KR101043932B1 - Non-sintering inorganic binder comprising bottom-ash and concrete composition using thereof - Google Patents

Abstract

The present invention relates to a non-baking binder including a bottom ash and a concrete composition using the same, the purpose of which is to produce a large amount of carbon dioxide during manufacture and eco-friendly to completely replace the cement that requires a high energy consumption firing process To provide a binder and a concrete composition comprising the same.

The binder of the present invention for achieving the above object is composed of a bottom ash, an alkaline inorganic material and sodium silicate, the bottom ash and an alkaline inorganic material and sodium silicate in the remaining binder is 70: 30 ~ 80: 20 by weight, The alkaline inorganic material and the sodium silicate are 80:20 to 20:80 by weight.

Concrete, bottom ash, alkaline inorganic material, sodium silicate, powder

Description

Non-plastic binder including bottom ash and concrete composition using same {NON-SINTERING INORGANIC BINDER COMPRISING BOTTOM-ASH AND CONCRETE COMPOSITION USING THEREOF}

The present invention relates to a non-baking binder comprising a bottom ash and a concrete composition using such a non-baking binder, and more particularly, to an appropriate ratio of the bottom ash, sodium or / and potassium-based alkaline inorganic materials and It relates to an environmentally friendly binder that does not require plastic working consisting of sodium silicate and to a concrete composition using the binder.

Cement is the most important and widely used structural material used in the modernization of the industry. Cement is the basic material for the construction of various SOCs such as roads, bridges, tunnels, ports, houses and buildings. Especially in the 20th century, construction technology has been advanced in accordance with the advancement of industrial structure, and accordingly, ordinary Portland cement, which began to be produced in earnest from the beginning of the 20th century, has greatly increased its production, producing about 1.5 billion tons. Technology has also evolved dramatically. In the future, construction projects such as high-rise buildings, deep underground structures, huge bridges, marine airports and underwater cities are planned to expand the SOC towards the information and age-oriented era, which is accompanied by the advancement of industrial structures and the diversification of social structures. Cement demand is expected to increase steadily.

As such, although cement has played an important role in the construction of SOC, the tendency is recently recognized as a negative material for the natural and global environment. In particular, cement is not only used limestone, but also is produced at high temperature (approximately 1,500 ℃) during the clinker manufacturing process, producing 1 ton of cement in this process. It is serious enough to account for 7-8% of the population. In Korea, cement production is about 63 million tons per year, releasing about 56.7 million tons of carbon dioxide, the second largest after the steel industry.

Meanwhile, since the climate change agreement for the prevention of global warming was adopted in Rio in Brazil in 1992, global warming has been recognized as a common human problem, and countries around the world have prepared a response. In particular, since the Kyoto Protocol on the Climate Change Convention was adopted in Kyoto, Japan in 1997, the Kyoto Protocol came into force in 2005, and 38 developed countries must comply with their obligations to reduce greenhouse gases. According to the Kyoto Protocol, there is a difficult task to reduce the average 5.2% of emissions in 1990 during the first commitment period (2008-2012). At the G8 Summit held in Toyako, Japan in July 2008, leaders from each country are considering reducing their emissions to 50% by 2050. Such strong GHG reduction efforts are no exception to Korea, and strong measures are needed at the government level as it is certain that they will be incorporated into countries subject to secondary obligations to reduce GHG emissions from 2013. As of 2004, Korea emits 461 million tons of carbon dioxide and ranks 10th in the world. In particular, the rate of increase of carbon dioxide emissions is the second highest in the world after China.

In line with this situation, we are making a lot of equipment investment and technology development to reduce greenhouse gas in all domestic industries.In the cement industry, we increase production efficiency and increase the use of alternative fuel instead of bituminous coal in the production process. Efforts are being made to reduce carbon dioxide by using mixed cements such as fly ash and blast furnace slag. However, in this situation, the demand for cement is expected to increase by 2.5 ~ 5.8% annually. Therefore, stronger measures should be taken because CO2 emissions from cement production cannot be reduced dramatically.

