KR20170090602A - Cement admixture composition with biomass ash - Google Patents

Abstract

The present invention relates to a cement admixture composition, and more specifically, to a concrete admixture composition capable of effectively preventing reduction in initial strength and using cement, which is a problem of conventional fly ash, widely used as a cement admixture. The cement admixture composition of the present invention contains 100 parts by weight of low alkali fly ash having a SiO_2 content of 45 to 70 wt% and a CaO content less than 10 wt%, and 20 to 500 parts by weight of a palm kernel shell material having a CaO content of 5 to 50 wt% and an SO_3 content of 1 to 15 wt% and being discharged from a combustion process of a circulating fluidized bed combustion boiler.

Description

TECHNICAL FIELD The present invention relates to a cement admixture composition containing a biomass burned material,

The present invention relates to a cement admixture composition, and more particularly, to a concrete admixture composition capable of effectively preventing reduction of initial strength and using cement, which is a problem of conventional fly ash, which is widely used as a cement admixture.

Approximately 8% of CO ₂ emissions, which account for 55% of greenhouse gases, are emitted from portland cement manufacturing. As a result, the amount of carbon dioxide emitted is about 0.50 tonnes in the calcining stage of limestone, about 0.40 tonnes in the calcining process through the burning of fossil fuels, and eventually about 0.9 tonnes of carbon dioxide is produced each time 1 ton of portland cement is produced.

As a countermeasure against this problem, it is necessary to develop a technology to minimize the amount of portland cement by using fly ash as a byproduct of thermal power plant.

Generally, fly ash which is used in Korea is discharged from a thermal power plant having a separate desulfurization facility. Since its main component is amorphous SiO ₂ and its CaO content is less than 10 wt%, neutral and low alkali Material.

The reaction of fly ash starts secondarily. For this reason, when using fly ash mixed with portland cement, problems such as delayed coagulation, initial strength reduction, and neutralization are caused. Due to such a phenomenon, problems may occur in the construction site, such as delay in form deformation, deterioration in initial strength, and deterioration in long-term durability due to neutralization, so that the content of fly ash is 5 to 20 wt% have.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, and it is an object of the present invention to provide a fly ash which is widely used as a cement admixture, And a cement admixture composition comprising a mixture of a cement paste, a mass flux, a slag powder, and a magnetic pole material.

In order to solve the above-mentioned technical problems, the cement admixture composition according to the present invention is characterized in that, in 100 parts by weight of low alkali fly ash having an SiO ₂ content of 45 to 70% by weight and a CaO content of less than 10% by weight, The CaO content is 5 to 50% by weight, the SO ₃ And 20 to 500 parts by weight of a palm kernel shell material having a content of 1 to 15% by weight.

And 10 to 1,000 parts by weight of a slag fine powder per 100 parts by weight of the low alkali fly ash, wherein the fine slag powder is selected from the group consisting of a converter fine powder, an electric furnace slag fine powder, a blast furnace slag fine powder, a ferronickel slag fine powder, It is preferable to include any one or a mixture of two or more selected from the group consisting of fine powder, fine copper slag powder, stainless steel refining slag fine powder, KR slag fine powder, and desulfurized slag fine powder.

The alkali stimulant may further comprise 5 to 200 parts by weight of an alkali irritant based on 100 parts by weight of the low alkali fly ash. The alkali irritant may be selected from the group consisting of quicklime, slaked lime, light dolomite, anhydrous gypsum, Or a mixture of two or more thereof.

According to the present invention, it is possible to prevent the initial strength reduction, which is a problem of conventional fly ash widely used as an admixture, and to secure economical efficiency by using low-priced industrial byproducts.

Hereinafter, the binder composition according to the present invention will be described in detail.

The cement admixture composition according to the present invention is discharged from a circulating fluidized-bed combustion boiler combustion process with respect to 100 parts by weight of low alkali fly ash having an SiO ₂ content of 45 to 70% by weight and a CaO content of less than 10% by weight and has a CaO content of 5 to 50 % By weight, SO ₃ And 20 to 500 parts by weight of a palm kernel shell material having a content of 1 to 15% by weight.

The palm kernel shell material is a kind of biomass soft material. Biomass refers to the use of trees, grasses, livestock manure, and food waste as energy sources. Biomass can be translated as biotic organic resources, biomass or biomass as the original ecology term. This means the organic quantity (usually expressed in dry weight or carbon content) of living animals, plants and microorganisms. In ecological terminology, therefore, stem roots and leaves of trees are representative biomass, and do not include fossil fuels such as petroleum or coal. In other words, organic wastes (waste materials, animal manure, etc.), which are dead organic matter, are not biomass. In general, however, industrial wastes are usually included in biomass.

