KR101971020B1 - High-performance water reducer composition for concrete - Google Patents

Abstract

The present invention relates to a high performance water-reducing agent composition for concrete, capable of substituting a large amount of crushed sand, which can provide economically excellent concrete. The high performance water-reducing agent composition for concrete of the present invention comprises a polycarbonic acid-based polymer, a physical property stabilizer, a thickener, and a viscosity stabilizer.

Description

Technical Field [0001] The present invention relates to a high-performance water reducer composition for concrete,

The present invention relates to a high-performance water reducing agent composition capable of controlling the separation of materials without causing deterioration in workability even when a large amount of crushed sand is added during the production of concrete, thereby providing concrete with improved physical properties.

In addition to cement, water, and aggregate, chemical admixtures are additionally used in concrete. The chemical admixture is a chemical added to the cement composition in order to change the physical and chemical properties of the concrete and maintain and improve the workability. The amount of the chemical admixture used is as small as about 0.5 to 3% of the weight of the cement used in the concrete , The physical properties of the concrete can be greatly changed or improved by using chemical admixtures. Chemical admixtures can be largely classified into AE agents, water reducing agents, high performance water reducing agents and high performance AE agents depending on their functions.

On the other hand, the types of sand are classified into natural history and crushed sand. The natural history is divided into river sand and washing sand, and river sand of good quality is impossible to collect and most of the clay material is inadequate for concrete mix design. Washing mortar is good in spherical shape but most of fine mortar with 2.0 or less granularity is limited to use in concrete mix design and it is difficult to use due to limited amount of wastes. Therefore, the use of crushed sand is emerging as an alternative.

For example, in Korean Patent Registration No. 1547895, 87.5 to 91.0 parts by weight of cement, 5 to 10 parts by weight of a pozzolanic reactive admixture selected from at least one of silica fume and fly ash, 0.1 to 2 parts by weight of a polycarboxylic acid-based water reducing agent, 0.1 to 1.5 parts by weight of a reinforcing fiber composed of monofilament fibers having a length of 6 to 12 mm of any one of glass fiber, vinyl fiber, polyvinyl alcohol fiber, polypropylene fiber and nylon fiber, 40 to 45 parts by weight of a cement admixture composed of 0.5 to 2.5 parts by weight of a shrinkage reducing agent composed of an expansion agent and an anhydrous gypsum (CaSO4); 36 to 47 parts by weight of a fine aggregate composed of at least one kind selected from river sand, silica sand, crushed sand and regenerated fine aggregate; And 5 to 15 parts by weight of a water-soluble latex composed of 47 parts by weight of a synthetic latex solid and 57 parts by weight of water.

However, when crushed sand is used, it has a large size compared to natural sand, and it has a low thickness and a low water absorption rate. Therefore, when concrete is manufactured by using the crushed sand, material separation, bleeding and deterioration of workability are adversely affected. There is a problem that it causes a lot of workability deterioration in transportation.

Although the above-mentioned technique shows an example of using crushed sand, it does not suggest any technique for solving the problems of workability deterioration, material separation, and bleeding due to the use of crushed sand.

Korea Patent No. 1547895

The present invention has been made in order to solve the problems of the prior art as described above, and it is an object of the present invention to provide a high performance concrete which can provide a concrete having good physical properties without deterioration of workability and control of material separation even when crushed sand is used in the production of concrete And a water reducing agent.

(Hereinafter referred to as " composition of the present invention "), which is capable of substituting a large amount of crushed sand according to the present invention, comprises a polycarboxylic acid polymer, a physical stabilizer, a thickener, .

As one example, the property stabilizer is a glycol ether compound.

As one example, the thickener includes a methylcellulose thickener.

As one example, the thickener is a mixture of carboxymethylcellulose and acrylamide alkylsulfonic acid.

As one example, the viscous stabilizer may include at least one selected from the group consisting of guar gum, locust bean gum, tamarind seed gum, carrageenan, and xanthan gum.

In one embodiment, the viscosifier is a mixture of carrageenan and triisooctyl phosphate.

