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Articles Regarding
Cast Stone
SPECIFYING CAST
STONE - Published Article, April 2011
By Jan Boyer, Cast Stone Institute®
Executive Director
•
View as PDF
Cast Stone has a bit of an identity problem. You see, it makes sense
that any material that replicates natural stone is cast stone. If it
looks like stone and is a manufactured product, then it must be cast
stone. Not true. It could be Adhered Manufactured Stone Masonry
Veneer (AMSMV), architectural precast, calcium silicate, or even a
natural stone. On many construction documents today, there is
confusion in both terminology and physical properties when a
material is called out as cast stone, adhered stone veneer or
architectural precast. Each product has its appropriate applications
dependent upon the project. How can you determine the difference so
that you are specifying the correct product for the building
application?
CAST STONE AND OTHER MATERIALS
Adhered Manufactured Stone Masonry Veneer (AMSMV) is a
light-weight architectural non-load bearing product produced from a
wet cast blend of cementitious materials, lightweight and other
aggregates, iron oxide pigments and admixtures. It is sometimes
referred to as simulated stone or adhered veneer and usually cast
into random sizes, in a variety of colors with a natural undressed
quarried or cleft stone finish. AMSMV is generally applied as a
residential or lightweight commercial masonry veneer adhered to
exterior and interior walls, structures, columns, landscape
structures, and other structures suitable to receive lightweight
adhered units. These simulated stone products are manufactured at
1,800 to 2,000 psi with 22% (UBC Standard 15-5) absorption to meet
Construction Specifications Institute (CSI) Division 04 73 00. There
are currently no ASTM standard specifications for AMSMV.
Architectural Precast is a wet cast architectural unit made
from coarse aggregates, grey or white cements, sand and color
pigments manufactured to meet CSI Division 03 45 00. According to
this specification, it must be a minimum of 5,000 psi and 6%
absorption with no Freeze Thaw durability requirement. It is
generally specified for architectural panels, columns and large
architectural elements and installed as a precast product as opposed
to a masonry product.
Cast Stone is defined as “a refined architectural concrete
building unit manufactured to simulate natural cut stone, used in
unit masonry applications and is manufactured to meet Division 04 72
00 requirements. Used as an architectural feature, trim, ornament or
facing for buildings or other structures, it is created with a fine
grain texture to simulate all types of natural cut stone including
but not limited to limestone, granite, slate, travertine or marble.
Cast Stone can be made from white and/or grey cements, manufactured
or natural sands, carefully selected crushed stone or well graded
natural gravels and mineral coloring pigments to achieve the desired
color and appearance while maintaining durable physical properties
which exceed most natural cut building stones. Cast stone is
generally built into a load bearing masonry wall system in
traditional commercial and residential buildings and other
structures. It is specified as per ASTM C1364, Standard
Specification for Architectural Cast Stone that was originally
approved in 1997.
Cast Stone requirements in ASTM C1364 are:
-
Compressive Strength - ASTM C1194: 6,500
psi minimum for products at 28 days
-
Absorption - ASTM C1195 of 6% maximum by
the cold water method, or 10% maximum by the boiling
method for products at 28 days
-
Air Content – ASTM C173 or C 231, for
wet cast product shall be 4-8% for units exposed to
freeze-thaw environments. Air entrainment is not
required for VDT products
-
Freeze-thaw – ASTM C1364: of less than 5% after 300
cycles of freezing and thawing. Of note is that Cast
Stone is the only product with a freeze thaw requirement
that must be met by all manufacturers.
|
Table #1 |
Physical Property
Requirements Comparison Chart |
|
|
PSI |
Absorption |
Freeze Thaw |
|
AMSMV |
1,800 - 2,000 |
22%
(UBC
Standard 15-5) |
None |
|
Architectural Precast |
5,000 |
Maximum 6% |
None |
|
Cast Stone |
6,500 |
Maximum 6% |
5%
loss or less at 300 cycles |
Cast Stone generally is a higher quality finish than other types of
precast products. It has a fine grained texture and is used as
architectural trim, veneer facing and ornamentation in unit masonry.
