|
|
| |
|
|
|
| GRANITE 101 |
| |
 |
| |
These
are the most frequently asked questions about granite. |
| |
|
|
|
• What is granite ?
• How can I use granite ?
• Why should I choose granite for my project ?
• What do I do with the samples that I already have ?
• What are the steps in the sample selection process ?
• What are the cost-factors in designing with granite ?
• Why is the color of the installed granite different
from the samples provided ?
• How to choose a granite producer ?
• Why can’t I substitute a similar granite to
the granite selected ?
• What do I do with similar granites that have different
names ?
• How can I be sure to select the right granite ?
|
| |
|
• What is
granite ?
Granite can be defined according
to two different interpretations: the geologists’
definition and that of the stone industry (commercial
definition).
Geologists and petrologists define granite as a
plutonic rock whose main components are colored
feldspar, white quartz and black ferromagnesian
minerals. All of these minerals are of different
composition and hardness. In the industry, granite
is defined as any igneous rock suitable for cutting
and polishing.
Granites are mineralogical aggregates, which change
in composition from one variety to another.
TOP |
| |
|
•
How can I use granite ?
Granite can be used traditionally
for massive structural work, the likes of which
can be seen on old buildings such as Churches, City
Halls and Courthouses built between the 1920’s
and 1950’s.
Nowadays, granite extracted out of Granicor’s
quarries is processed in fabrication plants that
use advanced technology in order to produce thin
panels, which lowers installation costs and provide
designers with unlimited possibilities.
Granite can be used indoors and outdoors. Here are
some of the most prevalent applications found in
modern architecture:
1. Architectural Stone
• Exterior and interior cladding panels
• Stairs and copings
• Columns
• Paving and floor covering
• Signage
• Window-sills and moldings, etc.
2. Urban Design
• Horizontal surfaces (pavers, steps, etc.)
• Security barriers and railings
• Urban furniture (park benches, picnic tables,
etc.)
• Monuments (urban and other)
3. Interior Design
• Bistro tables
• Countertops and vanities
• Reception desks
• Conference tables
• Pedestals
4. Civil Engineering
• Street curbs
• Bridge pillars
• Retaining walls
• Fire-break walls
• Well bed-plates, mains
TOP |
| |
|
•
Why should I choose granite for my project ?
When you are looking for
an enduring cladding material, elegant and easy
to care for, then what you need is the unique and
exclusive properties of granite.
Granite is available in a variety of colors, textures
and finishes which make it an excellent product
for countless applications related to building,
designing and civil engineering. Granite also possesses
indisputable strength and long-term durability;
moreover, it is an aesthetic and eye-catching material.
• Granite resists to corrosion, to our
cities’ polluted air and to acid rain.
• It also resists remarkably well to
wear and tear on interior flooring applications.
• Used outdoors, granite’s mineralogical
structure is not influenced by freeze-thaw cycles.
• Granite also provides a natural acoustic
barrier, which is another very practical and exclusive
advantage of this stone.
• Its thermal inertia is of great interest
to architects and promoters, who have to comply
with energy saving programs.
• Finally, granite is an all-natural
material to which nothing has been added, or removed.
TOP |
| |
|
•
What do I do with the samples that I already have ?
When you opted to work with
granite on your new project, you most likely already
had a few granite samples on the shelves of your
office library. Your librarian, or yourself, probably
also inquired with producers or quarriers that were
listed in your database, on the Web or with those
who had previously visited your office. You are
probably now (or will soon be) buried beneath a
mound of clashing samples, and have no idea of where
to begin to get to your final selection.
To make your first selection, you should ask the
following questions:
How long have you had
the samples?
Now and then, we receive
requests for pricing on granites whose quarries
have been closed for many years. Even if the quarry
still operates, the color or the grain may have
changed as the quarrying site evolved. First, you
should establish if the samples that you have are
still valid.
Your librarian, or person
in charge of keeping your samples, should always
note their date of receipt, before filing them away.
Who supplied the samples
and where did they come from ?
It is common for many firms
in the stone industry to promote the same granite
under different names. That is why it is very important
to know the source of your samples. Who gave you
these samples, and what is their firm's line of
work (quarrier, producer, importer/distributor,
mason contractor, consultant, etc.)?
Ideally, you should trace the granite's origin back
to its quarry in order to have factual answers regarding
rough production capacity, color uniformity, the
quarry's working cycles (i.e.: rain season in certain
countries, winter in others), quarrying methods,
etc. The producer is also a reliable source of answers
when he deals directly with the quarrier. The producer
knows about the product's source and its reliability.
The producer will be able to assist you with questions
related to optimal panel dimensions, range and texture
variations for different surface finishes, along
with the pros and cons of some architectural details.
In fact, the ideal situation is that of the quarrier/producer
who will be best informed to provide you with reliable
answers first-hand, as it knows more about its granites
and production than anyone else. Masons, importers/distributors,
and consultants are not always abreast of a quarry’s
evolution. They often base their opinions on obsolete
information, or on what profit margin can be made
on a product over another.