As described above, the composition of the present invention is advantageous in that it can improve physical properties such as bleeding resistance, material separation resistance, workability, and the like, even when the amount of crushed sand is increased.

Hereinafter, preferred embodiments and experimental examples according to the present invention will be described in detail.

The composition of the present invention is characterized by containing a polycarboxylic acid polymer, a physical property stabilizer, a thickener, and a viscosity stabilizer.

The polycarboxylic acid polymer exhibits a high water reducing rate which can reduce the amount of water used by about 18% by weight or more by improving the dispersibility of the cement particles. It is also possible to improve the fluidity of the composition even in such a high water- And the like. That is, the polycarboxylic acid polymer hardly causes deterioration in fluidity accompanied by the curing process, and can continuously carry out an appropriate amount of air to give good workability to the cement composition, while exhibiting high strength.

Preferably, the polycarboxylic acid polymer has a number average molecular weight in the range of 30,000 to 200,000. When the number average molecular weight is less than 30,000, the polycarboxylic acid polymer is adsorbed by the fine particles and the porous material present in the aggregate, And when it is more than 200,000, the sensitivity is excessively high to the cement dispersing effect, so that the cement dispersing effect can not be effectively dispersed and the material separation easily occurs. Therefore, it is proper to maintain the above range.

It is also preferable that the content of the polycarboxylic acid polymer is in the range of 5 to 30% by weight based on the total weight of the composition of the present invention. If the content of the polycarboxylic acid polymer is more than 30% by weight, the sensitivity of the cement is excessively increased to cause material separation, and if the content of the polycarboxylic acid polymer is less than 5% by weight, the performance as a chemical admixture for concrete deteriorates . More preferably 10 to 20% by weight.

As the above-mentioned property stabilizer, it is proper to use a glycol ether compound. The glycol ether compound is adsorbed on the surface of the crushed sand to improve the rough shape, thereby improving the workability.

The glycol ether compound may be at least one selected from the group consisting of propylene glycol monomethyl ether acetate, polyoxyethylene bisphenol-A ether, and polyethylene glycol trimethylnonyl ether.

When the degree of polymerization is less than 100, there is no function as a property stabilizer, that is, no improvement in workability. When the degree of polymerization exceeds 200, a large amount of large bubbles are generated on the surface of the concrete Thereby causing an adverse effect on the concrete surface.

The content of the material stabilizer is preferably in the range of 1 to 5% by weight based on the total weight of the composition of the present invention. When the content is less than 1% by weight, the effect of stabilizing the physical properties is insufficient. As well.

The thickener is easy to cause material separation when crushed sand is used, so as to improve the resistance to such material separation. A variety of thickeners such as cellulose, acrylic, and urethane may be used, but in the present invention, it is appropriate to use an admixture and a cellulosic thickener which is most easily liquefied.

More preferably, it is appropriate to use a methylcellulose thickener in order to control the sensitivity of the concrete to the unit water yield according to the use of the crushed sand.

The viscosity range of the methylcellulose thickener is suitably in the range of 1,000 to 5,000. When the viscosity range is less than 1,000, the separation reducing effect is inferior. When the viscosity is more than 5,000, the viscosity of the concrete is increased.

The content of the thickener is preferably in the range of 1 to 3% by weight based on the total weight of the composition of the present invention. When the content is less than 1% by weight, the separation reducing effect is insignificant. When the content is more than 3% do.

Further, in the present invention, as a more preferred embodiment, the thickener provides an example in which a mixture of carboxymethyl cellulose and acrylamide alkylsulfonic acid is applied.

The carboxymethylcellulose is obtained by introducing a water-soluble polymer into methylcellulose (MC) unlike ordinary methylcellulose (MC). Immediately after the water-soluble polymer is dissolved, Because of the thickening effect of rorolose (MC), the timing of the thickening effect is somewhat delayed. That is, the carboxymethyl cellulose provides a stirring time so that the mixing between the ingredients can be uniformly performed, and after the composition of the present invention is sufficiently mixed, the viscosity is developed to maximize the resistance to material separation, .

