JP2835926B2 - Thickening method of concrete slab - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for increasing the thickness of concrete slabs, and more particularly, to existing slab concrete as a measure for reinforcing concrete slabs on metropolitan expressways and expressways in heavy traffic departments. An object of the present invention is to provide a simple reinforcing method for increasing the thickness of a steel sheet.

[0002]

2. Description of the Related Art Thickening methods for reinforcing concrete slabs on expressways and the like are already known. BACKGROUND ART Conventionally, a thickening method for reinforcing concrete slabs has been performed using a large-sized concrete mixing plant and a dedicated powerful concrete finisher.

In such a thickening method, it is important how to achieve integration of existing concrete with newly installed new concrete for thickening and to resist external force. It is known that the treatment of the old concrete surface and the compaction of the new concrete by vibration have a dominant effect on the integration of the old and new concrete.

[0004] Therefore, in consideration of the stress caused by drying shrinkage after hardening of new concrete, conventionally thickened concrete has a small unit water amount, uses a relatively hard material, and prepares a dedicated powerful concrete finisher. A movable concrete mixing plant is installed near this, and a concrete of about 5 cm slump is supplied while moving the movable concrete mixing plant, or a belt conveyor, a carrier, a concrete mixing plant installed in an earthworking section. Payloaders transport concrete to concrete finishers.

[0005]

In the above-mentioned conventional method,
Raw materials such as cement and various aggregates to be supplied to the plant must be temporarily placed near a large-scale concrete mixing plant, which requires a large amount of weight. In addition, due to the load on the bridge, the plant is basically installed in the earthwork section, and a system that transports the super-hard concrete produced here to a separate casting site is adopted. Then, a bridge of about 500m is considered as one limit.

For this reason, in the case of a long bridge, material conveyance by "backward feeding" is being studied. This method uses the bridge on the bridge after completion of the construction as a concrete manufacturing place when curing is completed (about 3 hours after the completion of casting, the finisher advances about 100 m during this time)
Although a long bridge is aimed at shortening the material transport time, it is not always possible to achieve a sufficient effect.

[0007] On the other hand, in the current thickening method, in order to secure time for transporting, spreading, and compacting processes, ultra-rapid hardening cement, ultra-high-strength cement, or high-strength cement having excellent initial strength development. Cement is used. However, among these, in particular, there is a problem that a super-setting cement starts to harden during transportation, so that a setting retarder must be used in combination.

The present invention has been studied to solve the above-mentioned conventional drawbacks, and as a result, it uses simple cement and steel fiber, and does not use a large-scale concrete mixing plant and a dedicated powerful concrete finisher. Moreover, the present invention provides a good method for integrating old and new concrete.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a method for reinforcing concrete slab concrete, in which concrete, in which steel fiber, coarse aggregate and fine aggregate are blended with ultra-fast-hardening cement, ultra-high-strength cement or high-strength cement. Is a method of increasing the thickness of the concrete slab by spraying it onto the concrete slab.

[0010]

According to the present invention, instead of a large-scale on-site concrete mixing plant and a dedicated powerful concrete finisher, the present invention comprises
Use a wet or dry spray machine and install the spray machine at a location away from the construction site. The spraying machine is a conventionally known spraying machine, and is widely used because of its simple operation in addition to its small size.

Since the spraying machine is capable of transporting the material upward to some extent, an appropriate open space (including a riverbed) which separates the plant and the spraying machine from the site of the thickening construction site depending on the location conditions of the concrete construction site. For example, it is possible to reduce the amount of equipment and machinery to be transported to a repair site, such as an expressway, and the amount of work on the road.

Therefore, there is no need to arrange an operator for mixing various raw materials at the thickening construction site, and there is no need to separately transport raw materials such as water and a retarder to the traffic jam site during construction. Therefore, the thickening construction site is more organized than before, the work is easy, the working environment is good and the safety management is excellent. Further, since no finisher is used, the operation can be sufficiently performed with a minimum required operation band.

Further, as the concrete of the present invention, any of ultra-fast-hardening cement, ultra-high-strength cement or early-strength cement can be used. In addition to steel fiber, coarse aggregate, fine aggregate, Add high performance water reducer, set retarder and water. Generally, a setting retarder must be used when using ultra-fast setting cement.

However, the setting retarder can prolong the setting time, but has the disadvantage of decreasing the initial strength development.
Therefore, if construction without using a setting retarder is possible,
The curing time can be shortened without reducing the initial strength expression. According to the study by the present inventors, it is sufficient for the concrete to be able to maintain sufficient time for vibration compaction. For example, it is sufficient for the ultra-rapid hardening cement to maintain fluidity for about 3 minutes.

Therefore, in such a case, a dry spraying method in which a mixed material composed of cement, aggregate, and steel fiber is conveyed by a spraying machine and water is mixed by a spraying nozzle at a construction site may be applied. For example, using ultra-fast hardening cement, the total length of the working equipment is about 1.5 m, and the construction speed is 50 cm / mi
n.If it is, it is possible to significantly reduce the amount of setting retarder that is indispensable in the conventional method or to work without using a setting retarder, especially when using ultra-fast setting cement It is valid.

