KR20040105989A - Admixtures for super high early strengh concrete - Google Patents

Abstract

PURPOSE: A high early strength admixture added to Portland cement is provided to improve initial strength and fluidity of cement, and keeps the same application and transportation as a conventional concrete. CONSTITUTION: The high-early strength admixture comprises 5-80wt.% of sodium nitrate, 0-50wt.% of sodium gluconate, 20-95wt.% of high-performance AE water reducing agent or high-performance water reducing agent selected from lignin sulfonates, naphthalene sulfonates, melamine sulfonates and polycarbonic acids, and 0-50wt.% of mixture of anhydrous gypsum(II) and clinker in a ratio of 1:0.001-1:2, wherein the lignin sulfonate-based AE water or water reducing agent, having 1,000-100,000 of molecular weight, comprises calcium and sodium lignin sulfonates, the melamine-based AE water or water reducing agent, having 30,000 of molecular weight, comprises methyl melamine condensates, polymeric compounds and sulfonated melamine condensates. The cement composition comprises high early strength cement and 0.1-10wt.%(based on Portland cement) of prepared admixture.

Description

Roughening Admixtures {ADMIXTURES FOR SUPER HIGH EARLY STRENGH CONCRETE}

The present invention relates to a coarse rigid admixture for improving the initial strength of concrete and a cement composition comprising the same. More specifically, it is added to three crude steel portland cements to provide constructability, transportability and initial strength expression. It relates to a rigid admixture and a cement composition comprising the same.

Generally, cemented carbide, cemented steel or three types of portland cement are used to manufacture concrete for the purpose of emergency construction and shortening of air in civil engineering and building structures. In addition, when one type of ordinary portland cement is used, the amount of unit cement is increased and a susceptibility admixture and a promoted admixture are used.

However, cemented carbide and cemented steel cement are expensive and have limited working hours due to their short working time.In winter, there is a risk of damaging the structure due to freezing of concrete, so the temperature is below 5 ℃. In the situation it is difficult to install without a separate thermal curing process. In addition, the long-term use has a disadvantage that the durability is deteriorated, the situation is required to re-install within 2-3 years after construction.

On the other hand, the three types of crude steel portland cements are cheaper, have better workability, and have long-term durability than superhard cements and cemented steel cements, but require at least five to seven days to secure commonality. The crude steel portland cement, which is manufactured to meet the requirements of strength characteristics by age of the crude steel portland cement, is improved in comparison with the crude steel portland cement manufactured by changing the composition. There is a limit to this.

Accelerators used to promote concrete condensation and hardening to secure concrete coarseness are organic accelerators such as triethanolamine, alkalis, alkaline earth metals and sulfates such as iron and aluminum, nitrates, nitrites, carbonates, formates and cyanides. Acid salts, thiocyanates, hydroxides, halides and the like are known. However, it is necessary to increase the amount of cement in order to secure the superelastic stiffness of one type of ordinary Portland cement using such accelerators, and even if the water-cement ratio is lowered by using a high performance water reducing agent, the initial strength expression rate for the daily compatibility is low. In particular, it is difficult to secure the construction and transportability because it often causes quickness and the like. Therefore, it is difficult to apply to large-scale on-site casting and large-scale structures, such as the case of construction with super hard cement, super-steel cement. In addition, the accelerator containing chloride has a problem of lowering the durability of the concrete due to problems such as reinforcing corrosion, the situation is avoided its application.

In addition, the organic admixture has a disadvantage in that the initial strength is lowered by delaying the hydration rate of the cement with increasing usage. In particular, when the lignin sulfonic acid-based admixture is used in a large amount of 1% or more, the coagulation delay of cement concrete is large, and the polycarbonate acid-based high performance water reducing agent has a characteristic of delaying initial strength expression within 1 day. Such characteristics are obstacles to securing physical properties of the steel and the construction and transportability of the super-tough steel concrete, which is a problem to be improved.

Therefore, there is still a need for a new coarse admixture or cement composition that simultaneously improves the coarseness and workability of concrete and maintains durability and ensures commonality within one day.

The present invention improves the roughness and workability of the crude steel portant cement, and maintains long-term durability, secures commonality within one day, and transportability, workability can be modified to maintain the same properties as ordinary concrete And the compounding ratio thereof.

In addition, the present invention provides the crude steel properties to the crude steel portland cement and at the same time provide the workability and transportability of the one kind of ordinary portant cement, so as to be controlled to have ready-mixed concrete production and long-term transportability, and its mixing ratio The purpose is to provide.

