KR20120044011A - Geopolymer composition and manufacturing method thereof - Google Patents

Abstract

PURPOSE: A geo polymer composition and a manufacturing method thereof are provided to improve initial and post compressive strength without using cement by adding potassium silicate solution to a mixture of coal ash, blast furnace slag, and cinder. CONSTITUTION: A manufacturing method of GEO polymer composition comprises next steps: mixing coal dust, blast furnace slag, and fuel ash in a mass rate of 10-50:30-70:10-50; stirring the mixture at a speed of 250rpm for 5 minutes; and adding 30-60 parts by weight of modified liquid potassium silicate based on 100 parts by weight of the mixture. The modified liquid potassium silicate comprises 30-80 weight% of potassium silicate, 5-30 weight% of potassium hydroxide, and 15-60 weight% of water. A compressive strength of 28 days cured GEO polymer composition is 60MPa or greater.

Description

Geopolymer composition and method for manufacturing the same

The present invention relates to a geopolymer composition comprising coal ash, blast furnace slag and combustion materials.

Recently, technologies for using coal ash as a cement substitute have been developed. Coal ash is currently generated from thermal power plants and cogeneration plants. Such coal ash has a high ratio of amorphous glassy phase and clay-like chemical composition (SiO ₂ , Al ₂ O _3, etc.), which can replace natural clay in cement manufacturing. It also acts as a flux to lower the production temperature of cement. It is also a material that is utilized as a cement admixture due to its high amorphous glass phase content and spherical high fluidity.

In the dissolution process, the condensation process, and the condensation polymerization process by activating the coal ash and the blast furnace slag in the amorphous glass phase, the burned ash which was incinerated after construction was used as a coagulation delay and admixture to express higher strength than cement. It is to provide a geopolymer cement composition. Unlike the conventional cement manufacturing process, this geopolymer composition manufacturing process has a low energy consumption and does not emit a large amount of CO ₂ . In addition, there is an advantage that does not require mechanical mixing (milling), elution for a long time, high temperature reaction (more than 100 ℃) to give a special high energy. The geopolymer composition prepared by the present invention exhibits very stable volume stability, high initial and late compressive strength, excellent durability and high fire resistance.

Geopolymer composition according to the present invention is a geopolymer mortar, concrete and heavy metals for fireproof panels, fireproof panels, high-strength concrete, high-strength repair mortar, artificial marble, artificial rock, building materials, ceramic tiles, buildings, etc. It can be utilized as a useful binder for immobilization of various industrial by-products.

Geopolymer manufacturing techniques known to date have used silicates and hydroxides as alkaline materials such as pure alumina, silica, calcium oxide and the like. In Korean Patent No. 10-0846821, a geopolymer material is manufactured from fly ash, which is a step of pulverizing and milling raw fly ash material in a ball mill or vertical roller mill, which is a mechanical mixer. Mixing in the step of mixing, mixing with an alkaline activator such as silicate or hydroxide of potassium or sodium, and molding into a desired form, followed by curing in a temperature range of 60 to 250 ℃. However, this technique requires energy consumption for processing compared to using the generated fly ash as it is, and since it is manufactured in a temperature range of 60 to 250 ° C. after molding, it also has a disadvantage of consuming a lot of energy.

Korean Patent No. 10-0852215 relates to an eco-friendly ecobrick manufacturing method using a geopolymer reaction of briquette materials, and more specifically, eco-friendly and excellent performance of ecobrick production using sodium hydroxide aqueous solution as an alkaline stimulant to briquettes produced after briquette combustion. However, this technique uses high concentrations of NaOH, so whitening occurs due to remaining Na ions after the reaction, and whitening generated on the surface becomes a major factor that causes product contamination. In addition, since high concentration of NaOH is used, the alkalinity of the product is high, so when it is installed near a river or a human body, it may cause skin trouble by alkali, and thus there is a limit to use.

