), sulfuric acid, calcium oxide (CaSO _4), sodium sulfate (Na ₂ SO ₄₎ relates to a method, a mixture of calcium chloride (CaCl ₂₎ And the like crane compositions 1 to 4.5% and from 40 to 90% coal ash and cement Republic of Korea Patent Laid-Open Publication relates to a method for manufacturing blocks of a chair the coal ash is prepared by mixing 20 to 23% of the number 1999-0011079.

However, the conventional methods for producing mortars or bricks using coal ash have a problem that the amount of coal ash used is limited and the use of sand can not be totally excluded or the amount of used cement can not be reduced. However, There is a disadvantage that the manufacturing process is complicated such as the curing process of hot or high temperature.

The present invention solves a variety of problems including the above problems, and it is an object of the present invention to completely eliminate the use of aggregate such as sand, to cure coal at room temperature as well as general mortar manufacturing process, A mortar or concrete composition excellent in compressive strength of a molded article as compared with a conventional cement mortar molded article, and its use. However, these problems are exemplary and do not limit the scope of the present invention.

According to one aspect of the present invention, there is provided a cement composition comprising 7.5 parts by weight of coal ash, 1.5 to 3.0 parts by weight of cement, 1.0 to 2.0 parts by weight of calcite, 1.0 to 2.0 parts by weight of calcium oxide, 0.01 to 2.0 parts by weight of retarder, And water is mixed with the solid content including the water-soluble part.

In the mortar composition, the coal ash may be fly ash, bottom ash, or a mixture thereof.

In the mortar composition, the cement may be Portland cement, blast furnace slag cement or Portland pozzolan cement.

In the mortar composition, the retarder is used for the purpose of suppressing rapid curing of the mortar, and is preferably used as a water reducing agent for cement / concrete, a hydration retarder for cement, an inorganic acid, an alcohol, an amino acid, a protein or a sugar, Mixture, wherein the protein may be gelatin and the amino acid may be proline or glutamic acid.

In the mortar composition, the thickener may be a cellulose-based thickener, a polyacrylamide-based water-soluble polymer, polyvinyl alcohol or polyvinyl acetate as an additive added to improve the viscosity or cohesion of the mortar or concrete, As the thickening agent, methylcellulose, methylcellulose acetate or ethylcellulose may be used.

In the mortar composition according to an embodiment of the present invention, the solid content may include one or more kinds of concrete selected from the group consisting of a crack reducing agent, an antibacterial agent, a durability improver, a water reducing agent, a filler, an expanding agent, Additives may be further included.

In the mortar composition, water may be added in an appropriate amount within a range having appropriate fluidity of the mortar composition, and 100 to 300 wt% of the cement content may be added.

According to another aspect of the present invention, there is provided a concrete composition comprising 1 part by weight of the mortar composition and 0.5 to 3 parts by weight of aggregate.

In the concrete composition, the aggregate may be a fine aggregate, a coarse aggregate, a waste ash, a construction waste, a blast slag, a ceramic slab or a mixed aggregate thereof.

According to another aspect of the present invention, there is provided a method of manufacturing a mortar composition, And a curing step of curing the molded building material at room temperature. The present invention also provides a method of producing artificial building material containing coal ash.

In the method of manufacturing the artificial building material, the building material may be artificial sand, artificial gravel or brick.

According to another aspect of the present invention, there is provided an artificial building material containing coal ash produced by the above production method.

According to one embodiment of the present invention as described above, mortar having high compressive strength after curing can be manufactured without using any aggregate, and concrete having a high compressive strength can be manufactured while reducing cement consumption. In addition, when a building material is produced from a mortar composition according to an embodiment of the present invention, the fire resistance and the sound insulation are superior to those of ordinary cement bricks. Of course, the scope of the present invention is not limited by these effects.

According to one aspect of the present invention, there is provided a cement composition comprising 7.5 parts by weight of coal ash, 1.5 to 3.0 parts by weight of cement, 1.0 to 2.0 parts by weight of calcite, 1.0 to 2.0 parts by weight of calcium oxide, 0.01 to 2.0 parts by weight of retarder, A mortar composition is provided wherein water is compounded in the solids containing part.

In the mortar composition, the coal ash may be fly ash, bottom ash, or a mixture thereof.