Figure 1 is a graph showing the comparison between the freeze-thaw resistance between the super-tough steel concrete and conventional concrete prepared using the crude steel admixture of the present invention.

Figure 2 is a graph showing the comparison between the shrinkage characteristics of the dry steel and the conventional concrete prepared using the crude steel admixture of the present invention.

In order to achieve the above technical problem, the present invention is about 5 to about 80% by weight of sodium nitrate; About 0 to about 50 weight percent or less sodium glyconate; About 20 to 95% by weight of a high performance sensitizer or AE sensitizer consisting of at least one material selected from the group consisting of lignin sulfonate, naphthalin sulfonate, melamine sulfonate and polycarboxylic acid; And about 0 to about 50% by weight of Type II anhydrous gypsum and anwinclinker mixture, combined in a ratio of 1: 0.001 to 1: 2, to a roughening admixture for three types of steel cement.

The present invention also relates to three Portland cements, sodium nitrate; High performance sensitizers or AE sensitizers composed of one or more materials selected from the group consisting of lignin sulfonate, naphthalin sulfonate, melamine sulfonate and polycarboxylic acid; And about 0 to about 50 wt% or less of a type II gypsum and an adventurous clinker composed of a rough admixture. The coarse admixture is preferably included in about 0.1 to about 10% by weight relative to the three portland cement.

The properties of the high performance water reducing agent or AE water reducing agent used in the crude admixture of the present invention are as follows.

Lignin sulfonate-based water reducing agent, AE water reducing agent has a distribution of the molecular weight of 1,000 ~ 100,000, the average molecular weight of 20,000 ~ 30,000, calcium and sodium lignosulfonate water reducing agent, AE water reducing agent.

Melamine-based high-performance sensitizer, high-performance AE sensitizer is a high-performance sensitizer, high-performance AE sensitizer, characterized in that the molecular weight is about 30,000, composed of modified methyl melamine condensate, water-soluble special polymer compound, sulfonated melamine high condensate.

Amino sulfonic acid-based high performance sensitizer, high performance AE sensitizer has a distribution of molecular weight of 1,000 ~ 100,000, high performance sensitizer, high performance AE sensitizer, characterized in that composed of aromatic aminosulfonic acid polymer compound, aromatic polymer condensate and lignin sulfonic acid derivative to be.

Naphthalene-based high-performance sensitizer, high-performance AE sensitizer has a molecular weight of 1,000 ~ 50,000, modified lignin, alkylarylsulfonic acid and active sustained polymer, polyalkylylsulfonate and reactive polymer, alkylarylsulfonate high condensate and special sulfonic acid group carboxyl group It is a high performance water reducing agent, a high performance AE water reducing agent, comprising a polyunsaturated polymer, an alkylnaphthalenesulfonate and a special surfactant, an alkylaryl sulfonate-modified lignin co-condensate, a modified lignin, a lignin derivative and an alkylarylsulfonate.

Polycarboxylic acid-based high performance reducing agent, high performance AE reducing agent has a molecular weight distribution of 1,000 ~ 1,000,000, polycarboxylic acid ether complex, polycarboxylic acid ether complex and crosslinked polymer composite, polycarboxylic acid ether complex and orientation Complex of polymer, complex of polycarboxylic acid ether-based polymer and high-modified polymer, polyethercarboxylic acid-based high molecular compound maleic acid copolymer, maleic acid ester copolymer, maleic acid derivative copolymer, carboxyl group-containing polyester, terminal polysulfonic acid group A high performance water reducing agent, a high performance AE water reducing agent, comprising a polycarboxylic acid group-containing polypropylene polymer, a polycarboxylic acid-based graft copolymer, a polycarboxylic acid compound, a polycarboxylic acid and a modified lignin, and a polycarboxylic acid ether-based polymer.

The above-mentioned water reducing agent, AE water reducing agent or high performance water reducing agent may be used alone or in combination of two or more.

In the rough admixture of the present invention, type II anhydrous gypsum and anwinklinker may be used as powder type crude adjuvant. The anhydrous gypsum-wink clinker-based steelmaking aid is preferably a composition in which anhydrous gypsum to anwin clinker is combined in a ratio of from 1: 0.001 to 1: 2. The addition amount of the crude steel auxiliary material is preferably used in the range of about 0 to about 50% by weight based on the total weight of the crude steel admixture.

The expression about 0% when used to indicate the weight ratio of a compound used as a coarse admixture in the specification and claims of the present invention does not mean that the compound is not used, but a trace amount is included. Means that.

