KR100655260B1 - Water proof admixtures for concrete and mortar - Google Patents

Abstract

Provided are waterproof admixtures for concrete and mortar, which increase waterproof performance of concrete, impart proper expandability to concrete to inhibit formation of cracks, and are improved in seawater resistance, salt resistance, and freezing and thawing resistance. The waterproof admixtures for concrete and mortar comprise 10-60wt% of natural inorganic mineral consisting of tuff, volcanic ash, and perlite and comprising amorphous silica, philipsite, and sodium calcium aluminum silicate as elements, 10-30wt% of silica fume, 10-40wt% of fly ash or blast furnace slag fine powder, 5-25wt% of sulfates, and further 0.5-3.5wt% of water-soluble anionic surfactant. The silica fume has a silicon oxide content of 80% or more and is amorphous.

Description

Concrete waterproofing materials for concrete and mortars {WATER PROOF ADMIXTURES FOR CONCRETE AND MORTAR}

1 is a view showing the results of X-ray diffraction analysis of natural inorganic minerals used in the present invention.

2 is a view showing the results of X-ray diffraction analysis of fly ash, an artificial pozzolanic material.

The present invention relates to a concrete waterproofing material for concrete, and more specifically, it is added together with materials (cement, gravel, sand, water, concrete admixtures) used in the manufacture of concrete, thereby improving the watertightness of the final product of the cured concrete. It improves, improves the resistance to various chemical components that lead to the deterioration of concrete, and relates to a concrete waterproof material for concrete to suppress the formation of cracks in the concrete structure by reducing dry shrinkage.

In order to secure the quality and workability required for the manufacturing process and casting process, concrete and mortar use excess water other than the mixing quantity necessary for the hardening of the cement. It will have a large amount of voids. In addition, since the concrete structure is exposed to various physical and chemical conditions depending on the external environment, not only the crack is continuously generated, but also the deterioration progresses and the durability is greatly reduced.

The cracks generated in the concrete structure significantly reduce the waterproofness and promote the movement of various chemicals from the outside to the inside, thereby greatly reducing the durability of the concrete.

In order to make up for the problems of concrete structures, concrete structures that are currently used have various waterproof construction methods.However, as a general method of forming a waterproof layer on the concrete surface, the concrete structures are always satisfactory in various external environments. It cannot be represented.

Therefore, rather than merely improving the waterproof performance of the concrete surface, it is desirable to improve the waterproof performance of the concrete itself by improving the watertightness of the entire concrete structure, and at the same time, it is more desirable to suppress the formation of cracks by inhibiting the dry shrinkage of the concrete. effective. In addition, in order to achieve the above object, even if a waterproof material is included in various materials (fly ash, blast furnace slag fine powder, silica fume, metakaolin, concrete admixture for concrete, etc.) used in concrete, the performance of concrete itself should not be degraded. do.

Existing related technologies have a problem that solves only one of the above-mentioned methods of improving waterproof performance, or have problems such as deterioration of strength of concrete or inadequate mixing with concrete materials.

Patent Publication No. 01-38952 provides a spherical powder waterproofing composition prepared by adding silica fume as a main material and adding a higher fatty acid metal salt, a fluidizing agent, an AE reducing agent, and silica sand. This concrete powder waterproofing material improves the waterproofing performance by improving the watertightness of pozzolanic material and water repellent effect by fatty acid metal salt, but it does not effectively inhibit the dry shrinkage of concrete and has the problem of poor compatibility with other materials in concrete manufacturing. have.

In addition, in order to suppress crack formation, O type expansion material mainly composed of quicklime, which is widely used in Korea, and K type expansion material mainly composed of calcium sulfoaluminate, provide expansion property to concrete structures to offset dry shrinkage. Although it is effective in suppressing the effects, calcium hydroxide (Ca (OH) ₂ ) and ettringite (3CaO.Al ₂ O ₃ .3CaSO ₄ .32H ₂ O), the main products of these expanders, generate large amounts of voids. Watertightness has a problem that can be rather deteriorated.

