KR100537953B1 - Method of making latex-modified very-early-strength exerting concrete composition - Google Patents

Abstract

The present invention relates to a method for producing a latex modified cemented carbide concrete composition, and more particularly to latex modified cemented carbide concrete, characterized in that to optimize the function of the retarder to effectively improve and add the raw material input method of the concrete composition It relates to a method for preparing the composition.

The concrete composition according to the present invention is suitable for emergency repair of roads and bridge decks as well as a variety of concrete structures because it exhibits a high early strength at the same time showing the fluidity suitable for laying.

Description

METHODS OF MAKING LATEX-MODIFIED VERY-EARLY-STRENGTH EXERTING CONCRETE COMPOSITION}

The present invention relates to a method for producing a latex modified cemented carbide concrete composition, and more particularly, to the efficient input step of raw materials to overcome the degradation of workability due to the rapid condensation of the concrete composition and the use of optimized retarder It relates to a method for producing a latex modified cemented carbide concrete composition comprising a.

Recently, the demand for latex-modified concrete is increasing due to its excellent physical properties. Latex is generally a dispersion or emulsion of synthetic rubber or plastic, and is also called synthetic latex to distinguish it from latex made of natural rubber.

The latex added to the concrete composition fills the micro voids in the concrete, thereby improving the permeability, adhesion, freeze-thawing resistance, surface peeling resistance, etc. of the concrete and at the same time expressing high bending strength and tensile strength. In particular, it is expected to be utilized a lot for the packaging of bridge decks.

Due to the nature of the latex-modified concrete, it is true that it is highly useful for concrete pavement repair work or bridge deck concrete repair and re-packing work in common, but the strength development time is late and the cost of long-term vehicle control increases and impairs traffic. As it lasts for a long time, it is not applicable to public roads.

In order to overcome this problem, conventionally, superhard concrete having excellent early strength development has been applied, but the concrete has excellent early strength development, but it is limited in the construction range due to short working time due to rapid condensation after production. However, it has been used very limitedly because of poor adhesion of old and new concrete.

The superiority of the latex modified cemented carbide concrete composition using the properties of latex modified concrete with high utilization value and the properties of cemented carbide with high strength early on was proved as an overlay on the upper surface of existing concrete. However, the concrete composition, in addition to the problems caused by early coagulation of cemented carbide, especially when latex is mixed, the viscosity of the concrete composition is further increased, so that the working pot time is shortened and has not been put to practical use to date.

Another problem with latex modified cemented carbide concrete is the severe cold joint phenomenon.

Cold joint is a joint that occurs when pouring the concrete composition (joint) is caused by the difference in the curing rate at the boundary between the first laid and the later laid areas, causing problems in water resistance and durability.

In particular, when the construction and repair scale are large, several installations are required in the same area. At this time, when the work cycles leading from the manufacture of the concrete composition to the installation do not coincide, deterioration of work efficiency and cold joint phenomenon occur. Degradation spreads to the periphery of the cold joint.

This is a particular problem when using a latex-modified concrete composition, the difference in the working time of several minutes in actual construction may cause a large difference in the properties of the concrete after curing.

On the other hand, in the general concrete composition, the input amount of aggregate and cement occupies the largest specific gravity based on the weight of the whole composition. Therefore, it requires a lot of manpower and time in the input, which has been a major factor to reduce the work efficiency of concrete construction. In particular, when using a large volume mixer, the time required for the input of aggregates and cement increases rapidly.

Therefore, in the preparation of latex modified cemented carbide concrete compositions for emergency repair of roads and bridge decks, it takes a long time to input the raw materials of the concrete composition. It is impossible to restrain the cold joint phenomenon in the repaired area because it is impossible to construct it, and it delays the completion of the construction, which causes traffic inconvenience and increases the cost of repair work.

In order to solve the above problems due to the early curing properties of latex modified cemented carbide cement, in many cases, a retardant is used as an additive of the concrete composition. A retarder generally refers to a material that inhibits the hydration of cement to retard condensation or hardening of concrete.

