KR20090093612A - Ultra Rapid Hardning Mortar composition using Magnesia-Phosphate Cement and preparing method thereof - Google Patents

Abstract

A quick-hardening mortar composition and a preparing method thereof are provided to reduce a hardening time in a construction field while showing excellent compressive strength as well as good bond strength with base concrete. A quick-hardening mortar composition is composed of magnesia cement, a mono-ammonium phosphate, a retarder, a pozzolanic-activity powdered body and water. More particularly, the quick-hardening mortar composition consists of 100 parts of magnesia cement, 60-90 parts of the mono-ammonium phosphate, 2-4 parts of retarder and 4-18 parts of the pozzolanic-activity powdered body. The retarder represents anhydrous citric acid. The pozzolanic-activity powdered body represents fly ash.

Description

Ultra Rapid Hardning Mortar composition using Magnesia-Phosphate Cement and preparing method

The present invention relates to an ultra-fast-hard mortar composition using a mixture of magnesia cement and phosphate, and a method of manufacturing the same. More particularly, the present invention has excellent adhesion performance with ground concrete and can obtain required strength in a short time while maintaining good workability. The present invention relates to a superhard mortar composition suitable for use in repairing cross-sectional defects of a finished construction structure and a method of manufacturing the same.

Concrete structures are subject to various natural or artificial effects after construction, resulting in deterioration of physical performance due to physical and chemical deformation depending on the years of use. In particular, in recent years, in order to secure safety and performance of construction structures, efforts to restore safety and functional performance have been increased. Accelerating aging of such construction structures causes cross-sectional defects in the structure, ie concrete, due to expansion pressure due to reinforcing corrosion, freeze-thawing, carbonation, and so on. This may cause problems. In addition, if the maintenance or reinforcement is performed to improve such a problem, the function of the structure should be stopped due to the need to suspend the work during the construction period.

On the other hand, most of the fast or ultra-fast mortar currently used as a repair material is a mortar based on a common portland cement, and a variety of mortars have been produced and used before. There is a method of preparing mortar by adding CSA (calcium sulfoaluminate) or latex and adding a predetermined fine powder binder. These conventional per second rigid or in hard mortar is based on the intumescent substance eth- Lin gayiteu generated baneungjeom of obtained by the reaction of most of cement and water, as a main component a CA and CA _2, depending on the configuration mineral expressing in a rigid It can be divided into an aluminate mortar, a calcium fluoroaluminate mortar containing C ₁₁ A ₇ · CaF ₂ as a main component, and a sub-type mortar containing CSA as a main component. However, the aluminate-based mortar is not stable in the long term as the product is transferred to a secondary hydrate that exhibits a low strength after the hydration reaction, and particularly has a side that is vulnerable to calcium chloride, which implies that the durability performance may be reduced. In addition, calcium fluoroaluminate-based and sub-type mortars are relatively superior in performance, but it may not be economical because a separate firing process is required and a process to be pulverized into fine powder is added.

In addition, the mortar prepared through the alkali-activated material is not fast-hardening, but most of the mortar is required for at least one day of strength development after mixing with water. For example, road repair, bridge repair, construction in places where water is encountered, etc. are difficult to apply.

In order to overcome the problems of the strength development time of mortar, ultrafast hard mortar is manufactured by using alumina cement and jet cement developed in the cement industry, but due to the nature of the conservative mortar exposed to the external environment, mortar Its use is limited because it is very sensitive to the durability (freezing fusion, carbonation, etc.) and outdoor temperature (dry shrinkage, etc.) related to the quality.

In consideration of the problems of the prior art, in the present invention, the repair work can be completed in a short time, not only economical and stability is excellent, but also excellent adhesion performance with the ground concrete, while maintaining the good workability required strength in the short time after the beam It is to provide an ultra-fast mortar composition and a method for producing the same.

In order to achieve the above object, the present invention

An ultrahard mortar composition comprising magnesia cement, monophosphate, coagulant retardant, pozzolane reactive powder, and water,

The composition provides an ultra-hard mortar composition containing 60 to 90 parts by weight of mono-ammonium Phosphate (MAP) based on 100 parts by weight of magnesia cement.