As coal ash burns carbonaceous coal ash, first of all, it is called as bottom ash or clinker ash in the combustion exhaust gas, which first falls down to the boiler part and is quenched by water. Then, · Ashes that fall down in the heat recovery unit of the air feeder part are generated, which is called cinder ash. However, most coal ash is collected in the electrostatic precipitator of the last process, which is called fly ash or fly ash. The percentage of these three types of coal ash accounts for 10 to 15% of flooring, 3 to 7% of ash ash, and 80 to 90% of fly ash. The size of the fly ash particles is 0.1 to 10 mm for bottom ash, 0.1 to 1 mm for ash ash, and 1 to 100 ㎛ for fly ash. The chemical composition and physical properties of fly ash and bottom ash, which occupy the majority of coal ash, are shown in Table 1 below.

Chemical Composition and Physical Properties of Coal Ash Chemical Composition (%) Physical Characteristics CaO SiO ₂ Al ₂ O ₃ MgO Fe ₂ O ₃ density
(g / cm ³⁾ Particle size distribution
(탆) Bulk density
(g / cm ³⁾ Fly ash 1.2 66.1 23.3 0.8 4.2 2.13 1-100 0.75 Flooring 1.9 45.5 27.8 0.9 5.7 1.98 100-10000 0.85

Since coal ash has similar properties to cement, its utilization as cement substitute is sought. However, the concrete component ratio of the constituents is not so much different from that of the cement, so that the cement can not be replaced by 100%, and no method has been reported for replacing coarse aggregate such as fine aggregate such as sand or coarse aggregate such as gravel .

In the mortar composition, the cement may be a portland cement, a blast furnace slag cement or a portland pozzolan cement.

The chemical composition and physical properties of the most commonly used Portland cement among the above cements are shown in Table 2 below.

Chemical Composition and Physical Properties of Portland Cement Chemical Composition (%) Physical Characteristics CaO SiO ₂ Al ₂ O ₃ MgO Fe ₂ O ₃ SO ₃ density
(g / cm ³⁾ Particle size distribution (탆) Bulk density
(g / cm ³⁾ 64.9 22.0 5.3 1.3 3.0 1.9 3.15 20-30 1.5

In the mortar composition, the calcined gypsum is a chemical formula CaSO _{4 ·} H ₂ O as trivial name for calcium sulphate half flame. It is also called baked gypsum, half gypsum or calcined gypsum, and is a powder produced by heating gypsum (CaSO _{4 ·} 2H ₂ O) to 120 to 130 ° C and removing 3/4 of the number of crystals. The specific gravity of the calcined powder is 1.7 g / cm ³ , and the bulk specific gravity of the powder is 1.0 g / cm ³ . Although calcite is the oldest cement material, it has been used only for limited use in architectural interiors such as gypsum boards in modern times.

In the mortar composition, the calcium oxide is an oxide of calcium, and calcium carbonate (CaCO ₃ ) is generally produced by losing carbon dioxide (CO ₂ ) when heated in a state where air is blocked.

CaCO ₃ (S) - > CaO (S) + CO ₂ (G)

The quicklime has a melting point of 2,572 ° C., a boiling point of 2,850 ° C., a specific gravity of 3.3 g / cm ³ , and a bulk specific gravity of 1.0 g / cm ^3. When left in the air, water and carbon dioxide are absorbed and calcium hydroxide It becomes calcium carbonate (limestone). Because of its high melting point, quicklime is used to apply to the furnace and crucible walls, to be used as desulfurization and de-phosphorus in the steelmaking field, to neutralize the acidified land in agriculture, and to be used as a supplementary material in the manufacture of lightweight foamed concrete And it is used in an extremely limited manner.

The present inventors have found that when a mortar is produced by mixing an appropriate amount of cement, a calcined powder, a quick lime powder, a retarder, and a thickener based on a coal ash, a proper amount of water is added, It is possible to produce high-quality mortar at low cost without using and additional energy, and also it is possible to produce concrete having excellent characteristics even when reinforcing concrete is manufactured by mixing coarse aggregate without using sand in the mortar The present invention has been completed. Particularly, when a building material such as a brick is manufactured using the mortar composition according to an embodiment of the present invention, since the compressive strength satisfying the KS standard and the thermal conductivity of the cement brick are only about 1/3 and the water absorption rate is high, It is very suitable for use as

When the mortar composition of the present invention is mixed with coal ash and cement to produce mortar, when calcite and quicklime are added as additives other than coal ash and cement, ettringite is formed and the initial strength of the formed product is increased, The increase in tobermorite results in an increase in later strength.

When blending the calcined gypsum to the cement of the cement component C3A (3CaO · Al ₂ O ₃₎ reacts with the calcined gypsum to produce a ettringite, the ettringite formation process is shown in the following scheme.

