KR101305546B1 - Method of manufacturing portland cement for carbon dioxide reduction including calcined dolomite take advantage of hydration properties - Google Patents

Abstract

PURPOSE: A manufacturing method of carbon dioxide reduction type Portland cement and carbon dioxide reduction type Portland cement composition are provided to maintain initial strength of concrete while effectively reducing carbon dioxide by adding light burned dolomite to the Portland cement. CONSTITUTION: Carbon dioxide reduction type Portland cement composition comprises 100 parts by weight of water, 150-250 parts by weight of Portland cement, 10-80 parts by weight of plaster mixture, and 10-80 parts by weight of light burning dolomite. The light burning dolomite is manufactured by incinerating the dolomite raw ore at 600-1000 deg. Celsius. The light burning dolomite comprises 40-70 wt% of calcium oxide, 20-40 wt% of activated magnesia, 10-20 wt% of one or a mixture selected from silicon dioxide, dialuminum trioxide, iron oxide, and sulfur trioxide. The plaster mixture includes calcium sulfate, chemical gypsum and natural gypsum in a weight ratio of 1:1-2:1-2. The carbon dioxide reduction type concrete composition includes carbon dioxide reduction type cement composition and filler composition. The filler composition comprises 20-40 wt% of metakaolin, 40-60 wt% of silicate glass, 10-15 wt% of silica and 10-15 wt% of natural fiber. [Reference numerals] (A1,B1,C1,D1) 1 day; (A2,B2,C2,D2) 3 days; (A3,B3,C3,D3) 7 days; (A4,B4,C4,D4) 14 days; (A5,B5,C5,D5) 21 days; (A6,B6,C6,D6) 28 days; (EE) Example1-air drying curing

Description

Method of manufacturing portland cement for carbon dioxide reduction including calcined dolomite take advantage of hydration properties

The present invention relates to a method for producing a carbon dioxide-reduced portland cement utilizing the hydration properties of light and small dolomite.

The cement industry, along with steel and petrochemicals, is one of the essential material industries indispensable for the civil and building industries, one of the representative national infrastructure industries. In addition, the cement industry has played a major role in leading industrialization and urbanization from the 20th century to the present. However, it is also undeniable that some effects on resource depletion, global warming, and air pollution are caused.

In recent years, greenhouse gas emissions related to global warming, the global carbon dioxide emissions of the cement industry is equivalent to 5% of the total emissions, and only 8% of the total emissions in Korea. In addition, energy consumption is 3,878 Ton of Oil Equivalent (TOE), accounting for 4.8% of the total manufacturing sector emissions (as of 2004). As mentioned above, the cement industry is an energy-consuming industry, and efforts are being made to increase energy efficiency and reduce carbon dioxide emissions in the cement industry, which is a carbon dioxide emission industry.

As a technology to reduce the carbon dioxide generated during the production of cement, by using a large amount of blast furnace slag powder or fly ash, which is an industrial by-product such as Korea Patent Publication 10-2012-0113476, Republic of Korea Patent Registration 10-0975358, I'm going. However, the fly ash as described above is produced through a process of collecting and refining dust generated by burning anthracite coal, and the product is not uniform in shape, unburned carbon may occur, so the quality is not constant and the change is severe. have. In addition, the strength is low when the early age, when used in place of more than 20% of the cement is sharply reduced in strength, the generation of carbon dioxide due to the combustion of anthracite coal may be a problem.

As such, while maintaining the initial strength of the concrete, the development of a cement containing a stable substitute that can effectively reduce the carbon dioxide is required.

Republic of Korea Patent Publication 10-2012-0113476 (October 15, 2012) Republic of Korea Patent Registration 10-0975358 (August 05, 2010)

In order to solve the above problems, the present invention is to provide a carbon dioxide reduction portland cement comprising a stable substitute that effectively reduces carbon dioxide without reducing the initial strength of concrete.

In addition, an object of the present invention is to provide a carbon dioxide reduced concrete composition with improved physical properties by further comprising a filler in the Portland cement composition.

