JPH0149863B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a joining method that enables hardened concrete bodies to be joined together in a short time, and a rapidly hardening cement admixture used therein. Conventionally, when joining concrete blocks in the block construction method for hardened concrete bodies, such as PC girders, the conventional method of joining the blocks is to adhere the blocks together using epoxy resin and apply prestress to this, in consideration of rapid construction. It is. In addition, before using epoxy resin as an adhesive, mortar or concrete was poured between blocks and hardened and bonded, but these methods had the following drawbacks. . (1) In the method using epoxy resin, it is necessary for the joint surfaces to be in close contact with each other, and therefore, it is required to manufacture joint contact surfaces using pine casting or partition plates using iron plates. If the material is deformed, it will not be possible to form a bonding surface that will come into close contact even with these methods. In the case where the joint surface is deformed, the case shown in Fig. 1
In the schematic explanatory diagram of the PC girder, the girder shaft 2 of the girder member
The bonding surface 1 parallel to the bonding surface 1 is deformed after the bonding surface is formed due to warpage, shortening of the member due to prestress, etc., and the adhesion of the surfaces is impaired. (2) When mortar or concrete is used as a joint material, unlike the method using epoxy resin, there is no requirement for close contact between the joint surfaces, but it is generally inferior to the method using epoxy resin in terms of rapidity. The purpose of the present invention is to solve these drawbacks, and to create hardened concrete using cement paste or cement mortar containing a specific rapid hardening admixture that has excellent fluidity and develops strength in a short period of time. The object of the present invention is to provide a method for joining hardened concrete bodies, which can be used to join hardened concrete bodies to each other in a short time, and a rapidly hardening cement admixture used therein. That is, the first invention of the present invention is to place the hardened concrete bodies to be joined at a predetermined position, and to apply calcium aluminate mixed with a high performance water reducing agent and a setting retarder in advance in the gap between the joint parts provided between the hardened concrete bodies. The joint is formed by filling cement paste or cement mortar containing a rapidly hardening admixture consisting of gypsum and gypsum, and reinforcing it with prestressed steel after hardening.
The second invention is characterized in that it is a rapidly hardening cement admixture made of gypsum and calcium aluminate mixed with a high performance water reducing agent and a setting retarder for bonding hardened concrete. The present invention will be explained in more detail below. In the present invention, concrete bodies to be joined are placed in a predetermined position, and a rapid hardening admixture consisting of calcium aluminate and gypsum mixed with a high-performance water reducing agent and a setting retarder is mixed in the gap between the hardened concrete bodies at the joining point. An object of the present invention is to provide a method for joining a concrete body, characterized in that a joint is formed by filling cement paste or cement mortar and reinforcing it with prestressed steel or the like after hardening, and a rapidly hardening cement admixture for use in the method. It is something to do. Compared to the bonding method using epoxy resin as an adhesive, the present invention does not require the adhesion of the bonding surfaces of hardened concrete bodies. As shown in Table 1 of Examples, the elongation is unprecedented in that it develops strength in a short time over a wide temperature range. Next, the rapidly hardening admixture material of the present invention will be explained. The rapidly hardening admixture of the present invention includes calcium aluminate, especially its amorphous material, gypsum, a high performance water reducer,
and a setting retardant as main components. Amorphous calcium aluminate is melted in an electric furnace or sintered in a kiln and rapidly cooled, and its composition is C ₁₂ A ₇ , C ₁₁ A ₇ CaF ₂ ,
Calcium aluminates such as CA and C ₃ A (where C represents CaO and A represents Al ₂ O ₃ ) may be used alone or in combination of two or more thereof. Moreover, anhydrous gypsum is preferable as the gypsum, and the amount thereof is 1 to 2 times the weight of the amorphous calcium aluminate. The powder degree of the amorphous calcium aluminate and the gypsum is preferably about 3000 to 8000 cm ² /g in Blaine. High-performance water reducing agents include those based on polyalkylaryl sulfonates and those based on melamine-formalin condensate sulfonates, and commercially available ones of these can be used. To give specific examples, examples of the former include Kao Soap Co., Ltd.'s product name "Mighty", Takemoto Yushi Co., Ltd.'s product names "Pole Huain" and "High Fluid", Polyzoris Bussan Co., Ltd.'s product name "Pozolith ML10", Sanyo Kokusaku Pulp
Co., Ltd.'s product name "Sunflow PSP", the latter's product name is Showa Denko Co., Ltd.'s product name "Melment F", Pozolis Bussan Co., Ltd.'s product name "Pozolis ML4000", "Pozolis
ML20'', but it is not limited to these as long as it has a large water reduction effect. The setting retarder is a combination of one or more of citric acid, tartaric acid, gluconic acid, or their salts with a carbonate. The amount of the high-performance water reducer and setting retarder may be such that the rapidly hardening cement paste or cement mortar can exhibit specific fluidity and initial strength. For, 0.1~