On the other hand, fly ash generated from thermal power plants and blast furnace slag, which are by-products of steel mills, are used as cement materials and mixed materials for concrete, but about 50% of them are being treated by land and land reclamation. In addition, many environmental problems are caused by the leaching of coal ash composed of leachate and fine powder generated during landfill. In particular, coal ash generated as a by-product from coal-fired power plants is classified into fly ash and bottom ash, depending on where it is collected. Fly ash is a fine particle of coal ash produced during combustion. It is discharged through the combustion furnace together with the combustion gas of the furnace, and occupies 80 to 85% of the total coal ash generated, and the bottom ash falls into the lower part of the boiler in the combustion furnace, and the solidified material is crushed to a particle size of 25 mm or less using a crusher. As described above, 15 to 20% of the total coal ash is generated. As described above, the fly ash has been researched and used in various angles, but the bottom ash still has been researched and used. This is incomplete.

Therefore, the present inventors proposed the present invention by repeatedly researching and experimenting to use the bottom ash as a binder of concrete, and the present invention discharges a large amount of carbon dioxide during manufacture and produces a cement that requires a calcining process that consumes a lot of energy. An object of the present invention is to provide an environmentally friendly binder that can be completely replaced and a concrete composition comprising the same.

The binder of the present invention for achieving the above object is composed of a bottom ash, an alkaline inorganic material and sodium silicate, the bottom ash and an alkaline inorganic material and sodium silicate in the remaining binder is 70: 30 ~ 80: 20 by weight, Alkaline inorganic material and sodium silicate is characterized in that the weight ratio of 80:20 ~ 20:80,

In addition, the concrete of the present invention for achieving the above object is characterized in that it comprises a binder as described above.

As described above, the non-plastic binder and the concrete composition using the same provide compressive strength by presenting a suitable mixing ratio of a bottom ash, sodium-based and / or potassium-based alkaline inorganic material, sodium silicate, and water and the binder. There is an advantage that can be secured in the 25 ~ 55MPa range. In addition, the concrete composition according to the present invention has the advantage that the fluidity is maintained until a certain time after the concrete is poured to ensure sufficient workability.

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

The non-fired binder of the present invention comprises a bottom ash, sodium-based and / or potassium-based alkaline inorganic material, and sodium silicate.

The bottom ash is generated as a by-product from coal-fired power plants. (1) In the case of a concrete composition in which bottom ash is mixed with an existing aggregate or an existing aggregate, the existing concrete composition is determined by the water absorption of the bottom ash in terms of strength. Compared to the existing concrete, the strength is improved compared to the existing concrete. (2) The resistance to freezing and thawing is almost the same as that of the existing concrete. (3) The specific gravity of the bottom ash is small, so the possibility of material separation due to aggregate sedimentation is low. (4) There is an advantage, such as the water permeability is improved by the porosity of the bottom ash.

The bottom ash reacts with the alkaline inorganic material to dissolve the Al and Si components to harden. Here, the alkaline inorganic material (activator) may be applied with caustic alkalis in the form of MOH. M is an alkali metal ion such as Na, K and Li, and mainly Na or K is used. In addition, the alkaline inorganic material is preferably any one or a mixture of sodium hydroxide, potassium hydroxide, sodium carbonate in the range of 6 to 16M.

Alkali activation here is a chemical reaction between various aluminum-silicate oxides that make Si-O-Al-O composites under high alkali environment. Although the chemical reactor mechanism for alkali activation is not yet clear, reaction mechanisms derived from alkali hydroxides can be generalized as follows.

Both reaction mechanisms clearly show that the Al and Si components are the basis of alkali activation. These reaction rates are very fast and the reaction mechanism can be constructed as a step of dissolution, transfer and adaptation and polycondensation.

In the present invention, by inducing a polymerization reaction (Polymersation) through the combination of the bottom ash, alkali inorganic material and sodium silicate to enhance the strength by the binder material that can express a certain strength or more without the firing process without using cement in the end It is to provide, and also to provide a concrete composition using such a binder.

In the present invention, the binder is composed of a bottom ash (A), an alkaline inorganic material (B) and sodium silicate (C), wherein the bottom ash (A) and the alkaline inorganic material and sodium silicate (B + C) is a weight ratio It consists of 70: 30-80: 20, and the weight ratio of an alkaline inorganic material (B) and sodium silicate is comprised from 80: 20-20: 80. The weight ratio (A: B + C) of the bottom ash in the binder is 70:30 to 80:20 because Si and Al and Na in the proper ratio required for the polymerization reaction must be present. This is because the Na required for the reaction is relatively insufficient, and the strength is lowered. On the contrary, when smaller than this, the strength is decreased due to the lack of Si or Al which contributes to the strength.

