KR100929309B1 - Manufacturing Method for Concrete Body consisted of Waste Sludge as a Inorganic Binder using Meta-Kaolin - Google Patents

Abstract

The present invention relates to a method for producing a cured concrete using activated kaolin and waste concrete sludge, which can utilize waste clay sludge as a cement substitute hardener by mixing and curing activated kaolin to inorganic sludge disposed of by waste disposal or landfilling.

The concrete cured body using activated kaolin and waste concrete sludge according to the present invention is a binder mixture in which waste concrete sludge and activated kaolin are mixed, an alkali stimulant and an initial strength which are aqueous solutions of NaOH, KOH, LiOH, or a mixed aqueous solution thereof. It comprises a water glass that plays a role of imparting, the waste concrete sludge and activated kaolin is mixed in a weight ratio of 100: 10 to 70, the alkali stimulant is included in a ratio of 20 to 80% of the weight of the activated kaolin, The water glass is characterized in that it comprises a ratio of 10 to 30% by weight of the active kaolin.

Activated Kaolin, Waste Concrete Sludge, Binder

Description

Manufacturing Method for Concrete Body consisted of Waste Sludge as a Inorganic Binder using Meta-Kaolin}

The present invention relates to a method for producing a cured concrete using activated kaolin and waste concrete sludge. Specifically, by mixing and curing activated kaolin in an inorganic sludge to be disposed of by waste disposal or landfill, waste concrete sludge can be utilized as a cement hardener. The present invention relates to a method for producing a cured concrete using activated kaolin and waste concrete sludge.

Unlike conventional concrete, geopolymer concrete does not use Portland cement as a binder. Geo-polymers are named by Davidovits as binders known as inorganic alumino-silicate polymers and include activated kaolin, fly ash and the like.

In general, in construction sites, Portland cement, which is used as a binder of concrete, mixes and grinds materials containing potassium oxide (CaO), silicon dioxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), etc. at an appropriate ratio. Gypsum (CaSO ₄ · 2H ₂ O) as a coagulation retardant is added to the clinker made by firing at 1400 ~ 1500 ℃ until it melts, and it is made by grinding. Below is the chemical formula of the firing process.

_{5CaCO 3 + 2SiO 2 → 3CaO ·} SiO 2 + 2CaO · SiO 2 + 5CO 2

However, as shown in the above equation, there is a problem that a large amount of greenhouse gas represented by CO ₂ is emitted due to the firing process of cement manufacturing process. Globally, Portland cement production increases by 3% annually, and the greenhouse gas emissions generated by this process amount to about 1.35 million tons per year, accounting for about 7% of global greenhouse gas emissions.

In order to solve this problem of cement manufacturing, there have been attempts to use alumino silicate synthesized at room temperature as a cement substitute, but it is not fully examined whether it has a function equivalent to or higher than that of Portland cement. It is not being used as a substitute.

In addition, Portland cement is also used as a material for the production of porous carriers that can support microorganisms in addition to building materials. When using natural materials or general portland cement, the pore distribution in the carrier can not be varied. There is a problem falling.

The present invention was developed to overcome the limitations and problems of the prior art as described above, by using waste concrete sludge and activated kaolin and alkali stimulant to develop an inorganic binder that can replace the cement without the need for a separate firing operation For the purpose of

In order to achieve the above object, the hardened concrete concrete using activated kaolin and waste concrete sludge according to the present invention is a binder mixture in which waste concrete sludge and activated kaolin are mixed, and an aqueous solution of NaOH, KOH, LiOH, or a mixed aqueous solution thereof. It comprises a phosphorus alkali stimulant and water glass that serves to impart the initial strength, the waste concrete sludge and activated kaolin is mixed in a weight ratio of 100: 10 to 70, the alkali stimulant is 20 to 80 relative to the weight of activated kaolin It is included in the ratio of%, the water glass is characterized in that it is included in a ratio of 10 to 30% by weight of the active kaolin.

The alkali stimulant is an aqueous solution of 6 to 12M concentration, and may be composed of an aqueous solution of 6 to 12M in which NaOH and KOH are mixed at a ratio of 1: 1/3 to 3.

