KR101339332B1 - A Non-sintering Binder Having Bottom Ash - Google Patents

Abstract

The present invention relates to a non-baking binder including a bottom ash, more specifically, to the bottom ash which is physically activated by a pulverizing device instead of a cement for discharging a large amount of carbon dioxide by plastic working, and calcium carbide as an alkaline inorganic material By providing a binder in which sodium silicate is mixed with sodium hydroxide and silicate, it is possible to use a non-plastic, industrial waste bottom ash, thereby providing an environmentally friendly binder, and excellent workability in manufacturing mortar or concrete using the binder. The present invention relates to a non-plastic binder which may be provided with cementless mortar or concrete having a compressive strength of 20 to 60 MPa.

Description

A Non-sintering Binder Having Bottom Ash}

The present invention relates to a non-baking binder including a bottom ash, more specifically, to the bottom ash that is physically activated by a pulverizing device instead of a cement for discharging a large amount of carbon dioxide by plastic working, and calcium carbide as an alkaline inorganic material By providing a binder in which sodium silicate is mixed with sodium hydroxide and silicate, it is possible to use a non-plastic, industrial waste bottom ash, thereby providing an environmentally friendly binder, and excellent workability in manufacturing mortar or concrete using the binder. The present invention relates to a non-plastic binder which may be provided with cementless mortar or concrete having a compressive strength of 20 to 60 MPa.

With various efforts to prevent global warming (adopted in 1997, end of the Kyoto Protocol 2012, effective in 2005), and in December 2007, the Bali Roadmap was adopted in Bali, Indonesia. Negotiations are in progress for a climate change agreement.

As a result, global emissions of carbon dioxide and other greenhouse gases have to be significantly reduced.

On the other hand, the cement industry is a major carbon dioxide emission industry along with the steel industry, which produces about 0.9 tons of carbon dioxide to produce 1 ton of cement, which is the base for concrete production.

Domestic cement production amounts to about 60 million tons per year, which produces about 54 million tons of carbon dioxide. As a countermeasure for this, researches for replacing cement using industrial byproducts are continuously being carried out.

     Domestic and international blast furnace slag, fly ash, and some mixed with cement has been applied to a lot of concrete, but this method has a limit in dramatically reducing carbon dioxide.

Overseas, the technology of alkali-activated cement (concrete) by polymerization reaction was conceptually established by Davidovits (France) in 1978 as a mechanism for using kaolinite mineral and having a structure similar to zeolite. There was no practical use because of economics.

On the other hand, in the past, a technique for manufacturing concrete using only fly ash, which has similar chemical composition to bottom ash, without using cement at all has been proposed, and it reacts by breaking the glassy film of coal ash through a high temperature curing process of 60 ° C or higher. By inducing the present invention relates to a technology capable of securing 20 MPa or more. However, this technique is due to the polymerization reaction has a problem that there is a limit to increase the strength.

In addition, in the prior art, there is a case in which metakaolin is used, but since the kaolin is calcined at 700 to 800 ° C. to use metakaolin, carbon dioxide is discharged in this process, and the price is expensive, so there is a problem in practical use.

On the other hand, fly ash (fly ash) is mostly consumed as cement raw materials and concrete admixtures among coal ashes generated from thermal power plants.Bottom ash (floor ash) occupies about 15-25% of coal ash generated. Most of them are disposed of in landfills, which impedes economic losses due to huge disposal costs and the effective use of land due to landfill growth. Accordingly, research on cement mortar or concrete using bottom ash together with cement or as a substitute is being conducted.

Therefore, the present inventors proposed the present invention by repeatedly researching and experimenting to use the bottom ash as a mortar or a binder of concrete, and the present invention is a physically activated bottom ash instead of cement which emits a large amount of carbon dioxide during manufacture. The purpose of the present invention is to provide a binder which can produce cementless mortar or cement concrete which is excellent in workability and compressive strength by mixing sodium silicate with an appropriate compounding ratio of calcium carbide and / or sodium hydroxide and silicate as an alkaline inorganic material. There is this.

The non-baking binder including the bottom ash of the present invention for achieving the above object is blended with bottom ash, alkaline inorganic material, and silicate, the alkaline inorganic material and silicate in the weight ratio of 70:30 ~ 80: It is characterized by 20.

