JPS63156165A - Method of spading construction at time of concrete placing and tool thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a spacing method and a tool therefor which are extremely effective in concrete pouring work, particularly in the production of concrete products using formwork.

[Prior art and its problems]

In recent years, the manufacture of concrete products has progressed more and more due to advances in technology and research into management methods, and it has become possible to manufacture products of the quality required by various fields.

Starting with the mix design, the research efforts of those involved are continuing in areas such as kneading, driving, compacting, curing, and demolding methods.

However, what has recently become a problem is the impact of air pollution and deterioration of water quality on concrete. Air pollution is caused by sulfur oxides such as sulfur dioxide gas caused by petroleum-based fuels, and water pollution is caused by strong acidity caused by industrial wastewater.

Acidification of the atmosphere and water slows down the neutralization of concrete, corrodes the reinforcing steel in the concrete, and significantly shortens its lifespan. Examples of this are highway retaining walls, sewer manholes, pipes, and bridge girders.

In order to prevent this, it is necessary not only to improve the quality of concrete, but also to make the surface of concrete products smooth and dense.

This is also stipulated in the Japan Society of Civil Engineers' concrete standard specifications.

In other words, (surface not in contact with the weir), (surface in contact with the weir)
It emphasizes the importance of surface finishing for each item, such as , (the surface that receives the pick-up edge), etc. Particularly regarding the surface in contact with the weir: 1) Exposed concrete must be poured and compacted so that a flat mortar surface is obtained.

2) Remove any protrusions, slits, etc. that have formed on the concrete surface and flatten it. For chipped areas, remove the imperfections, wet them with water, and then patch them with concrete or mortar of an appropriate mix. It must be finished flat. As for the reason for (■), this is not only necessary for aesthetic reasons, but is also important for increasing the durability and watertightness of the structure.

Regarding 2), leaving defects on the concrete surface as is will not only harm the appearance but also have a negative impact on the durability of the structure, so it must be repaired.

He explains.

These air bubbles that appear on the concrete surface are unavoidable in the process of making concrete products.When pouring fresh concrete into formwork, a vibrator such as a bar vibrator is used, and when the formwork vibrates, air bubbles in the ready-mixed concrete move upwards or into the mold. Move to the frame wall. Due to the stickiness of the ready-mixed concrete, this is not released into the atmosphere and remains on the concrete surface.

For example, in the case of a block on the side of a sewer manhole, as shown in Figure 1, air bubbles 1 move to the wall of formwork 2 and try to rise, but because the concrete is viscous, they are not released and remain in the formwork. In particular, it adheres to the sloped surfaces of the formwork, the foothold fittings 3, and around the reinforcing bars.

At present, there is no effective way to prevent this, and the only methods available are to pour the ready-mixed concrete several times to expel the air bubbles, or to perform spacing.

As shown in Figure 2, the currently common method of spacing is to rub the inner surface of the formwork 2 with a thin strip of iron plate 4 to push the air bubbles that have collected in the formwork back into the concrete and smooth the surface. Make it. However, this method can only be done manually and is not possible with complex-shaped formwork, and it is impossible to perform spacing work when the concrete thickness is large.

Moreover, although the concrete made by this method looks good at first glance, it cannot be said to be of good quality because there are a few air bubbles inside the concrete.

If a concave part is formed on the surface of a concrete product due to air bubbles, it is difficult to use patching as a repair method. The patching material may peel off, and the appearance may become discolored and poor.

In addition, from an economic point of view, labor costs are very high, and 10% to 30% must be added as labor costs for patching wooden products for blocks on the side of manholes, etc.

Therefore, the present invention aims to provide a very simple spacing method and a tool for achieving a remarkable spacing effect.

[Means for solving problems]

That is, the present invention is a spacing method in which a rotating helical rod is pierced into concrete to crush or expel air bubbles in the concrete, and the tool is a helical rod of an appropriate length that is fixed to or detached from a rotary drive machine having a handle. It uses a freely mounted paging machine.

r Action] When pouring concrete products using formwork, after compacting using a pipe rake, generally a bar pipe rake, while rotating the spiral rod of the above-mentioned spacing machine up and down, Make sure to rub the formwork.

In this way, the air bubbles on the inner surface of the formwork are crushed, and
Due to the feeding action of the spiral rod, it rises with the concrete,
released.

〔Example〕

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a paging machine 5 according to the present invention, and this embodiment uses a commercially available electric hand drill.
In this example, a left-handed handle 6 is added to the side surface, and a spiral rod 7 is attached to the chuck 5a.

The structure of the spiral rod 7 is one in which a reinforcing bar 72 is wrapped around a round bar 71 and welded as shown in FIG.
) Twisted flat steel 73 as shown in Figure 5 (C)
As shown in FIG. 2, there is a structure in which a spiral 74 is integrally molded onto a round bar 71 using hard synthetic rubber, reinforced plastic, or the like. Practically speaking, the structure shown in FIG. 5(A) is easy to manufacture, but if the formwork is made of wood, the structure shown in FIG. 5(C) is suitable.

