JPS59179953A - Construction of concrete structure - 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 The present invention relates to a method of constructing a concrete structure, and more particularly, to a construction method in which compressive stress is applied in advance to concrete prefabricated wood or the like to prevent cracking thereof.

Generally, in reinforced concrete construction, tensile stress is generated at various locations due to drying shrinkage after the concrete hardens, and cracks occur over time due to this tensile stress. These cracks not only damage the appearance of the structure, but also cause the structure to become obsolete. Hurry up.

FIG. 1 shows a wall 2 of reinforced concrete structure in which an opening l is provided, and in such a case, cracks are likely to occur at the corners of the opening. Therefore, conventionally, such a wall t*2
When constructing the wall, reinforcing bars 8 separate from the wall reinforcements were placed around the 2σ opening of the wall to disperse shrinkage and shrinkage strains and completely prevent the occurrence of cracks. However, this conventional method cannot be said to be sufficiently effective, and eventually cracks occur at the corners of the opening.Therefore, some kind of improvement has been desired. Agent? An unbonded steel material with a full bearing plate is provided in the filled cylinder with a bottom, and this is placed in the entire concrete placement space.Concrete is poured in the concrete placement space, and the unbonded steel material is fully extended by the expansion of the expanding agent. The reaction force causes compressive stress to be generated in the poured concrete, completely eliminating the above-mentioned conventional problems. The overall purpose is to provide a method of constructing concrete trenches that can prevent th.

The inventive method will be explained in detail below based on the drawings.

Figures 1 and 3 show an example of a concrete structure constructed using the method of the present invention, in which a wall 12 having all openings 11 is constructed.

2σ) To construct a wall L2 such as 8, +, set 2 formworks according to the position tα and shape of the wall 12 to be constructed, and pour concrete. form, soσ"i ml S
The entire concrete is illuminated by placing predetermined wall reinforcements inside, but in the method of the present invention, when placing wall reinforcements,
A pair of bottomed cylindrical bodies 14 with unbonded stones 18 and 01η are filled with an expanding agent 15 inside the cylindrical body 1Φ.
With the bearing plate 16' for complete sealing attached to the unbonded steel material 18, it is placed at one angle of the casting space 5OIHI 0 part 11〇Here, the pair Q) of the bottomed cylinder 14 is attached to the bottom part. It is formed into a cylindrical shape that is slightly tapered as it approaches, and a through hole of the required diameter is bored approximately in the center of the bottom, and the bottoms are spaced appropriately from each other. They are arranged so that they face each other. -I: The above-mentioned expanding agent L5 is a chemical substance that expands in volume due to a hydration reaction, such as calcium oxide or magnesium oxide, and is mixed with sand that contains all water, and the mixing ratio of the chemical substance and sand is Alternatively, by adjusting the moisture content of the C sand, the total expansion bond can be set to the optimum value.
Here, it is recommended to use a mixture of multiple chemicals with different hydration reaction rates, such as calcium oxide and magnesium oxide.
Ji@--The optimum expansion speed of V can be achieved by fully adjusting the mixing ratio of each chemical substance. Roughly speaking, the bearing pressure plate 16 is attached to the upper side of each bottomed cylinder 14 and contains an expanding agent 15Th and a bottomed cylinder 1.
*Although sealed in L4, they are connected to each other by an unbonded steel material 1B inserted into the through hole of *14 with a bottom, and a nine-gobuck knob material 17 is provided on the upper side thereof.

When all of the concrete is poured in the concrete placement space S, the cast concrete 5 (11-) begins to harden, but
At that time, in the above-mentioned swelling agent 15, is the σ chemical substance in the 7 σ hydrated? By raising it, it expands at a predetermined speed. Due to this expansion, each bearing plate 16 moves in the direction of Ei-(,z) and the unbonded steel material 18 expands. Due to the restraint, a reaction force is generated at the bottom of the cylindrical body 14σ, and a compressive stress of 71σC is generated in the poured concrete, which causes the opening 1
Prevent the first crack from escaping.

This pressure JσC (well, the average cross-sectional area of the wall 1$12 is A
c, Young's modulus of wall 12 is 1 C, unbonded material 1
8σ] Cross-sectional area total As, unbonded steel material 18σ) Young's modulus hl S b unbonded art material 1:3 g) length 2r!
Further, when the sum of the shrinkage of the wall body 12 and the warping of the unbonded steel material 13 is Δl, it is expressed by the following equation.

■T, where AC-≠riQca, lJ-tao, Δl=
0. /cm and unbonded steel material 18 with 3 different diameters of w4 zelkova? When the compression stress σC is determined for each case, the following table σ] is obtained.

By the way, in the above, the unbonded steel material 18 is constructed so that both ends thereof are stretched by the expansion of the expansion agent 15, but one end of the unbonded art material 13α is fixed to the fixed part of the thio, and the other end is fully stretched by σ. However, it would have been possible to achieve the same effect.However, before the concrete was completely poured, un-7jζnd steel 18 and expansion agent 15, etc. were placed, but the concrete was poured before the concrete was completely hardened. It is also possible to set the unbonded steel material 18, expansion agent 15, etc. in one piece and push it in from the rear.〇As described above, the method of the present invention can improve the cast concrete σ) As the unbonded steel material fully elongates as it hardens, it is possible to apply compression stress to the poured concrete in advance, making it possible to construct a concrete structure that will not cause cracks even if the concrete shrinks during drying. . In addition, since the expansion amount of the expansion agent and the 1f tension speed can be easily adjusted throughout the holes, it is possible to apply the optimum strength of compressive stress to the concrete structural wood, and it is also possible to reverse the reinforcing bars as in the conventional σ. The troublesome work of arranging the items is worth 6 times.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing the conventional α) reinforcing method 7 around the IN opening of a concrete wall, Figures 2 and 3 are wider versions α) explaining the present invention in detail; A schematic diagram of a wall constructed by the method of the invention, and FIG. 3 is an enlarged view of the main part of the second diagram. 18... Unbonded steel material, [4°... Bottomed cylinder, L5... Expansion agent, 16... Bearing plate, σC... Pressure binding 1st grade. Figure 2

Claims (1)

[Claims] A bottomed cylindrical body filled with an expanding agent is placed in the amount of concrete to be poured, and the above expanding agent is filled in this bottomed cylindrical body. Bearing plate to seal? At the same time, the unbonded steel material is fully loaded on the bearing plate, and the concrete is poured at 1ft. As the poured concrete hardens, the expansion agent is fully expanded and the unbonded material is fully extended. A method of ditching concrete structures, which is characterized by producing IE k4 stress noise in concrete.