JPH0454785B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an extremely effective spacing method and tools used in concrete pouring work, particularly in the production of concrete products using formwork. [Prior art and its problems] In recent years, the production of concrete products has progressed more and more due to advances in technology and research into management methods, and it has become possible to produce 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, air pollution has recently become a problem.
This is the effect on concrete due to deterioration of water quality. 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 bridges. 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, it emphasizes the importance of surface finishing for each item, such as (the surface that does not touch the weir), (the surface that contacts the weir), and (the surface that receives abrasions). 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) Protrusions, streaks, etc. on the concrete surface should be
This shall be removed and leveled, and any imperfections shall be removed, wetted with water, and patched with concrete or mortar of an appropriate mix to make it flat. Regarding (1), 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. The currently commonly used paging is the second
As shown in the figure, the inner surface of the formwork 2 is rubbed with a strip-shaped thin iron plate 4 to push the air bubbles collected in the formwork back into the concrete and smooth the surface. However, this method can only be done manually and is not possible with formwork of complex shapes, and it is impossible to carry out the 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 make a patching material that is the same as the main concrete. 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 to the 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 the problem] That is, the present invention is a spacing method in which a rotating spiral rod is thrust into concrete to crush or discharge air bubbles in the concrete, and the tool is a rotary drive machine with a handle. A spacing machine is used which has a spiral rod of an appropriate length attached either fixedly or removably. [Operation] When pouring concrete products that use formwork, after compacting using a vibrator, generally a bar vibrator, the formwork is moved up and down by rotating the spiral rod of the spacing machine. Make sure to rub it. In this way, the air bubbles on the inner surface of the form are crushed, and due to the feeding action of the spiral rod, they rise together with the concrete and are released. [Example] Specific examples of the present invention will be described below with reference to the drawings. FIG. 1 shows a spacing machine 5 according to the present invention.The present embodiment uses a commercially available electric hand drill, and has a left-handed handle 6 added to the side surface of the main body. A spiral rod 7 is attached to 5a. As shown in FIG. 5A, the spiral rod 7 has a structure in which a reinforcing bar 72 is wrapped around a round bar 71 and welded.
A twisted flat bar 73 as shown in Figure 5B,
As shown in FIG. 5C, there is one in which a spiral 74 is integrally molded on a round bar 71 using hard synthetic rubber, reinforced plastic, or the like. In practice, the structure shown in FIG. 5A is easy to manufacture, but if the formwork is made of wood, the structure shown in FIG. 5C is suitable. Next, the actual spaging method according to the present invention using the above-mentioned spacing machine will be explained using an example of manufacturing a slanted wall of a manhole. FIG. 4 shows a sectional view of concrete 8 poured into the formwork 2, and compaction is performed using a bar vibrator (not shown) as usual. 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 the sagging 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 inner surface of the formwork 2 is rubbed with the spiral rod 7 as shown in FIG. If you move it up and down,
A concrete product with a very beautiful skin is 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 the driving machine may of course be pneumatic or hydraulic. The rotation speed 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 that it is now possible to easily process diagonal surfaces, which until now have been 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 if the air bubbles are large and penetrate deep into the concrete, the cover of the concrete becomes shallow and the reinforcing steel inside quickly rusts. This can be prevented by using the spacing method according to the present invention. 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 to increase the adhesion strength of the reinforcing bars, prevent rust, and protect against fire, so the minimum cover is (1) The cover should be at least the diameter of the reinforcing bars. (2) Slaboo 25 even when not exposed to wind and rain
mm, Harry 30mm, Pillar - 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.

【table】 The differences in working time are as follows.

〔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 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. 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...foot bracket, 4...iron plate, 5...spaging machine, 6...
Handle, 7...spiral rod.

Claims (1)

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