In order to solve the above problems of the concrete structure, the present invention improves the watertightness of the concrete to secure waterproofness, imparts expansion to the concrete and at the same time reduces dry shrinkage, thereby suppressing crack formation, and water resistance of concrete. The purpose of the present invention is to improve the durability of flame resistance, freezing and thawing resistance, etc., and to provide a concrete waterproof material for concrete having excellent affinity with various components and materials used in concrete production.

Provided to achieve the above object of the present invention, the spherical powder waterproofing material of the present invention is a natural inorganic mineral fine powder including tuff, volcanic ash, and perlite, which is a kind of volcanic rock, (Indicated as a natural inorganic mineral), as main components, silica fume, pozzolanic and / or latent hydraulic substances, and sulfates as auxiliary components, and anionic surfactants and fatty acid metal salts may be additionally added. Concrete waterproof material of the present invention can be applied to concrete as well as mortar can improve the waterproof properties and durability.

The natural inorganic mineral used as a main component in the present invention is a natural pozzolanic material, and has a characteristic of using tuff and volcanic ash, which are a kind of volcanic rock, as main components. These materials, also called Tuffasche, are caused by the deposition of volcanic pozzolan materials by weathering due to the natural environment and the loss of bonding between particles. In particular, weathering converts the glassy components present in tuff into components such as hershelite, cabazite, and phillipsite, which have zeolitisation properties. As the change of, the pozzolan reactivity of tuff increased significantly. Tuff also has higher reactivity than artificial pozzolanic materials because of its very high glassy state content.

Natural inorganic mineral of the present invention is composed of the components shown in the table below, the main chemical components are SiO ₂ , Al ₂ O ₃ , CaO, the main components are amorphous SiO ₂ (amorphous siliconoxide) and CaO · Al ₂ It is characterized by having a composition of O ₃ · SiO ₂ (or hydrate).

[Table 1] Chemical Composition of Natural Inorganic Minerals

 division Chemical component (%) SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO MgO SO ₃ K ₂ O Na ₂ O I / L IR-1 61.10 12.18 6.07  6.22 3.35  0.45 1.48 4.28  1.30

1 and 2 compare the results of X-ray diffraction analysis of a natural inorganic mineral used in the present invention and a fly ash, a representative artificial pozzolanic material. Compared to the peaks of quartz and mullite, which are observed in fly ash, phillipsite (potassium sodium aluminum silicate hydrate) and sodium calcium are produced by natural mineral minerals. The peak of aluminum calcium silicate is observed, and the peak of quartz is relatively weak. These results are due to the fact that the chemical composition of natural inorganic minerals is similar to artificial pozzolanic materials used in the prior art, but the actual composition of the minerals shows a big difference.

The natural inorganic minerals used in the present invention, unlike silica fume and fly ash, which are artificial pozzolanic substances, have only pozzolanic activity, react with sulphite together with pozzolanic reactivity. has a feature of generating _{(ettringite, 3CaO · Al 2 O} 3 · 3CaSO 4 · 32H 2 O) and Sommer site (thaumasite, CaSiO ₃ and CaCO ₃ and CaSO ₄ and 15H ₂ O).

The pozzolanic materials used as auxiliary components in the present invention are fly ash and silica fume, and the latent hydraulic material is blast furnace slag fine powder (hereinafter referred to as slag). Another subsidiary material, sulfate, may be selected from anhydrous gypsum, hemihydrate gypsum, dihydrate gypsum and aluminum sulfate.

In addition, in order to maximize the above characteristics, in the present invention, naphthalene formalin condensate or melamine formalin condensate, which is a water-soluble anionic surfactant, may be used, and as fatty acid metal salts, zinc stearate, calcium stearate, ammonium stearate, calcium oleate, aluminum oleate, Butyl sthiarate and derivatives thereof can be used.

In the present invention, the above-described natural inorganic mineral is used so that the total specific powder waterproofing material is 10 to 60% by weight. At a usage amount below the above range, the amount of production of ettringite and somersite is not sufficient, so that the drying shrinkage of the concrete is not suppressed and the watertightness is reduced. As a result, proper performance is not achieved. The optimal proportion of natural inorganic minerals is 15 to 40% by weight.

