Michigan road salt is destroying your concrete, quietly

What the salt actually does

De-icing salt does not damage concrete by being corrosive in the way people assume. It works by dissolving into brine, soaking into the pore structure of the slab, and then dramatically increasing the number of freeze-thaw cycles the concrete goes through — brine freezes and thaws at temperatures where plain water would stay frozen. Each cycle expands the water in the pores and pushes outward on the surrounding material. Metro Detroit runs through dozens of those cycles between December and March.

Spalling is the point of no return

Eventually the surface layer loses and pops off in flakes and sheets, exposing the aggregate. That is spalling, and it is where the cost changes category: a stained slab is a cleaning job, and a spalled slab is a patching or replacement job. Cleaning cannot bring a spalled surface back, because the surface is physically gone. Once it starts it accelerates, because the exposed, rougher, more porous concrete now absorbs more brine than it did.

Which parts of a commercial property get it worst

Anywhere salt is applied heavily and then tracked: entrance aprons, the first few feet inside a dock door, accessible-space approaches, stair treads and landings, and the curb line. Vehicle traffic also carries brine in from the road and drops it in parking areas and drive lanes, which is why lot concrete degrades even where nobody salted it. Newer concrete is more vulnerable than people expect — a slab in its first winter or two has not fully cured and is at its most absorbent.

Why spring, specifically

Chloride left in a slab does not leave on its own. It stays in the pore structure and is still there for the next winter, so the damage compounds rather than resets. Washing it out once the salt season is genuinely over — in this climate usually April into May — removes the accumulated chloride before it can contribute to another winter. That is the whole argument for the spring pass, and it is why "we cleaned it in the autumn" is not a substitute.

What else helps

Sealing the flatwork that takes the worst of it, after cleaning and not before, so the sealer is not locking chloride in. Using less salt, or a different de-icer, on the areas that matter — magnesium chloride and calcium chloride are gentler on concrete than rock salt, at a higher price. Getting drainage away from the slab, because standing meltwater is where this all starts. And for anything under about two years old, being deliberately conservative with salt through its first couple of winters.