JPH0465181B2 - - Google Patents

Description

[Detailed description of the invention]

"Industrial Application Field" This invention can be used as a substitute for reinforcing bars used in concrete structures.
The present invention relates to an alternative material for reinforcing bars that can provide concrete structures with higher durability, toughness, and workability. ``Prior Art'' As is well known, concrete structures are made by mixing cement, sand, and gravel with water and then molding and hardening them. Reinforcing bars are placed on the "Problems to be Solved by the Invention" By the way, reinforcing bars used as reinforcing materials for concrete structures have the following problems. (a) As is well known, iron is easily corroded by salt. Therefore, there is a disadvantage that deterioration of concrete structures near the coast is accelerated. Furthermore, river sand and river gravel are in short supply and expensive, but as mentioned above, the reinforcing steel deteriorates due to salt damage. Since sea gravel cannot be used, expensive river sand and river gravel must be used, leading to high construction costs for concrete structures. (b) Since iron has a large specific weight, it is difficult to carry it in and install it, which hinders productivity improvements during on-site construction. (c) As is well known, there is a trend toward higher-rise concrete structures. Therefore, reinforcing materials for concrete structures are required to have even higher specific strength and specific stiffness, but when building taller structures than the current one, concrete The members become too large for the structure, causing problems in terms of design and productivity. This invention was made in view of the above circumstances,
The objective is to provide a material to replace reinforcing bars that has high corrosion resistance against salt, etc., is lightweight, and has high specific strength and specific stiffness. "Means for solving the problem" The reinforcing bar substitute material for concrete structures according to the present invention is a base material made of potassium titanate whiskers dispersed in a thermosetting resin or a thermoplastic resin with excellent heat resistance. Carbon fibers are mixed along the longitudinal direction of this base material. Examples of the thermosetting resins include furan-modified epoxy resins, phenol resins, and unsaturated polyester resins, and examples of thermoplastic resins with excellent heat resistance include polyether/ether/ketone resins and polyether/sulfon resins. In addition, the diameter of potassium titanate whiskers is
It is a fiber with a length of 0.2 to 0.5 μm and a length of 10 to 20 μm.
It is mixed and dispersed in the above resin in an amount of 3 to 30 wt%. The carbon fiber has a diameter of 6 to 15 μm.
So, for the above base material, if the unit weight of carbon fiber 3000 filament is 0.2gr/m, it is 450 to 540.
It is mixed in at a rate of 1.0 cm2/ ^cm2 . "Effect" As is well known, in composite reinforcement by dispersion of particles (fibers), the particle volume content, particle diameter, and interparticle distance are factors.When the particles are metal, generally, the smaller the particles, the more dislocations will move. It restrains well and increases the reinforcement rate. The above potassium titanate whisker preferably has a thickness of 0.5 μm or less. However, if the thickness is less than a predetermined value (approximately 0.2 μm), good effects cannot be obtained. Therefore, it is desirable to use a material with a diameter of 0.2 to 0.5 μm. In addition, the composite reinforcement ratio F and fiber aspect ratio l/d of the fiber reinforcement material
A certain relationship is recognized between (l: fiber length, d: fiber diameter), and in general, when l/d is 10 or more, high strength is obtained, and thereafter it becomes almost a plateau. For potassium titanate whiskers, l/d
Since it can easily be obtained with 100 or more, it exhibits high composite reinforcing properties. Furthermore, as shown in the figure, when the amount of potassium titanate whiskers added to the resin is 3wt% or less, the reinforcement rate is 30%, which does not significantly contribute to composite reinforcement. On the other hand, when the content exceeds 30 wt%, the strengthening ratio reaches a plateau, as shown in the figure, and no increase in strength can be expected by adding more than that. In addition, the carbon fibers mentioned above have a diameter of several μm to several tens of μm.
Although there are those within the range of m, the present invention has a range of 6 to
A thickness of 15 μm is desirable from the viewpoint of workability. In order to obtain specific strength and specific rigidity higher than reinforcing bars, it is necessary to mix 3000 carbon fiber filaments into the base material at a density distribution of 450 to 540 filaments per cm ² . If it is less than 450 pieces/ ^cm2 , the specific strength is higher than that of reinforcing steel.
Specific rigidity cannot be obtained, and on the other hand, if the carbon fibers exceed 540 fibers/cm ² , the volume occupied by carbon fibers increases, resulting in poor moldability. As mentioned above, the reinforcing steel substitute materials of this invention include glass fiber reinforced plastics, aluminum alloys,
It requires high specific strength and specific stiffness because it is made by compositely reinforcing the base resin of carbon fiber-reinforced plastic with potassium titanate whiskers, which have high micro-reinforcing properties, and has a much higher specific strength and specific modulus than steel. It is possible to provide a reinforcing material for concrete structures that has sufficient specific strength and specific stiffness as a replacement for reinforcing bars. Furthermore, all of the constituent materials of this reinforcing bar substitute material have high corrosion resistance against salt and other corrosive substances such as alkaline components in concrete, so they can be used as a substitute for reinforcing bars, for example, near coastal areas. It is possible to obtain highly durable buildings even when using salt-containing sand or gravel as a concrete material, and it is possible to demonstrate concrete structure reinforcement properties that are greater than that of reinforcing steel. . Hereinafter, this invention will be explained in more detail with reference to Examples. "Example" Three types of base materials were made, consisting of the types shown in Table 1 below, additive resins, and potassium titanate whiskers, and these base materials were impregnated with carbon fibers having the dimensions shown in Table 1 to form carbon fibers with a diameter of 6 mm, We made a CFRP rod with a length of 40 cm.

[Table] The tensile strengths of the CFRP rods produced as described above were measured, and their specific strengths were calculated, as shown in Table 2. In contrast, the specific strength of conventionally known reinforcing bars is 3.85 Kg/mm ² , and it was found that the reinforcing bar substitute material of the present invention exhibits a specific strength 14.0 to 19.1 times that.

[Table] "Effects of the Invention" As explained above, the reinforcing bar substitute material for concrete structures according to the present invention has a much higher specific strength and specific modulus than glass fiber-reinforced plastics, aluminum alloys, steel, etc. Because it is made by compositely reinforcing a large carbon fiber-reinforced plastic base resin with potassium titanate whiskers with high micro-reinforcing properties, it can provide the following excellent effects. (a) Since it is lightweight, that is, its specific stiffness is high, the design of supertall structures can be greatly increased. (b) It can be easily formed using the filament widening method, and it is also possible to manufacture products with a surface structure similar to deformed reinforcing bars. (c) The inherent corrosion problem of reinforcing bars associated with the use of sea sand and sea gravel can be avoided. (d) A material with a much higher modulus of elasticity than reinforcing steel can be obtained. (e) Composite materials with much greater tensile strength than current piano steel wires can be obtained. That is, a composite material with high strength and high toughness can be obtained.

[Brief explanation of the drawing]

The figure is a graph showing the relationship between the amount of potassium titanate whiskers added to the base resin and its composite reinforcement ratio.

Claims (1)

[Claims] 1. Carbon fibers are mixed along the longitudinal direction of the base material into a base material formed by dispersing potassium titanate whiskers in a thermosetting resin or a thermoplastic resin with excellent heat resistance. Reinforcement alternative material for concrete structures.