Cement hydration occurs because cement produces calcium hydroxide, ethrinite, calcium silicate hydrate, etc. when it comes in contact with water. Therefore, the calcium ion (Ca ⁺² ) in the liquid phase increases and decreases again after reaching the highest value, and the time until reaching the highest value is the start time of production or the start of the condensation of calcium silicate hydrate. Therefore, a compound that extends the time (maximum supersaturation time) for the liquid Ca ⁺² to reach its highest level functions as a retarder and generally blocks the liquid Ca ⁺² (complexes Ca), Creating a hydration barrier on the cement particles is a retardant.

Retardants of this nature are largely classified into two types: organic cement coagulation retardants and inorganic cement coagulation retardants. As the inorganic retardant, lead oxide, boron oxide, boric acid, zinc chloride, zinc oxide, magnesium silicon fluoride and the like are used, and as the organic retardant, various sugars, oxycarboxylates, lignosulfonates, gluconic acid or salts thereof, tartaric acid Citric acid, pyruvic acid, α-ketoglutaric acid and other keto acids are used.

However, even if a retardant is used to secure working turnaround time for cemented carbide, it is difficult to achieve sufficient condensation delay effect without selecting the proper amount of use and optimizing treatment conditions. Will adversely affect.

Therefore, it is urgent to develop a new manufacturing method capable of overcoming the problem of fluidity deterioration due to early condensation of the latex modified cemented carbide concrete composition and ensuring sufficient construction time.

The present invention efficiently improves the raw material input method of the composition in the method of producing a latex modified cemented carbide concrete composition and by optimizing the function of the retarder added in addition to secure sufficient working time to ensure not only various concrete structures but also road and An object of the present invention is to provide a method for preparing a latex modified cemented carbide concrete composition suitable for emergency repair of a bridge deck.

The present invention relates to a method for producing a latex modified cemented carbide concrete composition containing cemented carbide cement and latex, aggregate and other additives using a mixer, wherein the aggregate contained in the vessel having a retractable outlet at the bottom of the vessel It provides a method for producing a latex modified cemented carbide concrete composition comprising the step of moving the bottom portion is located above the inlet of the mixer and the aggregate is introduced into the mixer by opening the outlet of the container.

The size of the container may be determined according to the volume and construction size of the mixer used, and the aggregate may be added to the container by dividing the quantity required for one production of the concrete composition into the container several times, but preferably It is preferred that the total amount required for one-time production of the concrete composition is put in one batch at a time.

When the aggregate is added by the above-described method, the loading time can be reduced to less than 1/4 of the time taken by the conventional loading method, and the reduction effect of the aggregate loading time is more pronounced as the amount of the production of the concrete composition is larger. . Therefore, the larger the volume of the mixer used, the more effective the effect of the present invention. In addition, it is possible not only to reduce the overall construction time but also to greatly reduce the cold joint due to the difference in curing speed between the post-installation areas in the large repair area.

The mixer used in the production method of the present invention may be a mixer generally used in the preparation of the concrete composition. The volume of the mixer is preferably at least 0.2 m ³ or more in order to ensure workability even when the construction and repair scale is large.

The latex used in the present invention is added as an aqueous dispersion of a polymer such as synthetic rubber or plastic to improve the impermeability of the concrete structure. Various kinds of latex may be used, but in particular, an aqueous dispersion of styrene / butadiene copolymer has excellent physical properties and is economical.

The container for inputting aggregate used in the present invention measures the amount of aggregate required in advance and puts it in the container, and then lifts the container using a lifting device such as a crane and opens the retractable discharge part provided at the bottom of the container on the mixer. Whereby the aggregate is used to feed the mixer.

Hereinafter, with reference to Figures 1, 2 and 3 will be described in detail the container for aggregate injection used in the present invention.

1 is a perspective view showing a state in which the container containing the aggregate is lifted by the lifting device, Figure 2 is a perspective view showing the shape of the bottom of the container, Figure 3 is a plan view of the discharge portion of the shell of the container.

The aggregate injection container 1 is composed of an outer shell 10 and an endothelial 20.

First, the outer shell 10 is preferably made of a woven fabric to secure the required working height when the aggregate is put and fold, so that it is easy to store or transport, and to secure the strength required when the aggregate is put. As the material of the fabric, a polyolefin-based material may be typically used, including polyethylene or polypropylene.

