KR101276085B1 - flooring cement mortar composition which can crack prevention - Google Patents

Abstract

The present invention is 15 to 25% by weight cement, 1-7% by weight cracking gypsum lime system, 0.1 to 8% by weight calcium sulfoaluminate, 0.2 to 8% by weight of alpha hemihydrate gypsum, 0.01 to 0.7% by weight fluidizing agent, acrylic Or a molar crack reduction floor cement mortar consisting of 0.1 to 5% by weight of ethylene vinyl acetate polymer, 0.001 to 0.01% by weight of olefin sulfonate anionic surfactant, 0.005 to 0.3% by weight of retardant, and 60 to 85% by weight of sand. It relates to a composition.

Description

Flooring cement mortar composition which can crack prevention}

The present invention relates to a cement crack mortar composition for reducing the floor cracks, and more particularly, it exhibits characteristics of fast diameter and quick drying while significantly improving cracking and lifting caused by shrinkage of existing floor cement mortar. The present invention relates to a cement mortar composition for lifting crack reducing floors, which can shorten the construction period.

In general, in the floor construction of shops, officetels, hospitals, schools, etc., the protective mortar is placed on the upper part of the concrete slab for thickness adjustment. The cement mortar used here is mostly mixed with aggregate and cement at an arbitrary ratio. The water is mixed with this and the plastering finish is placed on the upper part of the slab in the state of working dough. The cement mortar has a problem that a large amount of water is mixed to ensure workability, and cracks and lifting frequently occur due to the effect of drying shrinkage over time, which is a characteristic of cement mortar.

In order to improve the problem of cracking caused by dry shrinkage of cement mortar as described above,

Korean Laid-Open Patent Publication No. 2000-0024422 mentions a method of using quicklime (CaO) or anhydrous gypsum (CaSO ₄ ) together. When hydration of quicklime is used, the hydration reaction proceeds rapidly in a short period of time by using the mechanism of compensating for shrinkage caused by drying of cement mortar by using the expansion phenomenon caused by the growth pressure of calcium hydroxide (Ca (OH) ₂ ) crystal formation. The expansion pressure is driven. However, most of the expansion pressure is absorbed inside the cement mortar before hardening, so it is difficult to expect an effective expansion phenomenon. On the other hand, in order to control the high activity of quicklime, anhydrous gypsum is used to delay the hydration of quicklime, while unreacted quicklime is hydrated at the time of hard mortar formation of the mortar, that is, at the time of effective expansion, and calcium hydroxide (Ca (OH) ₂ ). This method uses the mechanism that induces expansion pressure through the crystal growth pressure of) .The amount of unreacted quicklime required for the control of quicklime activity can vary greatly depending on the physical properties such as the size of anhydrous gypsum. There is a problem.

In Publication No. 10-2006-0107202, an expandable CSA (Calcium sulfa Aluminate) system is added to the expandable CSA reacts with water to produce an expandable compound. To prevent cracking. However, the method has a limitation in stably controlling the expansion and contraction characteristics, that is, the degree of expansion and the degree of subsequent contraction.

Publication No. 2002-0004915 discloses shrinkage reducing materials for cement mortar obtained by baking a mixture of 30 to 70% of limestone and 30 to 70% of petroleum coke crushed to within 5 mm at a temperature of about 800 to 900 ° C.

Korean Patent Publication No. 1003032350000 describes a shrinkage reducing material for cement mortar composed of quicklime: 10-30 weight, gypsum: 20-40 weight, coal ash: 10-20 and the remaining petroleum coke combustors.

Publication No. 1003996180000 discloses 19.2% by weight of calcined alum, 12.5% by weight of raw stone, 50.8% by weight of anhydrous gypsum, 16.2% by weight of quicklime, methylcellulose 0.5 A method for producing a cement concrete crack preventing expansion material is disclosed, which is a mixture of a weight%, 0.6% by weight of zinc stearate, and 0.2% by weight of a fluidizing agent.

