Managing Efflorescence on Concrete Pavers

Managing

Ef f lorescence

on Concrete paveRs

A guide

for consumers

The Best Practical

Paving System

Congratulations! You have recently improved your prop-

erty with strong, colorful, attractive interlocking concrete

pavement. As a proud owner, you have invested in a

long-lasting, durable, yet flexible pavement that adds

value to your real estate. A truly beautiful yet practical

pavement graces your

property. If your project

is just about to begin,

you can anticipate

enhancing your property

with the best paving

system for your money.

What is Efflorescence?

There is a chance that after a few weeks or months pass,

a white haze may appear on the surface of the pavers.

This is known as efflorescence. It may appear randomly

or in certain areas, and will be more pronounced on dark

colored pavers. The white haze may give the impression

that the color of the

pavers is fading.

When wet, the white

disappears and the

color of the pavers is

enhanced. When

they dry, the white

haze reappears.

Efflorescence is Completely natural

and will disappear with time

There’s no reason to be

concerned that your

pavers are damaged or

defective. The concrete

pavers are experiencing

a natural process. It is a

condition in all cement-

based products, as well

as in many other paving

products. But the condition will usually correct

itself with time and exposure to the elements.

the Chemistry of Efflorescence

All concrete products contain cement which

produces lime or water soluble calcium oxide.

Lime can also be in the bedding sand, aggregate

base materials, or soil. Although concrete pavers are

solid, strong, and very dense, they contain millions

of microscopic capillaries that run from the

interior to the surface. Moisture from rain,

sprinkler systems,

underground

sources, poor site

drainage, or dew

enters these

microscopic

capillaries.

Efflorescence emerged from pores

Calcium oxide

within a magnified area of a concrete

paver.The calcium has been carried

inside the paver

to the surface by water.

reacts with the water in the capillaries and forms

calcium hydroxide. This rises to the surface, reacts

with the carbon dioxide in the air, and forms a white

haze of calcium

carbonate. When

moisture on the surface

evaporates, the white

haze of efflorescence

becomes visible. Pavers with efflorescence.

Eliminating

Pavers after cleaning.

Efflorescence

Most producers of

pavers put chemical

additives in the concrete

to reduce the likelihood

of efflorescence. In most cases, they do the job.

Completely eliminating the chance of efflorescence,

however, isn’t possible because it’s a natural byproduct

of hardened concrete. It will stop when no more

calcium hydroxide is available to move to the surface.

There are cleaners available that can remove efflores-

cence. These will enhance the natural beauty of your

concrete paver project. Consult your paver supplier to

find an appropriate cleaner.

Frequently Asked Questions

About Efflorescence

Q.When will efflorescence stop?

When the supply of calcium hydroxide is exhausted.

If you live in an area of frequent rain and sunny days,

efflorescence and its passing may occur quickly. The

process may take much longer in drier climates.

Typically, efflorescence will stop developing in approx-

imately 18 to 24 months.

Q.Will it go away naturally?

Since many factors are involved in its formation, it is

difficult to determine when efflorescence will stop.

Just as it appears naturally, efflorescence will eventual-

ly disappear. Over time, rainwater can wash and wear

it away. In urban areas with acidic rainfall, efflores-

cence may go away faster than in rural areas.

Q.Can it be Removed Without The wait?

Yes, efflorescence may be cleaned with commerically

available cleaners formulated specifically for concrete

pavers. Cleaning should be performed immediately

after efflorescence has appeared. It may reappear as

long as the chemical reaction continues and cleaning

may need to be done until efflorescence has stopped.

Most cleaners contain acid and detergents, so be

sure to follow all label directions and environmental

regulations. Careless or improper cleaning can result

in injury, damage, and discoloration to the surface of

the concrete pavers. Always conduct a test in a small,

inconspicuous area before applying any cleaner to the

entire area of concrete pavers. After cleaning, the

pavers should be completely dry and free from efflores-

cence prior to applying any sealers.

For more information on efflorescence contact your

nearest member, or visit our website to request: ICPI

Tech Spec 5, Cleaning and Sealing Interlocking Con-

crete Pavement–A Maintenance and Protection Guide.

UNITEDSTATES CANADA

1444 I Street- Suite 700 P.O. Box 23053

Washington, D.C. 20005-6542 55 Ontario Street

Tel: (202) 712-9036 Milton, Ontario L9T 2MO

Fax: (202) 408-0285

Email: ICPI@icpi.org

Web site: www.icpi.org

For further information on concrete pavers, installation,

and contractors, contact your local ICPI member supplier.

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Copyright©2001 ICPI