In order to clarify the use of Cast Stone it was ultimately
determined that the correct ASTM designation, ASTM C1364, be
referenced in the International Building Codes.
top
CAST STONE NOW AS PER ASTM C1364 IN BUILDING CODES
The International Code Council (ICC) Family of Building Codes,
including those for all structures, residential and others, have now
been adopted in most States. These Codes are legally binding and
supersede any other specification unless referenced in these
documents. So what does this mean for Specifiers?
Most all materials in the Codes are referenced by definition and as
per their ASTM number. In the past, Cast Stone was referenced by
definition only as a material that replicated natural stone with no
ASTM requirement. This allowed for other products to be referenced
in the Code under Cast Stone when it was not the same material.
The Cast Stone Institute ®, through the efforts of the Masonry
Alliance for Codes and Standards, forwarded a Code Change proposal
to the ICC to require that Cast Stone be defined by, and comply with
the requirements of ASTM C1364 in the International Building Code.
This proposal was voted at the final action hearings in May 2010 and
adopted. It will be included in the 2012 International Building Code
(IBC) which is available for distribution as of April 2011.
This is important as it means that Cast Stone specified on a project
must comply with all of the ASTM C1364
standards – including freeze thaw requirements.
Each of these materials is referenced in the IBC by the appropriate
category and Chapter. Cast stone is referenced under the Masonry
Section. As the International Residential Code references the IBC
for terminology, the ASTM C1364 reference applies to residential
structures as well.
ABOUT THE CAST STONE INSTITUTE®
As a non-profit trade association, the Cast Stone Institute ®
(Institute) was formed in 1927 for the purpose of improving the
quality of cast stone and disseminating information regarding its
use. Today our mission remains, not only to be the authoritative
spokesperson for Cast Stone, but also to provide expert counsel to
the architectural and engineering communities. The activities of the
Institute are designed to benefit both the industry and its patrons.
Institute Technical Specification, Bulletins, Details and related
material are included in the Cast Stone Institute Technical Manual
available for free download from the website www.caststone.org.
The most important valuable resource to Specifiers is our Certified
Producer Members who adhere to the high standards for quality and
are bound by a strict code of ethics. Prior to membership approval
by the Institute Board of Directors, all potential producer members
(manufacturers) must have been manufacturing cast stone for a
minimum of three years and pass a rigorous certification that checks
for outstanding quality control, safety procedures, consistency of
product, housekeeping, meticulous record keeping and many other
manufacturing processes which are involved in the production of high
quality cast stone elements. In addition, members must provide
testing of product every 500 cubic ft. for compression and
absorption as well as independent laboratory test results every six
months to confirm their product meets the Institute standard
specification and ASTM C1364. They must also have a current
compliant Freeze Thaw test.
These are tests mandated by ASTM C1364 and our members comply
with these strict regulations and provide proof to the Institute of
this compliant test data every six months. Since the products that
go into the mix design for Cast Stone come from the earth, there can
be variances in sands, aggregates, etc… Testing assures the Producer
Member, the specifier and owner that they are indeed producing cast
stone to specifications. Without this testing, there is no way to
assure quality cast stone production.
Cast Stone Institute® Producer Members must also undergo the
recertification process every two years by unannounced plant
inspections. This unannounced inspection is performed by an
independent Engineering Firm in order to assure compliance to
requirements. The Institute certification differs from others in
that they certify that not only the processes are in place to make
quality product but that the product itself is meeting
specifications.
CAST STONE INSTITUTE PRODUCER MEMBER 10 YEAR LIMITED PRODUCT
WARRANTY
As of January 1, 2011, all Certified Cast Stone Institute Producing
Members provide a 10 year Limited Product Warranty for the Cast
Stone they supply on projects.
Continuing to lead the industry, the Cast Stone Institute® Producer
Members voted on October 8, 2010 to adopt the language for a 10 year
Limited Product Warranty. Institute Producer Members are aware of
the evolving environment for products in the marketplace that demand
sustainability, durability and useable service life. This warranty
demonstrates that they embrace these principles and produce product
that will stand the test of time.