On the other hand, according to the current thickening method, at a construction site such as a bridge, a plant is basically installed in an earthwork section due to an overload, and the super-rapid hardened concrete produced here is transported to a casting site. Therefore, a bridge having a length of 500 m is considered to be one limit, but it is more advantageous to adopt the dry spraying method of the present invention. For example, a spraying machine can perform long-distance pumping depending on the model (it has a track record of about 1000 m). Therefore, when conveying a mixed material using a spraying machine, the transportable distance can be doubled. it can.
Further, if a carrier, a power shovel or the like is incorporated between the mixer and the spraying machine, the distance between the mixer and the casting place can be extended.

Further, at present, mixing of steel fiber reinforced ultra-rapid hardening concrete at a site requires a large mixer load at the time of concrete production. Therefore, in a general-purpose on-site mixing plant, the production capacity per hour is about 4 to 6 m ^3. is not possible correspondence for the ability, plants with production capacity of 1 hour per 10～12M ³ is used. However, there are currently only a few plants that have this capability, which is a bottleneck for mixing fiber-reinforced ultra-rapid concrete at the site.

On the other hand, in the dry spraying method of the present invention, since the plant produces dry concrete composed of cement, aggregate, and steel fiber, the mixer load is significantly larger than that of the conventional method. Reduced, and thus, the application of conventional on-site milling plants is possible.

[0019] In other words, dry concrete in it if at the scene kneading per hour 10~12m ^3, in some cases 18m ³ (d = 10c
m, it is considered possible to produce concrete for 50 cm / min. (assuming a construction speed of 50 cm / min.), and therefore, in the present invention, on-site kneading can be applied, and a normal type on-site kneading plant can be applied. This means that the number of concrete plants that can handle thickening work can be increased.

The concrete used in the present invention is:
A polymer such as an acrylic resin can also be blended into this. When a polymer is mixed, the following effects are generally obtained. The effect of the polymer improves the adhesive capacity of old and new concrete and increases the resistance to "warp stress". The polymer itself has a water reducing effect, so that the workability of concrete is improved even under the same unit water volume, polymer concrete. Has a thixotropic nature, making it easy to handle and to respond to horizontal and vertical gradients.

Therefore, the addition of the polymer can be used to improve the adhesive capacity of old and new concrete, and to improve the warpage of the old and new concretes if it is added as appropriate in accordance with the properties of steel fiber-containing ultra-fast-hardened concrete, ultra-high-strength cement, or early-strength cement, or on-site conditions. It is possible to obtain effects such as improvement of resistance to "stress", improvement of workability of concrete and easy handling, and easy handling of horizontal and vertical gradients.

[0022]

FIG. 1 shows an embodiment of the present invention.
The present invention will be specifically described with reference to FIG. Continuous mixer 1
After mixing and mixing predetermined amounts of raw materials such as super-hard cement, coarse aggregate, fine aggregate, steel fiber and necessary water reducing agent, the mixed material is supplied to the concrete spraying machine 2. The concrete spraying machine 2 is supplied with high-pressure air from a compressor 3 via an air hose 4, and the mixed material is sent to the bridge K at the site by a high-pressure air by a material hose 5.

On the bridge K, the operator can spray the mixed material sent by the material hose 5 to a predetermined location with the spray nozzle 6. The continuous mixer 1, the concrete spraying machine 2, and the compressor 3 may be all installed on the riverbed under the bridge, but may be installed on the bridge in some cases. In addition, in the case of FIG. 1, the dry spraying method is used, and the illustration is omitted. However, in the case of the dry type, a high-pressure water pump may be separately installed at the construction site outside the above-described apparatus.

[0024]

As described above, according to the present invention, in a concrete thickening method, a super-hard concrete, an ultra-high-strength cement or an early-strength cement, steel fiber, coarse aggregate, fine aggregate and other necessary materials are mixed to form a large-sized concrete. A simple spraying machine can be used instead of a concrete mixing plant and a dedicated powerful concrete finisher, and the material mixed directly from the spraying machine can be pumped to the site, greatly improving the construction method. The new concrete can be easily integrated with the existing concrete. In addition, since it is not necessary to arrange a large number of workers at the thickening construction site, the thickening construction site is relatively organized, work is easy, and the working environment is favorable.

When the dry spraying method is applied, the use of a super-hardening cement does not require a drastic reduction or use of a setting retarder. Can be sufficiently exerted without reducing the initial strength expression performance, and the curing time can be shortened.

According to the dry spraying method of the present invention, the load on the mixer is greatly reduced as compared with the conventional method, and therefore, a conventional on-site kneading plant can be applied for on-site kneading. There is also an effect that the number of concrete plants that can be used can be increased.

Further, in the present invention, in the case of the method of reinforcing from the lower surface as a measure for reinforcing the concrete floor slab, steel fiber and concrete containing steel are put on a reinforcing bar without requiring a large-scale equipment as in the prior art. It is sufficient to spray the mixed material with a spraying machine, and there is an advantage that the construction can be performed at lower cost as compared with the conventional method.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment of the present invention.

[Explanation of symbols]

 1: Continuous mixer 2: Concrete sprayer 3: Compressor 4: Air hose 5: Material hose 6: Spray nozzle

Claims (1)

(57) [Claims] 1. A concrete floor slab is reinforced by spraying a concrete in which steel fiber, coarse aggregate, and fine aggregate are blended with ultra-fast-hardening cement, ultra-high-strength cement, or high-strength cement. Thickening method of concrete floor slab characterized by spraying.