That is, by manifesting an immediate viscosity, sufficient workability can be exhibited without lowering the workability, and viscosity can be expressed so that workability and material separation resistance are satisfied at the same time.

On the other hand, in the case of adding only carboxymethyl cellulose as a thickening agent, the amount of carboxymethyl cellulose to be added should be significantly increased in order to maintain the thickening effect under acidic conditions of pH 5 or less. As described above, when the amount of carboxymethyl cellulose is increased, However, since the polycarboxylic acid-based polymer is mainly contained in the present invention, the polycarboxylic acid-based polymer is an acid and has a problem that the thickening effect of carboxymethylcellulose can be somewhat lowered.

In the present invention, acrylamide alkylsulfonic acid is further mixed with carboxymethylcellulose as a thickening agent. Carboxymethylcellulose in the presence of an acrylamide alkylsulfonic acid maintains the thickening effect even under acidic conditions.

That is, the mixture of carboxymethyl cellulose and acrylamide alkylsulfonic acid is added as a thickening agent without increasing the content even under the acidic condition of the polycarboxylic acid polymer, thereby improving the resistance to material separation without deteriorating physical properties such as strength . Also, as shown in the following experiment, the intensity is rather increased.

Preferably, carboxymethylcellulose and acrylamide alkylsulfonic acid are blended in a weight ratio of (2 to 8): (8 to 2).

On the other hand, when a methylcellulose thickener is used as a thickening agent in a polycarboxylic acid polymer, the separation reducing effect is lowered after a certain period of time (about 10 days). This is because, as mentioned above, the polycarboxylic acid polymer is an acid and the thickening effect of the methylcellulose thickener is reduced. In order to improve this, a viscous stabilizer is added in the present invention.

The viscous stabilizer may be at least one selected from the group consisting of guar gum, locust bean gum, tamarind seed gum, carrageenan, xanthan gum, etc. The preferable content of the viscous stabilizer is 0.5 - 2% by weight.

On the other hand, the above-mentioned viscous stabilizer such as carrageenan is advantageous in that the viscosity is not changed with time because of its excellent water holding capacity. However, in the curing process of concrete, especially in summer, There may be problems that appear.

Accordingly, the present invention provides an example of applying a mixture of carrageenan and triisooctyl phosphate as a viscous stabilizer. In other words, triisooctyl phosphate is added in addition to carrageenan as a viscous stabilizer. Triisooctyl phosphate has excellent heat resistance, so that the gel network is not broken even when the temperature rises. As a result, So that the problem of viscosity drop can be controlled.

Preferably, carrageenan and triisooctyl phosphate are mixed in a weight ratio of (2 to 8): (8 to 2).

Hereinafter, an experimental example of the present invention will be described.

In the following experiments, each sample was prepared by applying the unit quantity of slump 180 ~ 10mm according to the mixing standard of KS F 2560 concrete admixture for Korean industry standard, and the amount of admixture used was 0.7% by weight of cement amount. The concrete was mixed with 100% crushed sand. The slump, compressive strength and workability of each sample were measured with these samples.

<Experiment 1-Experiment according to the amount of polycarboxylic acid polymer used>

As shown in Table 1, it can be seen that when the content of the polycarboxylic acid polymer is 5% by weight, the strength does not develop. In addition, in the case of 30 wt%, material separation occurred and it was difficult to secure workability. Therefore, the preferable content of the polycarboxylic acid polymer is preferably 5 to 30 wt%, more preferably 10 to 20 wt%, based on the total weight.

&Lt; Experiment 2 - Experiment according to the amount of the property stabilizer used &

Table 2 shows experimental results according to the amount of the material stabilizer used. In each sample, the polycarboxylic acid polymer was blended to 20 wt% based on the total weight.

As shown in Table 2, when the amount of the material stabilizer is less than 0.5% by weight, the effect of stabilizing the physical properties is insufficient and the workability is poor. When the amount is 7% by weight, the strength is lowered. Therefore, it is judged that the optimum content of the physical property stabilizer is 1 to 5% by weight based on the total weight.