In addition, according to the present invention, 60 to 90 parts by weight of the first phosphate is added to 100 parts by weight of magnesia cement, and 2 to 4 parts by weight of the coagulation delay agent and 4 to 18 parts by weight of the pozzolane reactive powder are mixed by the dry beam method. It provides a method for producing an ultra-hard mortar composition comprising the step of adding 40 to 50 parts by weight of water with respect to 100 parts by weight of the magnesia cement.

Hereinafter, the present invention will be described in detail.

In the case of renovation work, the necessity of completing it in a short time is highlighted, and as the construction period is shortened, economical and safety will be secured. However, in the case of the conventional method has a disadvantage of economic and unstable, the present invention solves the problems in the prior art, and can be safely carried out in a short time, a construction structure by using a mixture of magnesia cement and phosphate The superhard mortar composition used for the repair of this product was developed and this invention was completed.

That is, the present invention improves the adhesion performance of the magnesia cement and the magnesia cement using the magnesia phosphate cement compounded and manufactured through the acid-base reaction in which the magnesia cement and the phosphate having excellent thermal properties are adjusted at a constant ratio. It is to provide an ultrafast hard mortar composition capable of securing pot life required for workability by adding citric anhydride, which is a retarder for adjusting the fast setting time of phosphorus, and also securing dimensional stability by ambient temperature.

Such super fast-hard repair mortar for construction structures of the present invention can be used for front repair or partial repair depending on the degree of cross-sectional defect of the construction structure. At this time, the most important quality item is to secure the pot life for improving the compressive strength of the mortar to be manufactured and thus the adhesive strength and construction properties of the ground concrete.

The magnesia cement used in the present invention is obtained by calcining magnesia used separately from seawater.

In addition, ammonium phosphate is divided into three groups: monoammonium phosphate ((NH ₄ ) H ₂ PO ₄ ), diammonium phosphate ((NH ₄ ) ₂ HPO ₄ ), and triammonium phosphate ((NH ₄ ) ₃ PO ₄ ). There are various types, and since ammonium triphosphate is unstable, mainly ammonium monophosphate and ammonium diphosphate are used. Ammonium diphosphate is a compound which is acidic with 61% nitrogen 12% phosphoric acid (P ₂ O ₅ ), and diammonium diphosphate is neutral with 21% nitrogen and 53% phosphoric acid. In the present invention, in order to prepare a more stable mortar, ammonium monophosphate (NH ₄ H ₂ PO ₄ , Mono-ammonium Phosphate: hereinafter referred to as MAP) is used as the phosphate.

As shown in the present invention, when the hard, hard magnesia (hereinafter referred to as MgO) and the first ammonium phosphate (MAP) are mixed in an appropriate ratio, they will be present in the form shown in Scheme 1 below. In particular, the reaction of MgO and MAP, which is formulated as in Scheme 1, by mixing water, MgO remains for 1 to 20 minutes after the start of hydration, and MAP is gradually dissolved and disappeared from the start of the hydration reaction to about 3 minutes. . Through this reaction, hydrogen tetrachloride of the tetragonal form of struvite magnesium ammonium phosphate of the hydrate-like plate crystal is produced, and gradually combines in a three-dimensional linear form to form a hardened body.

Scheme 1

MgO + NH ₄ H ₂ PO ₄ + 5H ₂ O → NH ₄ H ₂ PO ₄ ㆍ 6H ₂ O

However, when such magnesia and the monoammonium phosphate are combined, the reaction is rapid, so that condensation and curing proceed rapidly to such an extent that molding is difficult.

Therefore, in the present invention, the composition ratio of MAP and MgO is appropriately adjusted so that the water-bonding ratio (W / B) is 40 to 50%.

