KR100600079B1 - Method of fabricating shringkage compensation admixture for mortar having activated alumina - Google Patents

Abstract

The present invention relates to a cement related technology, and more particularly, to a shrinkage reducing material composition for mortar and a method of manufacturing the same. SUMMARY OF THE INVENTION An object of the present invention is to provide a shrinkage reducing agent composition for mortar and a method for producing the same, which can suppress an increase in construction cost due to addition of a shrinkage reducing material. According to an embodiment of the present invention, the step of reacting the lime filtrate with the filtrate produced in the acid clay production process; Producing a filter cake from the precipitate precipitated in the reacting step; Heat-treating the filter cake to remove moisture contained in the filter cake and to produce a material including activated alumina, quicklime, and anhydrous gypsum; And it provides a method for producing a shrinkage reducing material for mortar comprising the step of crushing the filter cake.

Mortar, shrinkage reducing material, crack, unit price, activated alumina

Description

Shrinkage Reducing Material Composition for Mortar Containing Activated Alumina {METHOD OF FABRICATING SHRINGKAGE COMPENSATION ADMIXTURE FOR MORTAR HAVING ACTIVATED ALUMINA}

1 is a view showing a general acid clay production process.

Figure 2 is a view showing a shrinkage reducing material manufacturing process for mortar according to an embodiment of the present invention.

3A is a diagram showing the results of measuring the change in paste length by forming a mortar test body (paste) by adding 12.5% substitution shrinkage reducing agent according to the weight of cement according to Table 5;

3B is a view showing the results of measuring the change in paste length by forming a mortar test body (paste) by adding 10 to 40% of the shrinkage reducing agent according to Table 6 to the cement weight.

Figure 4 is a view showing the measurement results of the length change of the mortar test specimen using the shrinkage reducing agent according to Table 6.

The present invention relates to a cement related technology, and more particularly to a method for producing a shrinkage reducing material composition for mortar.

Typically, the floor mortar is poured by an automated facility equipped with a high-rise pump for mass construction, and sufficient fluidity must be secured to facilitate the pouring by such an automated facility. In order to secure the fluidity of the floor mortar, the reality is that a large amount of water is added so that the water / cement ratio is almost 1 or more.

On the other hand, such a very high water / cement ratio is a factor of the occurrence of cracking mortar due to dry shrinkage, and shrinkage reducing material (or expander) is used to suppress the cracking of the mortar. Anhydrous gypsum mineral is widely used as a shrinkage reducing material, and is usually substituted by adding about 20 to 25% of the weight of cement used for floor mortar.

For reference, Korean Laid-Open Patent Publication No. 1996-034119 discloses anhydrous gypsum prepared by desulfurization with limestone when using petro-coke fuel when placing mortar for plastering ondol, as a shrinkage reducing material, from 20 to 20 About 25% substitution was added and the polymer fiber was reinforced to reduce dry shrinkage.

However, the anhydrous gypsum shrinkage reducing material as described above has a high unit cost of the shrinkage reducing material itself since the unit price of the anhydrous gypsum, which is a main component, is high. It is 20-25%, which is a factor in the rise of construction cost.

The present invention has been proposed to solve the problems of the prior art as described above, and an object thereof is to provide a method for producing a shrinkage reducing material composition for mortar that can suppress the increase in construction cost due to the addition of a shrinkage reducing material.

According to an aspect of the present invention for achieving the above technical problem, the step of reacting the filtrate and lime mineral produced in the acid clay production process; Producing a filter cake from the precipitate precipitated in the reacting step; Heat-treating the filter cake to remove moisture contained in the filter cake and to produce a material including activated alumina, quicklime, and anhydrous gypsum; And it provides a method for producing a shrinkage reducing material for mortar comprising the step of crushing the filter cake.

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In addition, according to another aspect of the present invention, in the mortar binder composition for floors using a mortar shrinkage reducing material prepared according to the method for producing a shrinkage reducing material for mortar, the shrinkage reducing material 5 to 15 by weight of cement There is provided a floor mortar binder composition, characterized in that the construction by the addition of% substitution.

Hereinafter, preferred embodiments of the present invention will be introduced in order to enable those skilled in the art to more easily carry out the present invention.

First, the present invention uses a filtrate (mother liquor / washing water), which is a waste by-product produced during the production of acidic clay, a kind of pozzolanic material, for the production of shrinkage reducing materials for mortar.

1 is a view showing a general acid clay manufacturing process, it will be described below with reference to this acid clay production process and waste by-products production process.

