Will efflorescence go away on its own?

The Interlocking Concrete Pavement Institute (ICPI) sets out efflorescence as a sequence in its Tech Spec 5, and every step in it carries a may. The whitish deposit may appear immediately after installation or within months of it. It may reach its peak in as short as 60 days. It may remain for months. And some of it may wear away.

Read in order, that is a range rather than a countdown. No step promises a date, and the last one says some of the deposit, not all of it, may wear away. The same timeline appears in one sentence in the efflorescence note under what a paver cleaning removes; the chemistry that makes the deposit is defined under efflorescence, where calcium hydroxide from the cement meets carbon dioxide and becomes calcium carbonate.

ICPI Tech Spec 6, the maintenance guide now published by the Concrete Masonry and Hardscapes Association (CMHA), gives the stopping point: the appearance of efflorescence stops when the calcium hydroxide supply is exhausted. The deposit is fed from inside the concrete, so once that supply is spent, no new haze forms. Tech Spec 6 adds that most paver producers put chemical additives in the concrete that in most cases prevent efflorescence, but that the chance of it cannot be eliminated entirely, because it is a natural by-product of curing concrete.

Tremron, a Florida concrete paver maker, says efflorescence is a natural process with almost all concrete and masonry products and that pavers showing it are not defective. Its FAQ answers this page's question in one line: "Eventually efflorescence will disappear on its own, but if you wish to hasten the process then use an Efflorescence Cleaner."

Waiting costs the pavers nothing structurally: Tech Spec 6 calls efflorescence an aesthetic rather than a structural concern. Dark colored pavers, Tech Spec 6 notes, show it more than lighter ones.

The clock does not always start at installation. ICPI notes that if pavers go in during a dry period of the year, the next cycle of wet weather may sometimes be necessary before efflorescence materializes. Tech Spec 6 describes the mechanism: water entering the microscopic capillaries in the pavers dissolves calcium hydroxide and carries it to the surface, and the white haze forms when that water evaporates.

So a driveway laid in a dry stretch can look clean for weeks and then bloom after the first real rain. That is the same chemistry getting the water it needed, not a second problem. How a wet month sits against a paver surface in Naples is set out under what September does to a driveway.

For anyone who would rather not wait, ICPI says that if deposits need removing before they wear away, best results come from a proprietary efflorescence remover. ICPI does not set the dilution itself: the paver supplier or the chemical company supplying the product gives the dilution and application recommendations. Results are checked after the area has dried for at least 24 hours.

Tech Spec 6 says efflorescence can be removed with cleaners made specifically for concrete pavers, and warns in the same passage that careless or improper cleaning can damage and discolor paver surfaces. Tremron is blunter about one product: muriatic acid will damage the surface of the pavers and cause pitting. SEK-Surebond's site preparation bulletin makes the same choice inside a sealing job, using an efflorescence cleaner in place of a general purpose cleaner when efflorescence is present.

Pressure washing alone is not a shortcut. Techniseal's product guide says a simple water jet will not dissolve efflorescence, and why a proprietary remover's acid is buffered is set out under the order of chemistry first, pressure last.

Two questions sit beside this one. Whether a given white deposit is efflorescence at all is for whoever supplied the pavers, since a page cannot identify a deposit it has not seen. And whether a sealer can go on while the haze is still there is answered under whether pavers with efflorescence can be sealed, with the general wait for brand new pavers under how soon new pavers can be sealed.