Silica fume can be used in any product if the content of silicon dioxide (SiO ₂ ) is more than 80% and in an amorphous state and is used so that 10 to 30% by weight. Silica fume not only improves the watertightness of the final concrete structure, but also improves the structure of the aggregate-cement mortar interface (transition zone), which is the most vulnerable part of concrete, and increases the durability of concrete by preventing the formation of calcium hydroxide. In addition, by lowering the CaO / SiO ₂ molar ratio of the CSH hydrate produced by the pozzolanic reaction, the free alkali component present in the cement hardened body can be solidified. If the amount is less than the above range, the effect of improving the watertightness and the improvement of the transition region is insignificant. If the amount is more than the range, sufficient mixing with other concrete materials is difficult, and workability of the concrete can be reduced.

In the present invention, in order to maximize the water-tightness of the concrete, in addition to silica fume, another pozzolanic material, fly ash and / or latent hydraulic material slag is used to be 10 to 40% by weight. Fly ash and slag react with calcium hydroxide produced during cement hydration to promote or directly produce calcium silicate hydration product, thereby improving the durability of concrete and improving the long-term strength. In order to enhance the effect of the present invention, it is preferable to use fly ash in summer, and to use slag in winter, and to use 10 to 20% by weight of fly ash or slag in winter.

As another subsidiary material, sulfate, anhydrous gypsum, hemihydrate gypsum, dihydrate gypsum, aluminum sulfate, and the like can be used, and most suitable is hemihydrate gypsum. The suitable amount of sulfate is 5 to 25% by weight, preferably 10 to 20% by weight, the production of ettringite and somersite is insufficient when out of the use range to reduce the effect of inhibiting dry shrinkage, This can lead to false setting, flash setting or overexpansion.

In the present invention, two or more additives are used to further enhance the above performance. As the additive, when the composition of the present invention is used in concrete, a water-soluble anionic surfactant for improving the workability and improving the mixing of the concrete and fatty acid metal salt for imparting water repellency or forming a waterproof coating to the concrete may be used. Can be.

The water-soluble anionic surfactant for maximizing the performance of the composition of the present invention is a water-soluble polymer in powder form, preferably naphthalene formalin condensate or melamine formalin condensate, and these water-soluble polymers should have sufficient solubility and water content. It is within 5% of the spherical fine particles and should not contain lumps and insolubles. An appropriate amount of the water-soluble anionic surfactant is 0.5 to 3.0% by weight, and when the amount is out of the amount, the effect of improving workability may be greatly reduced or bleeding may occur and material separation may occur.

In addition, fatty acid metal salts for improving the waterproofness of concrete include zinc stearate, calcium stearate, ammonium stearate, calcium oleate, aluminum oleate, or the like, or may be selected from butyl stearate and derivatives formed from these salts. In the present invention, an appropriate amount of fatty acid metal salt is 0.5 to 10% by weight, more preferably 3 to 5% by weight. Outside the above range, the effect of improving the water resistance is significantly reduced, or due to excessive water repellency, the proper mixing with the concrete material is not achieved.

The mechanism for improving the waterproofness and durability of concrete by the concrete powder waterproofing material according to the present invention can be expressed in three ways.

First is the promotion of the production of ettringite and somersite by natural inorganic minerals and sulfates. These hydration products have the shape of needles, and have the advantage of densifying the internal structure and the initial expansion effect to suppress the concrete cracking due to dry shrinkage. In addition, the presence of excess sulfate inhibits the transition of ettringite to the monosulfate phase (3CaO · Al ₂ O ₃ · 12H ₂ O), inhibits dry shrinkage and enhances resistance to erosion by seawater and sulfates. I can let you.

Schemes 1 and 2 below briefly summarize examples of hydration reaction mechanisms that produce ettringite and somersite in the present invention.