The present invention relates to a carbon dioxide-reduced portland cement composition utilizing the hydration properties of light dolomite.

One aspect of the invention relates to a carbon dioxide reducing cement composition comprising Portland cement, gypsum and light dolomite. In this case, the cement composition may include 150 to 250 parts by weight of Portland cement, 10 to 80 parts by weight of gypsum and 10 to 80 parts by weight of light dolomite based on 100 parts by weight of water.

The light dolomite is prepared by calcining dolomite ore at 600 to 1000 ° C., and the light dolomite is 40 to 70% by weight of calcium oxide; Active magnesia 20-40 wt%; And 10 to 20 wt% of any one or a mixture thereof selected from silicon dioxide, dialuminum trioxide, ferric trioxide, and sulfur trioxide.

In addition, the light dolomite may be 0.01 to 10% by weight relative to the total 100% by weight loss generated during calcination, the average particle diameter may be 0.01 to 3 mm, the powder may be 3,000 to 6,000 cm 2 / g.

In addition, the active magnesia included in the light dolomite may have a specific surface area of 50 to 60 m 2 / g.

Another aspect of the invention relates to a carbon dioxide reducing concrete composition comprising the cement composition.

Hereinafter, the carbon dioxide reduction cement composition according to the present invention will be described in detail.

The present inventors continue to research to reduce the carbon dioxide generated in the production of cement included in the concrete quality of the various curing process while bringing the effect of reducing the carbon dioxide by replacing cement when the light dolomite generated by heat treatment dolomite is added The present invention has been completed by discovering that equivalent or more physical properties are expressed without deterioration.

In general, when the dolomite is heat treated, it becomes a light dolomite state while undergoing a decarbonation reaction.

[Formula 1]

CaMg (CO ₃ ) ₂ → CaCO ₃ + MgO + CO ₂

The heat applied during the decarbonation reaction is 600 to 1000 ° C., and the active magnesia produced through the decarbonation reaction shows an active state with low crystallinity only within this temperature range. In contrast, magnesia may be produced when cement clinker is produced, but in this case it is produced at high temperatures above 1,000 ° C, has a small specific surface area and reactivity, very high lattice energy (3975 KJ / mol) and dead-burned crystals. Will be displayed.

Minor magnesia (periclase) generated during the cement clinker formation causes excessive expansion in the long-term hydration of concrete, which causes the concrete properties to be greatly degraded. However, the light-burned activated magnesia included in the light dolomite used in the present invention has a high specific surface area and a high reactivity, so that the hydration reaction is more likely to occur. When the cement containing activated magnesia reacts with water, a large amount of Mg (OH) ₂ · nH ₂ O gel is formed at the beginning of hydration, trapping a large amount of excess water as crystallized water, which reduces the proportion of pore hydrates, resulting in a dense texture. Will contribute to the formation. The hydration mechanism of the active magnesia may include the following Chemical Formulas 2-3.

[Formula 2]-early hydration

_{MgO + H 2 O → Mg (} OH) 2 · nH 2 O (brucite gel)

[Formula 3]-late sign language

Mg (OH) ₂ nH ₂ O → Mg (OH) ₂ (brucite) + H ₂ O

The Mg (OH) ₂ nH ₂ O gel produced through Chemical Formula 2 may contain about 39 to 42 mol% of water, and brucite produced at the end of hydration may have about 25 to 35 mol% of water. have. Moisture released as the brucite gel crystallizes C ₃ S, C ₂ S, 3CaO · SiO ₂ , 2CaO · SiO ₂ , 3CaO · Al ₂ O ₃ and 4CaO · Al ₂ O ₃ ㆍ Fe _{2 contained in the composition} It is used for hydration reaction such as O ₃ to express late strength, and moisture contained in brucite gel suppresses shrinkage that can occur during drying of excess water and expands the volume more than two times to compensate for chemical shrinkage. Done.

The carbon dioxide reducing cement composition according to the present invention may comprise portland cement, gypsum and light dolomite.