In particular, the present invention uses the bottom ash which physically activated the polymerization reaction by crushing and destroying the glass coating, and calcium hydroxide (Ca (OH) ₂ ) produced from calcium carbide by combining calcium carbide (CaC ₂ ) as an alkaline inorganic material. Cement-free mortar or concrete is prepared by incorporating sodium silicate with sodium hydroxide and silicate as an alkaline inorganic material to enhance long-term strength and chemically activate it. To be provided.

The calcium carbide (CaC ₂ ) is a by-product generated during the production of acetylene (CaH ₂ ) gas, and shows a process in which calcium hydroxide (Ca (OH) ₂ ) is formed by reaction with water of the following formula. The calcium hydroxide thus formed meets the components of Si, Al, and Fe in bottom ash, causing the CSH gel-type pozzolanic reaction, which is similar to the CSH obtained in the hydration reaction, which allows the strength to be expressed in mortar or concrete. Will be.

CaC ₂ + H ₂ O → CaH ₂ + Ca (OH) ₂

In other words, the physical strength of the bottom ash can be used to activate the polymerization of the polymer to improve the strength, and the pozzolanic reaction can be induced to increase the long-term strength in the production of mortar or concrete using such a binder. Will be.

The curing process of mortar or concrete to which the binder of the present invention is applied can be classified into 1) formation of precursors through the synthesis of hydroxide ions, 2) partial reconstitution of alkali-silica, and 3) reprecipitation for formation of inorganic structures. .

Thus, in the mortar or concrete to which the binder of the present invention is applied, the ratio of H ₂ O / SiO _{2 is also} important in addition to the ratio of Al / Si. This is because H ₂ O plays an important role in the dissolution of aluminum and silica ions.

In the present invention, by inducing a polymerization reaction (Polymerisation) through the combination of the bottom ash, alkali inorganic material and silicate to enhance the strength to eventually increase the strength without a cement without using a binder material that can express a certain strength or more To provide.

In the present invention, it is preferable that the above-mentioned calcium carbide and / or sodium hydroxide are used as the alkaline inorganic material, and sodium silicate is used as the silicate.

Thus, the binder of the present invention is composed of a bottom ash (A), an alkaline inorganic material (B) and a silicate (C), wherein the bottom ash (A) and the alkaline inorganic material and sodium silicate (B + C) has a weight ratio of 70: It is reasonable to consist of 30 to 80:20. The weight ratio (A: B + C) of the bottom ash, the alkaline inorganic material and the silicate of the binder is 70:30 to 80:20 because the appropriate ratio of Si, Al and Na necessary for the polymerization reaction must be present. If the weight ratio of ash is larger than this, the Na required for the reaction is relatively low, and the strength is lowered. On the contrary, if the ash ratio is smaller, the strength is lowered due to the lack of Si or Al which contributes to the strength.

In addition, it is reasonable that the weight ratio of the alkaline inorganic material (B) and the silicate (C) is composed of 75:25 to 25:75. It is a problem that when the alkaline inorganic material is used in excess of 75% by weight, the aluminosilicate is excessively generated, resulting in mortar or concrete cracking due to expansion, resulting in a decrease in strength. There is a problem in that the production of aluminosilicate is reduced, the initial strength is lowered, the shrinkage is somewhat increased, and the use of a large amount of silicate (sodium silicate) adversely affects the economics.

It is preferable to use a bottom ash having a powder degree of 3,000 to 4,500 cm 2 / g, which is low in reactivity when the bottom ash has a powder degree of less than 3,000 cm 2 / g. This is because when it exceeds g, the reactivity is large, but since the workability is somewhat lowered and it is not sold as a normal product, the economic efficiency may be lowered because it has to go through a grinding process or a classification process for fine powder. It is preferable to use a physically activated bottom ash. The physically activated method is to grind the glass coating of the bottom ash by a physical method using a grinding device to activate a polymerization reaction so that high strength is expressed. Valid

Sodium silicate used as the silicate is preferably used having a molar ratio of SiO ₂ and Na ₂ O has a value in the range of 1.0 to 3.4, when the molar ratio is less than 1.0, the viscosity of the binder is rapidly increased and the slump is lowered to workability Not only does this decrease, but the Si component required for the polymerization reaction decreases, the long-term strength is decreased, and when the molar ratio exceeds 3.4, it does not affect the workability, but there is a problem that the initial strength decreases due to less Na ions. Because.