Scheme 1. Generation of ettringite

3CaOAl ₂ O ₃ + 3CaSO ₄ + 26H ₂ O → 3CaOAl ₂ O ₃ 3CaSO ₄ 32H ₂ O

3 (CaOAl ₂ O ₃ ) CaSO ₄ + 9CaSO ₄ + 8CaO + 96H ₂ O → 3 (3CaOAl ₂ O ₃ 3CaSO ₄ 32H ₂ O)

Scheme 2. Generation of Somersite

CaMg (CO ₃ ) ₂ + 2MOH → Mg (OH) ₂ + CaCO ₃ + M ₂ CO ₃

2CaCO ₃ + 2SiO ₂ H ₂ O + 2 (CaSO ₄ 2H ₂ O) + 2Ca (OH) ₂ + 23H ₂ O

→ 2 (CaSiO ₃ ㆍ CaCO ₃ ㆍ CaSO ₄ ㆍ 15H ₂ O)

Second, pozzolanic is an improvement in water tightness by reactants and / or latent hydraulic materials. Silica fume and fly ash or slag used in the present invention are calcium silicate phase (CaO-SiO _2-) by calcium hydroxide produced during the hydration of calcium silicate phase (3CaOSiO ₂ , 2CaOSiO ₂ ), which is a major component of cement. Promoting or directly generating H ₂ O) (see Scheme 3) has the effect of greatly improving the water tightness of the concrete. In particular, silica fume has the effect of inhibiting the growth of calcium hydroxide crystals and improving the interfacial properties between aggregate and cement mortar, thereby improving the durability and strength of concrete. The CSH gel produced by the pozzolanic material and the latent hydraulic material, together with the ettringite and somersite, densely forms the concrete internal structure and greatly enhances the watertightness. In particular, when fly ash or blast furnace slag fine powder is used together with silica fume, since the particle size is different, the physical filling property is further increased to form a more compact microstructure.

Scheme 3. Generation of calcium silicate during hydration

_{3CaO · SiO 2 + (3 +} mn) H 2 O → nCaO · SiO 2 · mH 2 O + (3-n) Ca (OH) 2

Ca (OH) ₂ + SiO ₂ → calcium silicate hydrates (CSH)

Third, watertightness is enhanced by water-soluble anionic surfactants and fatty acid metal salts. Water-soluble anionic surfactants improve the dispersibility of the cement particles in the concrete, thereby improving the uniform formation and microstructure of the hydration product. In addition, fatty acid metal salts or derivatives obtained from these improve the water-tightness of the concrete by imparting appropriate water repellency to the concrete or by forming a waterproof layer inside the concrete.

With the above mechanism according to the present invention, concrete is not only improved in watertightness, but also crack formation by dry shrinkage is suppressed, and seawater resistance, chloride resistance, and freeze-thawing resistance are greatly improved.

Waterproofing material composition according to the invention can be used directly mixed with the base material of the concrete (cement, gravel, sand, water, concrete admixture), as well as fly ash, slag, used for the purpose of improving the performance of the concrete Silica fume, metakaolin, and water-inseparable admixtures, thickeners, retardants, such as specially used chemical admixtures such as a fastener can be used stably. In addition to the method of mixing the composition according to the invention in the concrete production process, it is also possible to mix and use the composition of the present invention in ready mixed concrete (Ready mixed concrete). In addition, the composition of the present invention may exhibit the above effects even when used in mortar for the purpose of improving the waterproof performance and durability.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited by this embodiment.

Example 1

40% by weight of natural mineral mineral, 20% by weight of silica fume, 20% by weight of slag, 15% by weight of half gypsum, 2% by weight of melamine anionic surfactant, 3% by weight of butyl stearate Prepared.

Example 2

40 wt% of natural mineral mineral, 20 wt% of silica fume, 20 wt% of fly ash, 15 wt% of half gypsum, 2 wt% of naphthalene anionic surfactant, and 3 wt% of zinc stearate are prepared in order to manufacture concrete powder waterproofing material for concrete. It was.

Example 3

30 wt% of natural mineral mineral, 20 wt% of silica fume, 25 wt% of slag, 20 wt% of semi-hydrated gypsum, 2 wt% of melamine anionic surfactant, and 3 wt% of calcium stearate were prepared in order to prepare concrete powder waterproofing material for concrete. .

In order to evaluate the performance of the prepared waterproofing material, the mortar was prepared by adding 10% by weight to 100% by weight of cement, and the compressive strength (general condition, artificial seawater condition, calcium chloride 5% solution condition), permeability ratio, and absorption ratio were measured. . In addition, in order to evaluate the compatibility with the admixture for concrete, compressive strength test was carried out by adding an excess of naphthalene-based sensitizer, lignin-based sensitizer, polycarboxylic acid derivative, sodium gluconate, air entrainer.

