JPS6085106A - Concrete for repairing extension joint of bridge - 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 highly durable concrete for use in repairing expansion joints of bridges.

Traditionally, expansion joints have been used to maintain the continuity of the road surface.
It is installed between bridges or between bridges and abutments.
Mainly, it is installed by joining a steel finger joint and reinforcing reinforcing bars of the concrete slab, and pouring concrete into the gap between the joint and the concrete slab.

However, due to long-term driving of cars, etc., there is a difference in level between the joint and the concrete floor slab, which receives impact from driving, and the reinforcing reinforcing bars stretch or break, causing the original function of the expansion joint to deteriorate. It will not be fulfilled.

Therefore, periodic repairs are carried out to prevent this from occurring, but in the past, rapid hardening concrete with alumina cement or commercially available rapid hardening cement as a binder has been used as the concrete. However, while this rapid hardening concrete has the advantage of developing practical strength in a short period of time, it has the disadvantage of poor durability. In other words, water penetrates due to the occurrence of cracks, etc.
There are drawbacks such as separation of the joint from the slab concrete, rusting of reinforcing bars, etc., and insufficient adhesive strength between the joint and the slab concrete.

The inventor of the present invention conducted various studies to solve this drawback, and found that if a repair concrete is made of a rapidly hardening polymer concrete made by adding a cement rapidly hardening material consisting of amorphous calcium aluminate and an inorganic sulfate, the above-mentioned joint It is possible to extend the period of occurrence of steps in the concrete floor slab, and the elastic modulus of the concrete is also reduced, which softens the impact caused by driving cars.In other words, it reduces the risk of fracture of reinforcing reinforcing bars the day before. It was discovered that it was possible to perform construction work that was durable, preventing the reinforcing steel from being cut due to exposure, and the favorite F'A.
? It is completed.

That is, the present invention provides at least one material selected from the group consisting of amorphous calcium aluminate and an inorganic sulfate in an amount of 0.5 to 6 times the weight of the amorphous calcium aluminate, a cement rapid hardening material, a rubber latex, a BoIJ material emulsion, and an acphalt. This is concrete for repairing expansion joints of bridges, which is made by mixing organic matter, cement, and an appropriate amount of aggregate.

The present invention will be explained in more detail below.

The amorphous calcium aluminate constituting the cement rapid hardening material is preferably obtained by rapidly cooling a molten material with a CaO content of 65 to 50% by weight and the remainder mainly consisting of At203. The body that is slowly cooled and crystallized has poor strength development and durability in a short period of time (Ca
If the O content is less than 65% by weight, short-term strength development will be insufficient, and if it is more than 50% by weight, concrete will have difficulty setting. The preferred CaO content is 4%.
It is 0 to 46% by weight. The degree of fineness is 3.000 anV in Blaine value considering strength development and economic efficiency! i' or more, preferably 4,000 to 6,000 ctaV i. - 10,000, as for inorganic sulfate which is another component, 2'
*, right front, hemihydrate gypsum, anhydrite gypsum, magnesium sulfate, sodium sulfate, etc. are used, and among them, ■-type anhydrite is preferred because it has a large strength development. The fineness is 2.000 c in Blaine value for the same reason as mentioned above.
mV,! i' or more preferably 4,000 to 6,000
tx2/, li'. In the present invention, the ratio of amorphous calcium aluminate and inorganic sulfate is important; if the latter is in an amount other than 0.5 to 3 times the weight of the former, short-term strength development will be impaired. Therefore, the construction work cannot be completed early.The preferred ratio of the latter is 1 to 2 times the weight of the former.

Considering the balance between short-term and long-term strength development, the mixing ratio of cement quick hardening material is 10 to 30.
ffff is preferably 1%, especially 15 to 25ff
iit%. If the content is less than 10% by weight, short-term strength development will be insufficient, and if it is contained in excess of 60% by weight, the effect will not improve significantly, but the durability will deteriorate. As the cement, commercially available Portland cements such as normal, early strength, super early strength, medium heat, and white Portland cements, as well as mixed cements containing silica, fly ash, and blast furnace slag, can be used.

Organic matter is necessary for improving the durability of concrete, adhesion to concrete slabs, and reducing the elastic modulus of concrete to % to % of that of ordinary concrete. The material used in the present invention is one or more selected from rubber latex, polymer emulsion, and asphalt. The blending ratio is preferably 5 to 60 parts by weight as a solid content to 100 parts by weight of the total of the cement rapid hardening material and cement (rapid hardening cement).
The amount is preferably 10 to 20 parts by weight. If the amount is less than 5 parts by weight, the above effect will be small, and if it exceeds 60 parts by weight, short-term strength development will be delayed.

Rubber latex includes natural rubber, polychloroprene rubber (OR), acrylonitrile butadiene rubber (NB
R), styrene butadiene rubber (SBR).

