What Are the Causes of Flakiness & Rusting of Concrete?

Excess Water

• Typically, concrete structures like a driveway are not sold ready-made. Instead, a property owner must mix the cement before pouring it or hiring someone to do it. Flaking and rusting occurs when the water-to-cement ratio is too out of balance. Too much water in the mixture produces a weaker, less-durable concrete that contributes to early flaking and spalling of the surface, reports the Portland Cement Association.

Constant Freeze and Thaw Cycle

• Constant freezing and thawing during cold weather causes cement to rust and flake. Whether the water forms from melting snow or rain, the water seeps through the cracks in the cosmetic layer of the concrete, penetrating its interior. The water freezes, causing cement to expand moving upward. The pressure results from the frozen water expanding the concrete, causing it to break into pieces and spall.

Salt

• During the winter months, a property owner uses different methods like shoveling to remove snow and ice on concrete. Another way of eliminating snow and ice involves using rock salt. However, using too much rock salt on concrete causes flaking and rusting. Rock salt gathers underneath the top layer of the concrete. Rock salt crystallizes, building pressure to create flaking and rusting on a concrete surface.

Metal Corrision

• Rusting appears on the surface of concrete when water infiltrates the cosmetic surface of concrete, causing metal such as rebar to moisten. Once the wet metal begins corroding and rusting, concrete then shows signs of metal corrosion. Over time, water damage corrodes the concrete, which exposes the metal rebar and causes a dangerous situation. The exposed metal can cause someone to trip or fall on the spalled concrete steps or pathway.