Preferably, according to the present invention, MAP is used in an amount of 60 to 90 parts by weight based on 100 parts by weight of MgO (MAP / MgO = 60 to 90%). At this time, if the water-bonding material ratio is out of the range, a suitable ultra-fast mortar may be used. It is not possible to secure initial strength and develop stable properties. That is, when the water-bonding material ratio is less than 40%, it is difficult to sufficiently mix the super-hard mortar due to the excessive binder amount, and cracks may be easily induced after construction due to the high dry shrinkage rate. In addition, when the water-bonding material ratio is set to more than 50%, it is difficult to secure the initial strength, it is difficult to secure durability in the long term. Therefore, in the present invention, the maximum and minimum ranges of the water-bonding material ratio are set to 40 to 50% in terms of pot life and initial strength through a preliminary experiment.

In addition, as described above, when MAP and MgO are mixed, due to the generation of high heat of hydration, the mixture is mixed with water and then cured in a few minutes, thereby making it impossible to use as a super fast hard mortar. In addition, as the ratio of the phosphate increases, the flow which is an indicator of the construction performance is reduced, or the working time for securing the pot life is extended. Accordingly, in the present invention, the maximum and minimum ranges of MAP / MgO are set based on flow and pot life through a preliminary experiment.

In addition, the water content is used 40 to 50 parts by weight based on 100 parts by weight of magnesia / phosphate cement substituted with fly ash.

In addition, the present invention uses a coagulation retardant to improve the problem of coagulation time. That is, when the pH is measured by mixing MgO and MAP with water with respect to the hydration reaction time, pH is immediately after the start of the hydration reaction, pH is about 8.5 after 16 minutes, pH 8.5 after about 20 minutes. From this, it can be estimated that the pH corresponds to the curing time of magnesia phosphate cement (meaning that the degree of hydration is active at a high pH), and inhibiting the increase in pH can delay the condensation. have.

The present invention uses citric anhydride as a coagulation delay agent, so that the content is 2 to 4 to the weight of the magnesia cement and the first phosphate in the total superhard mortar composition. It is added by weight and used. By the use of such a coagulation delay agent, the present invention can suppress the rise time of the pH to ensure the required compressive strength and pot life period early. At this time, if the content of the coagulation delay is less than 2 parts by weight, there is a problem related to the coagulation delay for securing the pot life, which may cause a shortage of working time. And there is a problem about securing long-term strength.

In addition, the present invention uses a pozzolanic reactive powder having pozzolanic properties to improve the long-term strength of the ultrafast hard mortar prepared and to suppress the rapid condensation of magnesia phosphate cement. Can be lowered and the long-term strength increased. As the pozzolanic reactive powder, it is preferable to use aggregate and powder fly ash. The fly ash is a material that does not react as long as there is no alkali stimulant. Generally, the fly ash reacts with calcium hydroxide generated when mixed with ordinary portland cement and water to cause a pozzolanic reaction, thereby initially lowering the heat of hydration, and very superior in terms of long-term strength. It can be called a material. Fly ash is used as a miscible material and generally excluded by the amount of fly ash to be used in the amount of the binder, and fly ash is used as an alternative material, the present invention can also be used by replacing the same method. Thus, in order to suppress the high initial heat of hydration through the use of magnesia and ammonium phosphate, the present invention can be used in combination with the citric anhydride to improve the properties of ultrafast mortar as intended herein. In addition, the amount of the pozzolanic reactive powder is used by excluding 4 to 18 parts by weight based on the weight parts of the magnesia cement and the first phosphate in the total superhard mortar composition. At this time, if the content is less than 4 parts by weight, there is a problem in that the initial heat of hydration due to the reaction of magnesia and the first phosphate may not be suppressed. Problems arise in securing strength.

When explaining the preferable example of the manufacturing method of the super hard cement mortar for achieving the objective of this invention as follows.

First, the ratio of magnesia phosphate cement (hereafter cement) and fine aggregate (hereafter aggregate) is adjusted to 1: 2 by adjusting the magnesia cement and MAP substitution rate, and the ratio between cement and mixed water is in the range of about 40-50%. To be In addition, the first ammonium phosphate is represented by a MAP / MgO ratio, and MAP is used in an amount of 60 to 90 parts by weight based on MgO. In addition, citric anhydride (C.A), a coagulation retardant used to improve the workability of the super fast mortar, may be added in an amount of 2 to 4 parts by weight, and 4 to 18 parts by weight of a pozzolanic reactive powder to prepare an ultra fast mortar composition. At this time, the mixing of each of the components is performed for at least three minutes or more, and can be performed using a conventional mechanical mixing method.

