JP2001226162A - Joint filler material for post-tension-prestressed concrete plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joint filler material for a post-tension-prestressed concrete plate, which is capable of remarkably suppressing stress loss of a post-tension- prestressed concrete plate body whose production process comprises joining many high-strength precast plates together to form a joined plate body, placing PC steel in the joined plate body so as to pierce through the body and integrally forming them into the objective post-tension-prestressed concrete plate body by introducing prestress. SOLUTION: This joint filler material consists of a mix containing at least cement, a pozzolanic fine powder, fine aggregate having <=2 mm grain size, a water reducing agent and water, wherein preferably, the mix further additionally contains metallic fiber and/or organic fiber, an inorganic powder having a 3-20 μm average particle size and fibrous or flaky particles having a <=1 mm average particle size.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint material for a post-tensioned prestressed concrete plate.

[0002]

2. Description of the Prior Art Conventionally, a number of precast prestressed concrete plates having a length of several hundred meters have been joined by joining a number of precast plates having a length of about 10 to 15 m, penetrating a PC steel material, introducing a prestress, and integrating them. It has been made. In such an integrated prestressed concrete slab, the conventional joint joint has a thickness of 30 to 50 MPa.
A grout material exhibiting a certain degree of compressive strength has been used.

[0003]

In recent years, precast plates have been made thinner and lighter in order to improve workability, and (ultra) high-strength concrete is used in the production of precast plates. ing. A number of such high-strength precast slabs are joined, penetrated by PC steel, prestressed and integrated to produce an integrated prestressed concrete slab with a length of several hundred meters. Although tension force must be introduced into the plate, the use of conventional grouting materials not only has insufficient strength levels, but also causes the shrinkage and creep of the grouting material to reduce the stress of the integrated prestressed concrete plate. There is a problem that loss increases.

[0004] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a joint material having a high strength and a small drying shrinkage and creep for an integrated prestressed concrete slab. is there.

[0005]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has found that the above object can be achieved by using a combination of specific materials as a joint joint material. The present inventors have found that they can do this, and have reached the present invention.

That is, the present invention provides at least cement,
A joint material for a post-tensioned prestressed concrete slab comprising a compound containing pozzolanic fine powder, fine aggregate having a particle size of 2 mm or less, a water reducing agent, and water (claim 1).
Further, the composition may contain metal fibers and / or organic fibers (Claim 2), inorganic powder having an average particle size of 3 to 20 μm (Claim 5), fibrous particles or flaky particles having an average particle size of 1 mm or less (Claim 6). ) Is preferable.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. Hereinafter, the jointing material of the post-tensioned prestressed concrete plate of the present invention is simply referred to as jointing material. The type of cement used in the present invention is not limited, and various types of Portland cement such as ordinary Portland cement, early-strength Portland cement, moderately heated Portland cement, low-heat Portland cement, etc. and mixed cements such as blast furnace cement and fly ash cement are used. can do. In the present invention, when it is intended to improve the early strength of the joint material after curing, it is preferable to use an early-strength Portland cement, and when it is intended to improve the fluidity of the compound, it is preferable to use a medium heat Portland cement or a low heat Portland cement. It is preferred to use Portland cement.

[0008] Pozzolanic fine powder includes silica fume, silica dust, fly ash, slag, volcanic ash,
Silica sol, precipitated silica and the like. Generally, silica fume and silica dust have an average particle size of 1.0
It is suitable for the pozzolanic fine powder of the present invention because it is not more than μm and does not need to be ground. The blending amount of the pozzolanic fine powder is preferably 5 to 50 parts by weight based on 100 parts by weight of cement, from the strength after curing of the joint material, drying shrinkage and creep. When the amount of the pozzolanic fine powder is small, the strength after curing decreases, and the drying shrinkage and creep increase. When the amount of the pozzolanic fine powder is increased, the unit water amount is increased, so that the strength after curing is reduced and the drying shrinkage and creep are also increased.