In addition, the composition of the alkaline inorganic material (B) and sodium silicate (C) in a weight ratio of 80:20 to 20:80 is not only poor workability when using an alkaline inorganic material in excess of 80% by weight, but also excessively aluminosilicate There is a problem in that the strength of the concrete due to the cracks generated by the expansion is reduced, and when used at less than 20% by weight, the production of aluminosilicate is reduced at the early stage of age, the initial strength is lowered, the shrinkage is somewhat increased In addition, there is a problem in that the use of a large amount of sodium silicate disadvantageously in terms of economics.

The bottom ash has a fineness 2,000 ~ 4,000cm ² / g is preferably used together in that, which is also less than 4000 Fineness is 2,000cm ² / g and the bottom ash has reduced reactivity detrimental to strength development, powder When it exceeds cm ² / g, the reactivity is high, but since the workability is slightly reduced and it is not sold as a normal product, the economic efficiency may be lowered because it must be pulverized or classified in order to finely powder. to be. Furthermore, in order to obtain more excellent reactivity and workability, the bottom ash is more preferably used having a powder degree of 3,000 to 3,500 cm ² / g.

It is preferable to use the sodium silicate having a molar ratio of SiO ₂ and Na ₂ O in the range of 1.0 to 3.5. When the molar ratio is less than 1.0, the viscosity of the binder increases rapidly and the slump is lowered, resulting in poor workability. This is because there is a problem that the Si component required for the polymerization reaction decreases, the long-term strength is decreased, and the molar ratio of more than 3.5 does not affect the workability, but the Na-ion decreases and the initial strength decreases. Furthermore, the sodium silicate is more preferably used in order to obtain the more excellent workability and strength, the molar ratio of SiO ₂ and Na ₂ O 2.8 ~ 3.2.

As described above, the alkaline inorganic material is preferably any one of sodium hydroxide, potassium hydroxide, sodium carbonate in the range of 6-16M, or a mixture thereof. If the alkaline inorganic material is less than 6M, the bottom ash may be insufficient than the amount necessary for all the bottom ash to react.Therefore, there is a fear that sufficient alkali activation reaction does not occur and the strength is reduced. This is because the effect of improving the strength compared to the amount of the input of the inorganic material is disadvantageous economically.

In addition, the present invention provides a concrete composition containing a non-baking binder including the bottom ash, such a concrete composition is a process of mixing, stirring the non-baking binder, the fine aggregate, coarse aggregate and water including the bottom ash, etc. It is prepared through the process of curing and curing.

In this case, it is preferable to apply the water and the binder within 20% by weight. When the water is not used at all, the fluidity can be secured by the alkali-inorganic material in the aqueous solution state, that is, the chemically bound water in sodium hydroxide and sodium silicate. This is because the fluidity can be sufficiently secured by using a chemical admixture such as a high performance water reducing agent by the correction of not using water.

More preferably, it is appropriate to apply water and the binder in a weight ratio of 10 to 20%. In order to reduce the blending ratio of the chemical admixture and to ensure ease of operation, the ratio of the blended water and the binder to the weight ratio is 10% or more. In case of exceeding 20%, the workability is improved, but the strength decreases sharply, so that it is not applicable to concrete structures with compressive strength of 25 MPa or less, and there is a problem such as increased drying shrinkage. Is limited to 20% or less.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Embodiments according to the present invention can be modified in many different forms, the scope of the present invention is not limited to the embodiments described below.

≪ Example 1 >

Influence of bottom ash powder

In order to analyze the effect of the bottom ash powder in the non-plastic binder including the bottom ash and concrete composition using the same presented in the present invention, as shown in Table 1 1,100 cm ² / g, 2,200 cm ² / g , 2,800cm was used as the bottom ash ^{2 / g, 3,200cm 2 / g} , 4,000cm 2 / g, 4,500cm 2 / g.

division Powder
(cm ² / g) BB1100 1,100 BB2200 2,200 BB2800 2,800 BB3200 3,200 BB4000 4,000 BB4500 4,500

These bottom ashes were 80% by weight, and the binder was composed of 10% by weight of 12M sodium hydroxide as an alkaline inorganic material and 10% by weight of sodium silicate (molar ratio 2.5 of SiO ₂ and Na ₂ O) by weight. It was. And water was used 10% by weight based on the weight of the binder, the remaining fine aggregate, coarse aggregate was used to produce concrete using the same ratio as conventional concrete. And as a comparative example, ordinary concrete (water-cement ratio 45%) using ordinary cement was prepared.

