SAVE THE WALL!

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SAVE THE WALL!
ask the expert
BY JAMIE FARNY
How Can Efflorescence Be Minimized in New Masonry Buildings
Photos courtesy of the Portland Cement Association
Efflorescence is a crystalline deposit, usually white, that may develop on the surfaces
of masonry construction. Sometimes it
appears just after the structure is completed and is termed new building bloom.
Deposits from efflorescence are less
noticeable on lighter-colored surfaces than
on darker-colored surfaces. Although unattractive, efflorescence is generally harmless, temporary and decreases with the
passage of time.
Recurrent efflorescence indicates a
chronic moisture problem, which should be
corrected.
Efflorescence is often called new building bloom
because it appears on fresh masonry surfaces.
A combination of three common circumstances causes efflorescence:
• soluble compounds (salts) in the
masonry or adjoining materials
• moisture to pick up the soluble compounds and carry them to the surface
• evaporation or hydrostatic pressure
that causes the solution to move
If any one of these conditions is eliminated, efflorescence will not occur.
All masonry and concrete materials are
susceptible to efflorescence, so a materialbased approach to controlling it is ineffective. During construction, moisture sources
include water used to achieve a workable
mortar or flowable grout, rain and snow.
Efflorescence is affected by temperature, humidity and wind. Usually efflorescence is more common in the winter when
a slower rate of evaporation allows migration of salts to the surface.
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The top of masonry
walls should be
protected with a tarp
whenever rain or
snow is expected. It is
good practice to cover
work at the end of
each day to help keep
excessive water out
and aid curing.
THE DRY-BLOCK® SYSTEM FOR CONCRETE
MASONRY WALLS
One Time-Proven Solution for Moisture Control
DRY-BLOCK® BLOCK ADMIXTURE
DRY-BLOCK® MORTAR ADMIXTURE
In most cases, salts that cause efflorescence come from beneath the surface.
Hydrated portland cement contains a substantial amount of calcium hydroxide, as a
product of the reaction between cement or
lime and water. Calcium hydroxide, brought
to the surface by moisture, combines with
carbon dioxide in the air to form calcium
carbonate, which then appears as a whitish
deposit often referred to as a lime deposit.
Since calcium hydroxide is much more soluble in cold water than warm water, such
deposits are more common in winter than
summer.
Many factors influence the formation of
efflorescence, so it is difficult to predict if
and when any will appear. It is virtually
impossible to eliminate all the soluble compounds, construct walls containing no free
moisture, or completely eliminate paths of
moisture migration. Therefore, good workmanship is one of the most effective means
of limiting the potential for efflorescence.
The following steps can be taken to minimize efflorescence.
Good drainage:
• Limit entry of water and provide for
its removal by using waterstops, flashing, weepholes and copings. Maintain
clean cavities and unobstructed
weepholes.
Good mortar joints:
• Tool all mortar joints with a concave- or
V-shaped jointer to compact the mortar
and create a tight bond between mortar
and masonry unit. Weeping, raked and
untooled struck joints are not recommended in exposed applications.
• Ensure that joints are properly filled,
and repair or repoint deteriorated or
defective mortar joints.
• Provides water-repellent blocks and mortar
• Improves mortar bond strength
• Unaffected by time or weathering
www.DryBlock.com
•
•
•
•
Product data sheets
Information on best practices in masonry construction
NCMA TEK Bulletins
CAD detail drawings
CONTACT YOUR QUALIFIED
DRY-BLOCK PRODUCER:
4-D, Inc.
Midland, MI
989-631-0400
www.4dblockandbrick.com
Bark River Concrete
Bark River, MI
906-466-9940
Fendt Builders Supply
Farmington Hills, MI
248-474-3211
www.fendtproducts.com
Fraco, Inc.
Marquette, MI
906-249-1476
www.fracoinc.com
Michigan Certified
Concrete Products, Inc.
Grand Rapids, MI
616-241-4461
www.micertconcrete.com
Miller Products
Iron Mountain, MI
906-774-1243
Superior Block Company
Houghton, MI
906-482-2731
www.superiorblock.com
The Concrete Service Inc.
Traverse City, MI
231-946-7880
www.theconcreteservice.com
or contact Dennis Hayes, Grace Masonry Representative:
414-870-0939
www.graceconstruction.com
DRY-BLOCK is a registered trademark
of W.R. Grace & Co.-Conn.
EFFICIENT DESIGN INC.
MASONRY SPECIALIST /
GENERAL CONTRACTOR
Seminole Academy, Mt. Clemens
Courtesy of French Associates
Raymond Saelens, President
586-598-0055
51935 North Gratiot
Chesterfield, MI 48051
PROUD MASON CONTRACTOR FOR THE SEMINOLE ACADEMY
JULY/AUGUST 2006
the story pole 31
ask the expert
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32 the story pole
JULY/AUGUST 2006
Proper curing:
• Ensure adequate hydration of cementitious materials by protecting masonry from cold temperatures or premature drying.
Limited water entry:
• Apply paint or other proven protective treatment to the outside surfaces of absorptive masonry units. Caulk around window and door openings. Seal or otherwise repair cracked
joints in walls. Also, use through-wall flashing at ground level
to prevent capillary rise of ground moisture.
• Install vapor barriers in exterior walls or apply vaporproof paint
to interior surfaces and use designs that minimize condensation within masonry.
• Carefully plan the installation of lawn sprinklers so that walls
are not subjected to unnecessary wetting.
• If feasible, use wide overhanging roofs to protect walls from rain.
Limited driving forces:
• Provide for pressure equalization between the outside and the
void within the masonry wall by appropriate venting of cavities.
To reduce the potential for efflorescence associated with new construction, the following steps may be taken to limit the moisture introduced into the wall during construction.
• Keep masonry units stored at job site covered and on pallets
placed in well drained locations.
• Cover the top course of masonry at the completion of each
day’s work, particularly when rain (or snow) is expected.
• Use washed ASTM C144 sand.
• Don’t use units known to effloresce while stockpiled.
• Use clean mixing water free from harmful amounts of acids,
alkalies, organic material, minerals and salts.
• Use insulating material free of salts when walls of hollow
masonry units are to be insulated by filling the cores.
• Be certain that mixer, mortar box, mortarboards and tools are
not contaminated or corroded. Never de-ice this equipment
with salt or antifreeze material.
• Use mortar materials (cements or admixtures) of lower alkali
content.
Inspired by Mother Nature
Engineered by Advanced
Remember how much fun it was to play in the rain
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MORTAR BREAK AND ACCESSORIES
Given time, efflorescence will often disappear by itself or at most
may require mild cleaning measures such as dry brushing or rinsing
and brushing with a stiff brush. If this does not produce satisfactory
results, it may be necessary to clean the surface by chemical methods. See the reference for further information about cleaning.
Jamie Farny is PCA’s program manager of Masonry and
Special Products, coordinating research and promotion
activities regarding cements for masonry and white cement.
He participates on committees on concrete, plastering,
mortars and masonry units of the American Society for
Testing and Materials (ASTM) and the American Concrete
Institute (ACI). He holds a B.S. degree in civil engineering
from the Illinois Institute of Technology.
REFERENCE Trowel Tips: Efflorescence, IS239, Portland Cement
Association, Skokie, IL, 2004, 4 pages. Free download at:
www.cement.org/bookstore
COP-R-KRAFT
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MORTAR BREAK II
[F]
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MORTAR BREAK

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