Although the blending ratio and the amount of the crude admixture of the present invention are controlled according to the desired workability and promoting effect, the amount of the admixture added admixture is preferably 0.1 to 10.0% based on the weight of cement, more preferably 1.5 to 8.0%. good.

In the present invention, by mixing the powder-like composition in a liquid composition in which three kinds of crude steel portland cement is mixed with a water reducing agent / AE water reducing agent and sodium nitrate or sodium glyconate, and adjusts the mixing ratio of the concrete according to the use and construction environmental factors As well as sex and transportability, by controlling the rate of expression of the initial strength can be ensured the commonality within 12 hours to 2 days. In addition, it is possible to ensure long-term transportability of 30 minutes to 90 minutes. Therefore, it is possible to produce in a ready-mixed concrete batching plant, which is not applicable to existing ultra-thick steel and superhard cement, and to be transported and placed in a long distance, and to be introduced into a management concept that can guarantee quality stability. It can also be used for on-site PC segments that require die demoulding and follow-up work within one day, depending on natural curing conditions.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Table 1 shows the fluidity and the compressive strength of the concrete produced using the admixture of the present invention in comparison with the concrete made of conventional cement. The amount of starting cement used in the experiment was 460 kg / m ^3, respectively.

Concrete of Example 1 is 16.1 kg of crude steel admixture mixed with three kinds of crude steel portland cement of 460 kg / m ³ and a polycarboxylic acid-based reducing agent, sodium nitrate and gypsum-Awin-based crude steel adjuvant ratio of 3: 2: 0.5 It was prepared using / m ³ . The concrete of Example 2 was prepared with 40.1 kg / m ³ of crude steel admixtures in which three kinds of crude cements contained a polycarboxylic acid-based water reducing agent, a sodium nitrate / sodium glyconate mixture, and a gypsum-arwin crude steel adjuvant in a ratio of 1: 2: 0.5. Was prepared using. In the case of Comparative Examples 1 to 4, the physical properties of the concrete manufactured using one ordinary cement, three crude steel portland cements, crude steel cements, and cemented carbide cements were measured.

division cement Crude admixture (kg / ㎥) Slump (cm) Compressive strength (N / ㎡) Kinds (Kg / ㎥) Early 60 minutes 1 day 3 days 28 days Example 1 Type 3 steel 460 16.1 23 22 33 46 63 Example 2 Type 3 steel 460 40.1 23 21 38 48 64 Comparative Example 1 Class 1 Normal 460 - 23 19 12 36 54 Comparative Example 2 Type 3 steel 460 - 23 18 19 43 59 Comparative Example 3 Rasp 460 - 8 0 22 41 52 Comparative Example 4 Carbide 400 - 12 0 27 30 34

As can be seen from the slump length of Table 1, the fluidity of the concrete prepared according to the embodiment of the present invention shows the same level of the three types of cement and one type of normal cement, cemented steel cement and super hard cement It can be seen that it is much better than using concrete.

In addition, it can be seen that the daily compressive strength is about 150% higher than that of Comparative Example 2 using three kinds of crude steel portland cement, and the same or more strength is expressed even in the 28-day strength.

Therefore, it can be seen that the concrete prepared by using the admixture of the present invention has an early strength and 28 days of strength equal to or higher than that of superhard steel cement and superhard cement which can exhibit early strength, and at the same time, better flowability.

Table 2 shows the results of evaluating the fluidity and the compressive strength of the super-tough steel self-filled concrete prepared by mixing the crude stiffener admixture of the present invention.

Here, in the case of Example 3, 16 kg / m ³ of crude steel admixture was used for three kinds of crude steel portland cement 500 kg / m ³ , and as the crude steel admixture, naphthalene, polycarboxylic acid-based high performance water reducing agent, sodium nitrate and gypsum- Irwin-based crude steel auxiliary was added at a ratio of 3: 2: 0.1. For Example 4, 45 kg / m ³ of crude steel admixture was used for the ^three crude steel portland cement 550 kg / m ³ , and the crude steel admixture was naphthalene, polycarboxylic acid based high performance water reducing agent, sodium nitrate and gypsum-wine based The crude steel aid was added at a ratio of 1.5: 3: 0.1. For Example 5, three crude steel cements and crude steel admixtures in the same proportions as in Example 4 were used, and about 100 kg / m ³ fly ash, corresponding to 20% of the total powder weight, was further added.