&Lt; Experiment 3 - Experiment according to amount of thickener used &

Table 3 shows experimental results using a thickener. In each of the samples, the polycarboxylic acid polymer was blended to 20 wt% with respect to the total weight and 5 wt% with the physical stabilizer. Carboxymethylcellulose was used as a thickener in the case of Samples 1 to 4 in the following table, and a mixture of carboxymethylcellulose and acrylamide alkylsulfonic acid in a weight ratio of 5: 5 was applied to Sample 5.

As shown in Table 3, when the content of the thickener is less than 0.5% by weight, the separation reducing effect is insufficient and the workability is poor. When the content of the thickener is less than 5% by weight, It is judged to be 1 to 3% by weight based on the total weight. Particularly, in the case of Sample 5, the comparative workability with Sample 3 is maintained and the resistance against the material separation is maintained, and it is understood that a favorable effect is exhibited in terms of compressive strength. This is because the thickening effect of carboxymethylcellulose can be somewhat lowered under the acidic condition by the polycarboxylic acid polymer. In the case of Sample 5, the thickening effect is maintained by adding the acrylamide alkylsulfonic acid in addition to the carboxymethylcellulose as the thickening agent, It is judged that the manifestation of such a thickening effect causes a favorable effect in terms of compressive strength.

<Experiment 4-Experiment according to the amount of the viscous stabilizer used>

Table 4 below shows experimental results according to changes in the amount of viscous stabilizer used. In each of the samples, the polycarboxylic acid polymer was blended in an amount of 20 wt%, 5 wt%, and 3 wt% based on the total weight. Carrageenan was used as a viscous agent in the case of Samples 1 to 5 in the following table, and a mixture of carrageenan and triisooctyl phosphate in a weight ratio of 5: 5 as a viscous agent was applied to Sample 6. Also, the following experimental results are obtained after 10 days from the preparation of the admixture.

As shown in Table 4, in the case of Sample 1 (with no viscous stabilizer), the separation reducing effect was poor after 10 days from the preparation of the admixture. The separation reduction effect was shown at 0.5 wt%, and the separation reduction effect was stable up to 3 wt%, but the separation reduction effect was not improved. Therefore, it is considered that the optimum content of the viscous stabilizer is 0.5 to 2% by weight based on the total weight in consideration of the strength and the like. Particularly, in the case of sample 6, the comparative workability with sample 4 is maintained and the resistance to material separation is maintained, and it is understood that a favorable effect is exhibited in terms of compressive strength.

As mentioned above, the carrageenan may be slightly reduced in viscosity due to the heat generated during the curing process of the concrete. In addition to the carrageenan as the viscous stabilizer, triisooctyl phosphate is added in addition to the case of the sample 6, The gel network caused by carrageenan is not destroyed even when the temperature is raised during the curing process so that the viscosity is maintained.

While the present invention has been described with reference to the particular embodiments and drawings, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Various modifications and changes may be made.

Claims (6)

A polycarboxylic acid polymer, a physical property stabilizer, a thickener, and a viscosity stabilizer,
Wherein the thickener is a mixture of carboxymethylcellulose to satisfy both workability and material separation resistance and an acrylamide alkylsulfonic acid for maintaining the thickening effect of the carboxymethylcellulose under acidic conditions and carboxymethylcellulose and acrylamide alkylsulfonic acid in a weight ratio (2 to 8) :( 8 to 2). &Lt; RTI ID = 0.0 &gt; 8. &lt; / RTI &gt;
The method according to claim 1,
Wherein the property stabilizer is a recollected ether compound.
delete delete The method according to claim 1,
Wherein the viscous stabilizer comprises at least one selected from the group consisting of guar gum, locust bean gum, tamarind seed gum, carrageenan and xanthan gum.
6. The method of claim 5,
Wherein the viscous stabilizer is a mixture of carrageenan and triisooctyl phosphate. &Lt; RTI ID = 0.0 &gt; 11. &lt; / RTI &gt;