KR102195172B1 - Method of constructing bridge expansion joint non-shrinkage mortar for crack reduction and concrete composition thereof - Google Patents

Abstract

The present invention exhibits strength early to be suitable for urgent construction such as highways, but prevents corrosion through low shrinkage strain and internal evaporation, and a method of constructing a bridge extension joint futa material for reducing cracks. And it provides the concrete composition.
To this end, in the present invention, in the method of constructing a bridge extension joint, the method of constructing a bridge extension joint after an extension joint is a step of reinforcing the reinforcing bar after placing the expansion joint in the extension joint construction part of the abutment or girder. Installing an evaporation pipe inclined to form a drainage passage at both ends and perforated at predetermined intervals, and placing a concrete composition in the expansion joint construction unit to construct a futa material in a state in which the evaporation pipe is buried. .
In addition, the concrete composition of the post of the bridge extension joint includes cement powder, water, fine aggregate, coarse aggregate, liquid latex, and water reducing agent, but the cement powder is composed of 4-5% by weight of an expanding agent mixed with ultrafast cement and ultrafast cement. Consists of
According to the above technical configuration, it is suitable for urgent construction such as highways, as well as corrosion prevention by exerting strength early by inducing internal evaporation due to low shrinkage deformation rate of the concrete composition using ultrafast cement and induction of internal evaporation by buried evaporation perforated pipes. , Through crack reduction, etc., it is possible to drastically reduce maintenance costs due to durability degradation.

Description

{Method of constructing bridge expansion joint non-shrinkage mortar for crack reduction and concrete composition thereof}

The present invention relates to a method for constructing a post-expansion joint for crack reduction and a concrete composition thereof, and more particularly, to a bridge for crack reduction that can prevent corrosion and suppress the occurrence of cracks through low shrinkage strain and internal evaporation. It relates to the construction method of the post-expansion joint and the concrete composition.

In general, bridge expansion joints smoothly accommodate the displacement and deformation of the upper structure to minimize the occurrence of secondary stress and allow the vehicle to travel safely on the bridge surface. It is a device that plays a role in preventing corrosion of concrete.

Since the bridge expansion joint as described above is exposed to the surface of the bridge, it is easy to be damaged by friction and impact caused by passing vehicles, and it loses its function as an expansion joint when a stricture occurs due to horizontal displacement of the abutment. It is a bridge element that is inevitable for maintenance during its proper life.

In the case of urgent need for repair work on bridge joints, especially on highways, ultra-fast hardness cement is used to develop early strength.

Despite the advantage of rapid strength development, ultra-fast-hard cement has the disadvantage of generating a large amount of cracks in the initial stage due to high heat of hydration.

As a result, when the repair work of the bridge expansion joint system is performed using ultra-fast cement, durability decreases due to concrete cracks, and maintenance costs increase.

Therefore, it is required to develop a high-performance concrete composition capable of suppressing cracking while exhibiting strength early so as to be suitable for urgent construction such as repair work of bridge expansion joints.

Hereinafter, the technology that is the background of the present invention will be disclosed.