In addition, in order to evaluate the workability and performance of the concrete using the composition of the present invention, after the concrete is prepared using the formulation shown in Table 2, the air volume, slump, compressive strength, freeze-thawing resistance, concrete free length change experiments It was.

Formulation without the use of a waterproofing material (Comparative Example 1), formulation using two types of concrete powder waterproofing materials currently commercially available (Comparative Example 2 for pozzolanic materials, re-emulsified powdered resins, fatty acid salts) The concrete waterproofing material used as the main component was used, and in Comparative Example 3, a combination using an organic chemical agent and a coating waterproofing material composed mainly of cement-based raw materials), fly ash (Comparative Example 4), and slag (Comparative Example 5) were tested together. It was. Two types of commercially available concrete powder waterproofing materials were used as a manufacturer's recommended amount, and the amount of fly ash and slag was used in an amount of 10% by weight based on 100% by weight of cement, in the same manner as the composition of the present invention.

[Table 2] Concrete Mixing Table

 Remarks S / A (%) W / C (%) Unit material amount (kg / ㎥) Water Cement Gravel Sand WRA Waterproof Example 1 46.5 52.0 182 350 965 834 1.75 35.0 Example 2 46.5 52.0 182 350 965 834 1.75 35.0 Example 3 46.5 52.0 182 350 965 834 1.75 35.0 Comparative Example 1 46.5 52.0 182 350 965 834 1.75 No addition Comparative Example 2 46.5 52.0 182 350 965 834 1.75 13.1 Comparative Example 3 46.5 52.0 182 350 965 834 1.75  7.0 Comparative Example 4 46.5 52.0 182 350 965 834 1.75 35 5 in comparison 46.5 52.0 182 350 965 834 1.75 35

Mortar compressive strength was measured according to KS L 5105 "Testing method for compressive strength of mortar of hydraulic cement" and KS L 5109 "Mechanical mixing method of hydraulic cement paste and mortar", and the permeability ratio and absorption ratio were incorporated into KS F 4926 "Concrete mixing" Water-proof material ". Artificial seawater was prepared by the method specified in ASTM D 114.

The concrete with the above formulation was prepared by KS F 2425 "Method of Making Concrete Samples in Laboratory", and the workability of concrete was KS F 2402 "Test method of slump of Portland cement" and KS F 2421 "Pressure method of unsolid concrete". By the air content test method ". In addition, the compressive strength of the concrete was evaluated according to KS F 2405 "Test method for compressive strength of concrete", and the free length change test was evaluated according to KS F 2424 "Test method for changing the length of mortar and concrete". Freeze thaw resistance was performed according to KS F 2443 "Test method of resistance of concrete to rapid freeze thaw".

[Table 3] Mortar compressive strength measurement results and waterproof performance comparison evaluation results

 Remarks Compressive strength (kgf / ㎠) 6 months compressive strength (kgf / ㎠) Pitcher Ratio (%) Absorption Ratio (%) 1 day 3 days 7 days 28 days Artificial seawater Calcium chloride 5% Example 1 128 253 351 437 465 491  40.8  39.7 Example 2 124 249 334 447 476 487  48.8  41.5 Example 3 132 258 348 442 485 482  44.2  36.2 Comparative Example 1  99 209 311 398 438 442 100.0 100.0 Comparative Example 2 102 201 304 405 448 451  66.2  70.4 Comparative Example 3  67 172 286 381 463 439  62.4  52.8 Comparative Example 4 112 224 345 454 487 517  70.4  59.7 5 in comparison 115 232 347 449 447 489  70.2  54.3

As shown in Table 3 in the comparative evaluation using the mortar, the waterproofing composition of the present invention according to Examples 1 to 3 was shown to greatly improve the waterproof performance by enhancing the water-tightness of the mortar. In addition, the initial strength was greatly increased without long-term decrease in strength, and the durability in artificial seawater and calcium chloride 5% solution was also excellent.

