Crack column strengthening

Project overview

A 7 Storey Reinforced Concrete Frame Structure Building in Guangzhou has a total construction area of about 11 thousand m2. It was completed and accepted in 1993 and reused in June,.2006. It is found that there are many cracks on the surface of the 3 and 4 layers of the structural columns. The local longitudinal reinforced bars are seriously corroded. It caused a serious hidden danger to the safety of the structural columns, while other structural members have not found the major safety problems.

(1) the concrete strength of columns can meet the requirements of original design strength grade:

(2) the content of chloride C L in cracked concrete is much higher than that in specifications. The steel bar has been seriously rusted. It causes the cracking of the concrete surface.

The above situation shows that the longitudinal force steel bar of the column can not work together with the concrete. The bearing capacity of the column depends entirely on the core concrete. Its bearing capacity has been seriously reduced, but other structural components are still intact. Therefore, the damaged components should be reinforced to eliminate potential safety hazards.

Stengthening scheme

• Loose concrete on the surface of a column

Chisel the loose stone and rinse with pressure water. After the steel wire brushes to float the slurry and the buoyancy, the 1:2 cement mortar is layered and compacted with the cement mortar. The 10%U EA micro expander is added in the steel bar to be layered and pressed, and the water is cured over 7d after the initial coagulation.

• Crack repair

The plastering layer on the surface of the component is chiseled at the crack position.

1 channels of width 30m M. deep 25, 30m m V grooves are cut along the crack direction. Using steel wire to clean the slots, wash and blow dry. Use the hand pump to pour the structure into the cracks. Then fill and compact the groove with the high standard cement mortar, then fix the 300m m wide wire net with the nail in the direction of the crack. Finally, the 1:2 cement mortar is layered and pressed, and the water is cured in time after the initial coagulation.

• The 4 angles of the column are reinforced by steel strip

For the above damaged columns, the original cylindrical plastering layer is first removed and exposed to fresh concrete surface. The 4 corners of the column should be milled with small fillet and properly straightened. The original corroded steel bar should be derusting, and the concrete surface should be cleaned with steel brush and water.

After completely drying, the defatted cotton is used to wipe the acetone. Then the structure glue is applied to the steel plate and the column with the scraper. The stick steel is fixed at the column angle with the fixture. The sticky steel is fixed on both sides of the column to fix the sticky steel. Then the patch is welded and the epoxy emulsion mortar is filled in the suffix plate after completion.

The epoxy and lacquer plates are glued on the glued steel and the surface of the batten and sprinkle with a small amount of coarse sand. Finally, use 20m m thick M 10 cement mortar as steel protection layer.