Publication No. 10-2015-0029221 (published on March 18, 2015) relates to a composition of a futa material used when installing a bridge expansion joint and a construction method using the same, and includes futa applied to a bridge expansion joint. The ash composition is composed of mixing 54.95 to 62.66% by weight of the powder composition of futa material and 8.34 to 10.05% by weight of the liquid composition of futa material, and then mixing 29 to 35% by weight of coarse aggregate, and the powder composition of the futa material is calcium aluminate-based Fast-hardening material 18 to 23% by weight, active silica-based concrete waterproofing material 0.52 to 2.0% by weight, supersynthetic agent 0.25 to 0.35% by weight, expansion material 0.7 to 2.0% by weight, antifoaming agent 0.09 to 0.3% by weight, amine-based rust inhibitor 0.1 to 0.3% by weight , The composition consisting of fine aggregates 27 to 43% by weight, and the futa material liquid composition, consisting of 4.5 to 5.15% by weight of styrene acrylic emulsion, 0.03 to 0.07% by weight of antifoam, 0.01 to 0.03% by weight of wetting agent, and 3.8 to 4.8% by weight of water The composition and the coarse aggregate is composed of a size of 13mm to 19mm with a well-cleaned surface, and the size of the fine aggregate is used up to 0.1mm to 3mm according to the construction thickness, and the vertical shape maximizes the bonding area between the aggregate and cement paste. In order to do this, the construction method using the composition and the above composition comprises the steps of removing the futa material and the expansion joint that have lost their function due to aging and breakage when the expansion joint is reinstalled; The anchor and reinforcing bars of the expansion joint are welded firmly to the reinforcing bars of the bridge slab, and the step of maintaining flatness; Removing dust cleanly using a high pressure washer on the pouring surface of the futa material, and preventing corrosion of the reinforcing bar by applying an amine-based reinforcing agent to the welded area of the reinforcing bar and the reinforcing bar; Applying a permeable primer to the futa material casting surface to increase the adhesion of the futa material; The futa material is made by mixing the powder composition and the liquid composition for 3 minutes and then adding the weighed coarse aggregate for 2 minutes.

Pouring the futa material composition; Compacting so that there are no voids by using a vibrator so as not to directly contact the welded portion of the expansion joint and the slab reinforcing bar after pouring the thicker material; After compacting using the vibrator, the surface of the futa material is quickly adjusted using a tool to adjust the gradient and level the surface; Curing by applying a water-soluble curing agent in an amount of 200 to 250 g/m 2 in order to prevent cracking due to rapid moisture evaporation after completion of the flattening work; The composition consisting of opening the road for passing the vehicle 3 hours after the pouring of the futa material, and the step of pouring the futa material composition includes 54.95 to 62.66% by weight of the powder composition of the futa material and 8.34 to 10.05% by weight of the liquid composition of the futa material. After mixing for 3 minutes, 29-35% by weight of the coarse aggregate is mixed for 2 minutes to quickly pour, and in the step of applying a water-soluble curing agent, the composition is cured by applying a water-soluble curing agent in an amount of 200 to 250 g/m². have.

The present invention exhibits strength early to be suitable for urgent construction such as highways, but prevents corrosion through low shrinkage strain and internal evaporation, and a method of constructing a bridge extension joint futa material for reducing cracks. And to provide the concrete composition.

In order to achieve the above object, the present invention is in the method of constructing a post-expansion joint for a bridge, reinforcing the reinforcing bar after placing the expansion joint in the expansion joint construction part of the abutment or girder, and both ends are on the upper side of the reinforced rebar. The perforations are drilled at predetermined intervals on the upper surface so that they are gradually lowered in the width direction of the bridge and induce moisture to the inside, but the perforations are arranged in a polygonal group shape, and the stud bolts are welded to the center to prevent the incoming rainwater. It characterized in that it comprises the step of installing an evaporation pipe guided through the perforations and a smooth lower surface, and constructing a futa material in a state in which the evaporation pipe is buried by pouring a concrete composition into the expansion joint construction unit.

delete

delete

delete

In addition, the concrete composition of the post of the bridge expansion joint includes cement powder, water, fine aggregate, coarse aggregate, liquid latex, and water reducing agent, but the cement powder is composed of 3 to 6% by weight of an expanding agent mixed with ultrafast cement and ultrafast cement. It characterized in that it is made of.

The expansion agent is characterized in that 4 to 5% by weight is mixed with respect to the ultrafast cement.

The concrete composition is composed of a mixture of 23% by weight of cement powder, 6.2% by weight of water, 32.7% by weight of fine aggregate, 35.6% by weight of coarse aggregate, 2.3% by weight of liquid latex, and 0.2% by weight of water reducing agent. It is characterized by consisting of a configuration in which a retarder of 0.3% by weight is further added.