In addition, 5 to 30% of the total weight of the waste concrete sludge is composed of any one or a mixture of fly ash, silica fume, <weight ratio of the one or a mixture of the fly ash, silica fume> and the activated kaolin. Silver may be from 30 to 70 to 270.

The method for producing a cured concrete using activated kaolin and waste concrete sludge according to the present invention comprises the steps of preparing a binder mixture by mixing waste concrete sludge and activated kaolin powder in a weight ratio of 100: 10 to 70; It comprises a step of preparing a mortar by mixing with water glass and mixed water and molding and curing the mortar, the alkali stimulant is an aqueous solution of any one of NaOH, KOH, LiOH or a mixed aqueous solution of 6 to 12M concentration The alkali stimulant is included in the ratio of 20 to 80% of the weight of the active kaolin, the water glass is included in the ratio of 10 to 30% of the weight of the active kaolin, the AE water reducing agent is included in the mixed water, the AE water reducing agent It occupies 0.5 to 2% of the total weight of the mixed water. At this time, the mortar may be cured at a temperature of 30 ~ 80 ℃.

According to the present invention, it is possible to recycle the inorganic sludge, which is a waste material generated in the process of recycling waste concrete, can be used as construction materials (such as cement substitutes, heat-resistant binders), landfilled waste concrete sludge and environmental dumping Problems can be solved and greenhouse gas emissions from Portland cement manufacturing can be reduced.

In addition, by using activated kaolin and stimulant, inorganic sludge can be used as a cement substitute without a separate firing operation, and thus resources can be recycled, thereby reducing the amount of cement used in natural raw materials, thereby improving economic efficiency.

Hereinafter, a concrete hardened body manufacturing method using the activated kaolin and waste concrete sludge according to the present invention will be described in detail through a specific embodiment of the present invention.

In general, when water is added to Portland cement, a chemical reaction between cement and water occurs and a condensation hardening occurs. Below is the hydration of Portland Cement.

<Reaction of Silicate Lime>

C ₂ S + (n + 2) H ₂ O = CS nH ₂ O + 2Ca (OH) ₂

C ₃ S + nH ₂ O = CSnH ₂ O + Ca (OH) ₂ , (n = 2)

<Reaction of Aluminate Lime>

C ₃ A + 3CaSO ₄ + nH ₂ O = C ₃ A · 3CaSO ₄ · nH ₂ O, (n = 30 ~ 32)

<Reaction of Iron Aluminate Lime>

C ₄ AF + Ca (OH) ₂ + 10H ₂ O = C ₃ A · 6H ₂ O + CF · 5H ₂ O

As described above, the strength expression of the Portland cement undergoing the pozzolanic reaction is dependent on calcium (Ca), whereas the aluminosilicate inorganic binder of the present invention exhibits structural strength by polymerization of Al and Si under strong alkali conditions. That is, rich inorganic substances such as Si and Al are activated by the alkaline liquid to act as a binder.

Both waste concrete sludge and activated kaolin are aluminosilicate minerals, which are hardened under alkaline environment to form geopolymers. At this time, if the activated kaolin is heat treated at 600 ℃ or lower, kaolin does not have enough activity to stimulate waste concrete sludge to act as a binder, and when heat treated at 900 ℃ or higher, the properties of kaolin may be changed. It is uneconomical. In addition, kaolin heat-treated at about 800 ° C. is most efficiently activated. Therefore, in the present invention, it is preferable to heat the kaolin at 600 ~ 900 ℃ to have a high activity. The activated kaolin heat-treated is higher than kaolin before heat-treatment, so it easily reacts with alkali and becomes a geopolymer. However, since waste inorganic sludge, which is a general inorganic sludge, does not easily react with alkali, it can increase reactivity by adding activated kaolin. have. In addition, by adding liquid water glass as an auxiliary binder, waste inorganic sludge can be further activated, and the waste inorganic sludge can be utilized as a geopolymer for cement.

Therefore, in order to utilize the aluminosilicate-based inorganic binder, an alkaline environment is required, and as an additive, activated kaolin (metakaolin, metakaolin) or by-products such as fly ash or rice bran may be used.

Tables 1 and 2 show the chemical composition and physical properties of recycled aggregate sludge, which is one of activated kaolin and waste inorganic sludge, respectively.