_{3CaO · Al 2 O 3 + 3CaSO} 4 · H 2 O + xH 2 O → 3CaO · Al 2 O 3 · 3CaSO 4 · 31H 2 O

  Cement + plaster + water → etringing

The tobermorite formation process is shown in the following reaction formula.

_{CaO · SiO 2 · H 2 O} (II) → Ca 5 Si 6 O 16 (OH) 2 · 4H 2 O

    C-S-H (II) - > tobermorite

However, in the process described above, a problem occurs in that sudden phenomenon occurs due to mixing ratio of coal ash, cement and calcite.

In order to solve this problem in the present invention, the present inventors arbitrarily adjusted the condensation rate for a time useful for the operation by adding a proper amount of retarder.

The retarder is used for the purpose of suppressing rapid curing of the mortar, and may be a water reducing agent for cement / concrete, a hydration retarding agent for cement, an inorganic acid, an alcohol or a sugar.

The retarder used in the specific embodiment of the present invention is gelatin, and glutamic acid or glutamic acid contained in gelatin or proline reacts in an alkaline aqueous solution to hydrolyze the carboxyl group (COOH). At this time, the carboxy anion (COO ^- ) formed by separating the proton (H ⁺ ) in the carboxyl group encircles the crystal surface of Ca ^{2+ in} the coal-cement-calcite, and congealing is delayed. The hydrolysis reaction formula with glutamic acid or proline is as follows.

1) Glutamic acid

2) Fullerene

As can be seen from the above formula, by appropriately adding a retarding agent in an alkali solution, the solidification speed of the molding can be appropriately controlled.

However, the solubility of the plaster is low due to low water content, and the curing time of the plaster can not be controlled without the adhesion improver. Therefore, it is possible to improve the water content, improve the plastering workability, and delay the hardening of the gypsum by homogeneously blending a trace amount of thickener in the calcined gypsum.

The thickener is an additive added to improve the viscosity and flocculation action of the mortar or concrete. Examples of the additives include cellulose thickener, polyacryl amide water-soluble polymer, polyvinyl alcohol or polyvinyl acetate acetate, and the cellulose thickener may be methylcellulose, methylcellulose acetate or ethylcellulose.

In addition, the solid content may further include at least one concrete additive selected from the group consisting of a crack reducing agent, an antibacterial agent, a durability improving agent, a water reducing agent, a rapid setting agent, an expanding agent, a foaming agent, and an admixture.

In the mortar composition, water may be added in an appropriate amount within a range having appropriate fluidity of the mortar composition, and 100 to 300 wt% of the cement content may be added.

The present inventors have been making efforts to manufacture bricks by using coal ash, cement and calcined gypsum using coal as a substitute for sand, but failed to produce bricks having required properties. Thus, the mortar was prepared by adding calcium oxide (CaO) to coal ash, cement and calcined stone, and adding the retarder and the thickener as described above, and as a result, succeeded in producing bricks having desirable physical properties.

As a result, the content of silica (SiO ₂ ) or alumina (Al ₂ O ₃ ) used in the process of ettringite or tobermolite formation is very high, but the content of calcium oxide (CaO) It is interpreted that the above reaction is not carried out smoothly despite the addition of a relatively high amount of calcium oxide.

According to another aspect of the present invention, there is provided a concrete composition comprising 1 part by weight of the mortar composition and 0.5 to 3 parts by weight of aggregate.

In the concrete composition, the aggregate may be a fine aggregate, a coarse aggregate, a waste ash, a building waste, a blast slag, a ceramic slab or a mixed aggregate thereof, and it is possible to use only coarse aggregate without fine aggregate.

According to another aspect of the present invention, there is provided a method of manufacturing a mortar composition, And a curing step of curing the molded building material at room temperature. The present invention also provides a method of producing artificial building material containing coal ash.

In the method of manufacturing the artificial building material, the building material may be artificial sand, artificial gravel or brick.

In the method of manufacturing artificial building materials, in the case of artificial sand, it is possible to form particles by using a body having a proper size in the process of curing the mortar composition. In the case of the artificial gravel or brick, the mortar composition And then separating the dried gravel or brick from the mold.

According to another aspect of the present invention, there is provided an artificial building material containing coal ash produced by the above production method.

Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples. It should be understood, however, that the invention is not limited to the disclosed embodiments and examples, but may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, It is provided to fully inform the owner of the scope of the invention.

Example

Preparation of mortar:

1 kg of gelatin as a retarder and 100 g of methylcellulose as a thickener were mixed in 7.5 kg of coarse pulverized coal less than 10 mm, 1.5 kg of cement, 1 kg of plaster and 1 kg of raw plaster, . ≪ / RTI > The water can be adjusted depending on the moisture content of each component.