The Portland cement is a calcium silicate compound such as tricalcium silicate (Alite, C ₃ S), dicalcium silicate (Belite, C ₂ S), aluminate tricalcium (aluminate phase, C ₃ A), calcium iron aluminate ( It consists of interstitial phase compounds such as ferrite phase, C ₄ AF) and various slags, which is one type of ordinary portland cement, medium hot portland cement, crude steel portland cement, low heat portland cement or Sulfate resistant portland cement and the like can be used.

The portland cement may include 150 to 250 parts by weight based on 100 parts by weight of water added during concrete production, and preferably, the amount of the cement is adjusted so that the water / cement ratio (W / C) is 45 to 55%.

The gypsum is used as a coagulant control agent of the concrete composition, and serves to promote early strength and increase durability. The gypsum is not limited to chemical gypsum, natural gypsum, desulfurized gypsum, and the like, which are commonly used in the art, but it is preferable to use desulfurized gypsum. The desulfurized gypsum is an incidental generation in petroleum refining, cogeneration, and coal-fired power plants.

The desulfurized gypsum has an ignition loss (Ig. Loss) of 5 to 30%, 20 to 60% by weight of calcium oxide (CaO), 1 to 5% by weight of magnesium oxide (MgO), and 0.1 to 5 weight of silicon dioxide (SiO ₂ ) %, Dialuminum trioxide (Al ₂ O ₃ ) 0.1 to 3% by weight, sulfur trioxide (SO ₃ ) 20 to 60% by weight, ferric trioxide (Fe ₂ O ₃ ) 0.1 to 3% by weight, potassium oxide (K ₂ O) 0.01 to 0.3 wt%, vanadium (V) 0.01 to 0.3 wt% is preferably included.

In the present invention, desulfurized gypsum may be used alone, but any one selected from chemistry and natural gypsum may be used alone, or a mixture thereof may be used. Preferably, it is preferable to use in the form of a mixture of chemical gypsum, natural gypsum and desulfurized gypsum, more preferably desulfurized gypsum: chemical gypsum: natural gypsum is 1: 1 to 2: 1 to 2 by weight It can contribute to the initial strength improvement of the composition. Desulfurized gypsum does not change the initial coagulation strength even if the added amount is increased, but when it contains 2 parts by weight or more, the termination is delayed and the 28 days strength increase rate is very low, so it is preferable to add it in the weight ratio.

The gypsum or gypsum mixture included in the cement composition may include 10 to 80 parts by weight, preferably 2 to 6% by weight based on 100% by weight of the total concrete composition. The desulfurized gypsum or gypsum mixture increases the coagulation delay effect as the addition amount increases, but when it exceeds 6% by weight, it inhibits the filling and growth of calcium hydrate, which contributes to the long-term strength due to the mass produced hydrates initially, resulting in long-term It is not desirable to have a drop in strength.

The light burned dolomite is pulverized dolomite ore to 20 to 50mm, and then calcined at 600 to 1000 ℃ for 24 to 48 hours, it is preferable to use the one prepared in the powder degree of 3,000 to 6,000 cm 2 / g. The prepared small dolomite includes active magnesia, and the active magnesia participates in the hydration reaction, and after three days of hydration, 100% of the active magnesia participates in the hydration reaction. It leads to a reduction effect and high strength expression. In this case, the active magnesia is preferably in a specific surface area of 50 to 60 m 2 / g in order to participate in the hydration reaction.

In the manufacture of light calcined dolomite according to the present invention, when the calcined temperature range is out of the calcined temperature, magnesia having crystallization of tetraburn is produced, and in this case, the proportion of magnesia participating in the hydration reaction is only 9 to 23% after 3 days of hydration. It is good to maintain the temperature range because it will not only reduce the crack reduction effect and strength but also cause excessive expansion in later age.

Light dolomite according to the present invention is 40 to 70% by weight calcium oxide; Active magnesia 20-40 wt%; And 10 to 20 wt% of any one or a mixture thereof selected from silicon dioxide, dialuminum trioxide, ferric trioxide, and sulfur trioxide.