Furthermore, in order to obtain better workability and strength, it is more preferable to use sodium silicate having a molar ratio of SiO ₂ to Na ₂ O of 2.8 to 3.2.

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

Meanwhile, the present invention may be composed of cement mortar by blending fine aggregate and water in the non-baking binder including the bottom ash mentioned above, and mixing coarse aggregate, fine aggregate, and water in the non-baking binder including the bottom ash. Cementless concrete can be constructed. In such mortars and concrete, admixtures, reinforcing fibers, etc. may be reinforced as necessary.

As described above, the non-plastic binder including the bottom ash of the present invention physically activates the bottom ash to favor strength expression, and activates the pozzolanic reaction based on calcium carbonate to express long-term strength at room temperature according to the mixing ratio thereof. Compressive strength can be secured to the range of 20 ~ 60MPa has the advantage that cement mortar or concrete can be provided.

In addition, the non-sintered binder including the bottom ash of the present invention has a merit that the fluidity can be maintained for a predetermined time or more during the production of mortar or concrete, thereby ensuring sufficient workability and sufficient applicability as a binder.

Further, since the cement is completely replaced by using the non-sintered binder including the bottom ash of the present invention, a large amount of CO ₂ Gas generation can be reduced and the bottom ash, which is an industrial by-product, is recycled, which not only has an economic burden for securing a landfill, but also has the advantage of reducing many environmental problems caused by leachate generated during landfilling.

Figure 1 is a graph showing the slump and compressive strength results according to the weight ratio of the bottom ash and alkaline inorganic materials and silicates in the binder.
Figure 2 is a graph showing the slump and compressive strength results according to the weight ratio of the alkali inorganic material and silicate when the relative relative weight ratio of the bottom ash in the binder.
Figure 3 is a graph showing the slump results according to the powder diagram of the bottom ash.
4 is a graph showing the compressive strength results according to the powder density of the bottom ash.
5 is a graph showing compressive strength results according to calcium carbide incorporation ratio when sodium hydroxide in an alkaline inorganic material is constant.

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

Since the embodiments according to the present invention can be modified in various other forms, the scope of the present invention is not limited to the embodiments described below.

≪ Example 1 >

Bottom ash  prepare Alkaline  Inorganic Materials and Silicate Weight Ratio Effect

The weight ratio of bottom ash, alkaline inorganic material and silicate in bottom ash, alkaline inorganic material (sodium hydroxide (NaOH) 9M) and silicate (sodium silicate having a molar ratio of SiO ₂ / Na ₂ O of 3.2) having a powder degree of 3,000 cm 2 / g 60:40, 70:30, 80:20, and 90:10, wherein the weight ratio of sodium hydroxide and sodium silicate was used as a binder in which each was 1: 1. And the remaining fine aggregate, coarse aggregate was used to produce concrete using the same ratio as conventional concrete. The slump and the compressive strength of each concrete manufactured in this way were measured and the results are shown in FIG. 1. Here, the slump test was evaluated for workability immediately after discharging from the mixer by mixing concrete in accordance with KS F 2402, the compressive strength was produced after the curing for 1 day at 20 ℃ to produce a φ100 × 200mm column test specimen Humidity was performed at 60 ° C. for 48 hours at 50 ± 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, when the weight ratio of the alkaline inorganic material and the silicate to the weight of the bottom ash is 60:40, the slump has a small compressive strength, 90:10 is the slump and the compressive strength is deteriorated appear. In other words, Si, Al, and Na in the proper ratios required for the polymerization reaction exist, but the weight of the bottom ash is constant, but if the amount of alkaline inorganic material and silicate is large, the lack of Si or Al, which contributes to the strength, causes a decrease in strength. As the amount of water contained in the alkaline inorganic material increases, the slump is increased, but residual water in addition to the water required for the dissolution process of aluminum and silica ions is believed to cause a decrease in strength. Therefore, it is determined that the weight ratio of the alkaline inorganic material and the silicate to the bottom ash is 70:30 to 80:20, which is an appropriate blending ratio in terms of strength and slump, and more preferably, the weight ratio of the alkaline inorganic material and the silicate to the bottom ash weight is 80:20 is valid.