Urban gas, oil, electricity, etc. are convenient, but cause a lot of pollution. Using chemical engineering, biotechnology, and genetic engineering techniques, you can turn many types of biomass into methane, hydrogen gas, and electricity, similar to alcohol (methanol, ethanol) or city gas. These things are made up of alcohol, gas, or rice briquettes, grains, fruits, vegetables, etc. - and they are good fuels - for example, straw straws, straw straws, soybeans, corn stalks, sesame stalks, pepper stalks and fruit trees. .

On the other hand, since the palm kernel shell has a calorie of 4,500 ~ 4,700 Kcal / kg, it can be used as a composite raw material of coal and has a property of igniting easily because it has fewer components than coal. There are no studies on the soft materials that are generated after the burning of the kernel of the palm kernel, and thus it has not been utilized at all in the industrial field to date.

The biomass burned material according to the present invention is discharged from a burning process of a circulating fluidized bed boiler such as a thermal power and a cogeneration power plant having a furnace desulfurization facility using a palm fruit husk or woody biomass as fuel.

In particular, the palm kernel shell material, which is a biomass burning material, is generated in a circulating fluidized bed boiler combustion process in which only the palm kernel shell is mixed with the fuel or the palm kernel shell and coal are mixed.

Palm kernels are produced in a conventional pulverized coal combustion process. When CaO and SO ₃ contents are high, they act as alkali and sulphate stimulants for slag fine powders when used in combination with low alkali fly ash or slag fine powders, And has the property of manifesting latent hydraulicity.

Preferably, the biomass burned material comprises 20 to 500 parts by weight of the low alkali fly ash, based on 100 parts by weight of the low alkali fly ash. When the biomass combustible material is mixed with less than 20 parts by weight, the strong alkali and sulfate stimulating effect is insignificant, and when it exceeds 500 parts by weight, surplus amount that does not react with fly ash or slag exists.

When water is added to ordinary low-alkali fly ash, an acidic glassy coating film is formed on the surface, and the internal silica component is not eluted. However, at this time, a pozzolanic reaction in which a highly alkaline substance such as Ca (OH) ₂ (for example, biomass burned material) destroys an acidic glassy coating and produces CaO-SiO ₂ -H ₂ O- do. However, since Ca (OH) ₂ is generated secondarily after C ₃ S or C ₂ S component of the cement component starts hydration reaction, the pozzolanic reaction of low-alkali fly ash occurs after at least 7 days It can contribute to the strength and the initial strength is very low. In addition, since the Ca (OH) ₂ component of the cement reacts with the low-alkali fly ash gradually in the long-term, the lack of the Ca (OH) ₂ component in the concrete decreases the generation of CSH hydrate in the long- And the neutralization of concrete is accelerated, so that the neutralization resistance function necessary for preventing corrosion of steel bars and steel frames is also lowered. Therefore, since the palm kernel shell material has a high CaO content, it is converted to Ca (OH) ₂ after the reaction with water, and then the Ca (OH) ₂ component continuously acts as an alkali stimulant of low- It is possible to manufacture concrete admixture which can improve the initial strength and neutralization resistance of concrete by supplying concrete.

In addition, the admixture according to the present invention may further include a slag fine powder, wherein the slag fine powder is selected from the group consisting of a converter fine powder, an electric furnace oxide slag fine powder, a blast furnace slag fine powder, an electric furnace reduced slag fine powder, a copper slag fine powder, a stainless steel slag fine powder, It is preferable to further include any one or a mixture of two or more selected from the group consisting of fine powder, KR slag fine powder, and desulfurized slag fine powder.

All of the above slag is discharged as a by-product of steel making and steelmaking process. It contains about 35% of CaO component and can act as an alkali stimulant and prevent neutralization. It is also possible to exhibit potential hydraulic strength, have.

The blast furnace slag fine powder melts in the iron ore producing furnace, and the molten slag is floated on the molten iron. It flows down and rapidly cooled with water (or air) to form small sand particles, Which is vitrified by quenching. Therefore, it is used as slag for blast furnace slag cement and as an admixture for cement and concrete with high reactivity.

The fine blast furnace slag powder is composed of SiO ₂ , Al ₂ O ₃ , CaO and MgO as major chemical components, accounting for 94 to 97% of total chemical components. In the case of portland cement, MgO content is more than 5%, it causes the formation of glass magnesia and causes abnormal expansion. However, it is reported that the blast furnace slag fine powder contains about 15% Or less.