Manufacture of bricks:

The prepared mortar was poured into a rectangular brick mold, and cured at room temperature for 7 days.

Manufacture of panel:

The prepared mortar was molded into a panel of 90 mm thickness (90 x 333 x 500 mm) and cured at room temperature for 7 days.

Experimental Example

Experimental Example 1: Measurement of compressive strength, water absorption rate and thermal conductivity:

The compressive strength, the water absorption rate and the thermal conductivity of the bricks prepared above were measured and submitted to the Korean Institute of Construction & Environment Test of Daejeon Materials. The results are shown in Table 3 below.

Physical properties of coal bricks Test Items Test result Test Methods Absorption rate 27.3% KS L 8520 2007 Compressive strength 86.7 kgf / cm ² KS L 8520 2007 Thermal conductivity 0.269 kcal / mh ° C KS L 9016

Compressive strength exceeded the KS standard of 80 kgf / cm ² for soft bricks. However, according to the KS L 8520 2007 standard, since the cured brick is immersed in water for 2 hours to measure the compressive strength in the state of being absorbed, the compressive strength is expected to increase when measured in a non-absorbed state, The coal brick according to an embodiment of the present invention is cured for 7 days. When the tobermorite forming reaction proceeds through long-term curing, the compressive strength is expected to further increase.

The water uptake was 27.3%, which was 82% higher than the standard absorption rate of cement bricks of 15% or less. However, when the bricks made of the mortar composition according to one embodiment of the present invention are used as building interior materials, And it is possible to control the humidity of the room by blowing moisture in reverse in winter. Alternatively, when the coal block brick according to an embodiment of the present invention is coated with a waterproofing agent, it may be used as a building exterior.

Experimental Example 2: Sound Insulation Test

The coal panel manufactured according to the above example was installed in a reverberation room having a sound source room capacity of 77.7 m ³ , a sound receiving room capacity of 218 m ³ , an opening area of 5.88 m ^2, and a sound source 1/3 octave band noise environment, The sound insulation test was carried out six times and the average value was obtained. The results are shown in Table 4.

Sound insulation effect of coal panel Frequency (Hz) Transmission Loss (dB) 125 36.0 160 35.3 200 39.8 250 37.6 315 37.0 400 34.6 500 36.8 630 39.8 800 42.9 1.0 k 46.3 1.25 k 48.6 1.6 k 49.6 2.0 k 51.0 2.5 k 53.5 3.15 k 55.5 4.0 k 55.0

* STC: 43 (dB)

The above result is equivalent to the sound insulation performance of the ALC block 200 mm + 10 mm double-sided remitelal (//www.alc.or.kr/sta-03.htm, refer to the Korea Lightweight Foam Concrete Association homepage) In the case of manufacturing a built-in plate by mortar according to an embodiment, a soundproof effect can be obtained while constructing a thinner wall.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

Claims (10)

Water is added to a solid content containing 7.5 parts by weight of coal ash, 1.5 to 3.0 parts by weight of cement, 1.0 to 2.0 parts by weight of calcined kaolin, 1.0 to 2.0 parts by weight of calcium oxide (CaO), 0.01 to 2.0 parts by weight of retarder and 0.01 to 0.5 part by weight of thickener Lt; / RTI > The method according to claim 1,
Wherein the coal ash is fly ash, bottom ash or a mixture thereof. The method according to claim 1,
Wherein the cement is Portland cement, blast furnace slag cement or Portland pozzolan cement. The method according to claim 1,
Wherein the retarder is a water reducing agent for cement / concrete, a hydration retarder for cement, inorganic acids, alcohols, amino acids, proteins or sugars, or a mixture thereof. The method according to claim 1,
Wherein the thickener is a cellulose-based thickener, a polyacrylamide-based water-soluble polymer, polyvinyl alcohol or polyvinyl acetate. A concrete composition comprising 1 part by weight of the mortar composition of any one of claims 1 to 5 and 0.5 to 3 parts by weight of aggregate. The method according to claim 6,
Wherein the aggregate is a fine aggregate, a coarse aggregate, a waste ash, a building waste, a blast slag, a ceramic slab or a mixture thereof. A molding step for molding the mortar composition according to any one of claims 1 to 5; And
And a curing step of curing the molded body at room temperature. 9. The method of claim 8,
Wherein the artificial building material is artificial sand, artificial gravel or brick. An artificial building material containing a coal ash produced by the manufacturing method of claim 8.