Referring to FIG. 1, first, clay (ore) is introduced into a reaction tank, and then sulfuric acid solution (H ₂ SO ₄ ) is used for oxidation of clay. Through this oxidation treatment, the reactant is precipitated in the reaction tank, and the waste acid solution except the precipitate is called mother liquor (lactic acid alumina).

Next, after separating the mother liquid in the reaction tank, the precipitate is washed with water (H ₂ O) about 10 times. The acid solution generated during this washing process is called washing water, and washing water has the same physical properties as the mother liquor diluted with water.

Subsequently, the washed precipitate is dried in a rotary dryer, and then pulverized in a crusher to obtain an acidic clay finished product.

The filtrate (mother liquor / washing water), which is a waste by-product produced in the acidic clay production process described above, is neutralized with alkaline substances such as Ca (OH ₂ ), Mg (OH) ₂ , NaCo ₃ , and then precipitated and filtered. It is made of by-product sludge and disposed of.

Clay is usually 50 to 60% of silica (SiO ₂ ), alumina (Al ₂ O ₃ ) 20-30%, consisting of other substances. In addition, the filtrate (mother liquor / washing water), a waste by-product generated during the sulfuric acid treatment on clay, contains Al ⁺³ , Si ⁺⁴ , SO ₄ ^-2 , H ^+, etc. Solution.

Figure 2 is a view showing a shrinkage reducing material manufacturing process for mortar according to an embodiment of the present invention.

Referring to FIG. 2, first, the filtrate (mother liquor / washing water) generated in the acidic clay manufacturing process as described above is added to a reaction tank, and reacted by adding lime mineral (neutralization reaction by lime mineral). Here, the mother liquor and the wash water only have a difference in concentration, and since the components are almost the same, only the mother liquor or the wash water may be used, and the mother liquor and the wash water may be mixed and used. Meanwhile, lime lime powder (CaCO ₃ ), hydrated lime (Ca (OH) ₂ ), quicklime (CaO) can be used as a mixture of one or more, and included in the SO ₃ component and lime mineral contained in the filtrate It is preferable to adjust the addition amount of lime mineral so that the molar ratio of the CaO component may be 1: 1-1: 3.

On the other hand, through the reaction as described above, a precipitate consisting of dihydrate gypsum (CaSO ₄ · 2H ₂ O), alumina, and other lime minerals is generated in the reaction tank, and the alumina (Al ₂ O ₃ ) content in the precipitate removes the attached moisture. It is preferable to make it at about 5 to 20%.

Next, the precipitate precipitated through the reaction in the reactor is put into a filter press to produce a filter cake.

Subsequently, the filter cake is put into a kiln to perform heat treatment (500 to 1200 ° C.) for a predetermined time. At this time, the water contained in the filter cake is removed, and through heat treatment, a material including activated alumina (Al ₂ O ₃ ), quicklime (CaO), anhydrous gypsum (CaSO ₄ ) and the like is produced. In particular, when limestone powder (CaCO ₃ ) is used as lime mineral, since decarboxylation reaction occurs at 800 ° C. or higher, it is preferable to perform heat treatment at a temperature of 800 ° C. or higher.

Subsequently, the dried filter cake is put into a pulverizer and subjected to a pulverization process to have a predetermined particle size (particle diameter of about 50 to 200 μm in which reactivity with cement can be maximized) to obtain a shrink-reducing material finished product.

Table 1 below shows the composition ratio of gypsum minerals produced according to the temperature during the heat treatment for the precipitate reacted by mixing the lime (Ca (OH) ₂ ) in the wash water so that the molar ratio of the SO ₃ component and the CaO component is 1: 1. It is shown. Here, quantification of gypsum minerals was carried out by XRD quantification.

division Room temperature 400 ℃ 600 ℃ 800 ℃ SO _{3 in the} precipitate (%) 29.36 34.97 34.69 34.41 Composition ratio by type of plaster (%) 2 gypsum 100 2.25 2.41 1.65 Half gypsum 0 14.02 0.40 0 Anhydrous gypsum 0 83.73 97.19 98.35 system 100 100 100 100

Referring to Table 1, the temperature conditions for having the performance as a shrinkage reducing material (the ratio of anhydrous gypsum in the total gypsum component of 90% or more) by heat treating the precipitate is 600 ℃ or more. However, at 600 ° C., the proportion of anhydrous gypsum in all gypsum components is increased to 97% or more. In fact, at 500 ° C. or more, the proportion of anhydrous gypsum in all gypsum components may be 90% or more.