The reaction characteristics of blast furnace slag fine powders are potential hydraulic substances that harden themselves when subjected to alkaline stimuli, although they are in themselves poorly curing properties.

It is also known that hardening is promoted by the action of calcium hydroxide and sulfate, which are cement hydration products, to improve the compressive strength. The quench blast furnace slag has an energy as high as the heat released when it is converted to vitreous. However, when contacted with pure water, a dense irregular acid film is formed on the particle surface of the blast furnace slag due to the elution of Ca ^{2 +} , so that the hydration reaction is not sustained because it inhibits water penetration and dissolution of internal ions. If irritant such as calcium hydroxide is present in this case, the irregular three-dimensional (-O-Si-O-Al-O-) chain bond of the blast furnace slag is surrounded by the network structure while being severed by the strong alkali action And Ca ^{2 +} , Mg ^{2 +} , and Al ^{3 +} ions. The eluted ions generate corresponding hydrates and contribute to the enhancement of the compressive strength. Further, since the alkaline component eluted from the slag in the blast furnace can maintain a high pH once the reaction is initiated, no further irritants are required.

The hydration product of the blast furnace slag is characterized by the formation of calcium hydrate (CSH, a typical composition is C ₃ S ₂ H ₃ ) although it depends on the type of irritant. When sodium hydroxide is added as a stimulant, CSH, C ₄ AH ₁₃ And C ₂ ASH ₈ are produced, and when Ca (OH) ₂ is used as a stimulant, CSH, C ₄ AH ₁₃ is produced but C ₂ ASH ₈ is not produced.

In addition, when sulfate is added as a stimulant, CSH, C ₃ A ₃ CSH ₃₂ and aluminum hydroxide are produced. When sulfuric acid salt and calcium hydroxide are mixedly added, aluminum hydroxide and ettringite are produced. Their hydration reaction formulas can be collectively expressed as follows have.

That is, it can be seen that addition of a stimulant is essential because Ca (OH) ₂ is not produced in the hydration reaction of blast furnace slag.

C ₅ AS ₃ + ₂ CaO + 16 H ₂ O → C ₄ AH ₁₃ + 3 (CSH)

C ₅ AS ₃ + CaSO ₄ + 76 / 3H ₂ O → 3 (CSH) + 2/3 (C _{3 A 3} CSH ₃₂ ) + Al (OH) ₃

Next, the stainless steel refining slag is an industrial byproduct generated in the stainless steel manufacturing process, which is generated in the refining furnace. The slag is obtained by quenching in a dry manner, and has a CaO content of 35 to 70 wt%, Al ₂ O ₃ The content is preferably 1 to 20% by weight, and the SiO ₂ content is preferably 5 to 35% by weight.

The stainless steel scouring slag has a vitreous surface on its surface after quenching, and an acidic coating is formed on contact with water, so that the hydration reaction is not initiated immediately, but the acidic coating is destroyed by OH ^- and SO ₃ ^{2 -} ions emitted from the palm kernel shell material And gradually develops strength.

Stainless steel refining slag is CaO and SiO ₂ as main components and is a crystalline phase which takes a gamma type calcium silicate (2CaOSiO ₂ ) crystal structure. The di-calcium silicate slowly undergoes crystal phase transition from the hot melt phase. Due to this crystal phase transition, volumetric expansion accompanies the volumetric change, which causes a self-collapsing dusting phenomenon during cooling. Such a dusting phenomenon is easy to manufacture a stainless steel refining slag fine powder by a simple manufacturing process because there are few requirements such as grinding.

The slag can be used by pulverizing into a fine powder having a specific surface area of at least 2,500 cm ² / g.

In order to improve the initial strength, it is preferable to further include any one or a mixture of two or more selected from the group consisting of burnt lime, slaked lime, dolomite plaster, anhydrous gypsum, and sintered desulfurized dust generated in steelworks. The alkali stimulant is a general industrial product distributed in the market, and can be used as a powder type product having a specific surface area of 2,500 cm ² / g or more. The cement, water, and aggregate may be mixed with the concrete admixture so that the concrete capable of improving initial strength and resistance to neutralization can be manufactured.

Hereinafter, preferred embodiments and comparative examples of the present invention will be described. The following examples are intended to illustrate the invention and should not be construed as limiting the scope of the invention.

Comparative Example

100 parts by weight of a binder prepared by mixing one kind of ordinary Portland cement in a weight ratio of 1: 1 with respect to 100 parts by weight of a low alkali fly ash having an SiO ₂ content of 45 to 70% by weight or more and a CaO content of 10% 50 parts by weight of water, and 300 parts by weight of ISO standard yarn were mixed to prepare a cement-molded body, and the compressive strength was measured according to the curing time.