Publication No. 1005440620000 discloses (1) 20 to 45% by weight of underlinked clinker pulverized product obtained by calcining limestone ore having a content of calcium oxide of 53.5 to 54.5% by weight at a temperature of 950 to 1100 ° C for 50 to 60 hours. (2) Mixtures of pulverized anhydrous gypsum produced during the hydrofluoric acid manufacturing process, crushed anhydrous gypsum produced during the hydrofluoric acid manufacturing process, and a pulverized product of gypsum-lime-based by-products generated during the sulfite gas collection process when burning coal or petroleum coke. , Any one selected from the group consisting of a pulverized anhydride crushed powder produced during the hydrofluoric acid manufacturing process and a pulverized waste by-product pulverized product produced during the synthesis of a naphthalene-based high fluidizing agent, and a mixture of these three mixtures; A crack preventing agent composition for cement mortar comprising a residual amount of reject ash, a waste remaining during fly ash refining, Inhibitor composition may be seen that the mesh 30 minutes more than 90% passes through a cement mortar cracking preventing agent composition for not more than a water content of 0.1% is disclosed.

To date, many proposals have been made to compensate for shrinkage by volume expansion of quicklime-anhydrous gypsum in cement. However, the excess cracked lime remaining in the mortar after cement hardening causes severe cracks due to the revolume expansion caused by contact with moisture. In the mid- to long-term age of gypsum addition, there are no measures to control the dry shrinkage.

The present invention is the name of the invention patent application No. 10-1999-0041536 (registration number (date) 1003402960000 (20020529)) filed by the applicant; Floor mortar composition and the name of the patent application No. 10-2008-0082780; Improved high performance floor mortar composition and its manufacturing method using fluidized compound, which significantly improves the occurrence of cracking and lifting due to dry shrinkage of floor cement mortar, and shortens the construction period by showing characteristics of fast diameter and quick drying. The present invention provides a cement mortar composition for reducing the cracks of the floor.

As described above, the present invention can greatly improve the defect reduction and quality of the floor finishing material with the low-floor crack reducing floor cement mortar, which drastically reduced the cracks and flaws frequently generated in the existing floor cement mortar. have.

Lifted crack reducing floor cement mortar composition of the present invention for achieving the above problem is 15 to 25% by weight cement, 1-7% by weight of gypsum lime-based crack reducing material, 0.1 to 8% by weight calcium sulfoaluminate, alpha half Gypsum 0.2-8% by weight, fluidizing agent 0.01-0.7% by weight, 0.1-5% by weight acrylic or ethylene vinyl acetate polymer, 0.001-0.01% by weight olefin sulfonate anionic surfactant, 0.005-0.3% by weight retardant, sand It provides 60 to 85% by weight of the cement mortar composition for reducing the crack cracking floor.

The gypsum lime-based crack reducing material is used to suppress the occurrence of cracks due to the initial and middle contraction by compensating for a certain amount of expansion compensation for the plastic shrinkage caused by the initial curing time and the dry shrinkage caused by late drying. The gypsum lime-based crack reducing material is prepared by firing a mixture of limestone 30 ~ 50% by weight, coke 50 ~ 70% by weight at a temperature of 800 ~ 900 ℃ or 30 ~ 50% by weight of quicklime, anhydrous gypsum It can be used one or more selected from the group consisting of 50 to 70% by weight.

The appropriate amount of gypsum lime-based crack reducing material is preferably used at a level of 1 to 7% by weight based on the total cement mortar.

When 1% by weight or less of gypsum lime-based crack reducing material is added, it is difficult to fully anticipate the effect of cracking due to the initial and medium dry shrinkage compensation effect with low expansion pressure, and when 7% by weight or more is added, moisture penetrates from the outside after curing. In this case, it is preferable to add at the level suggested in the present invention because it causes a problem that the secondary expansion may cause expansion cracks.

In addition, the calcium sulfoaluminate (CSA) has a particle size of 2,000 ~ 5,000 cm ² / g, including 3CaO · 3Al ₂ O ₃ · CaSO ₄ Anhydrous gypsum (CaSO ₄ ), quicklime (CaO) It may include. The calcium sulfoaluminate (CSA) is formed of ettringite (3CaO · 3Al ₂ O ₃ · 3CaSO ₄ · 32H ₂ O) needle crystals of several micrometers on the surface of the particles when the hydration reaction proceeds in the presence of gypsum. It grows, thereby giving expansion force, and increases the curing speed according to rapid free moisture consumption, thereby showing the characteristics of fast diameter and fast drying.