Slump and compressive strength were measured for each of the prepared concretes, and the results are shown in FIGS. 1 and 2, respectively.

Here, the slump test was evaluated for workability immediately after discharging from the mixer by mixing concrete according to KS F 2402, and the compressive strength was Φ100 × 200mm circumferential test specimens were cured for 1 day at 20 ℃ and then dried ( Humidity was performed at 60 ° C. for 48 hours at 65 ± 5% humidity and measured according to KS F 2405 at 3, 7, 28 and 91 days of age.

As can be seen in Figure 1, the larger the powder of the bottom ash, the workability was found to be slightly reduced, but the powder is also 4,000 cm ² / g slump is 210 ~ 180mm range, but the fluidity is not large, powder 4,500 In the case of cm ² / g, the slump was found to be significantly reduced fluidity to about 140mm.

From the results of FIG. 2, the smaller the powder density of the bottom ash, the lower the strength expression. In the case of the powder degree of 1,100 cm ² / g, the strength was relatively low at less than 25 MPa even at 28 days and 91 days. And the powder also 3,200cm ² / g, 4,000cm ² / g and 4,500cm A comparison of the ² / g powder in some cases used to 4,500cm ² / g and determined that there is effective in enhancement of the initial strength in a bit to age 7 days After that, there was little effect of increasing the strength due to the difference in powder level.

In summary, when the concrete composition is manufactured using a binder composed of bottom ash, an alkali inorganic material (sodium hydroxide) and sodium silicate, the bottom ash has a powder content satisfying the range of 2,000 to 4,000 cm ² / g. When used, it is possible to secure sufficient workability with a slump of 190 mm or more and to secure compressive strength in the range of 30 to 55 MPa in compressive strength at 28 days.

Particularly, considering the process of pulverizing or classifying the powder to satisfy the workability and advantageously in terms of strength and fine powder, the bottom ash powder is more preferably 3,100 to 3,300 cm ² / g, more preferably 3,200 cm ² / g. Would be most desirable.

<Example 2>

Effect of molar ratio of sodium silicate SiO ₂ to Na ₂ O

In order to analyze the effect of sodium silicate on the molar ratio of SiO ₂ and Na ₂ O in the preparation of concrete with the binder and the composition of the present invention, the molar ratio of SiO ₂ / Na ₂ O was 1.0, 1.5, 2.0, 2.5, 3.0, 4.0. Sodium silicate with 10% by weight was used throughout the binder. A bottom ash powder was also added to these powdery sodium silicates at a weight ratio of 3,000 cm ² / g at 80% by weight, and sodium hydroxide (12M) at 10% by weight. And the ratio of water and the binder was 10% by weight, and the remaining coarse aggregate and fine aggregate was used as the conventional concrete.

The concrete thus prepared was subjected to a slump test in accordance with KS F 2402, and a φ100 × 200 mm column test specimen was prepared and cured at 20 ° C. for 1 day, followed by high temperature curing at 60 ° C. for 48 hours in a dry state (humidity 65 ± 5%). The compressive strength was measured in accordance with KS F 2405 at 3, 7, 28 and 91 days of age. The results are summarized in FIGS. 3 and 4.

As can be seen in Figure 3, as the molar ratio of sodium silicate decreases, the viscosity of the concrete increases, resulting in a decrease in slump, resulting in poor workability. In particular, when the molar ratio of SiO ₂ and Na ₂ O is less than 1.0, the workability is deteriorated, and thus, a chemical admixture such as a high performance water reducing agent is required. In addition, the slump increase was not large as the slump was about 200 mm in the molar ratio of 3.0 and 4.0.