Table 1.

Ingredient Name Specific gravity (g / cm 3) Powder level (㎠ / g) Compressive Strength (Kgf / ㎠) 3 days 7 days 28 days Portland cement 3.15 3,450 210  262 348 Waste Concrete Sludge 2.53 - - - - Activated kaolin 2.83 5,580 - - - Fly ash 2.65 4,830 - - - Silica fume 2.16 200,000 - - -

Table 2.

Ingredient Name Specific gravity (g / cm 3) Powder level (㎠ / g) Compressive Strength (Kgf / ㎠) 3 days 7 days 28 days Portland cement 3.15 3,450 210  262 348 Waste Concrete Sludge 2.53 - - - - Activated kaolin 2.83 5,580 - - - Fly ash 2.65 4,830 - - - Silica fume 2.16 200,000 - - -

Waste inorganic sludge which is a cement substitute in the present invention is waste concrete sludge, water purification sludge, mineral sewage sludge, water purification sludge, stone powder sludge, incineration sludge, paper sludge, foundry sand sludge, coal ash sludge, slag, etc. Can be. As shown in Table 1, these waste inorganic sludges contain abundant SiO ₂ and Al ₂ O ₃ , so if they are slightly soluble, they can be cured in an alkaline environment. It can be mixed and self-hardened. The water glass refers to an aqueous solution of an alkali silicate salt in which silicon dioxide and alkali are fused, and typically, an aqueous sodium silicate solution (2SiO ₂ · Na ₂ O · xH ₂ O) and the like. The water glass not only induces the activation of waste inorganic sludge, but also has a property of being soluble in water, thereby shortening the curing time of cement. At this time, the water glass is preferably added in a ratio of 10 to 30% of the weight of the active kaolin.

On the other hand, it is also possible to replace all or part of the waste inorganic sludge with fly ash or silica fume to further add an alkali stimulant to increase the alkali environment or to enhance the strength.

In addition, the waste inorganic sludge may be used as a substitute for clay in ceramic products, such as clay bricks and tiles, as well as raw materials and substitutes for manufacturing Portland cement.

Among the waste inorganic sludges, the waste concrete sludge has already undergone hardening, and thus, the bonding strength is weak, but the cement content is contained as it is. Thus, when activated kaolin is added properly, it can have a bonding strength equivalent to that of general portland cement. In addition, even when the concrete aggregate is used as the recycled aggregate, it can be hardened together to the surface attachment portion of the recycled aggregate, so that the densification and strength of the bonded structure can be promoted.

Waste concrete sludge, which is a kind of waste inorganic sludge, and activated kaolin can be mixed in an appropriate ratio. When the waste concrete sludge is 100, the amount of activated clay is less than 10 when the activated kaolin ratio is 10 or less, so that the waste concrete sludge is not sufficiently activated. In addition, when the active kaolin ratio is 70 or more, even if the ratio is further increased, the waste concrete sludge can no longer contribute to the activation and the recycling rate of the waste concrete sludge decreases. Therefore, it is preferable to mix waste concrete sludge and activated kaolin at a weight ratio of 100: 10 to 70.

Meanwhile, as the alkali stimulant, any one or a mixture of NaOH, KOH, and LiOH may be used, and the alkali stimulant is preferably added in an aqueous solution having a concentration of 6-12 M. When the alkali stimulant is added to 6M or less, it is not possible to create an alkaline environment capable of sufficiently soluble waste concrete sludge, and if more than 12M, even if the addition ratio is increased, the pH does not increase any more, compared to the amount of waste This is because the availability efficiency of concrete sludge is lowered. More specifically, 6-12 M aqueous solution which mixed NaOH and KOH in the ratio of 1: 1 / 3-3 can be used as alkali stimulant. At this time, in the case of mixing KOH at 1 / 3M or less with NaOH 1M, or mixing KOH at a ratio of 3M or more, the solubility efficiency of the waste concrete sludge is lowered. On the other hand, the alkali stimulant is preferably added at a rate of 20 to 80% relative to the active kaolin weight.