Tables 2 to 4 below show the molar ratios of the SO ₃ component and the CaO component and the composition ratio of the resultant according to the heat treatment temperature.

Referring to Table 2, when the molar ratio of the SO ₃ component included in the filtrate and the CaO component included in the lime mineral is 1: 1, it can be confirmed that quicklime (CaO) is not produced. Therefore, in order to obtain the initial shrinkage compensation action by the CaO component, the molar ratio 1 of the CaO component included in the lime mineral with respect to the SO ₃ component included in the filtrate should be greater than.

Meanwhile, as shown in Tables 2 to 4, as the molar ratio of the CaO component included in the lime mineral to the SO ₃ component included in the filtrate increases, the production rate of activated alumina, which plays an important role in the early and late shrinkage compensatory action, is decreased. Therefore, the molar ratio of the CaO component contained in the lime mineral to the SO ₃ component contained in the filtrate is preferably not greater than 3.

In addition, Tables 2 to 4 show that when limestone powder (CaCO ₃ ) is used as lime mineral reacting with the filtrate, heat treatment should be performed at a temperature of 800 ° C. or higher.

Table 5 below shows the precipitate product and the precipitate product produced by filter pressing the precipitate reacted by mixing limestone powder (CaCO ₃ ) in a wash water so that the molar ratio of SO ₃ : CaO is 1: 1 to 5 kg / cm ² . It shows the chemical composition of the shrinkage reducing material produced by firing at 900 ℃ for 30 minutes.

ingredient  Sedimentation product Shrinkage Reducing Material (900 ℃ Heat Treatment) SiO ₂ 8.14 16.89 Al ₂ O ₃ 9.90 12.13 Fe ₂ O ₃ 5.26 6.40 CaO 20.39 23.98 MgO 0.81 1.31 SO ₃ 29.36 34.69 Na ₂ O 0.20 - K ₂ O 0.31 - Ig.loss 27.38 6.91 system 101.24 102.31 moisture 10.30 -

In addition, Table 6 below shows the precipitate produced by filter pressing the precipitate reacted by mixing slaked lime (Ca (OH ₂ )) in a wash water so that the molar ratio of SO ₃ : CaO is 1: 1.7 at 5 kg / cm ² . , And shows the chemical composition of the shrinkage reducing material prepared by firing the precipitate product at 600 ℃ for 30 minutes.

ingredient Sedimentation product High performance shrink reduction material (600 ℃ heat treatment) SiO ₂ 5.78 11.99 Al ₂ O ₃ 7.03 8.61 Fe ₂ O ₃ 3.73 4.54 CaO 43.48 46.03 MgO 0.58 0.93 SO ₃ 20.85 24.63 Na ₂ O 0.14 0.00 K ₂ O 0.22 0.00 Ig.loss 19.44 4.91 system 101.24 101.64 moisture 11.05 -

On the other hand, as shown in Table 2 to Table 6, the shrinkage reducing material prepared according to the present embodiment has an anhydrous gypsum, quicklime, activated alumina as a main component and other minerals included in the manufacturing process. The shrinkage reducing material prepared according to the present embodiment has excellent expandability due to the active alumina and quicklime produced by heat treatment as well as the expansion by anhydrous gypsum, which is well-known, and thus it is possible to secure excellent shrinkage reduction effect when mortar is applied even with a small amount. Can be.

The SO ₃ component in the shrinkage reducing material reacts with cement aluminate mineral (3CaO · Al ₂ O ₃ ) to produce acetrite (3CaOAl ₂ O ₃ · 3CaSO ₄ · 32H ₂ O) hydrated mineral in shrinkage. Induces reduction, and activated alumina (Al ₂ O ₃ ) can further increase the shrinkage reduction effect by reacting with water (dough water) to produce large amounts of ethrinzite hydrated minerals by itself or through reaction with cement. . The increased action of ethrinzite hydrated minerals by the use of such shrinkage reducing materials was actually confirmed through XRD analysis. Meanwhile, quicklime (CaO) produced by reacting the filtrate (mother liquor / washing water) with the lime mineral and then heat-treating the solids produced exhibits swellability as transition to calcareous lime (Ca (OH) ₂ ) during mortar construction reduces shrinkage of mortar. In addition, the high activity reactivity of quicklime itself can shorten the initial construction time. In other words, during the mortar construction, quicklime (CaO) and activated alumina (Al ₂ O ₃ ) among the shrinkage reducing agent components induce early expansion, and activated alumina (Al ₂ O ₃ ) and anhydrous gypsum induce late expansion.