Korean Patent No. 10-0807244 discloses an amorphous composition of a high refractory inorganic binder which improves the structural safety and heat shielding properties of main structural members by preventing cross-sectional loss and explosive explosion caused by high temperature due to fire in high-rise and underground concrete structures. The present invention relates to an orthopedic fireproof board manufactured from the composition, wherein the fly ash 5-20 wt%, the metakaolin 5-20 wt%, the fine aggregate 35-70 wt%, the alkaline stimulant 5-15 wt% and the alkali silicate solution 5-10 wt% Korean Patent No. 10-0759855 relates to a non-plastic inorganic binder using an alkali stimulant and fly ash, and replaces cement and cement secondary products by recycling a large amount of fly ash generated and discarded in Korea. To provide non-plastic inorganic binders, but these patents use fly ash and metakaolin, In age 28 days the compressive strength has a drawback stopping to about 20MPa since the property is not a composition which can sufficiently exhibit the compressive strength of the composition. This low compressive strength makes it possible to use the structure as an auxiliary but difficult to use as a structure.

Korean Patent No. 10-0796534 discloses a binder composed of 30 to 60% by weight of Portland cement, 30 to 60% by weight of blast furnace slag powder, and 10 to 30% by weight of fly ash as a binder of the concrete composition. This technology also uses blast furnace slag or fly ash as a substitute for cement, so it is not an efficient way to recycle waste resources. As a result, there is a problem that whitening occurs.

In addition, the above techniques also have problems of lack of compressive strength and fluidity. Cement-containing compositions solve the problem by adding a separate water reducing agent, a fluidizing agent, etc. due to the lack of fluidity.

In addition, the utilization of the combustibles to date is not present, and at the time of dumping off the sea at a cost of more than 100,000 won per ton. The present invention proposes to recycle the combusted material which has been treated only by landfill and ocean dumping as one of the circulating resources, and solves the problem of fastening the geopolymer material by using the characteristics of the components in the combusted material, and furthermore, a new binder. As one of the raw materials of, it is to make high added value.

The present invention aims to solve the problems of the prior arts, and in particular to provide a geopolymer composition as an alternative material for cement. Another object of the present invention is to provide a geopolymer composition having excellent initial and late compressive strengths. Another object of the present invention is to use a combustion material as a raw material for building materials, delay the rapid curing of the geopolymer by using the component properties of the combustion material to express high strength mechanical properties, recycling amount up to 50% by weight To enlarge. It is yet another object of the present invention to provide a wider range of construction materials and applications that require varying strengths by providing geopolymer compositions. It is still another object of the present invention to provide a new geopolymer cement that exhibits the same or higher strength as the cement concrete product and exhibits mechanical properties through the complementary action of the combustion material and the coal material.

In the geopolymer composition of the present invention, the ratio of coal ash: blast furnace slag: combustion ash is 10 to 50% by weight: 30 to 70% by weight: 10 to 50% by weight, and the modified liquid potassium silicate is added to 100 parts by weight of the mixed powder. To 60 parts by weight. Table 1 shows the chemical composition of the powder.

[Table 1]

The coal ash used in the present invention includes not only the coal briquette coal of the thermal power plant used in the above inventions, but also anthracite coal ash containing a large amount of coal ash and uncoal briquettes generated from cogeneration plants with little utility. Anthracite coal ash or cogeneration power plant coal ash, which could not be utilized for conventional cement production, is also a very important raw material in the present invention. The role of the coal ash serves to improve the strength of the geopolymer composition by expressing properties similar to the pozzolanic reaction in the cement system. The use of coal ash alone is difficult. It is difficult to express the physical properties of building / civil engineering materials with low physical properties. To express high physical properties with coal materials alone, high stimulation effect of high temperature hydrothermal method or high alkali solution (NaOH or KOH 10M or more) is used. Although possible, high temperature hydrothermal or high alkaline solutions are economically expensive, have a problem requiring equipment, and are undesirable due to excess alkalinity from excessive use of NaOH or KOH, which can lead to poor results in water-related environments.