<Example 2>

Alkaline  Effect of weight ratio of inorganic materials and silicates

Bottom ash having a powder degree of 3,000 cm 2 / g, an alkaline inorganic material (sodium hydroxide (NaOH) 9M) and silicate (sodium silicate having a molar ratio of SiO ₂ / Na ₂ O of 3.2), but as shown in Example 1 Similarly, bottom ash, alkaline inorganic material and silicate are blended in an appropriate weight ratio of 80:20, and the weight ratio of alkaline inorganic material and silicate is 100: 0, 75:25, 50:50, 25:75, and 0: 100, respectively. Blended binders were used. In the present embodiment, the remaining fine aggregate and coarse aggregate were used to produce concrete using the same ratio as conventional concrete, and the slump test and the test of compressive strength were performed in the same manner as in Example 1, and the results are shown in FIG. have.

As can be seen in Figure 2, when the alkaline inorganic material or silicate is not blended it can be seen that the disadvantage in terms of strength, the weight ratio of the alkaline inorganic material and the silicate is 75:25 to 25:75 It is understood that this is advantageous in terms of workability and strength. In particular, as can be seen in the present embodiment, the most preferable compounding ratio of the alkaline inorganic material and the silicate in consideration of the slump of the water content of sodium hydroxide and the strength of the contribution of Na of sodium hydroxide and Si of sodium silicate is preferred. 1: 1 is considered reasonable.

<Example 3>

Bottom ash Powdery  effect

In order to analyze the effect of the bottom ash in the non-plastic binder containing the bottom ash presented in the present invention, as shown in Table 1, the powder degree 1,500 cm 2 / g, 3,000 cm 2 / g, 4,500 cm 2 / g, 5,500 Bottom ash with cm 2 / g was used.

division Powder level (㎠ / g) BA1500 1,500 BA3000 3,000 BA4500 4,500 BA5500 5,500

The bottom ash with different powder levels was 80% by weight of the total weight of the binder, respectively, 9M sodium hydroxide as the alkaline inorganic material, 10% of the total weight of the binder, and silicate (sodium silicate with a molar ratio of SiO ₂ / Na ₂ O of 3.2). The binder was constituted by 10% of the total weight of the binder. In the present embodiment, the remaining fine aggregate and coarse aggregate were used to produce concrete using the same ratio as conventional concrete, and the slump test and the test of compressive strength were performed in the same manner as in Example 1, and the results are shown in FIGS. 4 is shown.

As can be seen in Figure 3, as the powder density of the bottom ash appeared to be somewhat lower in the workability, but the powder degree up to 4,500 ㎠ / g was shown that the slump is 210 ~ 185mm range has no significant effect on the workability 5,500 cm 2 / g powder, the slump was found to significantly reduce the fluidity of about 145mm. Therefore, in terms of construction properties, it can be seen that in the binder of the present invention, the powder density of the bottom ash is preferably 3,000 to 4,500 cm 2 / g.

Next, in terms of compressive strength, from the results of FIG. 4, the smaller the powder density of the bottom ash, the lower the strength expression, and especially when the unpulverized powder is 1,500 cm 2 / g, it is relatively low at less than 10 MPa even at 28 days. The strength is shown. In addition, although the initial strength and the long-term strength are increased up to 4,500 cm 2 / g of powder, it can be seen that the strength decreases when the powder degree of 5,500 cm 2 / g is used. In other words, the strength of the bottom ash in the binder of the present invention in terms of strength, it can be seen that the preferred is 3,000 to 4,500 cm 2 / g. In terms of strength, when the non-crushed bottom ash (powder 1,500 cm 2 / g) is used, it can be seen that it is not suitable as the binder of the present invention because of its low strength, which is used as the binder of the present invention. In this case, it is determined that the strength of the polymerization is to be achieved by activating the polymerization reaction by breaking the glassy film by pulverization (powder degree of 3,000 to 4,500 cm 2 / g).

On the other hand, the bottom ash used in the above and pulverized by using a vibration mill and when not shown in Table 2 by component analysis.