The outer shell 10 is composed of an inlet 11, the side wall 12, the bottom portion 13, the discharge portion 14 and the carrying hanger 15, the side wall 12 may be woven in a cylindrical shape or one It may be attached to each other by the above stitched suture (16).

The transport hook 15 is an annular portion that is coupled to a means such as a hook (a) attached to the lifting device when the container 1 for aggregate input is lifted by the lifting device. It may be configured, it is provided in the opposite position on the corner of the inlet 11 of the shell (10).

The transport hanger 15 is fixed to the inlet of the container using a lock or the like, or by folding the end of the inlet 11 of the outer shell to create a passage (17) of the transport hanger on the inlet 11 Two holes in each of the passages 17 are formed at four corner portions, and then a rope rope or the like is inserted into the passage 17 through these holes, and each corner portion is exposed to the outside of the passage 17 by an annular shape. It can be provided in such a way that the carrying hanger 15 is formed.

The shell 10 has a discharge portion 14 in the center of the bottom portion 13 so that aggregate can be introduced into the mixer. The discharge portion 14 is composed of a discharge port 18 located at the center thereof, several binding portions 19 arranged at predetermined intervals in the circumferential direction of the discharge port, and a fastening string 19 'for binding them. The string 19 'may be provided in a form in which the end of the binding portion 19 is sewn to form a passage 19' of the string and inserted therein. Thus, by adjusting the tension straps 19 ', the size of the outlet 18 can be varied to further control the rate at which aggregate is introduced into the mixer.

In addition, the inner shell 20 of the container 1 for aggregate injection is used to fit into the inner surface of the outer shell 10 to be inserted into the outer shell 10, and has an open top and bottom. Preferably, the endothelium 20 may be made of a material such as vinyl having waterproofness. The outlet portion 21 of the endothelium 20 is closed in a general manner by the bundle strap 22, it is provided in a shape projecting through the outlet 18 of the outer shell (10).

The aggregate input container 1 may be introduced into the aggregate by completely opening the discharge portion 14 of the outer shell 10 and the discharge portion 21 of the inner shell 20 at the same time, the discharge portion of the outer shell 10 14 may set the size of the outlet 18 to the desired size by adjusting the tightening string 19 ′, and aggregate may be introduced by releasing only the bundle 22 of the discharge portion 21 of the endothelium 20. .

In particular, when the aggregate input container (1) is lifted up by the lifter and placed on the inlet of the mixer to inject aggregate, it is preferable that the discharge portion 21 of the endothelial 20 extends to the inlet of the mixer. . By doing so, the discharge part 21 can suppress generation of scattering dust by acting as a passageway of the aggregate when the aggregate is poured down into the mixer.

The aggregate input container 1 may be composed of only the outer shell 10 except for the endothelial 20, wherein the discharge portion 14 of the outer shell is to be configured in the same shape as the discharge portion 21 of the endothelial. Can be.

In addition, the method of producing a latex modified cemented carbide concrete composition containing cemented carbide cement and latex, aggregate and other additives using a mixer of the present invention uses a cement bag thermal device equipped with the cemented carbide cement in the mixer inlet It is preferable to include the step of adding.

When cement is added in the above-described way, the time required for cement input is reduced by 1/2 to 1/3 compared to the case where a person uses a knife to open a cement bag. And it can minimize the contact with the moisture in the aggregate, hydrated and cured.

Figure 4 is a perspective view briefly showing the external appearance of the mixer equipped with a cement bag opening device on the inlet port, showing a preferred example of the cement bag opening device.

The cleavage device 31 may be toothed and mounted on the inlet 32 of the mixer 30. Preferably, several rods 35 capable of stably supporting the bag when the cement bag is opened may be provided at a predetermined interval to the left and right of the cleaver 31, and the cleaver 31 and the rod 35 may be provided. ) May be provided integrally installed in the lid frame 34 on the inlet 32 of the mixer and detachable from the mixer body 33. The cleavage device 31 may be provided on the rod 35 installed on the inlet 32 or a tooth and a rod may be integrally formed to constitute the cleavage device 31.