CONCLUSIONS
What does all of this mean for the specification of cast stone?
Certified Producer Members of the Cast Stone Institute are engaged
in the relentless pursuit of excellence in manufacturing. The
results of these efforts include consistently high product quality,
through continuous improvement in manufacturing methods and
materials, and the assurance that Cast Stone Institute Certified
Producer Members are keeping cast stone a premier building material.
Properly manufactured, designed and installed, cast stone can result
in an architectural project of enduring beauty to be enjoyed for
decades. When specifying cast stone on a project, be sure to call
out for a Cast Stone Institute Member and hold to that
specification. This provides Specifiers and Owners the quality
assurance the project deserves.
For more information, log onto
www.caststone.org.
###
top
Cast Stone Dilemma -
Published Article, July 2009
By Gary Fry
•
View as PDF
Make the cream rise to
the top!
Cast Stone is alive and well in these challenging times. But—the
construction industry struggles to maintain its’ equilibrium as the
nation’s economy is challenged and many markets shrink. If the
purchaser succumbs to the temptation of making the decision based
solely upon price it is more than likely that they will face a
dilemma with the resultant process. It’s a good time to think about
basics.
Cast Stone is a premier masonry product that provides ornamental or
functional features to buildings and other structures. It gives the
appearance of a variety of natural building stones and applications
range from the simplest windowsills to the most complicated
architectural elements. Properly manufactured, it has the same or
stronger physical properties as most dimensional building stone. In
essence Cast Stone is a highly refined architectural precast
(concrete) product manufactured to simulate natural cut stone.
Concrete is a very basic building material that adequately serves a
multitude of construction applications. The ingredients are readily
available and the skills required to make concrete are relatively
simple. So, what does “highly refined” mean? Basically, it means
manufactured in compliance with a set of standards.
The recognized standard for Cast Stone is ASTM 1364 Standard
Specification for Architectural Cast Stone which requires a
compressive strength greater than 6,500 psi as per ASTM C1194 test
and maximum absorption rates of 6% and 10% for cold water and
boiling methods, respectively as per ASTM C1195 test. The Cast Stone
Institute requires Producer Members to comply with these
specifications as well as ASTM C 666 – Standard Test Method for
Resistance of Concrete to Rapid Freezing and Thawing. Also
referenced within the ASTM C 1364 are a myriad of ASTM standards
that regulate the ingredients of cast stone, such as cement,
aggregates, reinforcing, color, etc…
Concrete, and therefore cast stone can be a very fickle product, as
evidenced by examples of failure in diverse applications. These
failures are most predominately caused by human actions rather than
ingredients. So, while it is a good start to assure compliance of
ingredients with these standards, it is not enough. Additional
standards regulate forming, mixing, placing, finishing, curing,
storage, etc… It is prudent that producers follow these “basics”
and document compliance in order to verify performance to the
purchaser. That means keep records verifying test results and have
certifications on-hand for all materials.
Cast Stone has been a prime building material for hundreds of
years.
top
The earliest known use of Cast Stone dates about to the year 1138
and was seen at Carcassonne, France, the Cité which contains the
finest remains of medieval fortification in Europe. Cast Stone was
first used extensively in London in the year 1900 and gained
widespread acceptance in America in 1920.
Today, Cast Stone is a truly superior alternative to natural cut
building stone. Combined with its ability to simulate or reproduce
an almost limitless variety of natural stones, Cast Stone offers
many advantages over cut stone. Cast Stone can be integrally
reinforced with steel and precisely colored through aggregates or
mineral oxides. Mix designs have tested engineering values which
result in a predictable durable life. Strength and weathering
qualities are consistently better than natural stone because the
manufacturing process is controlled. Properties such as these cannot
be assured in a quarried building stone. Repetitive treatment,
either as trim or ornament, can be achieved quite economically in
Cast Stone. The ability of Cast Stone to replicate deteriorating
natural stone on existing buildings makes it an ideal material for
the remodeling or restoration of old structures.