In addition, when the pH is 12 or less, the waste concrete sludge cannot be sufficiently soluble, and it is preferable to maintain the pH of the hydroxide which is an alkali stimulant at 12 or more to provide a strong alkaline environment.

In addition, 5-30% of the total weight of the waste concrete sludge may be replaced by fly ash or silica fume or a mixture of fly ash and silica fume to enhance the strength of concrete or mortar. When the above-mentioned substitutes are mixed at less than 5% of the waste concrete sludge, there is no sufficient strength increase effect, and when mixed at 30% or more, there is no problem of decreasing the recycling rate of the waste concrete sludge without any increase in strength. have.

On the other hand, the ratio of the material and the activated kaolin to replace the waste concrete sludge is preferably 30: 70 ~ 270. When the total weight of the substitute is 30, when the activated kaolin is mixed at 70 or less, sufficient strength enhancing effect is not obtained, and when mixed at more than 270, the recycling rate of waste concrete sludge is not increased any more. Falls.

In addition, by using the waste concrete sludge of the present invention, it is also possible to produce a carrier that can inhabit microorganisms. When the waste concrete sludge or the mixture of waste concrete sludge and activated kaolin is used instead of the portland cement, which is used at 250 to 400 kg per 1m3 of the material mixture of the carrier, the particle size and shape of the waste concrete sludge are lower than those of the portland cement. The variety of pores of various sizes and formations can be distributed to the bonding portion, and the waste water purification efficiency using the carrier is high. At this time, it is preferable to mix 1,500 to 2,000 kg of impacting aggregate per 1 m 3 of the material mixture of the carrier. In addition, it is possible to mix 80 to 150 kg of the mixed water to which the AE water reducing agent is added at a ratio of 0.5 to 10% of the total weight of the waste concrete sludge or the waste concrete sludge and the activated kaolin used as a substitute for the cement. When the AE water reducing agent is added less than 0.5% of the total weight of the mixture, fine pores are not well formed in the finished carrier, and when more than 10% is added, the concrete strength decreases rapidly, and thus, 0.5 to 10% is added. It is desirable to. On the other hand, by replacing all or part of the impacted aggregate with recycled aggregate can increase the absorption rate of the carrier surface.

At this time, the water mixture corresponding to 5 to 20% of the total weight of the mixed water of 6-12 M NaOH and the mixed water in the binder mixture of the waste concrete sludge and activated kaolin at a ratio of 100: 10 to 70, 0.5 of the total weight of the mixed water The carrier is formed by mixing the mixed water to which the AE water reducing agent corresponding to 2% is added, and the micropores are introduced to the surface of the concrete carrier by de-vacuating and curing for 1 to 5 minutes at 30 to 80 ° C and 0.1 to 0.3 vacuum pressure. can do. When the water glass is 5% or less of the total weight of the mixed water, the waste concrete sludge cannot be sufficiently soluble, and when 20% or more is added, the solubility efficiency does not increase. In addition, when the AE water reducing agent is less than 0.5% of the total weight of the mixed water, fine pores are not well formed, and when more than 2%, the concrete strength is reduced. In addition, if the curing temperature is lowered below 30 ℃ curing rate is too slow, polymerization does not occur vigorously, if curing temperature rises above 80 ℃ is a high risk of cracking after curing evaporated mixed water easily. On the other hand, if the de-vacuum treatment time in the curing process is shorter than 1 minute or at a pressure higher than 0.1 vacuum pressure, when the de-vacuum treatment is performed under the condition, fine bubbles are not drawn to the surface, and the de-vacuum treatment time is longer than 5 minutes. In the case of devacuation under a pressure lower than 0.3 atm, excessive air is drawn out on the surface of the paste to form cracks, which may cause a decrease in strength of the carrier. It is preferable to cure after treatment.

The present invention will be described in more detail based on the following examples.

<Example 1>

A mixture of waste concrete sludge and kaolin powder heat-treated at about 800 ° C. at a ratio of 7: 3, and a mixture of standard yarn and primary dry kneaded binder mixture at 65% of the total weight of mortar, to stimulate the sclerosis of the waste concrete sludge Mortar was prepared by mixing the mixed water added with 10 M NaOH and the same amount of water glass as the stimulant at 35% of the total weight of mortar and wet kneading the mixture. When the carrier produced by molding the mortar was cured at 30 ° C. at atmospheric pressure, the compressive strength of 3 days was 120Kgf / ㎠, the compressive strength of 7 days was 150Kgf / ㎠, and the compressive strength of 28 days was 205Kgf / ㎠, similar to that of general Portland cement. It was confirmed that.