In addition, as a result of testing the mechanical properties of the super-hard mortar, as the water-binder ratio (W / B), which is the ratio between the cement and the mixed water, was increased, the flow performance increased but the strength tended to be low. In addition, as the MAP / MgO ratio increased, the strength was decreased and the flow performance was increased. In addition, the citric anhydride used as a coagulation delay agent can confirm the shortage of working time at 2 parts by weight or less, and at least 3 parts by weight can secure more than about 30 minutes of working time for the construction of repair mortar. If it exceeds the weight part, there is a problem regarding securing the initial and long-term strength due to the long-term characteristics of the condensation delay effect.

In addition, in the present invention, a preferred composition capable of securing the most ideal physical properties is 70 parts by weight of MAP (70% MAP / MgO ratio), citric anhydride 3 with respect to 100 parts by weight of MgO so that the water-binder ratio is 45% It is the case of using 4 parts by weight and 4 parts by weight of fly ash.

The super-hard mortar composition prepared in this way can be used when the cross-section defects locally generated in the structure (for construction or civil engineering) made of reinforced concrete and the entire area is missing and repaired on the damaged part to expand the cross section. As a repair method, the hand plastering method is the most effective, and when the thickness of the cross-section is thick, the coating thickness is applied to the third to less than 10mm in the second to third installation. In this case, after about 30 minutes have passed since the first coating, the coated surface is scratched to increase the adhesive strength with the mortar to be applied next. In addition, during curing after application, it must be protected and cured to prevent dry shrinkage cracking caused by freezing or direct sunlight, and it may not be able to fully exhibit its intended effect. Therefore, in the summer when heated by direct sunlight, etc. It must be cooled by spraying on it, remove contaminants from the surface, and install it.

The ultrafast mortar using the magnesia phosphate cement of the present invention has a certain fluidity compared to the conventional fast hard polymer cement mortar. In addition, in terms of the setting time, compared to the existing mortar to secure the setting time to ensure a fast construction performance, the compressive strength and adhesive strength of the base concrete is very excellent. Therefore, the super-hard mortar composition prepared according to the present invention is quickly installed in the site of the cross-sectional defects to secure physical strength, significantly improving the durability of the structure and at the same time excellent in repairing or reinforcing the reinforced concrete structure Performance can be exhibited. In addition, the super-hard mortar composition of the present invention can exhibit a safe and excellent strength with fast condensation time, even when applied to emergency construction, such as road repair, bridge repair, construction in contact with water that requires fast construction. .

Hereinafter, preferred embodiments of the present invention are described. However, the following examples are only illustrated to aid the understanding of the present invention, but the contents of the present invention are not limited to the following examples.

Example 1

Aggregate, magnesia cement, phosphate, and coagulation retardant were added to the container and dried, and mixed with water to prepare an ultrafast mortar composition.

That is, in order to produce 1 m 3 of super-speed hard mortar, the following experiment was conducted such that the water-binding ratio of 45%, MAP / MgO ratio of 70%, citric anhydride 3 parts by weight, fly ash substitution rate of 4 parts by weight.

That is, a cement containing 351 kg of magnesia cement (MgO), 246 kg of monophosphate (MAP), and 25 kg of fly ash is 1, and the ratio of 1: 2 having 1,243 kg of fine aggregate is 2, and 18 kg of citric anhydride is simultaneously added to the container. It was put in a mechanical mixture according to the hand mixer, and stirred for 3 minutes or more. Thereafter, 280 kg of mixed water was slowly added at the time when each material was mixed evenly, and the mixture was stirred for about 3 minutes or more at high speed, and then the prepared mortar was discharged and used. At this time, the first phosphate used a material conforming to the provisions of JIS K 9006. In addition, the fine aggregate was used to order custom standard standard in accordance with the provisions of KS L 5100. That is, the quality of the material used is shown in Table 1 below.

