Project Overview

A high-rise commercial residential district project, shear wall structure, 18 floors above ground and 1 floor underground. Since the first to third floors of the original structure are designed as shopping malls, each floor is 4M high, and it is now converted into residential buildings due to new usage requirements. The floor height of the residence is 3M, and it is necessary to open a part of the opening in the concrete shear wall. This involves the adjustment of the position of the door and window openings and must be reinforced. After consultation with the design unit, experts decided to use the construction method of pasting carbon fiber(CFRP) for concrete strengthening.

Opening reinforcement materials and performance indicators

This reinforcement project uses Chinese Horse carbon fiber products. There are two kinds of materials used for reinforcement: one is carbon fiber fabric, and the other is a bonding agent matched with carbon fiber. The main technical data of the HM-30 carbon fiber cloth used this time: the fiber type is high-strength carbon fiber, the fiber tensile strength is 3450N/mm2, the elastic modulus is 234500N/mm2, and the service life is unlimited. Main technical data of bonding agent HM-180C3P matched with carbon fiber cloth: Mixing ratio A:B=2:1 (weight ratio). Construction temperature +5"C-+35"C (environment and substrate). The flexural modulus of elasticity is 3800N/mm2 (+23"C curing for 7 days), the tensile strength>30N/mm2 (+23"C curing for 7 days), and the bonding strength>4N/mm2 (concrete failure). The main performance indicators of the above two reinforcement materials meet the design requirements.

CFRP reinforcement construction process 

The construction process of carbon fiber reinforcement is: measuring and laying out the concrete surface, repairing and polishing, preparing the carbon fiber sheet, preparing the adhesive, sticking the carbon fiber cloth, curing and curing

Inspection and acceptance

In the reconstruction and reinforcement project of this project, the quality of the reinforcement materials used, the mixing ratio of the two components of the bonding agent, and the bonding of carbon fiber cloth were carefully checked and accepted. And before the construction of the large-area reinforcement treatment, a sample plate was made on the spot and the tensile test specimens were made at the selected parts. After on-site inspection, the measured results are that the concrete is damaged at 9.5KN and 7.0KN respectively. Calculate according to the bonding strength formula: f=P/A (f-positive tensile bonding strength Mpa, P-load value N when the sample is broken, A-cross-sectional area of the test metal standard block mm2). f1 = 9500N/1600mm2 = 5.94N/mm2 (A-The cross-sectional area of the outer end of the metal standard is 40mmX 40mm). f2 = 7000N/1600mm2 = 4.38N/mm2. The positive tension bond strength values f1 and f2 are all greater than the standard value of C30 concrete axial tensile strength ftk=2.01N/mm2. Therefore, it was determined that the construction quality of the carbon fiber reinforced concrete project of the project was qualified and met the requirements of the design and related regulations.