In the use of coal ash, it is preferable to use 10 to 50% by weight regardless of the kind of coal ash. When considering the role and ratio of the coal ash in the composition of the combustion ash and blast furnace slag and coal ash pursued in the present invention, it is difficult to achieve the amount of use and the compressive strength value of the combustion ash intended for the present invention. If it is used at less than 10% by weight, the role of coal ash itself is lacking, and the use of blast furnace slag and combustion ash should be relatively increased.Increasing the use of blast furnace slag causes a problem of rapid freezing. As a result, the final compressive strength of the paste for the purpose of the present invention cannot be achieved, and the amount of Cl in the combustion material is high, which greatly delays curing, which is not preferable. In this respect, the role of coal ash plays a very important role in the geopolymer composition.

Coal ash and combustor have spherical particle characteristics with particle size of about 20㎛, so it is easy to flow between particles and absorbs small amount of added liquid, so it can be molded by adding small amount of alkaline solution. good.

The blast furnace slag used in the present invention contains a large amount of an amorphous glass phase, and the high content of the amorphous phase has high activity during the geopolymer reaction, thereby showing a movement for lowering energy. This easily occurs even in contact with a small amount of alkaline substances. The main reactor of blast furnace slag is stimulation of Si-O and Al-O by hydroxy radicals when it comes into contact with highly alkaline modified liquid potassium silicate, which breaks covalent bonds and elutes ions. By condensation polymerization, monomers of [SiO ₄ ] ^-4 and [AlO ₄ ] ^5- are formed. In particular, blast furnace slag is the most important raw material expressing the high strength of the typical geopolymer cement of alkali activated cement, and is used in various fields with better reactivity than coal ash or metakaolin.

However, it is also true that blast furnace slag has limited utility due to too fast curing and unstable long-term mechanical strength. Therefore, in the present invention, for the purpose of fast curing control of the blast furnace slag, by adding a combustion material to control the initial reaction by Cl in the combustion material, by adding a coal material, a compact composition molded body is possible through the improvement of the filling properties of the coal ash. Since the high content of SiO ₂ and Al ₂ O _{3, which} are the chemical constituents, are higher than the blast furnace slag, it acts to increase the production of aluminosilicate gel, which is a product of geopolymer in the long term.

If the amount of blast furnace slag is less than 30% by weight, the compressive strength cannot achieve the target value of the present invention because the reactivity of coal and combustor must be dependent, and if it exceeds 70% by weight, blast furnace slag is used. Because of the increase in the use of cracks due to the initial generation of quenching and hydration heat generated therefrom, there is a concern that the cracks are caused by the expansion and growth of the generated cracks, such as long-term strength decreases. In addition, since the addition amount of coal ash and the amount of combustion ash is lowered, the recycling rate of the combustion ash is lowered, and the amount of the modified liquid potassium silicate is increased, thereby increasing the production price.

The combustor is an incineration ash remaining after incineration by heat treatment of industrial waste at a high temperature, and has similar characteristics to that of general household incineration ash. On the other hand, since it is a waste generated through all kinds of industrial activities, all the waste is disposed of by dumping at sea or by landfill. As shown in Table 1, these combustors have high Cl ions and CaO components from the neutralization treatment of slaked lime, hydrochloric acid, etc. during the combustion process. It also contains a lot of Na ions and K ions.

The CaO component is dissolved as an ion under the liquid (pH) of the highly alkaline reforming liquid upon formation of the geopolymer, and becomes a main component that forms CSH by reacting with the Si (OH) ₄ monomer. This reaction structure is the same as that of blast furnace slag. In addition, Cl ions often act as accelerators to form etringite when added in small amounts.

A small amount of NaCl, as identified in the Patent No. 10-0966293 (the prior patent of the present inventor) is a Cl adhering to the surface of fly ash ^- is because the elution of Al ⁺ ₃ ions and promoted by ions. At this time, NaCl is not particularly specified and may be used for commercial or edible products.