[Table 4] Evaluation of Compressive Strength Change by Excess Added Concrete Admixtures

 Remarks Daily compressive strength (kgf / ㎠) Reference Specimen Lignin PNS Sodium Gluconate Polycarboxylates Air entrainment Example 1 116 51  90 45 66 70 Example 2 119 57 102 56 71 65 Example 3 124 48 105 52 68 64 Comparative Example 1  96 31  67 21 36 50 Comparative Example 2  94 50  83 34 66 71 Comparative Example 3  62 12  48 15 14 24

As shown in Table 4 above, when an excessive amount of the chemical admixture for concrete was added, the strength was lowered compared to the reference specimen without the admixture. Compared with the non-added specimens or those using conventional techniques, the strength drop was found to be significantly reduced in the specimens using the composition of the present invention.

[Table 5] Comparison of concrete test results

 Remarks Workability Compressive strength (kgf / ㎠) Condensation time (hour: minute) slump Air volume 3 days 7 days 28 days First closing Example 1 16.0 4.3 138 257 352 6:10 8:10 Example 2 16.0 4.2 142 272 349 5:50 7:40 Example 3 15.0 4.5 147 265 341 5:40 7:50 Comparative Example 1 15.0 4.7 112 237 312 6:20 8:35 Comparative Example 2 15.5 4.3 118 245 309 6:10 8:10 Comparative Example 3 16.0 4.6  87 197 301 7:20 9:40 Comparative Example 4 14.0 3.8 122 248 356 5:40 7:40 5 in comparison 13.5 4.3 129 242 361 5:30 7:50

As shown in Table 5 above, since the workability and condensation characteristics of the concrete using the composition of the present invention are similar to those of the non-added concrete, no additional concrete mixing design is required according to the use of the concrete powder waterproofing material. The compressive strength measurement results show that the long-term strength increases with the initial strength. Therefore, the composition of the present invention is excellent in strength expression characteristics than the existing technology, it can be seen that the initial strength expression characteristics are superior to the case of using a general concrete mixture.

[Table 6] Freeze thaw resistance and length change test results

 Remarks Relative dynamic modulus (%) Length change rate (%) 100cycle 200cycle 300cycle 3 days 7 days 28 days Example 1 98 95 93 0.010 0.021 0.030 Example 2 97 93 92 0.009 0.020 0.031 Example 3 97 91 90 0.009 0.018 0.028 Comparative Example 1 95 90 86 0.015 0.027 0.043

As shown in Table 6, the composition of the present invention was superior to the relative dynamic modulus of the non-additive specimens, and was shown to reduce the length change rate.

Concrete waterproofing material for concrete according to the present invention not only improves the watertightness of the concrete to improve the water resistance, but also provides adequate expandability to the concrete to suppress the occurrence of cracks by reducing dry shrinkage, seawater resistance, chloride resistance, freeze-thawing resistance By increasing the durability of the concrete to enable the production of high-performance concrete.

Claims (9)

10 to 60% by weight of natural inorganic minerals, including tuff, volcanic ash, and perlite, including amorphous silica, philipsite, sodium calcium aluminum silicate, 10-30% by weight of silica fume, Fly ash or blast furnace slag fine powder 10-40 wt%, and Containing 5-25 wt% sulfate Concrete waterproofing material. The spherical waterproofing material of claim 1, wherein the silica fume has a silicon oxide content of 80% or more and is in an amorphous state. The spherical waterproofing material according to claim 1, wherein the sulfate is any one of anhydrous gypsum, hemihydrate gypsum, dihydrate gypsum and aluminum sulfate. The spherical waterproofing material of claim 1, further comprising 0.5 to 3.5% by weight of a water-soluble anionic surfactant. The spherical waterproofing material according to claim 4, wherein the surfactant is naphthalene formalin condensate or melamine formalin condensate. The spherical waterproofing material according to claim 1, further comprising 0.5 to 10% by weight of fatty acid metal salt. The spherical waterproofing material of claim 6, wherein the fatty acid metal salt comprises 0.5% to 10% by weight of zinc stearate, calcium stearate, ammonium stearate, calcium oleate, aluminum oleate, butyl stearate, and derivatives thereof. delete delete

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