In the present invention, fine aggregate having a particle size of 2 mm or less is used. Here, the particle size of the fine aggregate in the present invention is an 85% weight cumulative particle size. If the particle size of the fine aggregate exceeds 2 mm, the strength of the joint material after curing decreases. In the present invention, it is preferable to use fine aggregate having a maximum particle size of 2 mm or less, and it is more preferable to use fine aggregate having a maximum particle size of 1.5 mm or less. As fine aggregate, river sand, land sand, sea sand, crushed sand, silica sand, and a mixture thereof can be used. The amount of the fine aggregate is from 50 to 2 parts per 100 parts by weight of cement based on the strength after curing of the joint material, drying shrinkage and creep.
It is preferably 50 parts by weight, more preferably 80 to 180 parts by weight.

As the water reducing agent, a lignin-based, naphthalene-sulfonic acid-based, melamine-based, polycarboxylic acid-based water reducing agent, an AE water reducing agent, a high performance water reducing agent or a high performance AE water reducing agent can be used. Among these, it is preferable to use a high performance water reducing agent or a high performance AE water reducing agent having a large water reducing effect. The compounding amount of the water reducing agent is preferably 0.5 to 4.0 parts by weight in terms of solid content based on 100 parts by weight of cement. If the amount of water reducing agent is less than 0.5 part by weight with respect to 100 parts by weight of cement,
The kneading becomes difficult, and the fluidity and workability of the joint material decrease. Water reducing agent amount is 4.0 for 100 parts by weight of cement
If the amount is more than 10 parts by weight, the strength after curing decreases. The water reducing agent can be used in either liquid or powder form.

The amount of water is 10 to 3 parts per 100 parts by weight of cement.
The amount is preferably 0 parts by weight, more preferably 15 to 25 parts by weight. If the amount of water is less than 10 parts by weight with respect to 100 parts by weight of cement, kneading becomes difficult and the fluidity and workability of the joint material decrease. Water is 3 per 100 parts by weight of cement
If it exceeds 0 parts by weight, the strength after curing decreases,
Drying shrinkage and creep also increase.

In the present invention, from the viewpoint of increasing the cracking resistance of the joint material after curing, it is preferable that the compound contains metal fibers and / or organic fibers. Examples of the metal fiber include a steel fiber and an amorphous fiber. Among them, the steel fiber is excellent in strength, and is preferable from the viewpoint of cost and availability. The metal fiber preferably has a diameter of 0.01 to 1.0 mm and a length of 2 to 30 mm. When the diameter is less than 0.01 mm, the strength of the fiber itself is insufficient, and the fiber tends to be cut when subjected to tension. If the diameter is more than 1.0 mm, the number of pieces with the same compounding amount decreases, and the effect of improving the bending strength decreases. If the length exceeds 30 mm, fiber balls tend to be formed during kneading. If the length is less than 2 mm, the effect of improving the bending strength decreases. The amount of metal fiber
Preferably less than 4% of the volume in the joint material, more preferably 3%
%. When the content of the metal fiber increases, the unit water amount also increases in order to ensure workability during kneading, and the like, so that the above-mentioned amount of the metal fiber is preferable.

Examples of the organic fiber include vinylon fiber, polypropylene fiber, polyethylene fiber, aramid fiber, carbon fiber and the like. Organic fibers are 0.005-1.0m in diameter
m and a length of 2 to 30 mm are preferred. The blending amount of the organic fibers is preferably less than 10% of the volume in the joint material, and more preferably less than 8%. In the present invention, it is possible to use metal fibers and organic fibers in combination.

In the present invention, from the viewpoint of increasing the filling density of the joint material after curing, the compound has an average particle size of 3 to 20 μm,
More preferably, it is preferable to include an inorganic powder having an average particle size of 4 to 10 μm. Examples of the inorganic powder include quartz powder, limestone powder, carbide powder, and nitride powder. Quartz powder is preferable from the viewpoint of cost and quality stability after curing. Examples of the quartz powder include quartz and amorphous quartz, and opal and cristobalite silica-containing powders. The amount of the inorganic powder is preferably 50 parts by weight or less, more preferably 20 to 35 parts by weight, based on 100 parts by weight of cement, from the viewpoint of strength after curing of the joint material, drying shrinkage and creep.