The remaining structure of the mixer, such as the stirring shaft and the stirring blade in the mixer 30 can follow the structure of the general mixer (Utility Model Registration No. 207184, Patent Publication No. 1985-0003342, Utility Model Registration No. 116207, Utility Model) See publication 1993-0000585 et al.).

In addition, in the production method of the present invention, as a additive of the latex modified cemented carbide concrete composition, the retardant is preferably used after dilution for 30-180 minutes in advance with water, and most preferably, for 60 minutes. Dilution of less than 30 minutes or more than 180 minutes is difficult to obtain a sufficient condensation delay effect, and when the dilution of about 60 minutes, the condensation delay effect is most excellent. It is also desirable to place the retardant mixture in a closed container to prevent water evaporation during dilution of the retardant.

As the retardant, a general cement coagulation retardant capable of inhibiting the hydration reaction of cement can be generally used, and an organic acid retardant is particularly preferable, and citric acid, tartaric acid, oxycarboxylic acid, lignosulfonic acid and gluconic acid. Most preferred is pyruvic acid or salts thereof. At this time, the amount is preferably 0.3-0.9% by weight, and most preferably 0.5-0.7% by weight based on the cement used in the concrete composition.

According to the method described above, the retardant is unevenly mixed into the concrete composition to prevent local non-condensation from occurring, thereby increasing the strength of the hardened concrete, and exhibiting sufficient coagulation delay effect, thereby reducing the work-up time required for construction. It can be secured.

The physical properties of the latex modified cemented carbide concrete composition according to the retardant dilution time is shown below.

Property test of the concrete composition according to the dilution time of the retardant

1) Experimental conditions

▶ Test Period: August 25th and 20th, 2003 3:25 to 5:05 pm

Relative Humidity: 90% (19 days) and 89% (20 days)

Air temperature: 23 ℃ (19 days) and 26 ℃ (20 days)

2) Mixing condition

% By weight of water to cement Absolute volume% of fine aggregate to total aggregate Unit weight (㎏ / m ³ ) water cement sand Pebble mixture Latex Solid content of antifoaming agent (% by weight of solids of latex) Retardant (% by weight of retardant to cement) 38 58 2.05 9.79 23.05 18 3.06 One 0.6

◇ Cement: Super high speed cement (Ssangyong double)

◇ Latex: SB Polymer (Dow Chemical)

Solid content (%) Butadiene Content (%) Styrene Content (%) pH Average particle size Surface charge importance Glass transition temperature (℃) Film forming temperature (℃) 48 34 ± 1.5 66 ± 1.5 9.5 1900-2500 yen Nonionic 1.01 8 4

◇ Defoamer: Lucky 101A (Sea Han Chemical Co., Ltd.)

           Specific gravity 1.0, pH 6.5, solid content 15%, white appearance

◇ Delay agent: Citric acid (Wonjin Chemical Co., Ltd.)

3) Preparation of Concrete Composition

The sand and gravel were added to the mixer and mixed for 30 seconds, and then cement was added and mixed again for 30-60 seconds. Then, latex was added, and the mixed water containing the delayed agent and the antifoaming agent diluted for a certain time was added, mixed for 90 to 120 seconds, and discharged from the mixer to measure the slump, the setting time and the compressive strength.

4) Experimental method

4-1. Slump experiment

Slump experiments were performed according to KS F 2402. Slump was measured over time after the initial discharge, the slump was measured every 5 minutes, the end of the experiment was measured up to 2 ± 1cm, which is considered to be impossible to work due to the hardening of the cemented cement.

4-2. Condensation experiment

Condensation experiments were performed according to KS F 2436. In the condensation test, the time required for the penetration resistance of mortar obtained by sieving concrete to sieve after reaching 35kgf / ㎠ is called the setting time, and the mortar penetration resistance is 280kgf / ㎠ The time taken by is defined as the termination time. The sample container containing mortar shall be strong, watertight, non-absorbent, non-oiled metal, with a cross section of cylindrical shape, measuring 15 cm and having a depth of at least 15 cm. The needles should have a support area of 640, 320, 160, 64, 32, 16 mm 2, and the needles should be interchangeable. The sample should be filled with sufficient concrete. The sieve was sifted into four bodies, and the sample container was taken to have a depth of 15 cm. The penetration resistance at the beginning and end is calculated in kgf / cm2 by dividing the force required until the penetration depth of the needle is 25 mm by the support surface of the needle. At this time, the time when the calculated penetration resistance reaches 35 kgf / cm 2 is referred to as the termination time.