The calcium sulfo aluminate (CSA) is preferably used at a level of 0.1 to 8% by weight based on the total cement mortar, and when added to more than 8% by weight, the problem of expansion cracking due to deterioration of workability and rapid expansion Since it has, it is preferable to add it at the level proposed by this invention.

The alpha hemihydrate gypsum can be produced by hydrothermal synthesis processing flue gas desulfurization gypsum, chemical gypsum and natural gypsum generated as an industrial by-product, natural hemihydrate gypsum can be used as it is.

In addition, a small amount of Ⅱ anhydrous gypsum, Ⅲ anhydrous gypsum, and beta hemihydrate gypsum may be contained in one or two or less types of less than 10kg per 100 kg of alpha hemihydrate gypsum. It is preferable to remove because it causes problems such as degradation. Alpha hemihydrate gypsum has the same mechanical strength as cement, and it has the characteristics of fast curing and quick drying with about 0.5% expansion due to the formation of needle crystals and growth pressure in the dihydrate gypsum.

By using this mechanism to partially mix the alpha hemihydrate gypsum with cement mortar plastering, it is possible to prevent cracking and lifting due to dry shrinkage, which is a problem of cement cement plastering, in terms of material. Hardening time can have advantages of shortening working time and fast drying speed by consumption of free moisture by hardening of gypsum and conversion of ettringite (3CaO · 3Al ₂ O ₃ · 3CaSO ₄ · 32H ₂ O) crystals.

The alpha hemihydrate gypsum is preferably used at a level of 0.2 to 8% by weight with respect to the total cement mortar, and if it is 0.2% by weight or less, it is sufficient to suppress the effect of cracking caused by plastic shrinkage and dry shrinkage generated during initial condensation hardening of the cement mortar. It is difficult to expect, if the weight of more than 8% by weight of the gypsum itself due to the decrease in workability and plastic shrinkage cracks due to the increase in the initial moisture drying rate, there is a problem of cracks caused by late overexpansion in the present invention Preference is given to adding at the indicated levels.

As said fluidizing agent, polycarboxylic acid type, lignin sulfonate type, polynaphthalene sulfonate type, polymelamine sulfonate type dispersing agent, etc. which are common dispersing agents can be used individually or in mixture of 2 or more types.

The fluidizing agent increases the fluidity of the cement mortar composition, thereby reducing the amount of water mixture while maintaining the same workability. The effect of reducing the amount of water mixture reduces the amount of voids in the cement mortar, so that an additional effect of reducing the shrinkage due to the improvement of strength and drying can be obtained.

Appropriate amount of the fluidizing agent is preferably used at 0.01 to 0.7% by weight relative to the total cement mortar. If the fluidizing agent is more than 0.7% by weight, it is uneconomical because it can not be expected to improve the fluidity significantly compared to the amount used, it is preferable to add at the level suggested in the present invention because it can cause bleeding and material separation and excessive condensation delay phenomenon. .

The polymer may be used alone or as a mixture of two or more as an acrylic or ethylene vinyl acetate copolymer, and includes both liquid and powder forms. The polymer enhances the surface abrasion resistance of cement mortar, and serves to increase the resistance to lifting by providing proper viscosity to exert resistance to material separation and excellent adhesion to improve adhesion properties with the bottom surface. In addition, the amount of air entrained by the polymer can reduce the stress generated inside the cement mortar and at the same time improve the freeze-thawing resistance.

The amount of polymer titration added in the present invention is preferably used at 0.1 to 5% by weight relative to the total cement mortar. When 0.1 wt% or less of polymer is added, the above resin properties in cement mortar are not sufficiently expressed. Excess addition of 5 wt% or more rapidly decreases the compressive strength of mortar and forms a thick coating on the mortar surface. It is preferable to add it at the level suggested in the present invention because it causes problems.

