Spalling
Definition:
Spalling concrete is concrete that has broken up, flaked, or become pitted.
On a low level, it can be purely cosmetic in nature, but it can also result in structural damage, such as damage to reinforcing bars positioned inside the concrete. For this reason, it is important to address spalling when it first starts to appear.
Types:
/Spalling caused by a combination of poor concrete installation.
/Spalling due to chemical action (Sea water etc) of the reinforcement
/Spalling in response to high temperatures (fire) and/or mechanical pressure
/Spalling due to weather ( freezing and thawing) conditions
Prevention:
/Provide adequate concrete cover during design.
/The W/C ration ~0.45. It also needs time to cure properly and should be handled carefully during curing.
/Sealing (screeding, painting etc.) of the concrete can also protect it from the elements.
/Use coated reinforcement in extreme situations.
Remediation:
/Consult a concrete professional to get advice.
/Remove the concrete at the spalled areas to expose the corroded steel bars
/Scrape/clean the exposed steel bars and apply 2 coat antirust paint if reusable (or if required provide additional reinforcement).
/Apply a bonding agent to the affected surface to ensure proper adhesion and patch using polymer modified cement mortar.