In addition, the ignition loss (lg.loss) of the light dolomite is preferably from 0.01 to 10% by weight relative to 100% by weight of light dolomite.

The cement composition according to the present invention preferably comprises 150 to 250 parts by weight of Portland cement, 10 to 80 parts by weight of gypsum and 10 to 80 parts by weight of light dolomite based on 100 parts by weight of water added during concrete production.

In addition, the cement composition according to the present invention may prepare a concrete composition including the cement composition, aggregate and water.

The aggregate refers to fine aggregate, crushed sand, gravel, crushed coarse aggregate, sea sand, blast furnace slag fine aggregate, blast furnace slag coarse aggregate, and other similar materials, which are mixed with cement and water to produce mortar or concrete, and the present invention. Aggregate that can be used in can be used to classify as coarse aggregate and fine aggregate according to the size of the particles.

The coarse aggregate and fine aggregate is preferably used to satisfy the KS F standard, and in detail, fine aggregate is used in the average particle diameter of more than 0.074mm, coarse aggregate is more than 4.76mm 40mm or less, but is not limited thereto.

The coarse aggregate and fine aggregate can freely adjust the addition ratio according to the role of the concrete composition to be constructed and the reduction of cement cost, the physical properties of the composition, and preferably the aggregate aggregate ratio (the total volume occupied by fine aggregate of the total aggregate volume, S / a) ) Is preferably 40 to 55%, but is not limited thereto.

Aggregate included in the concrete composition may include 400 to 2,000 parts by weight based on 100 parts by weight of water, including coarse aggregate and fine aggregate.

In addition, the concrete composition according to the present invention may further include a filler composition composed of any one or a mixture thereof selected from metakaolin, water glass, silica and natural fibers. Preferably, the filler composition may be composed of a mixture of 20 to 40% by weight of metakaolin, 40 to 60% by weight of water glass, 10 to 15% by weight of silica and 5 to 10% by weight of natural fibers, wherein the filler composition is made of whole concrete It is preferable to mix 20-30 weight part with respect to 100 weight part of compositions.

The metakaolin is a homogeneous combination of kaolin, the main component of kaolin, and then activated by special pretreatment and calcining, and then finely divided to a certain particle size.Aluminum is eluted upon hydration, and short-term ettringite is produced. The initial strength is increased by the increase of the reaction rate due to the activation of alite, which is a major component of cement, and the pozzolanic reaction with calcium hydroxide makes the structure of concrete compact, improving the strength and durability.

The metakaolin preferably has a specific gravity of 2.5 to 2.8, and a powder degree of 120,000 to 150,000 cm 2 / g.

When the metakaolin is added in less than 20% by weight in the filler composition, the desired strength is not achieved in the present invention, when the content exceeds 40% by weight, the effect is maintained but disadvantageous in terms of cost.

The water glass is a kind of salts in which silicate and silica are the main components of silicic acid and sodium hydroxide or potassium hydroxide, which is high in the case of potassium-based, but expensive. This is possible. The water glass used for this invention may use any kind as said sodium silicate or potassium silicate.

The water glass in the filler composition is preferably added 40 to 60% by weight. If less than 40% by weight of the hydration reaction and polymerization does not occur properly, the compressive strength is lowered, if it exceeds 60% by weight is a sudden occurrence of the problem occurs in the construction.

The silica not only generates calcium silicate hydrate by reacting with calcium hydroxide in the concrete composition, but also plays a role of improving durability of natural fibers included as a reinforcing material. Absorption of natural fibers reduces the durability of fiber-reinforced concrete. Absorption causes a volume change that can cause cracking of concrete. Mixing silica, however, modifies the matrix of the fiber to prevent deterioration of the fiber.

The silica is a by-product generated during the production of ferrosilicon or metal silicon, and may include powder silica, granular silica, slurry silica, etc., preferably 85 wt% or more of SiO ₂ , and a unit volume mass of 0.4. It is preferable to use granular silica of 0.8 to 0.8 ton / m 3.