The surfactant includes an olefin sulfonate anionic surfactant, an alkyl ether anionic surfactant, sodium hydroxystearate, lauryl sulfate, alkylbenzene sulfonic acid, alkanesulfonate, polyoxyethylene alkyl (phenyl) ether, The polyoxyethylene alkyl (phenyl) ether sulfate ester or its salt, alkenyl sulfosuccinic acid, imidazoline betaine, etc. can be used individually or in mixture of 2 or more types, and it contains both a liquid form and a powder form. The surfactant acts to entrain air in the cement mortar to improve the material separation resistance, workability and freeze-thawing durability, and to lower the surface tension of the pore water in the cement mortar to reduce the stress by drying the capillary water. By reducing the shrinkage and forming a continuous air layer of several ㎛ size increases the drying rate of the mortar and at the same time serves to increase the resistance to cracking by absorbing the stress generated in the cement mortar in the air layer.

The appropriate amount of surfactant in the cement crack mortar composition for lifting crack reduction type floor of the present invention is preferably used at a level of 0.001 to 0.01% by weight of the surfactant relative to the total cement mortar. Addition of 0.01 wt% or more of surfactant is preferably added at the level suggested in the present invention because the amount of air suspended in cement mortar is excessively increased and mortar strength is sharply lowered.

The retarder is added to retard the rapidity of calcium sulfoaluminate or alpha hemihydrate gypsum to secure workability for a certain time, and as a retarder, citric acid and its sodium, potassium, calcium, magnesium, ammonium and triethanolamine Inorganic salts such as or salts such as tathalic acid, citric acid, gluconic acid, polyoxymethylene amino acid copolymer, gluconheptonic acid, arabic acid, malic acid, oxycarboxylic acid, oligosaccharide, dextran, etc. may be used alone or in combination of two or more thereof. Can be.

In the present invention, sodium citrate was used as a retardant, and the proper use level is changed depending on the amount of use and reactivity of calcium sulfoaluminate or alpha hemihydrate gypsum, and it is preferable to use 0.005 to 0.3% by weight of the total cement mortar. . When the addition amount of the retarder is excessive, it is preferable to add it at the level suggested in the present invention because it has a very large effect on the material separation and the strength decrease.

The sand is preferably used in 60 to 80% by weight based on the entire lifting crack reduction cement mortar composition.

Cement mortar containing the above components at an appropriate level ratio significantly improves the occurrence of cracking and lifting due to shrinkage of the existing floor cement mortar, and at the same time, shortens the construction period by showing the characteristics of fast diameter and quick drying. It can be effective.

Examples of the present invention are described below, but these are for illustrative purposes and do not limit the scope of the present invention.

Example 1

1st process

1 kinds of ordinary portland cement 100kg, gypsum lime-based material reduced crack 25kg, fineness 3,800cm ² / g of calcium sulfo aluminate (CSA) 10kg, fineness 1,500cm ² / g alpha half gypsum 15kg, of the polycarboxylic acid-based 0.25 kg of a fluidizing agent, 9.5 kg of an ethylene vinyl acetate (EVA) -based powdered resin polymer, 0.02 kg of an olefin sulfonate anionic surfactant, and 0.23 kg of sodium citrate as a retarder were added to a powder mixer and mixed for 1 minute to prepare a compound composition. next,

Second Step

Cement mortar composition was prepared by adding 480 kg of sand having a particle size of 6.0 mm or less to the mixer prepared in the first step, and homogeneously mixing for 1 minute.

Example 2

1st process

Type 1 ordinary portland cement 100kg, gypsum lime-based crack reducing material 25kg, powder 3,800cm ² / g calcium sulfoaluminate (CSA) 15kg, powder 1,500cm ² / g alpha hemihydrate gypsum 10kg, polycarboxylic acid 0.25 kg of a fluidizing agent, 9.5 kg of an ethylene vinyl acetate (EVA) -based powdered resin polymer, 0.02 kg of an olefin sulfonate anionic surfactant, and 0.23 kg of sodium citrate as a retarder were added to a powder mixer and mixed for 1 minute to prepare a compound composition. next,

Second Step

Cement mortar composition was prepared by adding 480 kg of sand having a particle size of 6.0 mm or less to the mixer prepared in the first step, and homogeneously mixing for 1 minute.