Now, let's move on to the present invention using the above-mentioned spacing machine.
Let us explain the actual use of the spacing method using the case of manufacturing slanted walls of manholes as an example.

Figure 4 shows a cross-sectional view of concrete 8 poured into the formwork 2, and a bar vibrator (not shown) is used as usual.
Perform compaction work using.

Through this compaction work, 80% of the air bubbles in the right-hand straight wall part are removed, but the left-hand slanted wall part collects on the inner surface of the outer formwork as shown in FIG. 1, as described above.

This group of bubbles cannot be removed by spacing using conventional plate materials.

In fact, when spacing is performed using the conventional method, after removing the formwork, looking at the skin of the straight wall and slanted wall, it is well known that the depressions caused by air bubbles on the surface of the straight wall are small, but Since large air bubbles remain on the surface of the wall, large recesses are formed, and the difference is remarkable.

In addition, the large air bubbles remaining in the sloping wall section cause the concrete product to sag below the surface defined by the formwork.

However, when the spacing machine according to the present invention is held as shown in FIG. 3, the spiral rod 7 is used to scrape the inner surface of the formwork 2 up and down two to three times as shown in FIG. When the concrete is moved while being allowed to move, a concrete product with a very beautiful skin can be obtained, which is surprising.

The rotation direction of the spiral rod 7 is preferably the screwing direction. The air bubbles will then be sent upwards with the concrete and effectively released.

The action of the spiral rod 7 is not only to provide a stirring effect, but also to crush and refine air bubbles and discharge them upward.

In this embodiment, a commercially available electric hand drill was modified and used as the spacing machine, but it goes without saying that the driving machine may be pneumatic or hydraulic.

The speed of the rotation of the spiral rod 7 is changed by the slump of the concrete, and air is efficiently degassed. This construction method is capable of spacing not only vertical cylinders but also trapezoids with slanted surfaces in a short time. In particular, it is revolutionary in that it allows easy processing of diagonal surfaces, which until now were impossible.

By the way, there are the following problems regarding air bubbles on the surface of concrete.

These air bubbles not only neutralize the appearance of the concrete surface, but also, if the air bubbles are large and penetrate deep into the concrete, the concrete will become shallowly covered and the reinforcing steel inside will quickly rust. This can be prevented by using the spacing method.

Regarding this cover, the Japan Society of Civil Engineers' Standard Specifications for Concrete specifies as follows. In other words, the reinforced concrete cover is necessary from the viewpoint of increasing the adhesion strength of the reinforcing bars, preventing rust, and protecting against fire, and the minimum cover should be (1) The cover should be equal to or larger than the diameter of the reinforcing bars.

(2) Slab -25mm even if not exposed to wind and rain
, barry 30mm, column - 35mm or more.

However, as mentioned above, large and deep bubbles cause shallow cover and shorten the lifespan of reinforced concrete.

Next, when manufacturing a manhole side block (slanted wall type) with the same structure, the difference in air bubble generation when the present invention spacing method is used and when the conventional spacing method is used is as follows. It is.

The differences in working time are as follows.

When using the spacing method of the present invention, the total time is 2 minutes,
In the case of the normal spacing method, it takes 36 minutes, and the difference is 34 minutes, which is huge.

In addition, in the case of conventional methods, the surface of the finished product needs to be repaired due to the generation of large bubbles, and rosin wood is required for repair, which is difficult to manage.

Moreover, when the economic efficiency was calculated, it was 115 by adopting the construction method of the present invention.

As can be seen from the above results, the spacing method according to the present invention is not only useful for improving the quality of concrete currently required in architecture and civil engineering, but also contributes significantly to the concrete industry economically. It is a construction method that can be used.

〔Effect of the invention〕

It is an extremely economical method that allows even amateurs to carry out the spacing work very easily and takes only a short amount of time. Additionally, the spacing machine is easy to use and requires no skill to operate.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a state in which single-sided wall type side block concrete is poured, Fig. 2 is an explanatory diagram of a conventional spacing method, and Fig. 3 is a perspective view of a spacing machine according to the present invention. , FIG. 4 is an explanatory diagram of the spacing method according to the present invention, and FIG. 5 is a diagram showing various embodiments of the spiral rod. 1.1'...Bubble 2...Formwork 3...Holding bracket 4...Iron plate 5...Spaging machine 6...Handle 7...Spiral rod

Claims (2)

[Claims] (1) A spacing method for pouring concrete, which is characterized by piercing the concrete with a rotating spiral rod to crush or expel air bubbles in the concrete. (2) A spacing machine characterized in that a spiral rod of an appropriate length is fixedly or detachably attached to a rotary drive machine having a handle.