From the results of FIG. 4, the lower the molar ratio of sodium silicate, the lower the long-term intensity expression, and the higher the molar ratio, the lower the initial strength and eventually, the lower the long-term intensity. The molar ratio of SiO ₂ and Na ₂ O was excellent in both initial strength and long-term strength at 3.0, and the molar ratio of less than 1.0 decreased the amount of Si necessary for the polymerization reaction. In the above case, it is difficult to use the concrete structure because Na content decreases and the strength of 7 days is relatively low, about 20 MPa.

Based on the above results, when the concrete is manufactured using a binder composed of bottom ash, sodium hydroxide, and sodium silicate, when the sodium silicate satisfying the molar ratio of SiO ₂ and Na ₂ O in the range of 1.0 to 3.5 is used, It is analyzed that cementless concrete can be produced with excellent over compressive strength. More preferably, in the sodium silicate, the molar ratio of SiO ₂ and Na ₂ O was 2.8 to 3.2, which was satisfactory in workability and was superior in strength. In addition, when the molar ratio of SiO ₂ and Na ₂ O is 3.0, the initial strength (age 7 days) and long-term strength (age 28 days) were 47MPa and 49MPa, respectively.

<Example 3>

Effect of Weight Ratio on Binder Material

In the production of concrete using the binder according to the present invention, the effect of the bottom ratio, the alkali inorganic material (sodium hydroxide), the weight ratio of sodium silicate, firstly the effect of the relative weight ratio of the bottom ash to the total weight of the binder, and secondly the bottom When the relative weight ratio of ash was constant, it was analyzed by dividing it by the effect of the weight ratio of alkaline inorganic material and sodium silicate.

Fineness 3,000cm ² / g bottom ash, 12M aqueous sodium hydroxide, SiO ₂ / Na in the sodium silicate weight ratio of a molar ratio of 2.5 of ₂ O 60:20:20, 70:15:15, 80:10:10 with, 80: 20: 0, 80: 16: 4, 80: 12: 8, 80:10:10, 80: 8: 12, 80: 4: 16, 80: 0: 20 A binder consisting of was used. And the ratio of water and the binder was 10% by weight ratio, the remaining coarse aggregate, fine aggregate and the like was used as conventional concrete.

The concrete thus prepared was subjected to a slump test in accordance with KS F 2402, and a φ100 × 200 mm column test specimen was prepared and cured at 20 ° C. for 1 day, followed by high temperature curing at 60 ° C. for 48 hours in a dry state (humidity 65 ± 5%). The compressive strength was measured in accordance with KS F 2405 at 28 days of age. The results are summarized in FIGS. 5 and 6.

As can be seen in Figure 5, according to the relative weight ratio of the bottom ash to the total weight of the binder, the slump and compressive strength results are good when the relative weight ratio of the bottom ash is 70% or 80%, but the slump is not large when 60% However, when the compressive strength was greatly lowered and the relative weight ratio was 90%, the slump was small and the compressive strength was also small. In other words, Si and Al and Na in an appropriate ratio for the polymerization reaction are present, but if the weight ratio of the bottom ash is larger than this, the Na necessary for the reaction is relatively insufficient, and the strength is lowered. Al is insufficient and strength falls.

As can be seen in Figure 6, when the relative weight ratio of the bottom ash is constant, depending on the weight ratio of the alkali mineral material and sodium silicate, the slump becomes smaller and the compressive strength decreases, especially when more than 16% sodium hydroxide, less than 4% sodium silicate Larger, less than 4% of sodium hydroxide and more than 16% of sodium silicate showed a decrease in slump and compressive strength. In other words, when sodium hydroxide is more than necessary, the workability is reduced due to the occurrence of rapid freezing, and the strength expression is deteriorated due to the lack of polymerization reaction in the early age due to the lack of sodium silicate. Sodium silicate is more than necessary. In the case of use, the workability was reduced due to the occurrence of rapid freezing, and the strength was decreased because the polymerization reaction was not activated due to the lack of sodium hydroxide.

From the above results, the composition ratio of bottom ash, sodium hydroxide, and powdered sodium silicate has a relative weight ratio of bottom ash to 70% or 80% of the total weight of the binder, and an alkali inorganic material and sodium silicate in a weight ratio of 80:20 to 20: In case of 80, construction and compressive strength were found to be excellent, so cement concrete can be manufactured.