The silica is preferably added 10 to 15% by weight based on 100% by weight of the total filler composition. If less than 10% by weight, the strength expression of the concrete composition is lowered, if more than 15% by weight, there is a fear that the strength and water resistance of the concrete composition is weak.

The natural fiber is a complex having a cellular structure, cellulose, hemicellulose, lignin is a generic name for a naturally produced material constituting a different layer, it is currently available in general forms of natural fibers such as cotton, hemp, silk However, it is preferable to use one or a mixture thereof, preferably selected from eucalyptus, sisal, banana and bamboo fiber. The fibers have the effect of reducing the plastic shrinkage of the concrete, inhibiting or retarding crack diffusion. In addition, the mechanical properties and impact strength are improved, and the load is distributed and transferred from the concrete matrix to the fiber, resulting in stable fracture behavior. However, the natural fibers may reduce the durability of the concrete according to the absorbency, it is preferable to treat the waterproofing agent before the addition. The waterproofing agent is not limited to the type as long as it is commonly used in the art, preferably siloxane-based, stearyloxymethylpyridinium chloride, such as poly (hydrogenmethylsiloxane) or poly (dimethylsiloxane) It is preferable to use pyridinium chloride type, fluoropolymer type, such as (stearylmethylpyridinium chloride), stearamidomethylpyridinium chloride, and the like. The waterproofing agent may appropriately adjust the concentration and treatment time, etc. according to the amount of natural fiber added.

The natural fiber is preferably 1 to 10 denier, short fibers of 0.5 to 3mm in length, the addition amount is preferably 5 to 10% by weight in 100% by weight of the total filler composition. If less than 5% by weight, the effect of the natural fiber is not properly expressed, if more than 10% by weight, the physical properties of the concrete may appear due to the large amount of addition.

Carbon dioxide-reduced concrete composition added to the light dolomite according to the present invention can significantly reduce the carbon dioxide generated in the production of cement by replacing the clinker, and can maintain physical properties equal to or higher than the active magnesia. In addition, by changing the composition ratio of the gypsum to be added to produce a concrete composition excellent in the initial strength expression, it may further include a reinforcing filler to suppress the initial crack diffusion and improve the mechanical performance and impact strength.

Figure 1 shows the compressive strength of the concrete composition according to the air curing conditions and calcining temperature and addition amount of light calcined dolomite.
Figure 2 shows the compressive strength of the concrete composition according to the curing conditions and calcined dolomite temperature and the amount of addition in the water curing conditions.
Figure 3 shows the compressive strength of the concrete composition according to the carbonation curing conditions and calcined dolomite temperature and the addition amount.
Figure 4 shows the result of the heat insulation temperature rise of the concrete composition according to the addition amount of light and small dolomite.
Figure 5 shows the results of the drying shrinkage of the concrete composition according to the addition amount of light and small dolomite.
Figure 6 shows the result of the weight change of the concrete composition according to the addition amount of light and small dolomite.
Figure 7 shows an apparatus for measuring the thermal insulation temperature of the concrete composition prepared through the Examples and Comparative Examples of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the following examples and comparative examples. However, the following examples are only examples for describing the present invention in more detail, and the present invention is not limited to the following examples, and modifications and variations are freely possible within the spirit and scope of the present invention. Obviously, it belongs to the scope of the present invention.

Unless otherwise defined in the technical and scientific terms used in the above examples and comparative examples, those having ordinary knowledge in the technical field to which the present invention belongs have the meanings that are commonly understood.

The physical properties of the concrete composition prepared through the Examples and Comparative Examples were measured as follows.

(Material used)

The specifications of the compositions used in the following examples and comparative examples are shown in Table 1 below.

[Table 1]

Paste flow

Mini-slump method was used to measure the initial flowability of the paste. The water / cement (W / C) of the paste was 0.4, and 3.9 g of a naphthalene liquid admixture (NP, naphthalene) was added. The mixture was uniformly mixed in the container for 1 minute, and the flow rate of the cement paste was expressed in diameter (cm) using a Conc having a height of 50 mm and an upper and lower diameter of 50 mm. After mixing the cement paste into Conc, the diameter of the cement paste was measured, and after 60 minutes, the change was observed in the same manner.