Typical cast stone elements include modular base panels, water
table, sills, jambs, heads, keystones, door surrounds, cornice, pier
caps, coping, band course, balustrade, stair treads & risers,
plaques, quoins, signs, and columns.
Several manufacturing processes have been utilized in the storied
history of cast stone, with mixed results. Modern cast stone is
almost exclusively produced by the three processes defined by CSI
Specification 04-72-00-04
The Cast Stone Institutes Technical Manual has become the most
widely accepted standard for the industry. Most specifications will
defer to the requirements for cast stone expressed in its standard
specifications.
CSI’s contemporary initiatives address the challenges that most
businesses struggle with during such an economic climate, providing
accountability for the manufacturing process and offering added
value to the end-user. Jan Boyer, Executive Director, believes "
Leadership for a national trade association requires the vision to
look for opportunities that will: set your members above others in
the industry, create and maintain market share, work with related
associations toward common goals and much more. The Cast Stone
Institute believes in partnering within the cement based products &
masonry industries to work toward the common goals of appropriate
sustainable development as a socially responsible initiative as well
as building codes and standards that correctly specify our product
toward building a safe, secure environment for communities."
topDilemma
- a situation in which somebody must choose one of two or
more unsatisfactory alternatives.
There is an axiom that says “Things equal to the same thing are
equal to each other.” In order for the product of a non-certified
plant to be compared (equal) to that of a certified plant it is
reasonable to require verification of compliance with the usually
requisite ASTM C 1364. To not do so is to risk ending up with an
unsatisfactory alternative.
The cream will rise to the top! Quality cast stone producers
and masons will do the right things during these challenging times
because they are competent and understand that short cuts cost more
in the long run and are self destructive. The purchasing decision
must follow suit and provide quality product that has been
manufactured in compliance with the appropriate standards. The
purchaser best serves his requirements by including product in the
list of choices that is demonstrably capable of fulfilling all of
his requirements, not just those in the short run.
Author: Gary Fry is immediate Past President of the Cast Stone
Institute, and has held the offices of Secretary/Treasurer and Vice
President. Upon his retirement recently from Sun Precast Company he
was elected as an Honorary Member of CSI and continues to serve the
Membership and Ethics committees. His 11 year tenure at Sun Precast
as Vice President and President/CEO followed a diverse background in
general construction and manufacturing. Gary resides in Milton, Pa.
and enjoys a full schedule of golf, fishing, and animal rescue, as
well as advocating for Cast Stone and Lean Manufacturing.
Cast Stone Vs. Adhered Veneer -
Published Article, September 2008
•
View as PDF
Submitted 9/16/08
For publication - Feb 2009 Masonry Construction Magazine
The Difference Between Cast Stone and Adhered Manufactured
Stone Masonry Veneer
by Bill Russell
Chairman, Cast Stone Institute Committee on Educational Standards
On many construction documents today, there is confusion in both
terminology and physical properties when a material is called out as
cast stone or adhered stone veneer. This article attempts to clarify
the differences in the two products.
DEFINITIONS
Cast Stone is defined as “a refined architectural concrete building
unit manufactured to simulate natural cut stone, used in unit
masonry applications.” Cast Stone is a masonry product, used as an
architectural feature, trim, ornament or facing for buildings or
other structures. It is created to simulate all types of natural cut
stone and is referenced in the International Building Code under
Chapter 14, Anchored Masonry Veneer.
The earliest known use dates to about the year 1138 and can still be
seen at Carcassonne, France, a city that contains some of the finest
remains of early architecture in Europe. Cast stone was first used
extensively in London beginning around 1900 and has gained
widespread acceptance in America since the 1920s. According to Gary
Fry, President of Board of Directors of the Cast Stone Institute,
“Many lessons have been learned throughout this history and they can
be used to improve the mason contractor’s experience with cast stone
at the current state of the art.” The requirements for Cast Stone
are referenced in the current ASTM International C1364 Standard for
Architectural Cast Stone which was originally approved in 1997 and
most recently updated in 2007, although various trade groups had
published specifications as early as 1927.