Example 3

1st process

1 kinds of ordinary portland cement 100kg, a calcium sulfo aluminate of lime-based plaster cracking reduced material 30kg, Fig 3,800cm ² / g powder carbonate (CSA) 15kg, fineness 1,500cm ² / g alpha half gypsum 5kg, of the polycarboxylic acid-based 0.25 kg of a fluidizing agent, 9.5 kg of an ethylene vinyl acetate (EVA) -based powdered resin polymer, 0.02 kg of an olefin sulfonate anionic surfactant, and 0.23 kg of sodium citrate as a retarder were added to a powder mixer and mixed for 1 minute to prepare a compound composition. next,

Second Step

   Cement mortar composition was prepared by adding 480 kg of sand having a particle size of 6.0 mm or less to the mixer prepared in the first step, and homogeneously mixing for 1 minute.

Comparative Examples 1 to 5

  For comparison with the examples within the presented levels of the admixtures presented in the present invention, compositions were prepared in the same manner as above without mixing some of the component materials of the admixtures.

Hereinafter, the compounding tables for Examples and Comparative Examples of the present invention are shown in Table 1, and their physical properties are described in Table 2. This will be described in detail as follows.

 Cement mortar composition formulation (unit: kg) division cement Gypsum lime system crack reducing material Calcium Sulfoaluminate (CSA) Alpha Half Gypsum Fluidizing agent EVA system
Powdered resin Interface
Active agent Retardant Less than 6mm
sand Example 1 100 25 10 15 0.25 9.5 0.02 0.23 480 Example 2 100 25 15 10 0.25 9.5 0.02 0.23 480 Example 3 100 30 15 5 0.25 9.5 0.02 0.23 480 Comparative Example 1 100 - - - - - - - 300 Comparative Example 2 100 25 - - - - - - 375 Comparative Example 3 100 - 25 - - - - - 375 Comparative Example 4 100 - - 25 - - - - 375 Comparative Example 5 100 25 10 15 - - - - 450

Comparative Table of Properties of Cement Mortar Composition Constructed by Mixing Cement Mortar Composition with Water division water
Addition amount
(kg) Flow
(mm) Air volume
(%) congelation
(minute) Length
change
(28 days)
(%)
Compressive strength
(N / mm ² ) crack Lifting Moisture content
(28 days)
(%) 0 min 15 minutes First closing 3 days 7 days 28 days Example 1 110 209 191 9.8 210 320 -0.012 14.8 19.2 25.8 none none 5.4 Example 2 111 204 185 9.2 190 280 -0.016 13.9 18.8 24.5 none none 5.8 Example 3 116 202 183 10.5 180 250 -0.025 13.0 16.7 22.1 none none 5.9 Comparative Example 1 137 197 190 3.1 510 690 -0.138 8.2 13.4 21.3 Occur Occur 8.9 Comparative Example 2 141 198 172 3.4 420 530 -0.087 9.8 14.8 23.2 Occur Occur 8.5 Comparative Example 3 141 195 151 3.2 130 180 -0.079 11.8 15.2 22.9 Occur Occur 7.8 Comparative Example 4 142 203 152 4.2 150 220 -0.062 9.3 13.6 17.8 Occur Occur 7.2 Comparative Example 5 148 198 132 4.5 90 140 -0.048 7.8 11.4 15.4 Occur Occur 7.6

Mortars in the above examples and comparative examples were mixed for 1 minute according to the mechanical mixing method of the hydraulic cement paste and mortar of KS L 5109, the amount of water mixing unit so that the flow value is about 200 ± 10mm to ensure the same initial workability The amount was adjusted and added, and the flow was measured 15 minutes after the beaming, and the workability deterioration with time was also examined. The flow of the mixture was measured by using a flow cone having a diameter of 70 mm, a diameter of 100 mm, and a height of 50 mm specified in KS L 5111, and then measuring the flow by lifting the flow cone without compaction.

The air content of the bibeam mixture was measured using a mortar air flow meter, and the setting time of the mortar was measured according to the test method of concrete setting time by penetration resistance needle of KS F 2436.

To measure the plastic shrinkage and dry shrinkage of the cement mortar, the length change measurement of 100mm (width) X 1000mm (length) X 50mm (height) was inserted and closed with a ring to fix the tau mortar at one end of the length. The other end is freely movable, and the mortar of the above examples and comparative examples is poured into a length change rate measuring device connected with a resolution 1 / 1000mm dial gauge, and the standard state temperature is 20 ± 2 ℃ and humidity is 65 ± 5%. The change in length over 28 days was measured under curing conditions of.