4-3. Compressive strength test

Compressive strength test was performed according to KS F 2405. In the preliminary test of cement selection, the compressive strength test to analyze the strength characteristics is based on the strength characteristics of cemented carbide, and the three-hour strength is equivalent to one week of ordinary portland cement. The focus was on the characteristics.

5) Experiment result

* The experimental results indicated in parentheses in Table 1 are measured on the 20th day.

* The dilution time is defined as 0 hours when the delay agent is added to the mixer immediately after adding water.

From the above slump test results, it can be seen that the dilution time of the retardant acts as a very important factor in the production method of the latex modified cemented carbide concrete composition, and the dilution time is 1 hour for the operation of the concrete composition. Appropriate fluidity can be sustained in the long term, and at the same time it has been shown to express high early strength.

Therefore, in the manufacturing method of the present invention, when the appropriate dilution time of the retardant is applied, it shows a high early strength and the limitation of the working time due to early coagulation, which is the biggest obstacle to the field applicability of latex modified cemented carbide concrete. The problem can be greatly alleviated.

It is preferable that the manufacturing method of the present invention also includes the following steps.

Iii) a conveying step of moving the aggregate contained in a container having a retractable discharge part at a bottom such that the bottom of the container is positioned on an inlet of the mixer;

Ii) an input step of injecting the aggregate into the mixer by opening the discharge portion of the container;

Iii) a premix step of preliminarily mixing the aggregate;

Iii) a cement input step of injecting cemented carbide into the premixed aggregate;

Iii) a latex input step of injecting the latex to the mixture of the above step; And

Iii) a compound water input step of adding a mixture of diluted retardant and antifoam in water to the mixture of the above step

Iii) a mixing step of stirring the mixture of the above step

When the production method of the present invention is carried out according to the above steps, the latex modified supersonic acid is finally produced by preventing the cemented carbide cement from being hydrated in advance by the moisture contained in the aggregate and allowing the latex to be well mixed with the cement. Light concrete compositions are more desirable to ensure sufficient fluidity for subsequent laying.

Hereinafter, examples for describing the present invention will be described, but the scope of the present invention is not limited thereto.

Example

Table 2 below compares the manufacturing time according to the example and the manufacturing time of the comparative example using the conventional charging method.

◇ Cement: Super high speed cement (Ssangyong double)

◇ Latex: SB Polymer (Dow Chemical)

Solid content (%) Butadiene Content (%) Styrene Content (%) pH Average particle size Surface charge importance Glass transition temperature (℃) Film forming temperature (℃) 48 34 ± 1.5 66 ± 1.5 9.5 1900-2500 yen Nonionic 1.01 8 4

◇ As said additive, the retarder (0.6 weight% with respect to the used cement) and the antifoamer (solid content of the antifoaming agent is 1 weight% with respect to the solid content of latex) were used.

◁ Defoamer: Lucky 101A (Sea Han Chemical Co., Ltd.)

                  Specific gravity 1.0, pH 6.5, solid content 15%, white appearance

◁ Delay retardant: Citric acid (Wonjin Chemical Co., Ltd.)

In contrast to the Examples and Comparative Examples, the time required for the preparation of the same latex modified cemented carbide concrete composition was reduced 110 seconds as a whole in the embodiment was able to improve the work efficiency.

In addition, when the production amount of the concrete composition is 0.3m ³ as in the present embodiment and the comparative example, according to the conventional charging method, it was possible to match the working cycle for continuous pavement maintenance only by using two mixers. When manufacturing the concrete composition according to the embodiment it is possible to shorten the manufacturing time it was possible to maintain the continuous packaging with only one mixer.