In addition, inorganic chlorides such as KCl, CaCl ₂ and MgCl ₂ may be used instead of NaCl as a stimulant. From the above characteristics of improving the strength of NaCl and fly ash, it is explained that the product manufactured by the present invention has a property of maintaining durability without using a surface reinforcing agent or a glossing agent such as a model of the product. In addition, a certain amount of Cl ions serves to suppress the quenching phenomenon of the geopolymer. This ion forms a certain amount of HCl ions by reaction with water, and the high alkaline liquid of the geopolymer is inhibited for a certain time by acidic ions, and then gradually loses its inhibitory power, and the geopolymer reaction proceeds. However, since the higher the content of Cl ions, the inhibitory power is maintained, the higher the content of the combustor, the greater the effect on the geopolymer composition, thereby reducing the mechanical strength. In addition, excessive addition of the combustion material may cause a whitening problem because excess Na ions are provided.

In the present invention, a large amount of Cl in the combustion material is present in the form of NaCl and KCl, it is impossible to achieve the target of the present invention if it is out of the specified range. The amount of the combustion material used is preferably in the range of 10 to 50% by weight. If it is used less than 10% by weight, it is not only insufficient in terms of recycling, but it is not possible to obtain a target delay effect, and when it is used more than 50% by weight, the target compressive strength cannot be obtained, and there is a possibility of whitening. It is not desirable to increase.

In addition, the modified liquid potassium silicate used in the present invention is composed of 30 to 80% by weight potassium silicate, 5 to 30% by weight caustic and 15 to 60% by weight of water. Potassium silicate is used in the range of 30 to 80% by weight, most preferably 50% by weight. Also caustic is preferably 5 to 30% by weight, most preferably 10% by weight. Caustic carry's role is to promote alkali irritant effect through pH increase. The amount of caustic and potassium silicate added is determined according to the amount of water used, and the amount of water is preferably 15 to 60% by weight. Most preferably 30% by weight is added.

It is necessary not to use existing alkaline materials with any Na ₂ O. The use of Na ₂ O in high dissociation properties is not desirable because the object of the present invention is to be exposed to nature to contact with rain or to be used in the air temperature change and in water. In addition, Na ₂ O, which is highly dissociable, is included in the condensation or evaporation process of moisture and is transferred to the surface and reacts with CO ₂ gas in the air to generate substances such as Na ₂ CO ₃ , causing whitening. Since cracking of the surface occurs, there is a problem of inferior long-term stability. For this purpose, it is necessary to design low dissociation of Na ₂ O or to use materials having excellent water repellency or waterproofing properties, thereby decreasing general utility. Potassium silicate used in the present invention and caustic used in the reforming is one of the main raw materials mainly used where whitening is concerned because the rate of curing at room temperature is low and the carbonic acid reaction is lower than that of sodium silicate.

The modified liquid potassium silicate composition used in the present invention is in the range of 30 to 80% by weight potassium silicate, 5 to 30% by weight caustic and 15 to 60% by weight of water, respectively, the amount of each of which is out of this limited range, In case of potassium, when used less than 30% by weight, the amount of monomer production of Si (OH) ₄ , which acts as a seed in geopolymer formation, is insufficient, and thus initial and long-term strength cannot be satisfied. In this case, the concentration is very high, and the fluidity is greatly reduced. In order to secure the minimum flowability of 180mm to 230mm to fill the mold, it is necessary to add an excessive amount to secure the target flowability, which may raise the cost. At the same time, problems such as whitening occur due to the generation of free SiO ₂ due to the formation of excess monomers.

In addition, if a modified liquid suitable for economical efficiency is added, a relatively small amount should be used, so that molding is difficult due to lack of fluidity, which causes a quenching, which makes the molding operation itself difficult. In addition, when less than 5% by weight of caustic carry the pH value can not achieve the target 12.5, when exceeding 30% by weight, the pH value is> 14, the alkali irritation effect is increased, but the excess alkali Cationic and OH radicals can cause problems that adversely affect the environment. In addition, there is a problem that the weight ratio rises sharply, and the economic feasibility decreases.