(Condensation time)

The mixing of samples for the measurement of the setting time was in accordance with KS L 5109, and the measurement conditions were carried out in a constant temperature and humidity chamber (23 ± 1 ℃, relative humidity of 95% or more). The measurement time of condensation was measured using the Vicat apparatus of KS L 5108.

(Compressive strength)

Samples mechanically mixed in a mortar mixer according to KS L ISO 679 were filled into a molding mold for measuring the compressive strength of 4 × 4 × 16 cm with a two-layer compaction using a jolting machine, and the number of times was 60 times for each layer. After compaction, demoulded after curing for 24 hours in constant temperature and humidity (23 ± 1 ℃, relative humidity 95% or more). Water (water temperature: 22 ± 1 ℃), air condition (humidity: 60 ± 5%, temperature: 20 ± 1 ℃) and carbonation (humidity: 60 ± 5%, temperature: 22 ± 1 ℃, CO ₂ concentration: 5 ± 1 Compression strength was measured at 1 day, 3 days, 7 days, 14 days, 28 days, 56 days, and 91 days of age, according to the embodiment after curing.

(Freeze fusion)

Based on the test method for the resistance of concrete to rapid freezing melting, the freeze-thawing test cycle alternates the specimen temperature between 2 and 4 hours for 4 days to -18 ° C, -18 The test was conducted at 4 ° C.

(Concrete Mixing Experiment)

The samples tested for quality were tested for 60 seconds using a lab test for 150 seconds, and the slump and air volume tests were carried out on the solid concrete, and the durability of each curing condition was measured on the solid concrete.

(Change of length)

According to KS F 2424 test method for changing the length of concrete, the first length was measured immediately after demolding the specimen according to KS F 2403, and the specimen was cured in water at 20 ± 1 ℃ after measuring the length. Measure the second length. After the second length measurement, the length change is measured at 1, 4, 8 weeks and 3, 6, 9, and 12 months, respectively, while maintaining the preservation conditions.

(Thermal insulation temperature)

By using the adiabatic temperature rise test equipment (Tokyo Rico Co., Ltd.) of the water circulation method shown in FIG. 7, a thermal insulation container containing a concrete sample is stored in a thermostat, and the temperature difference between the sample and the thermostat is zero based on the temperature rise of the sample. Keep close to complete insulation. After that, the temperature rise process and final temperature rise by the calorific value of the concrete sample itself were recorded while the insulation state was maintained. The insulation temperature measurement time was measured at 1 hour intervals from immediately after the beam to 7 days.

(Production Example 1)

The cement clinker was crushed to an average particle diameter of 2 mm or less, and 5 wt% of desulfurized gypsum was added to 100 wt% of the total composition. . The light dolomite was obtained by obtaining a dolomite gemstone in Danyang, and then ground to an average particle diameter of 30 mm and calcined at a temperature of 600 ° C. The calcined light dolomite was pulverized again to an average particle diameter of 2 mm or less. Crushed light dolomite was added 3% by weight relative to the total composition, and the other amount was prepared according to the following Table 2.

(Production Examples 2 to 4)

Cement compositions were prepared under the same conditions as in Preparation Example 1 except that the calcining temperatures of the light calcinal dolomite were set to 650 ° C., 700 ° C. and 750 ° C., respectively.

(Production Example 5)

Cement composition was prepared under the same conditions as in Preparation Example 1, except that the content of the light dolomite was 5% by weight.

(Production Examples 6 to 8)

Cement compositions were prepared under the same conditions as in Preparation Example 5 except that the calcining temperature of the light calcinal dolomite was set to 650 ° C., 700 ° C. and 750 ° C., respectively.

(Preparation Example 9)

A cement composition was prepared under the same conditions as in Preparation Example 1, except that 10 wt% of the content of light dolomite was added.