The excellent shrinkage reducing effect of the shrinkage reducing material prepared according to the present embodiment is due to the complex expandability of the materials constituting the shrinkage reducing material, so that even when a small amount of the shrinkage reducing material is used compared to the existing, it is possible to obtain an excellent shrinkage reducing effect. For example, when placing a mortar for water having a water / cement ratio of 1 or more, even if only 10-15% of the cement weight is substituted, shrinkage reduction using conventional anhydrous gypsum is 20 ~ 25% of the cement weight. The effect does not fall.

3a is a diagram showing the results of measuring the change in paste length by forming a mortar test body (paste) by adding 12.5% substitution of the shrinkage reducing material according to Table 5 to the cement weight.

3B is a diagram showing the results of measuring the change in paste length by forming a mortar test body (paste) by adding 10 to 40% of the shrinkage reducing agent according to Table 6 with respect to the cement weight.

Mortar test specimens used were 300 mm long, 25 mm wide, and 25 mm high. Dough water was added in the same flow as the dough without the shrinkage reducing material added, and the length measurement was performed using a digital gauge.

3A and 3B, the shrinkage reducing effect of the shrinkage reducing material prepared according to the present embodiment can be easily confirmed. In particular, referring to FIG. 3B, the shrinkage reducing material prepared according to the present embodiment is compared with the cement weight. It can be confirmed that sufficient shrinkage reduction effect can be obtained even by adding only about 15% of substitution.

Figure 4 is a view showing the measurement results of the length change of the mortar test specimen using the shrinkage reducing material according to Table 6. Mortar test body (paste) was length 1000mm, width 100mm, height 50mm, length measurement was using a digital gauge. The maximum used sand was 6.7mm, and the cement: sand ratio was 3: 7, and 12.5% of high-performance shrinkage reducing agent was added to the cement, and the kneading water was added so that the flow became 21 ± 1cm after kneading. The change in length was measured. The dough was mixed for 1 minute at 1 speed by KS L 5109 (mechanical mixing method of hydraulic cement dough and mortar). The flow measured the diameter which mortar dough spreaded when it fell three times by KSL 5111 (flow table for cement test).

Referring to Figure 4, when the shrinkage reducing agent is not added (no addition) it can be seen that the length of the mortar test specimen is reduced immediately after pouring, and the rapid length decrease is caused as the age is increased. On the contrary, the mortar test specimen to which the present invention is applied increases its length after pouring and shows a value close to the original length with little change in length after 15 days, thereby proving that there is no contraction of mortar.

The shrinkage reducing effect of the shrinkage reducing material of the present invention was verified through actual construction.

The binder was prepared by substituting 12.5% of the shrinkage reducing agent (SO ₃ : CaO ratio 1: 1.7, the heat treatment temperature of 600 ° C.) with respect to the cement weight, prepared according to the present invention, and having a particle diameter of 0.5 mm or less 25%, 0.5 It was mixed with sand having a composition of 2% 55% and 2.0% to 6.7mm 20% and applied to the floor mortar casting. At this time, the solid mortar consisted of 30% of binder (cement + shrinkage reducing material) and 70% of sand based on the general binder: sand weight ratio of 3: 7 when pouring mortar for floor. Add 24% of the dough water based on solid components so that the flow becomes 210 ± 10mm (KS L 5111 cement test flow table, 3 drops). It was constructed.

As a result, there was no cracking caused by plastic shrinkage after construction, and dry shrinkage cracks, which are long-term cracks, did not occur even after three months. Therefore, it was confirmed that the shrinkage reducing material prepared according to the present embodiment was most effective to be applied at the time of construction of a mortar for a floor using a large amount of dough water.

On the other hand, Table 7 below shows the results of measuring the compressive strength (KS L 5105, compressive strength test method of hydraulic cement mortar) of the mortar test specimen prepared according to the present embodiment.

division 3 days (kg / cm ² ) 7 days (kg / cm ² ) 28 days (kg / cm ² ) No shrinkage reducing material added 130 156 240 Use of shrinkage reducing material (SO ₃ : CaO ratio 1: 1) 127 151 222 Use of shrinkage reducing material (SO ₃ : CaO ratio 1: 1.7) 123 148 214

Referring to Table 7, the compressive strength of the mortar poured using the shrinkage reducing material according to the present embodiment is compared with the case where the cement is not substituted with the shrinkage reducing material (no addition). Each of the 28-day strength shows a similar value, it can be seen that the decrease in compressive strength due to the use of shrinkage reducing material.

