Repair Techniques for Cracks in Concrete – Crack Repair
-submitted by Shereef MI , – K.S.R. College Of Engineering
Various types of Repair Methodologies
- Stitching
- Muting and sealing
- Resin injection
- Dry packing
- Polymer impregnation
- Vacuum impregnation
- Autogenous healing
- Flexible sealing
- Drilling and plugging
- Bandaging
Stitching of Concrete
In this technique, the crack is bridged with U-shaped metal units called stitching dogs before being repaired with a rigid resin material. A non- shrink grout or an epoxy resin based adhesive should be used to anchor the legs of the dogs. Stitching is suitable when tensile strength must be re established across major cracks. Stitching dogs should be of variable length and orientation.
Benefits Of Cracked Stitching
- Quick, simple, effective and permanent.
- The grout combination provides an excellent bond within the substrate.
- Masonry remains flexible enough to accommodate natural building movement.
- Non-disruptive structural stabilization with no additional stress
Muting And Sealing
This is the simplest and most common method of crack repair. It can be executed with relatively unskilled labor and can be used to seal both fine pattern cracks and larger isolated cracks. This involves enlarging the crack along its exposed face and sealing it with crack fillers. Care should be taken to ensure that the entire crack is routed and sealed.
Resin Injection
Epoxy resins are usually selected for crack injection because of their high mechanical strength and resistance to most chemical environments encountered by concrete. Epoxies are rigid and not suitable for active cracks. This method is used to restore structural soundness of members where cracks are dormant or can be prevented from further movements.
Underpinning
Underpinning is the process of strengthening and stabilizing the foundation of an existing building or other structure. Foundation underpinning is a means of transferring loads to deeper soils or bedrock.
Purpose Of Underpinning
- To obtain additional foundation capacity
- To modify the existing foundation system
- To create new foundations through which the existing load may be wholly or partially transferred into deeper soil
- To arrest the excessive settlement
- To improve the future performance of the existing foundations
When Underpinning Is Required?
- Construction of a new project with deeper foundation adjacent to an existing building.
- Change in the use of structure
- The properties of the soil supporting the foundation may have changed or was mischaracterized during planning.
- To support a structure which is sinking or tilting due to ground subsidence or instability of the super structure
Methods Used For Underpinning
- Pit Underpinning
- Push Piers System
- Helical Pier System
- Pile Underpinning
- Other Methods
- Chemical Grouting
- Micro fine Grouting
- Micro piles
Fire Damage Repairs
- Timber structures may be repaired with new timbers or composites of steel and timber members.
- Steel structures are normally repaired with steel.
- Both concrete and masonry structural elements are frequently repaired with fiber reinforced polymers (FRP).
- Concrete structures are occasionally repaired with shortcrete
Repair of leakage structure