Cast stone is generally built into a load bearing masonry wall
system, and used as an architectural feature, trim, ornament or
veneer in traditional commercial and residential buildings and other
structures. It is most often specified as a replacement for full
bed-depth natural dressed dimensional limestone.
Adhered Manufactured Stone Masonry Veneer (AMSMV) – is a
lightweight man made concrete masonry product which is usually cast
into random sizes, in a variety of colors with a natural undressed
quarried or cleft stone finish. It is sometimes referred to as
Simulated Stone or adhered veneer. AMSMV is generally applied as
a residential or lightweight commercial masonry veneer adhered to
exterior and interior walls, structures, columns, landscape
structures, and other structures suitable to receive lightweight
adhered units. It is known by a variety of different product
names with a variety of proprietary specifications. Several
companies manufacture stone-like products that are used primarily as
veneers on other substrate materials such as concrete masonry units.
These simulated stone products are manufactured to meet Construction
Specifications Institute (CSI) Division 047300 classification for
simulated stone while cast stone is manufactured to meet Division
047200 requirements. There are currently no ASTM standard
specifications for AMSMV. top
PHYSICAL PROPERTIES
There are substantial differences between cast stone and adhered
veneer in regard to physical properties that should be considered
when specifying. Adhered veneer is a lightweight product that is
applied to a structural wall with an adhesive. Therefore, it cannot
be used to add to the load bearing capacity of the wall. Cast stone,
however, can be used to add to the load bearing capacity of a
masonry wall and is usually integrated into the brickwork, becoming
part of a composite wall system rather than being adhered to it. It
provides additional strength because it is anchored within the
masonry structure, therefore will stand the test of time. In
addition, while adhered stone products are made light in weight so
they will work easily on the exterior of other wall material, cast
stone weighs approximately the same as natural cut limestone.
Test methods dictate how the materials are tested while the
specification stipulates what the requirements of the test results
must be, as well as the ingredients each product must contain.
|
|
PSI |
Absorption |
Unit Density |
Max Density |
|
Cast Stone |
6,500 |
6% |
135 pcf |
40 psf |
|
AMSMV |
1,800 - 2,000 |
22%
(UBC
Standard 15-5) |
75
pcf |
15
psf |
For example, cast stone is required to have a minimum compressive
strength of 6,500 psi, maximum moisture absorption of 6 percent, and
unit density of approximately 135 pcf. The minimum compressive
strength of adhered veneer is approximately 1,800 to 2,000 psi,
absorption may reach 22% (UBC Standard 15-5), unit density is
approximately 75 pcf, and much emphasis is put onto a shear bond
test which is presently under development. Each product must pass a
rigorous freeze-thaw test. Because AMSMV is an adhered unit, most
building codes such as UBC/IBC require the maximum density to be 15
lbs per square foot, and allow the minimum thickness to be
approximately ¼”. Cast stone when used in conventional 3-5/8”
thickness weighs approximately 40 psf.
APPEARANCE
The use of a high percentage of durable fine aggregate in any
manmade stone creates a very smooth, consistent texture for the
building elements being cast, resembling natural limestone,
brownstone, sandstone, marble or granite. Applications that use cast
stone can range from the simplest window sill to the most
complicated classical architecture. Therefore, the number of
profiles and sizes required for any given project can vary from a
single shape shown on a sketch to hundreds (or more) shapes, perhaps
not so clearly shown in a set of architectural contract documents.
AMSMV usually has a natural quarried stone appearance and can be
used for many of the same applications, although it is primarily
used as adhered veneer. Both products have many of the same
properties inherent in a material which is primarily intended to
simulate natural building stone, although cast stone is typically
custom made to approved shop drawings and AMSMV is most often laid
out and cut to suit field conditions.
INSTALLATION
Cast Stone is generally used as the veneer or trim component of a
conventional masonry cavity wall system, similar to brick veneer.
Therefore, concrete masonry units (CMU), steel frame, concrete or
metal studs are typically built out from a backup wall with a 1” to
4” air space, which may include insulation. Sizes of cast stone are
typically made to accommodate pallet lengths of 4’ to 5’ and are
commercially available in sizes up to 24 sf in area. Larger sizes
are still possible, subject to local availability, but may not be
recommended for use in mortar set systems.