<Example 4>

Formulation water Effect of weight ratio of binder

In order to analyze the ratio of the blended water and the binder in the production of concrete according to the present invention, the bottom ash (powder 3,000cm ² / g), sodium hydroxide (12M), sodium silicate (molar ratio of SiO ₂ / Na ₂ O 2.5) Use a binder composed of 80:10:10 by weight ratio, and mix the ratio of blending water and binder to 0, 5, 10, 15, 20, 25, 30% by weight, and the remaining coarse aggregate, fine aggregate, etc. Concrete was prepared using the same as conventional concrete.

The concrete thus prepared was subjected to a slump test in accordance with KS F 2402, and a φ100 × 200 mm column test specimen was prepared and cured at 20 ° C. for 1 day, followed by high temperature curing at 60 ° C. for 48 hours in a dry state (humidity 65 ± 5%). The compressive strength was measured in accordance with KS F 2405 at 28 days of age. The results are summarized in FIG. 7.

As can be seen in Figure 7, the smaller the composition ratio of the blended water and the binder, the smaller the quantity, the fluidity is lowered, but the compressive strength was found to be improved. This result shows the same result in ordinary concrete. Specifically, when no blended water is used, fluidity is ensured by the chemically bound water in sodium hydroxide and sodium silicate in aqueous solution. Slump appears slightly smaller, but it is not completely impossible to construct. When using the chemical admixture of the seems to be able to secure sufficient fluidity, more preferably, the slump value is 190mm ~ 210mm in the ratio of the mixing water and the binder 10 to 20%, and the workability can be secured in terms of strength 35 ~ 50MPa It is considered to be applicable to concrete structures.

From the above results, the ratio of the blended water and the binder composed of bottom ash, sodium hydroxide, and powdered sodium silicate is excellent in constructability and compressive strength when it is composed within 20% by weight. I think it will be possible.

Figure 1 is a graph showing the slump results according to the powder diagram of the bottom ash.

2 is a graph showing the compressive strength results according to the powder density of the bottom ash.

Figure 3 is a graph showing the slump results according to the molar ratio of sodium silicate.

4 is a graph showing the compressive strength results according to the molar ratio of sodium silicate.

5 is a graph showing the slump and compressive strength results according to the relative weight ratio of the bottom ash of the binder to the total weight of the binder.

6 is a graph showing the slump and compressive strength results according to the weight ratio of the alkali inorganic material and the sodium silicate when the relative weight ratio of the bottom ash of the binder component material is constant.

7 is a graph showing the slump results and the compressive strength results according to the ratio of the blended water and the binder.

Claims (9)

It is composed of bottom ash, an alkaline inorganic material and sodium silicate, the bottom ash and the alkaline binder, the inorganic inorganic material and sodium silicate is 70: 30 ~ 80: 20 by weight, the alkaline inorganic material and sodium silicate in a weight ratio of 80: Non-plastic binder comprising a bottom ash, characterized in that 20 to 20:80. The method of claim 1, The bottom ash is a non-plastic binder comprising a bottom ash, characterized in that the powder is 2,000 ~ 4,000cm ² / g. The method of claim 2, The non-plastic binder comprising the bottom ash, characterized in that the bottom ash powder is 3,000 ~ 3,500cm ² / g. The method of claim 1, The alkaline inorganic material is a non-plastic binder comprising a bottom ash, characterized in that any one or a mixture of sodium hydroxide, potassium hydroxide, sodium carbonate in the range of 6 to 16M. The method of claim 1, The sodium silicate is a non-plastic binder comprising a bottom ash, characterized in that the molar ratio of SiO ₂ and Na ₂ O is 1.0 to 3.5. The method of claim 5, The sodium silicate is a non-plastic binder comprising a bottom ash, characterized in that the molar ratio of SiO ₂ and Na ₂ O is 2.8 to 3.2. In the concrete composition comprising fine aggregate, coarse aggregate, water and binder, The concrete composition, characterized in that the binder is the non-plastic binder of any one of claims 1 to 6. The method of claim 7, wherein The water is concrete composition, characterized in that applied to within 20% by weight relative to the binder. The concrete composition according to claim 8, wherein the water is applied in a weight ratio of 10 to 20% with respect to the binder.

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