TABLE 1

The superhard mortar thus prepared was uniformly filled in a forced mold of size 40 × 40 × 160 mm, left at room temperature (20 ± 2 ° C.) for 24 hours, and then cured under atmospheric conditions. Thereafter, the strength was measured, and mortar which was not hardened on the flow table was placed on the flow table in accordance with KS L 5111, followed by falling motion at a height of 17 mm for 25 times for 15 seconds to measure the diameter after the mortar was spread in the left and right directions. Furthermore, the mortar which was not hardened was put into the metal container of Ø150x150mm, and the condensation test was performed as penetration resistance value based on KSF2436. In addition, base concrete was prepared and adhesive strength was performed according to KS L 1593. The property test was repeated three times, and the results are shown in Table 2 below.

TABLE 2

One 2 3 Flow (mm) 170 180 185 Setting time (minutes) Final: 17 Termination: 30 Final: 18 Final: 19 Compressive strength (MPa) 1 hour: 1128 days: 20 1 hour: 1328 days: 22 1 hour: 1228 days: 22 Adhesive strength (MPa) 3 days: 1.328 days: 2.2 3 days: 1.328 days: 2.4 3 days: 1.228 days: 2.5

Through the results of Table 2, the ultra-high-speed mortar of the example using magnesia phosphate cement, citric anhydride as a coagulation delay agent, and fly ash, which is a pozzolanic reactive powder as a binding material, showed good physical properties and stable quality. It was confirmed that.

Comparative Example 1

A mortar composition was prepared in the same manner as in Example 1, except that Portland cement (45 wt.%) Was used instead of magnesia cement.

Comparative Example 2

A mortar composition was prepared in the same manner as in Example 1, except that citric anhydride was not used.

For the mortar compositions prepared in Comparative Examples 1 and 2, physical properties were measured in the same manner as in Example 1, and the results are shown in Table 3 below.

TABLE 3

Example 1 Comparative Example 1 Comparative Example 2 Flow (mm) 180 170 Setting time (minutes) Final: 18 Final: 360 Closing: 1,080 Final: 3 Termination: 6 Compressive strength (MPa) 1 hour: 1328 days: 21 1 hour: No measurement 28 days: 40 1 hour: No measurement 28 days: 17 Adhesive strength (MPa) 3 days: 1.528 days: 2.4 3 days: 0.528 days: 1.7 3 days: 1.028 days: 1.6

From the results of Table 3, Example 1 according to the present invention can be seen that both the compressive strength and the adhesive strength is excellent and the setting time (initialization, termination) is also very excellent. On the other hand, in Comparative Example 1, the time difference between the initial and the termination was large, and the setting time was excessively long, and the adhesive strength was poor even though the compressive strength was excellent at 28 days. In addition, in the case of Comparative Example 2, the setting time was excellent, but the compressive strength and the adhesive strength were poor.

Claims (8)

An ultrahard mortar composition comprising magnesia cement, monophosphate, coagulant retardant, pozzolane reactive powder, and water, The composition is ultra-hard mortar composition containing 60 to 90 parts by weight of mono-ammonium Phosphate (MAP) based on 100 parts by weight of magnesia cement. The superhard cement mortar composition according to claim 1, wherein the coagulation delay agent is included in an amount of 2 to 4 parts by weight based on the total composition. The super fast-acting mortar composition of claim 1, wherein the coagulation delay agent is citric anhydride. The super fast-acting mortar composition of claim 1, wherein the pozzolane reactive powder comprises 4 to 18 parts by weight based on the total composition. The super fast-hard mortar composition of claim 1, wherein the pozzolane reactive powder is a fly ash. According to claim 1, wherein the water is super fast hard mortar composition containing 40 to 50 parts by weight based on 100 parts by weight of magnesia phosphate cement substituted fly ash. 2. The superhard mortar composition of claim 1, wherein the composition is used for repairing cross-sectional defective building structures or aged concrete structures. 60 to 90 parts by weight of the first phosphate is added to 100 parts by weight of magnesia cement, and 2 to 4 parts by weight of the coagulation delay agent and 4 to 18 parts by weight of the pozzolane reactive powder are mixed by a dry beam method, and then the fly ash is substituted. 40 to 50 parts by weight of water is added to 100 parts by weight of magnesia phosphate cement.