In addition, when the amount of water used is less than 15% by weight, the specific gravity is increased, so that a large amount of modified liquid potassium silicate must be added to secure effective fluidity, and the market competitiveness is lowered due to the price increase. In addition, if it exceeds 60% by weight, it is advantageous in securing fluidity and economical efficiency, but it is difficult to manufacture a high strength binder targeted in the present invention, and in particular, the amount of the combustion material suitable for expressing the compressive strength required as a building material is There is a problem of being very low.

The modified liquid potassium silicate used in the present invention is preferably used so that the ratio (molar ratio) of K ₂ O / SiO ₂ to industrial potassium silicate is 0.63 to 1.0 so as to have a pH of 12.5 or more. When the K ₂ O / SiO ₂ ratio of potassium silicate used is less than the above range, the initial compressive strength is hardly expressed, and when it exceeds the above range, it breaks down even at a small impact due to lack of fluidity and cracking. Problems may arise. More preferably, the ratio of K ₂ O / SiO ₂ is adjusted to be used in the range of 0.60 to 0.80.

The amount of the modified liquid potassium silicate is preferably 30 to 60 parts by weight based on 100 parts by weight of the mixture of coal ash, combustion ash and blast furnace slag. If this range is exceeded, it is difficult to secure the target fluidity and compressive strength, and the business feasibility is lowered due to the lack of economy due to liquidity and use.

The geopolymer composition of the present invention comprises the steps of mixing the coal ash: blast furnace slag: combustion material in a ratio of 10 to 50:30 to 70:10 to 50% by weight; 5 minutes high speed mixer at 250 rpm; It consists of adding 30 to 60 parts by weight of modified liquid potassium silicate consisting of 30 to 80% by weight potassium silicate, 5 to 30% by weight caustic and 15 to 60% by weight water, based on 100 parts by weight of the mixed powder. Such a composition is a high-strength geopolymer composition that exhibits a compressive strength of 40 MPa or more and 60 MPa or more at 28 days of age only by performing low temperature curing for 4 to 24 hours at room temperature to 100 ° C. after mixing. In addition, the geopolymer concrete manufactured using the same has a characteristic of expressing at least 30 MPa, which is a reference strength of cement concrete, with 28 days strength.

The high-strength geopolymer composition of the present invention exhibits initial and later compressive strengths above the cement level even without the use of cement, and can effectively secure crack generation and fluidity that adversely affects the strength by effectively using a combustion material. The geopolymer composition may be used together with sand, aggregate, and the like, and may be effectively used as road paving materials, building materials, repair materials, and the like. In addition, it can be mixed with ceramic fiber and ceramic chamotte, etc., and used as a heat insulation material for fireproof, fireproof panel, and concrete anti-expanding coating.

1 is an electron micrograph of the fracture surface of the specimen prepared in Examples 1 and 2,
2 is a graph showing the compressive strength of the geopolymer composition prepared by Examples and Comparative Examples,
3 is a graph showing the results of chemical component analysis in the microstructure of the specimen prepared by Example 1,
4 is an electron micrograph of the fracture surface of the specimen prepared by Comparative Examples 1 and 2.

An embodiment of the present invention is as follows.

( Example  One)

Coal ash: Blast furnace slag: Combustion ash mixture ratio of 50:40:10 was 100 parts by weight, and the ratio of K ₂ O / SiO ₂ was adjusted to 0.80, and the modified liquid potassium silicate having a solid content of 45%. Was added to 53 parts by weight of the slurry to make a flow of 230mm, and then molded in such a way to remove and fill the bubbles while applying vibration to a 5 × 5 × 5cm triple cube mold, and maintained at room temperature for about 4 hours After balancing the evaporation of water on the surface and curing for 8 hours at a temperature of 60 ° C, the compressive strength of the specimen measured after 3, 7, and 28 days of age was 117.8 MPa, 120.9 MPa, and 128.9 MPa, respectively. Expressed high compressive strength.

