Houses, large buildings and even bridges can all be vulnerable to spalling – an unpredictable natural process which exposes aggregates beneath concrete constructions.
Although concrete can be extremely versatile, its durability must still be protected or else concrete spalling will occur and compromise any loads it supports.
Causes
Concrete is renowned for being highly durable, yet its high compression strength often comes at the cost of poor tensile strength. To compensate for this shortcoming, most structures feature steel reinforcement embedded within them – however corrosion of these steel elements could lead to spalling in concrete surfaces resulting in surface defects or spalling of entire sections of surface concrete.
One of the primary causes of spalling in concrete is due to freeze/thaw cycles. Since concrete is made up of porous material, when water freezes it expands which puts pressure on it, eventually leading it to crack, weaken and ultimately spall off over time.
Sealing concrete to prevent moisture penetration is one of the best ways to stop spalling. Regular maintenance to a structure also can aid in its protection; for instance, checking rebar for corrosion and installing cathodic protection systems if possible are both excellent ways of stopping moisture penetration and carbonation, both which accelerate spalling processes.
Symptoms
Concrete spalling occurs in older structures and manifests itself by chipping, flaking, or peeling sections that expose coarse rocky aggregate beneath. This form of damage to a building and its inhabitants may even include large chunks falling off unexpectedly; additionally it can be unsightly and detract from its aesthetic value over time – which only gets worse.
Conditioned concrete often experience surface erosion due to water absorption into its pores and freezing, then expanding over time, eventually eroding away at its surface. Other causes may include poor concreting practices, unprotected rebar or poorly built joints – each factor contributing in different ways to this condition.
Waterproofing issues may also contribute to foundation spalling and concrete cancer; for instance, multiple trades working in one area (e.g. a strata roof). Be sure to address foundation spalling and concrete cancer as soon as you notice it or it will only get worse! Don’t delay in seeking treatment as any delay could only exacerbate its severity!
Repairs
Concrete spalling is an immediate threat that must be resolved as quickly as possible before it spreads and compromises the strength of its concrete structures. Left unchecked, spalling could threaten their very integrity.
Repairing spalling begins with using a hammer and chisel to break loose concrete from its surrounding surfaces, followed by cleaning to eliminate bond breaker materials and sounding the pavement to identify delaminated or unsound areas, marking these for partial or full depth repairs.
Once repairs have been made, a waterproofing membrane should be applied to prevent further damage and any patching should extend four inches beyond spalled areas for an optimal bond and curing process. In addition, it’s crucial that rebar corrosion be addressed as part of this restoration process, since it often leads to concrete spalling; regular inspections and preventative maintenance are effective tools in combatting its onset.
Prevention
Concrete’s incredible versatility has seen it used in everything from super structures and swimming pools to car parks and car parking facilities. However, concrete does not remain undamaged forever and requires ongoing care in order to preserve its longevity and structural integrity.
Spalling can have a devastating impact on a structure’s aesthetic appeal and be hazardous to public safety, creating trip hazards or dislodging debris, as well as undermining its integrity. Therefore, it is crucial that concrete spalling be addressed immediately upon discovery to avoid worsening problems further.