When replacing the liquid latex with solid latex powder, it is characterized in that 5% by weight of cement powder is used.

According to the present invention, it is suitable for urgent construction such as highways, as well as corrosion prevention and crack reduction by exerting strength early by low shrinkage deformation rate of concrete composition using ultrafast cement and induction of internal evaporation by buried evaporation pipe. It has a very excellent effect that it can dramatically reduce maintenance costs due to a decrease in durability through the use of the same.

1 is a schematic diagram showing the location of an expansion joint construction unit,
2 is a plan view showing the structure of a conventional bridge expansion joint futa material,
3 is a cross-sectional view showing the structure of a conventional bridge expansion joint futa material,
4 is a perspective view of an evaporation pipe according to the present invention,
5 is a front view of an evaporation pipe according to the present invention,
Figure 6 is a plan view showing the structure of the bridge expansion joint futa material according to the present invention,
Figure 7 is a cross-sectional view showing the structure of the bridge expansion joint futa material according to the present invention,
8 is a table showing the concrete mixing ratio of the futa material according to the present invention,
9 is a graph showing the shrinkage strain and compressive strength of the thicker test specimen according to the present invention.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to a preferred embodiment of the concrete composition and a method of constructing a bridge extension joint for reducing cracks.

First, referring to Figs. 1 to 3, the method of constructing a bridge expansion joint after the crack reduction according to the present invention includes an expansion joint device 10 in the expansion joint construction part A of the abutment 1 or girder 2 The step of binding to the pre-installed reinforcing bar and reinforcing the reinforcing bar 20, installing an evaporation pipe 40 having a bent and perforated hole 41 to form a drainage passage on both sides above the reinforced reinforcing bar 20, and It includes the step of constructing the futa material 30 in a state in which the evaporation pipe 40 is buried by pouring the concrete composition in the expansion joint construction unit (A).

Specifically, the expansion joint construction part (A) is provided between the abutment (1) and the girder (2), and between the girder (2) and the girder, and the installation of the expansion joint (10) facilitates displacement and deformation of the upper structure. To minimize the occurrence of secondary stress and allow the vehicle to travel safely on the bridge surface.

That is, reinforcing reinforcement is performed after placing the expansion joint device 10 in the expansion joint construction part (A) of the abutment (1) or the girder (2), and the anchor part 11 of the expansion joint is already installed. Or to reinforce the reinforcing bar in the anchor part 11.

Next, referring to FIGS. 4 to 7, an evaporation pipe 40 is installed on the upper side of the reinforced reinforcing bar 20 so as to form a drainage channel on both sides of the bridge and has a perforation 41 perforated therein, in detail, the evaporation pipe 40 is provided with a perforated hole 41 perforated in a predetermined size so as to induce moisture inward, and both ends are bent to gradually lower in the width direction of the bridge and are arranged in a curved shape.

And a concrete composition is poured into the expansion joint construction part (A), and the futa material 30 is constructed in a state in which the evaporation pipe 40 is buried, and the evaporation pipe in which the perforations 41 are perforated in the futa material 30 ( As 40) is buried, moisture evaporates smoothly through the perforated holes 41 during curing, so that it can be applied well to urgent repair work by shortening the curing period, and flows into the futa material 30 after completion. It is possible to reduce cracks, such as corrosion prevention, by guiding the formed rainwater to the inside through the perforations 41 and discharging them to the outside.

Next, the evaporation pipe 40 has a perforated hole 41 on its upper surface to induce and discharge moisture that has penetrated into the futa material 30 to the inside.

As described above, rainwater flowing into the futa material 30 is guided to the inside of the evaporation pipe 40 through the perforations 41 and discharged. When the evaporation pipe 40 is divided up and down, the upper surface is The perforations 41 are perforated to induce inflow, and the lower surface has a smooth shape in which the perforations are not perforated so that the induced moisture can be smoothly discharged to the outside.

Next, the perforations 41 are arranged in a polygonal group shape.