Example  One

A biomass burning process in which a CaO content is 10 to 30% by weight and an SO ₃ content is 1 to 15% by weight based on 100 parts by weight of a low alkali fly ash having an SiO ₂ content of 45 to 70% by weight or more and a CaO content of 10% And 20 parts by weight of a jinin palm kernel shell material were mixed to prepare an admixture. 100 parts by weight of the binder prepared by mixing the admixture thus prepared and one kind of ordinary portland cement in a weight ratio of 1: 1 was mixed with 300 parts by weight of ISO standard yarn of 50 parts by weight to prepare a cement- The compressive strength was measured and shown in Table 1.

Example  2

A biomass burning process in which a CaO content is 10 to 30% by weight and an SO ₃ content is 1 to 15% by weight based on 100 parts by weight of a low alkali fly ash having an SiO ₂ content of 45 to 70% by weight or more and a CaO content of 10% 20 parts by weight of Jinyin palm kernel husk material, 100 parts by weight of blast furnace slag powder and 10 parts by weight of anhydrous gypsum were mixed to prepare an admixture. 100 parts by weight of the binder prepared by mixing the thus-prepared admixture and one kind of ordinary Portland cement in a weight ratio of 2: 1 was mixed with 300 parts by weight of ISO standard yarn of 50 parts by weight to prepare a cement- The compressive strength was measured and shown in Table 1.

At this time, the production and strength evaluation method of each of the comparative examples and examples was evaluated in accordance with KS LISO 679 "Method for testing the strength of cement ", and the compressive strengths were measured at 3 days, 7 days, and 28 days and 90 days , And the average value of the measured values of three test specimens on each measurement day is shown as the compressive strength value. In order to measure the neutralization resistance, the cured product of ages of 28 days was set to 20 ± 3 ° C, relative humidity 60 ± 5% and CO2 concentration 10 ± 2% Are shown in Table 2.

division Compressive strength 3 days
(MPa) Compressive strength 7 days
(MPa) Compressive strength 28 days
(MPa) Compressive strength 90 days
(MPa) Comparative Example 14.2 23.3 45.1 50.2 Example 1 15.5 27.7 46.2 51.1 Example 2 15.5 25.4 48.4 52.6

As shown in Table 1, the comparative example shows the compressive strength of a molded article obtained by mixing 1: 1 weight ratio of low alkali flyash and 1 ordinary Portland cement. In Example 1, low alkali fly ash, palm kernel shell It is the compressive strength of the molded body mixed with 1: 1 weight ratio of admixture mixed with material and ordinary Portland cement. Compared with Comparative Example 1, the strength of Example 1 was about 8% higher than that of Comparative Example 1.

Example 2 shows the compressive strengths of a mixture of a concrete admixture prepared by mixing a low-alkali fly ash, a palm kernel shell material, a blast furnace slag powder, a blast furnace slag powder and an anhydrous gypsum powder and a Portland cement in a weight ratio of 2: 1 to be. Although the amount of concrete admixture is increased and the amount of one kind of ordinary Portland cement is reduced, the strength is higher than that of the comparative example, not only from 3 to 7 days but also after 28 days of age. It can be seen that the incorporation of palm kernel shell material and anhydrous gypsum, which are Vice-mash combustion material, is very effective for improving initial strength as well as long-term strength.

Claims (3)

Based on 100 parts by weight of a low-alkali fly ash having an SiO ₂ content of 45 to 70% by weight and a CaO content of less than 10% by weight,
And 20 to 500 parts by weight of a palm kernel shell material having a CaO content of 5 to 50% by weight and an SO ₃ content of 1 to 15% by weight, the mixture being discharged in a combustion process of a circulating fluidized bed combustion boiler.
The method according to claim 1,
Further comprising 10 to 1,000 parts by weight of a slag fine powder per 100 parts by weight of the low alkali fly ash,
The slag fine powder is selected from the group consisting of a converter slag fine powder, an electric furnace slag fine powder, a blast furnace slag fine powder, a ferronickel slag fine powder, an electric furnace reduced slag fine powder, a copper slag fine powder, a stainless steel refining slag fine powder, a KR slag fine powder and a desulfurized slag fine powder Wherein the cement admixture composition further comprises one or more of the mixture.
The method according to claim 1,
Further comprising 5 to 200 parts by weight of an alkali irritant based on 100 parts by weight of the low alkali fly ash,
Wherein the alkali stimulant further comprises at least one selected from the group consisting of quick lime, slaked lime, light dolomite, anhydrous gypsum, and desulfurization and deoxidization processes of steel mills.