Latex such as methyl methacrylate rubber, and
Polymer emulsions include polyvinyl acetate, ethylene vinyl acetate copolymer, vinyl acetate beova copolymer,
Emulsions and epoxies of thermoplastic resins such as vinyl chloride and vinylidene chloride copolymers and polyacrylic esters,
Emulsions of thermosetting resins such as epoxy asphalt are used. Among these, polychloroprene rubber, acrylonitrile butadiene rubber, styrene butadiene rubber, and d(xy) rubber are selected from the viewpoint of durability and adhesion.

Epoxy asphalt, asphalt latex or emulsion is preferred, particularly polychloroprene rubber latex or asphalt emulsion.

If the working time is short (if this is a problem, for example, use oxycarboxylic acids such as malic acid, tartaric acid, gluconic acid, citric acid, or their salts, carbonate alkali, silicofluoride, phosphoric acid, or phosphates) to delay setting. It is only necessary to use the appropriate agent.It is preferable to adjust the setting start time to 30 to 9 U minutes.Also, by blending the above organic substances, if the cement is vertically oriented, it is necessary to avoid inhibiting the water-flowing reaction. It is recommended to add a stabilizer such as polyoxyethylene nonylphenol ether or polyoxyethylene octylphenol ether, and if the foaming in the mixture is prolonged, add an antifoaming agent such as silicone. Yes.

When mixing concrete with carp, the amount of aggregate such as sand or gravel and water is appropriately selected depending on the desired properties. Also,
By blending steel fibers and cement water reducing agents, suitable concrete can be obtained.

As described above, the following work can be done by removing cracks in concrete according to the present invention.

(1) Since the wear resistance of concrete IJ and -t is high, it is possible to extend the period of occurrence of a step with a joint such as a steel finger joint.

(2) Therefore, the impact caused by vehicles traveling is small, and the reinforcing steel bars do not stretch or break (3) Concrete has low elasticity, so it can absorb and soften vibrations and shocks.

(4) Cracks may occur.

(5) Provides strong adhesion to joints and concrete slabs.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 The concrete shown in the first batch was mixed. In addition, 0.7 weight of sodium citrate was uniformly mixed into the concrete based on the total of cement and cement hardening material.

Test specimens were prepared using the above concrete and physical property tests were conducted. The results are shown in Table 2.

0 Bending strength change rate (%) ○ Weight reduction rate (%) 20 tc 10 x 10 cured for 1 day at -80%RH
×10 cIrL test specimen was used to determine the concrete strength (kgf/cyn”) when applying a rotational speed of 5 [JOO (B)] using a J Engineering SA 11210 Suanzels Nigishi Testing Machine (kgf/cyn”). 10 x 10 x 20 concrete is poured into the 10 x 406 rIL formwork, and 7 days later, the above concrete is poured into the concrete. Strength of the immersed part at 4 weeks of age (by shear test) o5H bending strength (k41f/ am”)20℃-80%
Flexural strength of 1° x 10 , if the gypsum ratio deviates from the scope of the present invention (Experiments/169 and 10),
All physical properties are lower than those of the present invention (Experiment/I61-5).

Example 2 In a bridge consisting of 6 expansion joints (steel finger type) with width 1 (1 m length 100rn), width 20cIrL depth 30cIr was installed on both sides of the 6 locations north of the center line.
Concrete of mix 1 shown in No. 6 was poured over a length of 5 m using a Mopil vehicle. It hardens in 65 minutes after pouring.
The bending strength for hours was 49~f/am2.

For comparison, concrete of Mixture 2 was poured in Ill B locations south of the center line, and concrete of Mixture B was similarly poured in the remaining six locations.

Concrete with mix 2 hardens in 15 minutes and has a 5-hour bending strength of 46 kg f /cm2, concrete with mix 6 hardens in 20 minutes and has a 5-hour bending strength of 69 to 4If/cII.
It was L2.

After the concrete was poured, the road was opened and the condition of the narrow surface was observed one year later, and the f1 concrete had a maximum abrasion of 0.7 mm and no cracks were observed. On the other hand, concrete with Mixture 2 had a maximum abrasion of 1.7cm and four cracks with a width of 0.2' and a length of 20cm occurred on the surface, and concrete with Mixture 6 had a maximum abrasion of 1.7cm. Width 0.1 ~ on the surface with a maximum of 2.8 seaweed
There were six cracks of 0.5 haze.

Blend 1 is an example of the present invention, and Blends 2 and 3 are comparative examples.

0 cement rapid hardening material (mixtures 1 and 6) has a cao content of 43
% amorphous calcium aluminate 100 parts by weight and 1-
0aS04150 It is a mixture with N storage part.

0 blend 2 cement has a, s, crystalline 011A70
This is a commercially available express cement whose main ingredients are aF2 and Sekiho.

0 water reducing agent is one in which a commercially available product containing β-naphthalene sulfonate as a formalin alloy component is added in terms of solid content.

Patent applicant Denki Kagaku Kogyo Co., Ltd.

Claims (1)

[Claims] Amorphous calcium aluminate and 0.5 to 6
A bridge made of a cement rapidly hardening material made of unsulfurized R-salt in a double weight amount, at least one concrete material selected from rubber latex, polymer emulsion and asphalt, cement and an appropriate amount of aggregate. Concrete for repairing expansion joints.