<Example 2>

In Example 1, the curing temperature was increased to 80 ° C., and high temperature curing resulted in 3 days of compressive strength of 205Kgf / ㎠, 7 days of compressive strength of 240Kgf / ㎠, 28 days of compressive strength of 260Kgf / ㎠ and both initial and later strengths. It confirmed that it became high compared with Example 1.

<Example 3>

In Example 2, KOH was used instead of NaOH as a stimulator for stimulating the alkalinity of the waste concrete sludge, and the 3rd compressive strength was 180Kgf / ㎠, the 7th compressive strength was 260Kgf / ㎠, and the 28th compressive strength was 280Kgf / ㎠. . From this, it was confirmed that the initial strength was slightly lower than the case of using NaOH when KOH was used as the alkaline stimulant, but the later strength was increased.

<Example 4>

In Example 2, when NaOH and KOH were mixed at a 3: 1 ratio as an alkaline stimulant, and LiOH was added at a ratio of 1% to the total weight of the stimulant mixture, the compressive strength of 3 days was 220 Kgf / cm 2. It was confirmed that the initial strength was greatly improved.

Example 5

In Example 2, when the amount of waste concrete sludge is reduced from 70% to 60%, and 10% of the reduced amount of waste concrete sludge is replaced with silica fume, the 3-day compressive strength is 220Kgf / ㎠ and the 7-day compressive strength is 255Kgf. Compressive strength of 28 days / ㎠ appeared 280Kgf / ㎠, it was confirmed that both the initial strength and the late strength improved.

<Example 6>

After mixing the impacting aggregate with particle diameter of 13mm or less, 2,000kg, waste concrete sludge 200kg, and 50kg of kaolin powder heat treated at 800 ℃ The second wet kneading was carried out by mixing 120 kg of the mixed water to which the AE water reducing agent was added at a ratio of 1% by weight. The carrier was prepared by molding the mold and cured for 2 minutes under vacuum at 0.1 ° C. at 60 ° C., and the compressive strength was confirmed to be 207 Kgf / cm 2 for 3 days.

<Example 7>

1,500 kg of recycled aggregate with a particle diameter of 13 mm or less, 1 kg dry waste concrete sludge, and 100 kg of activated kaolin powder were first mixed and kneaded, and then 10% NaOH, the same amount of water glass and 1% of the total weight of the mixed water were added to the AE water reducing agent. 150 kg of a mixed water was mixed and subjected to second wet kneading. Molding was carried out to prepare a carrier, and cured for 2 minutes under vacuum at 0.1 ° C. at 60 ° C., and curing was confirmed at 183 Kgf / cm 2 for 3 days.

Claims (7)

delete delete delete delete Preparing a binder mixture by mixing the waste concrete sludge and the activated kaolin powder in a weight ratio of 100: 10 to 70; Mixing the binder mixture with an alkali stimulant, water glass, and mixed water to prepare a mortar; And Forming and curing the mortar is made, The alkali stimulant is an aqueous solution of any one of NaOH, KOH, LiOH or a mixed aqueous solution of 6 to 12M concentration, the alkali stimulant is contained in a ratio of 20 to 80% of the weight of the active kaolin, The water glass is included in the ratio of 10 to 30% by weight of the active kaolin, The AE water reducing agent is included in the mixed water, wherein the AE water reducing agent comprises 0.5 to 2% of the total weight of the mixed water, and the method of producing hardened concrete using activated clay and waste concrete sludge. 6. The method of claim 5, wherein the mortar is cured at a temperature of 30 to 80 ° C. According to claim 5, 5-30% of the total weight of the waste concrete sludge is composed of any one or a mixture of fly ash, silica fume, The weight ratio of <any one or a mixture of the fly ash and silica fume> and the activated kaolin is 30: 70 to 270, the method of producing a cured concrete using activated kaolin and waste concrete sludge.