Deteriorated concrete isn't just unsightly—it can compromise structural integrity. A spall is simply a section of concrete that is breaking away or has broken away from the original structure. To repair this defect the cause must be correctly diagnosed.

Spalls can be as simple as popouts, which are cavities in concrete, caused by the expansion of porous aggregates. Popouts develop shortly after placing concrete or up to one year or more afterward. Another type of spalling occurs along joints (see EXPANSION/CONTROL JOINTS). Spalling that compromises structural integrity begins within the concrete at the reinforcing steel.

Concrete's high alkalinity causes a thin, invisible, protective oxide film to form on the steel. However, when sodium chloride or calcium chloride are present, along with moisture and oxygen, carbonation occurs and the protective film is broken down and corrosion begins. As the corrosion builds and occupies more space inside the concrete, tremendous force is exerted on the concrete. Cracking is seen first and if not properly repaired large sections of concrete begin to breakaway. The American Concrete Institute and the International Concrete Repair Institute have both issued guidelines for the proper long-term repair of corrosion induced spalling.

We at Intron Technologies, Inc. have seen the benefits of these guidelines for long term results. Proper repair of spalls includes precise surface preparation, inspection and replacement of reinforcing steel that is degraded by 25 percent or more, use of corrosion inhibiting bonding agents, placement of high early strength polymer modified repair mortars and proper curing. We are experienced in shoring techniques to ensure the stability of your structure during repair and are certified applicators for SIKA, Master Builders, and STO repair mortars.

Whether your application calls for hand lay-up, form and pour, form and pump, shotcrete or a combination of methods—WE DO them all.

See also:
CATHODIC PROTECTION SYSTEMS to end the corrosion cycle. CFRP STRUCTURAL STRENGTHENING to provide added load requirements. EPOXY INJECTION for crack repair before spalling begins. CRACK REPAIR for cracks with spalling edges on horizontal slabs.

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