The fracture surfaces of the specimens prepared in Examples 1 and 2 were observed through an electron microscope, and are shown in FIG. 1. The compressive strength graph of the geopolymer composition prepared according to the present embodiment is shown in FIG. 2. 3 shows the chemical component analysis results in the microstructure.

From the chemical component analysis results of the dense part of the geopolymer composition, it was confirmed that the peaks of Si and Al, which are the main components of the coal ash and the amorphous aluminosilicate gel (geopolymer product), were strongly developed (Table 2).

TABLE 2

( Example  2)

It carried out similarly to Example 1, but changed the mixing ratio of coal ash: blast furnace slag: combustion ash to 40:50:10, and changed the modified liquid potassium silicate to 43 weight part. As a result, the compressive strengths of 3, 7, and 28 days old specimens were 96.4 MPa, 83.0 MPa, and 134.6 MPa, respectively.

( Example  3)

It carried out similarly to Example 1, but changed the mixing ratio of coal ash: blast furnace slag: combustion ash to 30:50:20. As a result, the compressive strengths of 3, 7, and 28 days old specimens were 82.4 MPa, 98.3 MPa, and 114.6 MPa, respectively.

( Example  4)

It carried out similarly to Example 1, but changed the mixing ratio of coal ash: blast furnace slag: combustion ash to 20:50:30. As a result, the compressive strengths of 3, 7, and 28 days old specimens were 67.0 MPa, 88.6 MPa, and 95.0 MPa, respectively.

( Example  5)

It carried out similarly to Example 1, but changed the mixing ratio of coal ash: blast furnace slag: combustion ash to 10:50:40. As a result, the compressive strengths of 3, 7, and 28-day-old specimens expressed 47.0 MPa, 67.7 MPa, and 83.5 MPa, respectively.

( Example  6)

It carried out similarly to Example 1, but changed the mixing ratio of coal ash: blast furnace slag: combustion ash to 10:40:50. As a result, the compressive strengths of 3, 7, and 28-day-old specimens expressed 47.9 MPa, 47.6 MPa, and 63.5 MPa, respectively.

( Example  7)

In the same manner as in Example 1, the mixing ratio of coal ash: blast furnace slag: combustion ash was changed to 28:30:42. As a result, the compressive strengths of 3, 7, and 28-day-old specimens expressed 40.5 MPa, 45.9 MPa, and 63.7 MPa, respectively.

( Example  8)

It carried out similarly to Example 1, but changed the mixing ratio of coal ash: blast furnace slag: combustion ash to 18:70:12. As a result, the compressive strengths of 3, 7, and 28-day-old specimens expressed 70.3 MPa, 92.7 MPa, and 121.9 MPa, respectively.

( Comparative example  One)

It carried out similarly to Example 1, but changed the mixing ratio of coal ash: blast furnace slag: combustion ash to 0:30:70. As a result, the compressive strengths of 3, 7, and 28-day-old specimens expressed 16.7 MPa, 18.2 MPa, and 30.8 MPa, respectively. These results indicate that the hardening characteristics of the binder composition, which is composed of combustible ash and blast furnace slag, which are weak in fluidity and reactivity as coal is formed in the absence of coal ash, are greatly influenced by the organic curing characteristics of coal ash, combustion ash and blast furnace slag. Because it is not crazy. In particular, the increase in the amount of Cl and the increase in the Cl component in the combustor suppresses the hardening of the inorganic binder as the amount of the combustor is increased (Fig. 4 (left)).