A typical masonry cavity wall has five essential elements. top
The exterior wythe provides first resistance against moisture
penetration. Cast Stone should be laid with full joints in mortar
meeting the requirements of ASTM C 270, Type N mortar. Care should
be taken when laying the stone to ensure the cavity behind this
wythe stays clear. A tapered bed joint can help minimize mortar
droppings and protrusions into the drainage cavity. Stainless steel
building stone anchors are used to tie the cast stone to the backup
wall. They are designed to be stiff enough to resist tension and
compression, and flexible enough to permit in-plane differential
movements. Non-corrosive type anchors should be used for all
anchoring. Stainless steel Type 302 or 304 are the standard type
used in this class of work.
Typical stone anchor sizes are 1/8" x 1" straps, 1/4" rods and 1/2"
dowels. Dowel holes for 1/2" or 3/4" dowels are usually 1" diameter
filled completely with mortar during setting. Anchor slots are
typically 3/4" wide and similarly are filled with mortar.
The anchors for attaching cast stone may be required to penetrate
flashing and building paper to allow a secure connection to the
structure. Where this occurs, proper steps must be taken to ensure a
watertight connection at the interface so that the anchor does not
compromise the integrity of the flashing.
Alternative Cast Stone Thin Veneer Installation Methods
Over the past twenty years alternative thin veneer methods have been
successfully installed and accepted within the masonry industry and
most recently have been designed for thin veneer cast stone. These
new methods of installation using corrosive protective steel as a
support panel to anchor the steel panels in place have incorporated
specially designed tabs to assist in holding the weight of each
masonry unit without the use of hung lintels or relieving angles,
some even offer a mortar locking feature to mechanically lock the
mortar & thin veneer onto the steel support panel. These systems are
designed to match the different types of expansion and contraction
between the veneer, panel, and substrate. They offer greater
fastener pull through resistance than cement board, polystyrene,
plywood, OSB and asphalt board. Some of these systems even offer a
true moisture control system, which allows the water to drain.
Depending on the type of system used, structural steel support panel
systems will successfully hold thin masonry cast stone veneer up to
150 MPH wind-loads at 400’ high, per exposure D (ASTM-E-72). top

Figure 5 (Courtesy TABS Wall Systems)
Regardless of the material selected and the degree of care exercised
during construction, a final wash down will be needed after
installation and, normally, whatever is specified to clean the
masonry will adequately clean the stone. A variety of commercial
cleaners are available and most contain detergents combined with
mild solutions of phosphoric and/or muriatic acids. Extreme care
should be taken when applying acidic cleaners to areas where joints
are left open or where sealant is used as jointing material. As with
any cleaning solution, always consult with the stone manufacturer
and try a test area first, before proceeding with the wash down. The
window and sealant manufacturer should also be contacted to
ascertain compatibility with cleaning materials.
AMSMV is an aesthetic wall covering, but it is the structural backup
behind the adhered veneer that does all the work in resisting loads.
The backup wall may be wood framing, sheet metal, steel framing,
concrete block, or poured in place concrete. With adhered
applications, the stone veneer will move with the backup wall as the
structure responds to loads, temperature variations, and soil
settlement. AMSMV veneer is relatively stiff, and is well-matched to
a concrete block or poured in place concrete backup system. Wood and
steel framing, on the other hand, are relatively flexible. Choosing
a stiff backup structure (L/600 to L/1,000) is
required to prevent future cracking of the adhered veneer.
Wood framing is particularly susceptible to movement as the wood
swells during damp periods, and shrinks when it dries.