It is sufficient to add about 2.0% by weight. When used on-site, for example, rapid-hardening cement paste or mortar is prepared by mixing rapid-hardening cement and fine aggregate such as sand or silica sand in advance on-site with the addition of only water, and then kneading the material into a material with an inner diameter of 14 mm. The flow value of J-roto is 5~
It is preferable to fill with a blend of 15 seconds of softness. If the time is less than 5 seconds, the specified strength will not be obtained, and therefore it will not be possible to tension the prestressed steel material in a short period of time to introduce prestress, and if it is more than 15 seconds, the paste will be completely stuck to the joint of the hardened concrete body. Otherwise, it becomes impossible to fill with mortar, which is undesirable. Adding the above-mentioned rapid hardening admixtures to cement
A rapidly hardening cement paste is obtained by blending 10 to 30% by weight of water, adding a predetermined amount of water such as a water/cement ratio of 30 to 40%, preferably 32 to 38%, and kneading. In the case of rapidly hardening cement mortar, a predetermined amount of sand may be added to the above formulation. Next, an example of the construction method of the present invention will be explained. Place the concrete hardened body in place,
The distance between the hardened concrete bodies is determined depending on the size of the poured portion, but is usually about 5 to 50 mm. Next, joint patching is performed on the side and bottom surfaces of the hardened concrete body to prevent the rapidly hardening cement paste according to the present invention from leaking from the gaps of the hardened concrete body. The rapidly hardening cement paste comes into contact with the surface of the hardened concrete, and even if the joint surface is slightly deformed, it is uniformly injected, adheres, and hardens. Next, they may be reinforced by introducing prestress or the like in accordance with a conventional method. As explained above, the present invention provides a method for joining hardened concrete bodies using a specific rapidly hardening cement paste or cement mortar and introducing prestress into the hardened concrete bodies, and a method for joining hardened concrete bodies using a specific rapidly hardening cement paste or cement mortar. According to the present invention, which is a hard cement admixture, the hardened concrete body does not require pine casting, and a sufficiently large prestress etc. is applied as a PC member within 3 to 6 hours after applying the joint material. This method is unprecedented as a method for joining hardened concrete bodies in that it can complete the joining of hardened concrete bodies in an extremely short period of time. Hereinafter, the present invention will be further specifically explained with reference to Examples. Example: A pouring test in which two 1200 x 30 x 300 mm concrete plates shown in Figure 2 were placed parallel to each other with a gap of 10 mm, joint seals were provided in the gap, and they were fixed from the outside in two places, the top and bottom. A model was made and a rapid hardening mortar injection test was conducted using this model. The rapidly hardening cement composition used in the present invention is produced by melting and manufacturing in an electric furnace, quenching amorphous C ₁₂ A ₇ clinker, and mixing and pulverizing anhydrite at a weight ratio of 1:1.5 to achieve a Blaine value of 5500 cm ² /g, 0.2 parts by weight of Kao Soap Co., Ltd.'s "Mighty" as a high performance water reducing agent, 75% by weight of potassium carbonate, 15% by weight of citric acid, and 10% by weight of gluconic acid as setting retarders. A predetermined amount of water was added to 0.7 parts by weight of a cement mortar, 75 parts by weight of Portland cement, and 100 parts by weight of river sand from Himekawa to prepare a rapidly hardening cement mortar. Table 1 shows the compressive strength test results. As a comparative example, the results of a conventional early-strengthening cement mortar consisting of early-strengthening cement, Ca(NO ₂ ) ₂ , and Mighty as a high-performance water reducer are shown.

【table】

[Table] As is clear from the above, according to the present invention, strength is developed in an extremely short time compared to conventional construction methods. In addition, due to its high fluidity, according to the example, if the joint width is 10 m/m or more, it will be completely filled, and a sufficiently large prestress can be applied to the joint material as a PC member within 3 to 6 hours after construction, and it can be used in a wide temperature range. We were able to complete the joining of the concrete body in an extremely short time.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of a PC girder, and FIG. 2 is a perspective view of a test device according to an embodiment of the present invention. 1... Joint surface, 2... Girder axis, 3... Concrete plate, 4... Joint packing.

Claims (1)

[Claims] 1 Place the hardened concrete bodies to be joined in a predetermined position, and mix a rapidly hardening admixture consisting of calcium aluminate and gypsum mixed with a high-performance water reducer and a setting retarder in advance in the gap between the joints between the hardened concrete bodies. A method for joining hardened concrete bodies, which is characterized by forming a joint by filling cement paste or cement mortar and reinforcing it with prestressed steel or the like after hardening.