( Comparative example  2)

Usually, 30 parts by weight of water is added to 100 parts by weight of Portland cement, followed by slurrying, followed by vibration filling molding in a vibration molding machine. The molded specimens were naturally cured for 4 hours and then demolded and cured at 60 ° C. for 8 hours. After curing, the specimens were cured for 3, 7, 28 days, and the compressive strength characteristics were evaluated. As a result, the compressive strengths of 3, 7, and 28 days old specimens were 48.1 MPa, 57.4 MPa, and 60.6 MPa, respectively, which are very low values compared to the compressive strength of the geopolymer composition. In addition, the pH value after 28 days of water contact of the 28-day age specimen was 13.3. 4 (right) shows a microstructure photograph after 28 days of age of cement. In the picture, the needle-shaped particles, which are expected to be cement hydrates, are well developed between the plate-shaped particles. This can be confirmed that very different from the microstructure of the geopolymer composition of FIG.

[Table 3]

FA1: coal ash, FA2: combustion ash

[Table 4]

TABLE 5

TABLE 6

( Example  9)

The same procedure as in Example 1 was carried out, but the modified liquid silicic acid was added to 100 parts by weight of the secondary mixture of 23% by weight of a mixture of coal ash and blast furnace slag, 25% by weight of sand, and 52% by weight of natural granite aggregate (13 mm). 37 parts by weight of potassium was added to prepare geopolymer concrete using a geopolymer composition consisting of coal ash, blast furnace slag and combustion materials. Preparation conditions and strength measurements are shown in Tables 5 and 6. As a result, after 3, 7, 28 days of age, the compressive strength was 39.5MPa, 47.6MPa, 48.3MPa, respectively. In addition, the flexural strength after 3, 7, 28 days of age was 4.4MPa, 4.9MPa, 5.7MPa, respectively.

( Example  10)

In the same manner as in Example 9, the binder production conditions were carried out in the same manner as in Example 2, the mixture conditions of the mixture of coal ash, blast furnace slag and combustion materials. As a result, after 3, 7, 28 days of age, the compressive strength was 41.3MPa, 46.2MPa, 49.9MPa respectively. In addition, the flexural strength after the age of 3, 7, 28 days was 4.4MPa, 4.4MPa, 6.6MPa, respectively.

( Example  11)

Example 9 was carried out in the same manner as in Example 4, but the conditions of the mixture of coal ash, blast furnace slag and combustion ash were carried out in the same manner as in Example 4. As a result, after 3, 7, 28 days of age, the compressive strength was 28.0MPa, 33.3MPa, 38.5MPa respectively. In addition, the flexural strength after 3, 7, 28 days of age was 3.0MPa, 4.3MPa, 6.1MPa, respectively.

( Example  12)

In the same manner as in Example 1, but the conditions of the mixture of coal ash, blast furnace slag and combustion ash was carried out in the same manner as in Example 5. As a result, after 3, 7, 28 days of age, the compressive strength was 27.0MPa, 27.3MPa, 35.7MPa respectively. In addition, the flexural strength after the age of 3, 7, 28 days was 2.6MPa, 2.6MPa, 3.4MPa respectively.

Claims (4)

Mixing the coal ash: blast furnace slag: combustion material in a ratio of 10 to 50:30 to 70:10 to 50% by weight; High speed mixing the mixture at 250 rpm for 5 minutes; High strength consisting of adding 30 to 60 parts by weight of a modified liquid potassium silicate consisting of 30 to 80% by weight potassium silicate, 5 to 30% by weight caustic, 15 to 60% by weight water based on 100 parts by weight of the mixed powder Method for preparing geopolymer composition.
A high-strength geopolymer composition prepared by the method of claim 1 and having a compressive strength of 40 MPa or more for 3 days of age only by performing low temperature curing for 4 to 24 hours in a temperature range of room temperature to 100 ° C.
The high strength geopolymer composition of claim 2 wherein the compressive strength at 28 days of age is at least 60 MPa.
The geopolymer concrete of claim 2, which is made of the high-strength geopolymer composition, sand and aggregate, wherein the 28-day compressive strength expresses at least 30 MPa, which is the reference strength of cement concrete.

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