In the present invention, from the viewpoint of enhancing the toughness of the joint material after curing, it is preferable that the composition contains fibrous particles or flaky particles having an average particle size of 1 mm or less. Here, the particle size of a particle is the size of its largest dimension (particularly,
Length of the fibrous particles). As fibrous particles, wollastonite, bauxite, mullite, etc.
Examples of the flaky particles include mica flake, talc flake, vermiculite flake, and alumina flake. The compounding amount of the fibrous particles or flaky particles is preferably 35 parts by weight or less based on 100 parts by weight of cement, and more preferably 10 to 25 parts by weight, from the strength after curing of the joint material, drying shrinkage and creep, and further toughness. Is more preferred. From the viewpoint of enhancing the toughness of the joint material after curing, it is preferable to use fibrous particles having a needleiness expressed by a length / diameter ratio of 3 or more.

In the present invention, the method of kneading the joint material is not particularly limited. For example, 1) materials other than water and water reducing agent are previously mixed (premix), and the premix, water, water reducing The agent is put into a mixer and kneaded. 2) Materials other than water are mixed in advance (a premix, but a water reducing agent of a powder type is used), and the premix and water are charged into a mixer and kneaded. 3) Each material is individually charged into a mixer and kneaded. And the like.

The mixer used for kneading may be of any type used for kneading ordinary concrete, for example, an oscillating mixer, a pan-type mixer, a biaxial kneading mixer, or the like.

In the present invention, the joint material may be poured into the joint. The joint material of the present invention has a flowability of not less than 200 mm, which is measured without performing 15 falling motions in the method described in “JIS R 5201 (Physical test method of cement) 11. Flow test”. It is also excellent in workability.

In the present invention, the joint material can be cured by covering with a curing sheet and curing. The joint material of the present invention exhibits a compressive strength exceeding 200 MPa after curing. Also, drying shrinkage and creep are small.

[0020]

The present invention will be described below with reference to examples. 1. Materials used The following materials were used. 1) Cement; Low heat Portland cement (manufactured by Taiheiyo Cement Co., Ltd.) 2) Pozzolanic fine powder; silica fume (average particle size 0.7 μm) 3) Fine aggregate: 2: 1 of silica sand 4 and silica sand 5 (weight ratio) 4) Metal fiber; steel fiber (diameter: 0.2 mm, length: 15 mm) 5) High-performance AE water reducing agent; polycarboxylic acid-based high-performance AE water reducing agent 6) Water; tap water 7) inorganic powder; quartz Powder (average particle diameter 7μm) 8) Fibrous particles; wollastonite (average length 0.3mm, length / diameter ratio 4)

Example 1 100 parts by weight of low heat Portland cement, silica fume 3
2.5 parts by weight, 120 parts by weight of fine aggregate, 1.0 part by weight of a high-performance AE water reducing agent (solid content with respect to cement), and 22 parts by weight of water were charged into a twin-screw mixer and kneaded. The flow value of the formulation
In the method described in "JIS R 5201 (Physical test method for cement) 11. Flow test", the measurement was carried out without performing the falling motion 15 times. As a result, the flow value was 270 mm. Further, the composition was poured into a mold having a size of φ50 × 100 mm, cured at 20 ° C. for 24 hours under a moist air condition, demolded, and air-cured for 27 days. The compressive strength (average value of three strands) of the cured product was 210 MPa. Further, the composition was poured into a mold having a size of 10 × 10 × 40 cm, cured at 20 ° C. for 24 hours under a moist air condition, demolded, and air-cured for 27 days. Flexural strength (average value of three) of the cured body is 25 MPa
Met. Further, the composition was poured into a mold having a size of 10 × 10 × 40 cm, cured at 20 ° C. for 24 hours under a moist air condition, demolded, and air-cured for 27 days. The specimen was stored at 20 ° C. and 60% humidity for 91 days,
The amount of drying shrinkage from the time of demolding was determined. The amount of drying shrinkage of the cured product (average value of three pieces) was 48 μm. Further, the composition was poured into a mold having a size of 10 × 10 × 40 cm, cured at 20 ° C. for 24 hours under a moist air condition, demolded, and air-cured for 27 days. The creep coefficient of the specimen at a load of 40 MPa was determined. The cured product had a creep coefficient of 0.2.