AMSMV may be set using one of the following International Building
Code methods, in lieu of another approved method, after properly
installing a metal lathe to the substrate:
Back-butter and squeeze - Brush a paste of neat Portland cement on
the backing and on the back of the veneer unit. Then apply Type S
mortar to the backing and to the veneer unit. Sufficient mortar
shall be used to create a slight excess to be forced out the edges
of the units. The stones shall be tapped into place so as to
completely fill the space between the stones and the backing. The
resulting thickness of mortar in back of the units shall not be less
than 1/2" or more than 1-1/4". Grout and finish joints as necessary. top
- 1. Back-butter and squeeze - Brush a paste
of neat Portland cement on the backing and on the back
of the veneer unit. Then apply Type S mortar to the
backing and to the veneer unit. Sufficient mortar shall
be used to create a slight excess to be forced out the
edges of the units. The stones shall be tapped into
place so as to completely fill the space between the
stones and the backing. The resulting thickness of
mortar in back of the units shall not be less than 1/2"
or more than 1-1/4". Grout and finish joints as
necessary.
- 2. Mortar setting bed - The setting bed of mortar shall
be a minimum of 3/8" thick and a maximum of 3/4" thick.
A paste of neat Portland cement or one half Portland
cement and one half graded sand shall be applied to the
back of the exterior veneer units and to the setting
bed, and the veneer shall be pressed and tapped into
place to provide complete coverage between the mortar
bed and veneer stone. Grout and finish joints as
necessary.
- 3. Use a combination of the two methods listed above.
Adhesion developed between adhered veneer units and backing shall
have shear strength of at least 50 psi based on gross unit surface
area. For veneer units weighing less than 3 pounds per square foot,
there is no limit on its dimensions or area. Veneer units may not
weigh more than 15 pounds per square foot. For veneer units between
3 and 15 pounds per square foot, the following dimension and area
restrictions apply. No side of the veneer units can exceed 36 inches
in length and the overall face area of the stone may not be greater
than 5 square feet.
SPECIFICATION OF PRODUCTS
In November 2006, ASTM International Committee C15 on Manufactured
Masonry Units created a new subcommittee, C15.11 on Adhered
Manufactured Stone Masonry Veneer. The purpose of C15.11 is to
develop and maintain product specifications and installation
guidelines for adhered manufactured stone masonry veneer. The new
standard was still under development at the time this article was
written.
ASTM International (founded in 1898 as the American Chapter of the
International Association for Testing and Materials and most
recently known as the American Society for Testing and Materials)
exceeds 30,000 technical experts from more than 100 countries who
comprise a worldwide standards forum. The ASTM method of developing
standards has been based on consensus of both users and producers of
all kinds of materials. The ASTM process ensures that interested
individuals and organizations representing industry, academia,
consumers, and governments alike, all have an equal vote in
determining a standard's content.
According to Brenda Harris, chair of the new subcommittee, adhered
manufactured stone masonry veneer has recently been defined by
Committee C15’s executive subcommittee as “a light- weight
architectural non-load bearing product. It is a wet cast blend of
cementitious materials, lightweight and other aggregates, iron oxide
pigments and admixtures.”
Harris says that the subcommittee was formed because there are not
currently any well-known standards for adhered manufactured stone
masonry veneer. “The lack of a uniform and nationally recognized
product standard and the lack of specific and appropriate
installation procedures for this product have allowed untested and
substandard products to find their way into both residential and
commercial construction,” says Harris. “The development of these
standards would create the critical definitions and procedures
needed by project owners, as well as design and installation
professionals.”
Considering the many advantages which man made stone has over
natural building stone, it is surprising that wider use has not been
made of this versatile and economical building material. Many
architects are only now discovering Cast Stone. Although it has
existed for more than centuries, the merits of it as a versatile
ornamental building material are still far from universally
recognized.
For thousands of years, architects and builders have chosen stone as
an architectural medium - for its beauty -- for its permanence. So,
what will man do when the last natural stone is quarried?
He will make his own.
###
Author: Bill Russell is the Chairman of ASTM Committee C 27.20 on
architectural and structural concrete products, and President of
Continental Cast Stone East, by Russell, Inc., Berlin, NJ. He is a
founder and past president of the Cast Stone Institute, served as
its Technical Director for 14 years and presently chairs its
Committee on Educational Standards.
top
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End Of Section |
Revised 3/27/12 |
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