SiO ₂
(%) Al ₂ O ₃
(%) Fe ₂ O ₃
(%) CaO
(%) MgO
(%) SO ₃
(%) K ₂ O
(%) Na ₂ O
(%) LOI
(%) Bottom ash 57.7 23.6 9.36 4.57 0.16 0.71 2.56 0.82 0.01 Crushed
Bottom ash 58.3 22.4 8.8 4.53 1.37 0.42 2.38 0.70 0.04

As can be seen in Table 2, when the bottom ash is pulverized using a pulverizing device, it is determined that there is little difference in the constituents due to a very small variation in chemical composition. In other words, when the bottom ash is pulverized to form an appropriate powder, it can be seen that it has an activity for polymerization by physical fluctuations (breaking the glass coating) without a change in its chemical composition. Or it is considered that the strength of the concrete can be improved.

In summary, when the mortar or concrete is manufactured using a binder composed of bottom ash, alkaline inorganic material and silicate, the bottom ash should change physical activity by pulverization. In the range of g, slump 180mm or more can secure sufficient workability, and the compressive strength in the range of 30 ~ 60MPa compressive strength can be secured in 28 days. . In particular, considering the workability, strength and economics, it is most preferable that the bottom ash powder is 3,000 cm 2 / g.

<Example 4>

Calcium carbide Mixing fee  effect

In order to analyze the effects of the mixing ratio of calcium carbide on the alkaline inorganic material in the binder of the present invention, calcium carbide was added in an amount of 0, 5, 10, 15, 20% by weight based on the total weight of the binder, and the powder was 3,500. Bottom ash, cm 2 / g, was used 75, 70, 65, 60% of the total weight of the binder, respectively. In all four cases, sodium hydroxide (NaOH-9M) was used as 10% based on the total weight of the binder, and sodium silicate was used as 10% based on the total weight of the binder. In the present embodiment, the remaining fine aggregate and coarse aggregate were used to produce concrete using the same ratio as conventional concrete, and the test of the compressive strength was performed in the same manner as in Example 1, and the results are shown in FIG. 5.

As can be seen in Figure 5, the strength was increased as the mixing ratio of calcium carbide up to the substitution rate 10%, it was found that all excellent in the long-term strength of 91 days when calcium carbide was mixed. The reason for this is that the calcium hydroxide produced by calcium carbide is mixed to cause synergistic effects such as pozzolanic reaction with the polymerization of bottom ash, and thus the long-term strength is judged to be excellent. It was found that the strength decreased when the calcium carbide exceeded 10% by weight. The reason for this is that the bottom ash decreases as the calcium carbide increases.

In summary, when concrete is manufactured using a binder composed of bottom ash, calcium carbide, sodium hydroxide, and sodium silicate, it is preferable to mix calcium carbide in excess of 0 and 200 parts by weight or less with respect to 100 parts by weight of sodium hydroxide. It was found that the best effect occurred in the initial strength and long term strength improvement.

Bottom ash calcium carbonate
Sodium hydroxide sodium silicate
Sodium Silicate Binder

Claims (9)

The bottom ash, the alkaline inorganic material and the silicate, the bottom ash and the remaining inorganic inorganic material and the silicate is characterized in that the weight ratio of 70:30 ~ 80:20, the alkaline inorganic material and the silicate is 75: Characterized in that the 25 to 25:75, the bottom ash is characterized by activating by physically breaking the glass coating by using a grinding device, characterized in that the powder degree of 3,000 ~ 4,500㎠ / g,
The alkaline inorganic material is a mixture of calcium carbide (CaC ₂ ) and sodium hydroxide (NaOH) in the range of 6 to 16M, wherein the alkaline inorganic material is calcium carbide in excess of 0 and 100 parts by weight or less relative to 100 parts by weight of sodium hydroxide. and,
The silicate is a non-plastic binder comprising a bottom ash, characterized in that sodium silicate having a molar ratio of SiO ₂ and Na ₂ O 1.0 to 3.4.
delete delete delete delete delete delete In mortar including fine aggregate, coarse aggregate, water and binder,
The binder is mortar, characterized in that containing the binder of claim 1.
In concrete composed of fine aggregate, coarse aggregate, water, binder,
The binder is concrete, characterized in that the binder of claim 1 is included.

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