This is a configuration for maintaining the rigidity against the load acting on the evaporation pipe 40 embedded in the futa material 30, and the perforations 41 are formed in a triangular, square, pentagonal, or hexagonal group shape to form an unperforated surface. As a certain space is secured, it has a greater support force when a load is applied.

Next, the perforations 41 are arranged in a polygonal group shape, and a stud bolt 50 is welded at the center thereof.

According to the above technical configuration, in the evaporation pipe 40, the perforated perforations 41 are arranged in a polygonal group shape such as a triangle, a square, a pentagon, a hexagon, and the stud bolt 50 is welded to the center thereof. It is possible to effectively suppress the occurrence of cracks, such as corrosion prevention, since the rainwater flowing into the futa material 30 and the solid binding with the ash 30 is better guided to the perforations 41 through the stud bolt 50.

Hereinafter, with reference to Figures 8 and 9 will be described with respect to the concrete composition of the bridge expansion joint futa material for reducing cracks according to the present invention.

In the present invention, a concrete composition of the futa material 30 having low shrinkage strain and excellent compressive strength is proposed. To this end, in the present invention, it was verified with various concrete mixing ratios as disclosed in FIG. 8 (unit kg).

Experimental material

Cement and aggregate

For cement, ultra-fast hardness cement produced by I and S in Korea was used, and 0.3% by weight of a citric acid-based retardant was used as an additive to secure the working time required for mixing and pouring.

The characteristics of ultra-fast cement are as follows.

The ultra-fast-hardening cement can obtain practical strength in 2 to 3 hours, but exhibits practical strength of 20 MPa to 30 MPa by blending.

Similar to Portland Cement, it exhibits stable strength enhancement over a long period of time, and also exhibits practical strength in a short period of time even at low temperatures. Ultrafast cement has low slump value and excellent workability, so it works smoothly, and it has low shrinkage after hardening, so it has excellent adhesion to reinforcement and old concrete.

For coarse aggregate (gravel), crushed stone with a maximum dimension of 13 mm was used, and for fine aggregate (sand), natural steel sand was used. The fine aggregate ratio (S/a) was blended at 47.9%.

The coarse aggregate used in the present invention limited the maximum dimension in order to reduce the amount of air and increase the strength in concrete mixing, but the concrete mixing ratio of the present invention is well applied to aggregates of sizes generally used in the field.

Latex

Liquid acrylic latex from I and S was used as the latex. Latex is a milky liquid substance, consisting of 50% solids and 50% water containing a small amount of surfactant. When mixing concrete, the amount of mixing water to be added can be adjusted in consideration of the water contained in the latex.

In the present invention, a mixing ratio of 10% by weight relative to the cement powder was proposed using a liquid latex having a solid content of 50%, but when using a pure latex made of powder, 5% by weight is used relative to the cement powder, and water may be added accordingly. .

Expanding agent

CSA inflating agent produced by S company in Korea was used as the inflating agent, and caution should be taken when using it in that excessive use compared to ultra-fast hardness cement may lead to deterioration of the structure such as cracks due to expansion.

When referring to the concrete mixing ratio and graph of FIGS. 8 and 9 attached, the concrete composition for bridge expansion joints after the crack reduction according to the present invention includes cement powder, water, fine aggregate, coarse aggregate, liquid latex, water reducing agent, The cement powder is composed of a composition in which 3 to 6% by weight of an expanding agent is mixed with respect to the ultrafast cement and the ultrafast cement.

In addition, it is preferable that 4-5% by weight of the expanding agent is mixed with respect to the ultrafast cement.

And the concrete composition is composed of a mixture of 23% by weight of cement powder, 6.2% by weight of water, 32.7% by weight of fine aggregate, 35.6% by weight of coarse aggregate, 2.3% by weight of liquid latex, and 0.2% by weight of water reducing agent. It consists of a configuration in which a retarder of 0.3% by weight is further added.