The compressive strength of cement mortar is filled with a bibeam mortar in a mold of 40mm x 40mm x 160mm under the above curing conditions, and it is demolded for 24 hours in a temperature of 20 ± 2 ℃ and saturated humidity, and then demolded. After curing for 28 days under curing conditions of 65 ± 5% humidity, the compressive strength of cement mortar for each age was measured.

To measure the moisture content in mortar for comparing the drying rate of cement mortar, fill the above-mentioned mortar with 40mm thickness of acrylic mold of 300mm (width) X 300mm (length) X 50mm (height), temperature 20 ± 2 ℃, humidity 65 After curing for 28 days under curing conditions of ± 5%, the moisture content of mortar was measured.

On the other hand, a ring test was conducted to check for cracks and lifting, and a donut-shaped mold having an outer diameter of 400 mm X inner diameter 100 mm X height 50 mm was placed on an extruded plate, and a bibeam mortar was filled with a 10 mm thickness between the outer ring and the inner ring. After curing for 28 days in the curing conditions, it was confirmed whether the lift with the base plate by the cracking state and the impact method.

In the case of not mixing a part of the cement mortar composition properties prepared by changing the level of the level of the present invention of Examples 1 to 3 and the component materials of each admixture of the present invention of Comparative Examples 1 to 8 As a result of comparing the composition properties,

In Examples 1 to 3, drying shrinkage length change was less than 1/4 level compared to Comparative Examples 1 to 2, which are generally used in the field, and no cracking or lifting occurred, and drying was quick even in water content. It shows speed.

In the case of cement mortars of Comparative Examples 3 to 4, CSA or alpha hemihydrate gypsum showing expandability and fastness were added, respectively, but these additions alone had limitations in controlling the change in the dry shrinkage length of the mortar, and the amount of mixed units increased. As a result, the strength and water content reduction rate is also lowered.

In the case of Comparative Example 5, although three types of gypsum lime-based crack reducing material, CSA, alpha hemihydrate gypsum were mixed within the suggested level of the present invention, the reason why cracks were lifted due to shrinkage was due to the increase in the amount of water added to ensure workability and The plastic shrinkage crack occurred at the time of curing due to the rapid increase of drying speed due to the lack of control of fast curing rate.

Therefore, in order to prevent the lifting crack of the cement mortar for floors should be composed of a composition consisting of a combination of the components as shown in Examples 1 to 3, and must be kept at the addition level proposed in the present invention.

Claims (6)

In the cement mortar composition for lifting crack reduction type floor, 100kg of cement, 25 ~ 30kg of gypsum lime-based crack reducing material, 10 ~ 15kg of calcium sulfoaluminate (CSA) of 3,800cm ² / g powder, 1,500cm ² / 5 g of alpha hemihydrate gypsum, 0.25 kg polycarboxylic acid-based fluidizing agent, 0.25 kg ethylene vinyl acetate (EVA) -based powdered resin polymer, 0.02 kg olefin sulfonate anionic surfactant, 0.23 kg sodium citrate as retardant, sand 480 kg Floor cement mortar composition, characterized in that consisting of delete According to claim 1, The alpha hemihydrate gypsum is produced by hydrothermal synthesis of flue gas desulfurization gypsum, chemical gypsum and natural gypsum produced as an industrial by-product, the flooring cement, characterized in that the powder is 800 ~ 2,000cm ² / g Mortar composition The floor cement according to claim 1, wherein the fluidizing agent is at least one selected from the group consisting of a polycarboxylic acid compound, a polynaphthalenesulfonate compound, a polymelamine sulfonate compound, and a lignin sulfonate compound. Mortar composition The cement mortar composition for a floor according to claim 1, wherein the polymer is at least one selected from acryl or ethylene vinyl acetate. The method of claim 1, wherein the surfactant comprises an olefin sulfonate anionic surfactant, alkyl ether anionic surfactant, sodium hydroxystearate, lauryl sulfate, alkylbenzene sulfonic acid, alkanesulfonate, polyoxyethylene Cement mortar composition for floors, characterized in that at least one selected from alkyl (phenyl) ether, polyoxyethylene alkyl (phenyl) ether sulfate or salt thereof, alkenyl sulfosuccinic acid, imidazoline betaine