Example 2 100 parts by weight of low heat Portland cement, silica fume 3
2.5 parts by weight, fine aggregate 120 parts by weight, high-performance AE water reducing agent 1.0 part by weight (solid content with respect to cement), water 22 parts by weight, steel fiber
(2% of the volume in the formulation) was charged into a twin-screw kneading mixer and kneaded. The flow value of the formulation was measured as in Example 1. As a result, the flow value was 250 mm. Further, the compression strength and the bending strength were measured in the same manner as in Example 1. As a result, the compressive strength was 210 MPa and the bending strength was 47 MPa. Further, the amount of drying shrinkage was measured in the same manner as in Example 1. As a result, the drying shrinkage was 47 μm. Further, the creep coefficient was measured in the same manner as in Example 1. As a result, the creep coefficient was 0.2.

Example 3 100 parts by weight of low heat Portland cement, silica fume 3
2.5 parts by weight, fine aggregate 120 parts by weight, high-performance AE water reducing agent 1.0 part by weight (solid content with respect to cement), water 22 parts by weight, quartz powder
30 parts by weight, 24 parts by weight of wollastonite, and steel fiber (2% of the volume in the composition) were put into a twin-screw mixer and kneaded. The flow value of the formulation was measured as in Example 1.
As a result, the flow value was 250 mm. Further, the compression strength and the bending strength were measured in the same manner as in Example 1. As a result, the compression strength was 230 MPa and the bending strength was 47 MPa. Further, the amount of drying shrinkage was measured in the same manner as in Example 1. As a result, the drying shrinkage was 46 μm. Further, the creep coefficient was measured in the same manner as in Example 1. As a result, the creep coefficient was 0.2.

[0024]

As described above, the joint material of the present invention has high fluidity and excellent workability. Also,
The strength after curing is extremely high, and the drying shrinkage and creep are small. Therefore, by using the joint material of the present invention, a large number of high strength precast
The stress loss of the post-tensioned prestressed concrete slab that is integrated by penetrating steel and introducing prestress can be greatly suppressed.

Claims (6)

[Claims] 1. A joint material for a post-tensioned prestressed concrete plate comprising at least a compound containing cement, fine pozzolanic powder, fine aggregate having a particle size of 2 mm or less, a water reducing agent, and water. 2. The joint material for a post-tensioned prestressed concrete slab according to claim 1, wherein the composition contains metal fibers and / or organic fibers. 3. The metal fiber has a diameter of 0.01 to 1.0 mm and a length of 2 to 30.
The joint material of the post-tensioned prestressed concrete plate according to claim 2, which is a steel fiber of mm. 4. An organic fiber having a diameter of 0.005 to 1.0 mm and a length of 2
The joint material for a post-tensioned prestressed concrete plate according to claim 2, wherein the joint material is at least one fiber selected from vinylon fiber, polypropylene fiber, polyethylene fiber, aramid fiber, and carbon fiber having a size of about 30 mm. 5. The joint material for a post-tensioned prestressed concrete plate according to claim 1, wherein the composition contains an inorganic powder having an average particle size of 3 to 20 μm. 6. The joint material for a post-tensioned prestressed concrete plate according to claim 1, wherein the composition contains fibrous particles or flaky particles having an average particle size of 1 mm or less.