Facility Maintenance Division of Kukje Chemical & Construction Co., Ltd.
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Facility Maintenance Division of Kukje Chemical & Construction Co., Ltd.

KHC Method

Kukje Hybrid Composite

Fiber reinforcement sheet in concrete structures & Method for reinforcement of concrete structures by using the fiber reinforcement sheet(Patent no. 10-1540243)

<High ductile fiber sheet reinforcement material>

1. Overview of KHC Method

It is a ductility-increasing seismic reinforcement method that improves load-bearing capacity of structures by embedding high-strength aramid fiber and sheet-shaped high-ductility PET fiber sheet into the structure that requires reinforcement such as old concrete and steel structures, using the impregnating agent. As the fiber, lighter than reinforced concrete, is used, lightweight features can be achieved. In addition, this Method has the advantage of excellent safety, compared to other reinforcement methods, as the abrupt brittle fracture caused by linear behavior can be prevented by mixing two or more types of fiber at appropriate ratio while enabling an increase in ductility.

2. Advantage of the Method

1) As it is a high ductile material(elongation rate: 8.0% or higher), it provides more excellent seismic reinforcement effect, compared to other fiber reinforcement methods.
2) It is more cost-effective, compared to other fiber reinforcement methods.
3) As it is a nonconductive material, no electricity can flow through it.
4) As it is a lightweight material, it causes no additional strain of weight on the structures.
5) It enables seismic reinforcement for bridges, various architectural, civil engineering structures.
6) With the water permeability rate of '0', it prevents infiltration of contaminants.
7) The high ductile fiber sheet, which is corrosion-free, protects the structures from corrosion.

3. Characteristics of Material

Size of KHC fiber & Characteristics of Material

Item Name Width (mm) of reinforcement material Thickness (mm) of reinforcement material Test data
KHC-P Fiber(200) 100 ~ 300 2.0, 3.0 Elongation rate : 8.0% or higher
Tensile strength: 200MPa or higher
KHC-P Fiber (400) 100 ~ 300 2.5 Elongation rate: 8.0% or higher
Tensile strength: 400MPa or higher
Glass Fiber 500 1.0 Elongation rate: 2.0% or higher
Tensile strength: 500MPa or higher

Physical Properties & Comparison with Other Methods

The KCH fiber shows the deformation rate of 8.0% at its fracture, making it effective for seismic retrofit that increases ductility, compared to existing carbon fiber(CF), glass fiber(GF), and hybrid fiber sheet(HFC).

파단시 변형율

Deformation rate at fracture (%)

Comparison of deformation rates of fiber sheets

Types of fiber sheet CF Sheet (carbon fiber) GF Sheet (glass fiber) HFC Sheet (hybrid fiber) KHC Sheet (high ductile fiber)
Deformation rate (%) at fracture 0.94 2.0 2.8 8.0
Note Deformation rate at fracture: Deformation rate when fiber is fractured during the tensile test of fiber sheet.

4. Applications of KHC Method

In case of earthquake, bending and shear fracture occur in the vulnerable part of concrete structure(bridge, civil engineering and architectural structures) that does not have any built-in seismic countermeasures.

Brittle fracture can be prevented with reinforcement of vulnerable part, using the KHC fiber that has excellent ductility.

Seismic reinforcement with KHC fiber sheet

Various civil engineering and architectural structures can be reinforced, such as bridges, slabs, walls of various forms.

5. Seismic failure test of real-scale bridge(similar dynamic loading test)

Comparison of the seismic failure test conducted by Hankyong National University on the non-reinforced real-scale bridge and the KCH fiber-reinforced real-scale bridge

Seismic failure test of non-reinforced ordinary bridge (test result : brittle fracture)

Seismic test of KHC fiber-reinforced real-scale bridge (test result: ductile fracture)

Graphical representation of seismic failure test of real-scale bridge & Table for comparison

The KHC-fiber reinforced real-scale bridge showed an 122% increase in maximum load, 198% increase in deformation rate, and 275% increase in ductility rate, compared to ordinary bridges not reinforced, thus demonstrating the ductile behavior that prevents brittle fracture.

Testpiece P max (kN) △max(mm) Ductility rate
Structure not reinforced 172 44.6 2.95
KHC sheet reinforcement 211 88.4 8.11
Remarks 122% 198% 275%

Note. Pmax : maximum load, △max : maximum displacement, ductility: seismic performance indicator for the seismic reinforcement that increases ductility(Seismic reinforcement effect is larger as the ductility rate is higher)

6. Scope of the Method

1) It can prevent collapse caused by bending and inadequate load-bearing capacity of compression members during the earthquake, and enables restoration and increase of the load-bearing capacity of structures.
2) It enables protection and repair of the surface of concrete and steel structures affected by chemical actions such as seawater, sewage, freezing-thawing, salt damage, etc.
3) It enables repair and reinforcement of concrete structures that require extension of lifetime and greater durability.

7. Sequence of Works

8. Certificate of Patent