Here, the cement powder is a composition in which 0% by weight, 3% by weight, 6% by weight, 9% by weight, and 12% by weight of the expanding agent are mixed with respect to the super-fast-hard cement and the super-fast-hard cement, so that the total weight of the cement powder is the same. A test body was prepared.

According to the above technical configuration, the test specimen having a mixing ratio of latex and expansion agent of 0% shrinks the most, and it can be seen that the larger the shrinkage strain, the more cracks occur.

In other words, if latex or an expanding agent is not added, the strength is excellent, but the shrinkage deformation occurs so that cracks are easily generated. This increases the maintenance cost, such as corrosion due to moisture penetration and durability degradation due to cracking.

Accordingly, in the present invention, this problem is solved by mixing the expanding agent and the latex in the ultrafast cement.

However, as the strength of the test specimens with a mixing ratio of 6% by weight or more compared to the ultra-fast-hardening cement showed a tendency to decrease rapidly, an appropriate mixing ratio should be applied to the expanding agent and latex.

In the present invention, 23% by weight of cement powder, 6.2% by weight of water, 32.7% by weight of fine aggregate, 35.6% by weight of coarse aggregate, 2.3% by weight of liquid latex, and 0.2% by weight of a water reducing agent are mixed to form a concrete composition. It consists of a configuration in which a retarder of 0.3% by weight is further added, and the best result was obtained when 10% by weight of the liquid latex and 4 to 5% by weight of the expanding agent were mixed with respect to the cement powder.

Therefore, it can be seen that it is effective in maintaining strength and reducing cracks by mixing an appropriate latex and an expanding agent with the ultra-fast cement, and it is possible to reduce maintenance costs through corrosion prevention and crack reduction.

Although the present invention described above has been described by a limited embodiment, the present invention is not limited to the above embodiment, which is various modifications and variations from these descriptions for those of ordinary skill in the field to which the present invention belongs. This is possible. Therefore, the idea of the present invention should be grasped only by the claims set forth below, and all equivalent or equivalent modifications thereof will be said to belong to the scope of the inventive idea.

A: Expansion joint construction part
1: shift
2: Girder
10: expansion joint
11: anchor part
20: rebar
30: futajae
40: evaporation pipe
41: merit
50: stud bolt

Claims (8)

In the method of construction of the post-construction joint of the bridge,
Reinforcing the reinforcing bar after placing the expansion joint device on the expansion joint construction part of the shift or girder,
On the upper side of the reinforced reinforcing bar, both ends are gradually lowered in the width direction of the bridge to be inclined and perforations are drilled at predetermined intervals on the upper surface to induce moisture inward, but the perforations are arranged in a polygonal group shape, and a stud bolt is placed at the center thereof. Inducing rainwater introduced by welding into the perforations through the stud bolts and installing an evaporation pipe having a smooth lower surface, and
And constructing a futa material in a state in which the evaporation pipe is buried by pouring a concrete composition into the expansion joint construction unit. delete delete delete The concrete composition of claim 1, which is poured into the expansion joint construction unit,
Including cement powder, water, fine aggregate, coarse aggregate, liquid latex, and water reducing agent, wherein the cement powder is composed of a composition in which 3 to 6% by weight of an expanding agent is mixed with the ultrafast cement and the ultrafast cement. The concrete composition of the post of the bridge expansion joint for the purpose. The method of claim 5,
The expansion agent is a concrete composition of a bridge expansion joint futa material for reducing cracks, characterized in that 4-5% by weight is mixed with respect to the ultrafast cement. The method of claim 5,
The concrete composition is composed of a mixture of 23% by weight of cement powder, 6.2% by weight of water, 32.7% by weight of fine aggregate, 35.6% by weight of coarse aggregate, 2.3% by weight of liquid latex, and 0.2% by weight of water reducing agent. Concrete composition of a bridge extension joint futa material for crack reduction, characterized in that consisting of a configuration in which 0.3% by weight of a retarder is further added.
delete

Images