(Production Examples 10 to 12)

Cement compositions were prepared under the same conditions as in Preparation Example 9 except that the calcining temperature of the light calcinal dolomite was set to 650 ° C., 700 ° C. and 750 ° C., respectively.

(Preparation Example 13)

It was prepared in the same manner as in Preparation Example 1, except that light dolomite was not added at all. The addition amount of the concrete composition of Preparation Examples 1 to 13 is shown in Table 2 below.

[Table 2]

(OPC: ordinary portland cement (plain), W: water, C: cement, S: sand, G: gravel)

(Example 1)

 The concrete compositions prepared through Preparation Examples 1 to 13 were cured under the above-mentioned curing conditions, and the compressive strengths of 1 day, 3 days, 7 days, 14 days and 28 days of age were shown in FIG. 1.

(Examples 2 and 3)

The concrete composition prepared through Preparation Examples 1 to 13 was cured under the conditions of curing in water (Example 2) and carbonation curing (Example 3), respectively, 1 day, 3 days, 7 days, 14 days, 28 days of age The compressive strength of the was measured and shown in FIGS. 2 and 3.

Despite the different curing conditions as shown in Figures 1 to 3 it was confirmed that the sample added to the calcined dolomite of 650, 700 ℃ calcining temperature is the best physical properties, Preparation Example 1 to 4 added 3% by weight compared to the cement composition In the case of water, air condition, carbonation, it was confirmed that the physical properties of the equivalent or more without deterioration in the curing process of three conditions. This suggests that a large amount of Brucide gel produced at the beginning of hydration contains a large amount of excess moisture as crystal water, thereby reducing the hydrate ratio of pores and eventually forming a dense tissue. In addition, the moisture released during the crystallization of the Brucite gel is characterized by C ₃ S, C ₂ S, 3CaO · SiO ₂ , 2CaO · SiO ₂ , 3CaO · Al ₂ O ₃ and 4CaO · Al ₂ O ₃ ㆍ Fe ₂ O _It is judged to express late strength by being used continuously in hydration reactions such as ' ₃ '.

(Examples 4 to 6 and Comparative Example 1)

Among the cement compositions prepared in Preparation Examples 1 to 13, the cement compositions of Preparation Examples 2, 6, and 10, and OPC prepared in Preparation Example 13 of OPC having a calcination temperature of 650 ° C. having the best physical properties were prepared, and immediately after preparation, After 30 minutes, the slump after 60 minutes, the air amount and the setting time were measured and shown in Table 3, respectively. In addition, the compressive strength of the hardened concrete was measured at 3 days, 7 days, 14 days, 28 days, 56 days, and 91 days, respectively, and the weight loss degree according to the number of freeze-thawing cycles is shown in Table 4, respectively. In addition, by measuring the degree of rise of the thermal insulation temperature of the concrete produced through the manufacturing examples 2, 6, 13 in Figure 4, by measuring the dry shrinkage and weight change of the concrete manufactured through the manufacturing examples 2, 6, 10, 13 5 and FIG. 6. In Figures 4 to 6, plain is OPC, LB is light burned, 3% or LB_3% is the addition amount of light dolomite, 3%, 5%, 10% are respectively 3%, 5% , 10% added.

[Table 3]

[Table 4]

[Table 5]

As shown in Table 3, as the substitution amount of the light dolomite increased, the slump and air amount showed a tendency to decrease somewhat, but it was similarly measured without significant difference in the setting time.

As can be seen from Table 4 and Table 5, the compressive strength according to the age was measured at almost the same level of compressive strength of Examples 4 to 6 as compared to Comparative Example 1, which is OPC. The decrease in elasticity and weight ratio was found to be small. This seems to be due to the formation of dense tissue due to the large amount of Brucite gel with the addition of light dolomite.

In addition, it can be seen from FIG. 4 that the light dolomite-added sample is almost identical to the plain sample (OPC) without any difference in curve, and that the similar dry shrinkage is measured compared to the plain sample in FIGS. 5 and 6.