In addition, step by step was able to reduce the weighing container from nine to one in the aggregate input step, the input time was not only reduced to 1/4 to 1/5, but also 5 to 2 personnel input to the aggregate input step. Saved to people.

In particular, the time required for cement input is shortened to 1/3 compared to the conventional one, so that cemented carbide is in contact with the water contained in the aggregate, causing partial hardening before latex is introduced, thereby preventing the mixing from becoming difficult. It was possible to produce latex modified cemented carbide concrete compositions.

Compared to the physical properties of the latex modified cemented carbide concrete compositions according to the Examples and Comparative Examples after finishing the mixing process, 5 cm is measured in the slump test, the laying and finishing work is impossible while the composition according to the Example In the case of measured by 20cm it was found that the fluidity is much better, showing the excellent coagulation delay effect was able to perform the laying and finishing smoothly.

In addition, in the case of the concrete composition according to the comparative example, the compressive strength and the bending strength of the hardened concrete were poor due to partial quenching and non-condensing phenomenon, but in the case of the concrete composition according to the embodiment due to good mixing rate and fluidity The compressive strength of the hardened concrete was high in 230-260kgf / ㎠ and flexural strength in 40-50kgf / ㎠ in 3 hours.

The production method of the present invention shortens the input time of raw materials used in the concrete composition and delays the condensation time of cemented carbide, thereby ensuring sufficient working time, so that the latex-modified concrete composition according to the manufacturing method is suitable for laying fluidity. At the same time, it expresses high early strength and is suitable for emergency repair of roads and bridge decks as well as various concrete structures.

In particular, it minimizes cold joint phenomena, reduces workforce and work time, maximizes work efficiency, and at the same time suppresses generation of scattering dust during work, enabling more efficient work progress.

1 is a perspective view showing a state in which the container for adding the aggregate is lifted by the lifting device.

Figure 2 is a perspective view showing the shape of the bottom of the container for aggregate injection.

Figure 3 is a plan view showing the discharge portion of the outer shell of the aggregate injection container.

4 is a perspective view showing a mixer equipped with a cement bag opening device.

<Description of the symbols for the main parts of the drawings>

1: aggregate input container 17: transport hanger passage

a: hook of lifter 18: outlet

10: jacket 19: binding unit

11: inlet 19 ': drawstring

12: side wall 19 ″: drawstring passage

13: bottom

14 outlet 20: endothelial

15: carrying hanger 21: discharge part

16: suture line 22: tie string

30: mixer 33: main body

31: cement bag opening device 34: cover type frame

32: inlet 35: rod

Claims (5)

A method of preparing a latex modified cemented carbide concrete composition containing cemented carbide cement and latex, aggregate and other additives using a mixer, comprising the following steps; (1) Aggregate input container consisting of an outer shell and an inner shell, the bottom portion of which has an openable discharging portion, the discharge portion of the outer shell includes a binding portion and a fastening string for binding them, and the discharge portion of the endothelial aggregate includes a bundle string Placing aggregate in a container for dosing; (2) a conveying step of moving the aggregate contained in the first step so that the bottom portion of the aggregate input container is located on the inlet of the mixer; And (3) Input step of injecting the aggregate into the mixer by releasing the adjusting strap of the outer shell discharge portion and the bundle of the endothelial discharge portion when opening the discharge portion of the container for inputting the aggregate. The method of claim 1, wherein the aggregate of the conveying step is a method for producing a latex modified cemented carbide concrete composition, characterized in that the total amount of aggregate required for one-time production of the concrete composition is contained in the container for inputting the aggregate. The method of manufacturing a latex modified cemented carbide concrete composition according to claim 2, comprising the step of injecting the cement using a sawtooth cement bag opening device provided in the inlet of the mixer. The latex reforming flux according to any one of claims 1 to 3, wherein the retardant as an additive is used by diluting 0.3-0.9% by weight with respect to the cement in water for 30-180 minutes. Method for preparing light concrete composition. In the container for inputting aggregates consisting of an outer skin and an inner skin, a bottom opening thereof includes a retractable discharge part, the discharge part of the outer shell includes a binding part and a fastening string for binding them, and the discharge part of the endothelial container includes a bundle string. .