division cement Crude admixture (kg / ㎥) Slump Flow (cm) Compressive strength (N / ㎡) Kinds (Kg / ㎥) Early 45 minutes 1 day 3 days 28 days Example 3 Type 3 steel 500 16 70 65 37 51 68 Example 4 Type 3 steel 550 45 72 68 41 53 72 Example 5 Type 3 steel 550 45 72 68 30 48 75 Comparative Example 5 Type 3 steel 500 - 70 68 20 48 69 Comparative Example 6 Class 1 Normal 500 - 68 68 7 34 65

As can be seen from the slump flow and compressive strength data of Table 2, the concrete prepared by adding the admixture of the present invention can secure fluidity of 45 minutes or more, and at the same time excellent in initial strength development characteristics when applied to the actual site Formwork demoulding and subsequent processing can be carried out within one day without the introduction of a steam curing process. In addition, the concrete to which the admixture of the present invention was maintained equal or more than three kinds of crude steel and one kind of ordinary concrete in 28 days strength.

Figure 1 shows the results of measuring the change in the dynamic modulus of elasticity by repeating the freeze-thaw cycle of the concrete produced according to the present invention.

The average elastic modulus was measured by measuring the dynamic modulus of the concrete of Examples 1 to 5 through about 300 freeze-thawing cycles in about 4 to about 12% of CaCl ₂ solution. For comparison, the dynamic modulus of elasticity of concrete made from one ordinary cement and three crude steel portland cements was also measured.

Such elastic modulus is widely used in the art as an index for predicting the strength change when the concrete structure undergoes a freeze-thawing action. From the graph shown, the concrete (C) according to the embodiment of the present invention has almost no change in the elastic modulus of elasticity even after undergoing a freeze-thawing cycle, so that the conventional one cement (A) and three crude steel portland cement (B) It can be seen that it has very excellent freeze-thaw resistance compared to the prepared concrete.

Figure 2 shows a graph comparing the dry shrinkage characteristics of the concrete blended with the crude steel admixture of the present invention compared to ordinary concrete. As can be seen from the graph shown, it can be seen that the concrete (C) of the present invention exhibits a lower dry shrinkage property than the concrete (D).

The admixture according to the present invention not only acts very effectively on the initial flowability and initial strength of the three crude steel portland cements, but also maintains strengths equal to or higher than those of conventional concrete in 28-day strength. Therefore, by adding the admixture according to the present invention, it is possible to produce concrete having both superelastic steel characteristics and construction properties and transportability equal to or higher than those of ordinary concrete.

In addition, the concrete blended with the admixture of the present invention has a very excellent freeze-thawing resistance, it is possible to eliminate the risk of damage to the structure due to freezing without introducing a separate heat curing process even at a temperature of 5 ℃ or less.

In addition, the concrete blended with the admixture of the present invention has a small dry shrinkage characteristics compared to ordinary concrete.

Therefore, the crude steel admixture of the present invention and its cement composition are superior in initial flowability and its retaining performance compared to the cemented steel concrete manufactured using the conventional cemented steel cement, and thus have excellent workability and early strength expression characteristics. It is possible to secure commonality within days and omit the winter heat curing, and furthermore, the durability performance such as dry shrinkage, long-term stability, and freeze-thawing characteristics are greatly improved compared to the existing products, and it is possible to provide low-strength steel at low cost. do.

Claims (3)

About 5 to about 80 weight percent sodium nitrate; About 0 to about 50 weight percent or less sodium glyconate; About 20 to 95% by weight of a high performance sensitizer or AE sensitizer consisting of at least one material selected from the group consisting of lignin sulfonate, naphthalin sulfonate, melamine sulfonate and polycarboxylic acid; And 1: A roughly admixture for three types of crude steel cement comprising from about 0 to about 50% by weight of type II anhydrous gypsum and anwinclinker mixture combined in a ratio of 1: 0.001 to 1: 2. Three crude steel portland cements; Sodium nitrate; High performance sensitizers or AE sensitizers composed of one or more materials selected from the group consisting of lignin sulfonate, naphthalin sulfonate, melamine sulfonate and polycarboxylic acid; And a coarse admixture composed of Type II anhydrous gypsum and Irwin clinker, The coarse admixture is cement composition comprising about 0.1 to about 10% by weight relative to the three crude steel portland cement. The method of claim 1, The coarse admixture includes about 5 wt% to about 80 wt% of sodium nitrate, about 20 wt% to about 95 wt% of the high-performance sensitizer or AE sensitizer, and about 0 wt% to about 50 wt% of the Type II dry gypsum and anwinclinker. Cement composition.