(Examples 7 to 10, Comparative Examples 2 to 4)

In order to find out the change in the physical properties of the cement according to the gypsum composition ratio, as shown in Table 6, the gypsum composition ratio was mixed to add 5% by weight compared to the total composition, and the rest was mixed in the same manner as the composition ratio of Preparation Example 2 The composition was prepared. The settling time of the prepared concrete composition and the compressive strength of 3 days, 7 days 28 days age is measured and shown in Table 6.

TABLE 6

Looking at the Table 6 it can be seen that in the case of Example 9 the initial and termination time is rather fast, and in Example 10, the initial and termination time is somewhat delayed. This seems to be due to the difference in dissolution characteristics of the gypsum mixture. In addition, the strength of the 28-day age is almost similar to both examples and comparative examples, but shows a large difference in the initial strength, and Example 8, which is added to the chemical gypsum 2 weight ratio in the example is 3 days, 7 days of age than other examples The compressive strength at work is slightly lower than that of natural gypsum, which suggests that natural and desulfurized gypsum continue to produce ettringite after termination, contributing to the initial strength improvement of concrete.

(Examples 11 to 13 and Comparative Examples 5 to 7)

In order to determine the change in the physical properties of the concrete according to the addition of the filler, the composition ratio of the filler was determined as shown in Table 7, and 20 parts by weight of the filler composition was added to 100 parts by weight of the total concrete composition. At this time, the composition ratio of the fiber used was mixed short fibers mixed with 40% by weight of coconut fiber and 60% by weight of sisal fiber, each fineness was 2 denier, the length was 1mm. The fibers were also treated with 5% by weight of fiber weight of polyhydrogenmethylsiloxane. The other concrete composition was mixed in the same manner as the composition ratio of Preparation Example 2 to prepare a concrete composition. The settling time of the prepared concrete composition and the compressive strength of 3 days, 7 days and 28 days of age are shown in the table.

[Table 7]

(Metakaolin: MK100 / Nikeon Material, Water Glass: Hosung Chemical, Silica: Nikon Material)

[Table 8]

In the case of the setting time as shown in Table 8 it does not show a large difference depending on the amount added. However, in Example 11, in which the amount of water glass is added, the first grain is shorter than the other examples and the comparative example, and it seems that the water glass played a role of a fastener in the concrete composition.

In addition, the compressive strength of Examples 11 to 13 with the addition of the filler was found to be superior to the comparative strength than Comparative Example 7 without the addition. It was found that the comparative examples 5 and 6 degrees of compressive strengths of silica and natural fiber added out of range were lower than those of the examples, and maintaining the composition ratio of the filler had a significant effect on the properties of concrete.

Claims (7)

100 parts by weight of water;
Portland cement 150 to 250 parts by weight;
10 to 80 parts by weight of the gypsum mixture;
Dolomite ore is prepared by calcining at 600 to 1000 ° C., 40 to 70 wt% calcium oxide; Active magnesia 20-40 wt%; And 10 to 80 parts by weight of light dolomite, including 10 to 20% by weight of any one or a mixture thereof selected from silicon dioxide, dialuminum trioxide, ferric trioxide, and sulfur trioxide; And
20 to 30 parts by weight of a filler composition consisting of 20 to 40% by weight of metakaolin, 40 to 60% by weight of water glass, 10 to 15% by weight of silica and 5 to 10% by weight of natural fibers;
Carbon dioxide reduced concrete composition comprising a,
The gypsum mixture is desulfurized gypsum: chemical gypsum: natural gypsum is a carbon dioxide reduction concrete composition is mixed in a weight ratio of 1: 1 to 2: 1 to 2, respectively. The method of claim 1,
The desulfurized gypsum is carbon dioxide reduction concrete composition of 5 to 30% loss of ignition. delete delete The method of claim 1,
The light dolomite is a carbon dioxide reduction concrete composition having a loss of ignition 0.01 to 10% by weight based on 100% by weight of light dolomite, an average particle diameter of 0.01 to 3mm, and a powder of 3,000 to 6,000 cm 2 / g. delete delete

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