What is Discolouration?
Discolouration of concrete refers to the non-uniformity of colour or variations in hue on the concrete surface that may include dark blotches, mottled marks, gross colour changes across large areas, or light patches of discoloration.
This phenomenon can result from various factors such as changes in the concrete mix, the interaction between the concrete and formwork system, or specific concrete deterioration processes. Leaching and the corrosion of embedded steel elements can also lead to discolouration, with rust staining being a common manifestation of the latter.
Discoloration is complex to understand as many factors can contribute to the problem, however, the phenomenon generally boils down to one root cause: inconsistency.
How does Discolouration damage concrete structures?
While discolouration itself does not structurally damage concrete, it can be indicative of underlying issues that may compromise the integrity of a structure.
Discolouration caused by rust staining suggests steel corrosion within the concrete, which can weaken the structural support provided by the reinforcement and lead to cracking, spalling, and ultimately, structural failure.
Furthermore, discolouration affecting large areas might indicate problems with the concrete mix or deterioration processes such as leaching, which can further undermine the concrete's durability and longevity.
In addition to these potential structural implications, discolouration can also diminish the aesthetic value of concrete structures, affecting their appearance and possibly impacting their perceived quality and maintenance levels.
What causes Discolouration?
Water accumulation
High porosity concrete
Inconsistent concrete mixes
Uneven application of finishing water or curing compounds
How can I identify Discolouration in concrete structures?
Visual survey | Non-destructive testing | Destructive testing |
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How can I repair Deflection in concrete structures?