On the other hand, while the above described the shrinkage reducing agent prepared using the filtrate (mother liquor / washing water) which is a waste by-product generated during the production of acidic clay, the shrinkage reducing agent of the present invention is a complex expansion of activated alumina, quicklime, anhydrous gypsum By preventing the dry shrinkage of the mortar, it can be implemented through other manufacturing methods. For example, in the case of acidic clay, the filtrate is processed to make Busan sludge, and the neutralization process is performed using lime minerals such as slaked lime and quicklime, and the neutralized material can be used without filtrate. Of course, in this case, it is difficult to control the molar ratio of the SO ₃ component and the CaO component.

However, in any shrinkage reducing agent, active alumina, quicklime, and anhydrous gypsum must be included in the shrinkage reducing material, and 5 to 15 wt% of activated alumina, 30 to 50 wt% of quicklime, and 40 to 60 wt% of anhydrous gypsum. It is most desirable to implement.

Since the shrinkage reducing material of the present invention uses a large amount of activated alumina and quicklime, which are inexpensive compared to anhydrous gypsum, the unit cost itself is lower than that of the conventional anhydrous gypsum shrinkage reducing material, and the initial expansion and expansion of the activated alumina during mortar construction By the late expansion action, a much smaller amount of cement substitution (5 to 15%) can be applied compared to the amount of cement substitution (20 to 25%) of the conventional anhydrous gypsum shrinkage reducing material.

Although the technical idea of the present invention has been described in detail according to the above preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will appreciate that various embodiments are possible within the scope of the technical idea of the present invention.

For example, in the above-described embodiment, a case in which the shrinkage reducing material is applied to the floor mortar is described as an example. However, the case in which the shrinkage reducing material is applied to the mortar construction for other purposes is lower than the conventional shrinkage reducing material, and the addition amount is also low. Since it is small, it is advantageous in terms of construction cost.

In addition, the shrinkage reducing material according to the above embodiment can be used by additionally mixing the fly ash and the like for the purpose of activity control and increase.

The above-described shrinkage reducing material for mortar of the present invention has a low manufacturing cost and exhibits excellent shrinkage reducing effect even by the addition of a small amount, thereby suppressing the increase in construction cost due to the addition of the shrinkage reducing material. On the other hand, the present invention has the effect of changing the characteristics of the waste generated in the industry as a harmless building material, the value is more expected in terms of active recycling of industrial waste.

Claims (10)

delete delete Reacting the filtrate produced in the acidic clay production process with lime mineral; Producing a filter cake from the precipitate precipitated in the reacting step; Heat-treating the filter cake to remove moisture contained in the filter cake and to produce a material including activated alumina, quicklime, and anhydrous gypsum; And Pulverizing the filter cake Method for producing a shrinkage reducing material for mortar comprising a. The method of claim 3, The filtrate is, For the mortar, characterized in that the acidic clay is a solution containing at least one of the mother liquor generated during the sulfuric acid treatment process for the clay during the manufacturing process, the wash water generated during the washing process for the precipitate produced in the sulfuric acid treatment process Shrinkage reducing material manufacturing method. The method of claim 4, wherein The lime mineral is limestone powder (CaCO ₃ ), calcined lime (Ca (OH) ₂ ), quicklime (CaO) characterized in that it comprises at least one of the shrinkage reducing material for mortar. The method of claim 4, wherein In the step of reacting, Method for producing a shrinkage reducing material for mortar, characterized in that for controlling the addition amount of lime mineral so that the molar ratio of the SO ₃ component contained in the filtrate and the CaO component contained in the lime mineral is about 1: 1 to 1: 3. The method of claim 4, wherein In the step of producing the material, The method for producing a shrinkage reducing material for mortar, characterized in that the filter cake is heat-treated at a temperature of 500 to 1200 ℃. The method of claim 4, wherein In the step of crushing, A method for producing a shrinkage reducing material for mortar, characterized in that the filter cake is crushed into particles having a particle size of 50 to 200 µm. The method of claim 4, wherein Method for producing a shrinkage reducing material for mortar, characterized in that it further comprises the step of mixing the fly ash to the material produced in the step of crushing the filter cake. In the mortar binder composition for floors using a shrinkage reducing material for mortar prepared according to the method for producing a shrinkage reducing material for mortar of claim 3, Mortar binder composition for a floor, characterized in that the construction by adding the shrinkage reducing material 5-15% substitution relative to the weight of the cement.

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