Insist to know the origin of the sample (country,
quarry and producer), so that you can do your own
research, if need be. Serious masons and contractors
will not hesitate to reveal their sample's origin.
Why was the sample submitted
to you, initially?
If the sample was presented
for a previous project, it may not be valid for
your current one. A quarry can produce different
color variations, depending on the section of the
quarry where the blocks are extracted.
When the quarrier/producer prepares a sample for
a specific project, he takes into account the required
quantities, timing of the project's delivery, budgetary
constraints, panel dimensions, fabrication delays,
etc. If one, or more, of these variables change,
then it is possible that another color variation
of the granite be considered instead.
Sample selection can differ depending on its purpose.
Is the sample for preliminary selection, to determine
an acceptable range, or to make a final selection?
When you inquire for samples, you should make sure
to mention at which stage you are within your decision
process.
When you receive a sample, take a few seconds
to write down the name of the project for which
the sample was submitted, as well as the stage in
your decision process (preliminary, range, final,
etc.).
Is there a quarry behind
the sample?
Any child is able to give
you a good-looking piece of stone (kids generally
have lots of them in their pockets). The Earth is
covered with stones and rocks. However, it is hard
to find and operate sites from which one can commercially
extract quality blocks in sufficient quantity to
meet today's production demands, while maintaining
color and grain uniformity. Therefore, make sure
there is a quarry behind the sample, before you
choose a stone from the most exquisite little piece
of rock.
Ask about the age of the quarry, how many categories
are there in terms of quality and color, and what
is its monthly production for each category. Obtain
a list of projects that were made with blocks from
the quarry, and ask about the quarry's constraints
(average block dimensions, natural intrusions, etc.).
TOP |
| |
|
• What are the
steps in the sample selection process ?
PRELIMINARY SAMPLES
Objective : To review
available granites in order to make your first selection.
Go through your sample library. Not only this will
enable you to become familiar with granites, but
with the producers as well. Contact the producers
directly to obtain new samples. Try to avoid middlemen.
Take this opportunity to obtain as much information
as possible on the granites that are accessible
through the producer.
GRANITE COLOR RANGE
APPROVAL
Objective: To obtain larger
samples, validate color conformity with preliminary
samples, and review the first color range.
When a first elimination has been made out of preliminary
samples, obtain larger samples that will depict
the color range you can expect, on account of the
project's required quantity and budget. These samples
should have a minimum of 12" x 12" so that the color,
structure and grain orientation are emphasized.
SLAB REVIEW
Objective: To visualize the
desired effect on larger surfaces, to better observe
the selected granite's typical characteristics,
and to approve the range of these characteristics
together with color range.
For an important project, both the client and the
architect should request a meeting at the producer’s
plant in order to inspect full size slabs. In this
case, the displayed slabs should have a minimum
of four feet by six feet (1.2 x 1.8 meters). These
slabs should be displayed outdoors, so they can
be seen in natural daylight. There should be several
slabs originating from different blocks. This exercise
should not be taken as a beauty contest. The purpose
is to show the granite's most common features (such
as possible intrusions, color variation, line or
grain orientation) and to discuss them in order
to approve, or reject, some of these features. This
stage of the selection process should take place
shortly after having selected your granite.
TOP |
| |
|
• What
are the cost-factors in designing with granite ?
The cost of granite varies
according to:
• The type
of granite chosen
Some types of granite are
more costly than others on account of quarrying
conditions at the site, and because some quarries
are located farther from processing plants than
others. The price of a granite has very little to
do with its structural features.
• Repeating
pieces and details
The more an item is repeated,
the less expensive it becomes to fabricate, as equipment
is set-up to optimize production on the assembly
line. Therefore, risks in fabrication and drawing
errors considerably diminish.
• Transformation
ratio and surface finish ordered
A project’s value is
largely influenced by the quantity and complexity
of finishing details, such as polished edges, anchor
preparations and special cuts. All these elements
must be scrutinized in order to minimize their impact
on the total cost of granite. The producer that
you will select for your project should be able
to assist you with architectural details and value
engineering.
• Desired
granite uniformity
As previously mentioned,
granite is a natural product which presents certain
characteristics that some people will like, others
not. Approving or rejecting some of these characteristics
will directly influence the waste factor, hence
the cost. It is crucial that you understand the
particulars of the granite you have selected. Some
intrusions, for example, could be approved on panels
that would not be apparent to the eye, such as window-reveals,
high-level elevations, etc.
• Panel shape
and thickness
Thickness has a direct impact
on total cubic meters necessary to fabricate a project,
on installation costs, as well as on freight charges
(weight versus surface).
Square or rectangular pieces are cheaper to fabricate.
Rounded shapes and angles increase the waste factor
and the number of stages in the production line.
• Anchoring
and installation systems
Hand-setting each piece on
the building is the most expensive installation
method, which is generally used for very complex
work (often at the base of a building). When the
hand-setting is performed by skilled stone-crafters,
the effect is exemplary.
The curtain-wall system,
which consists in integrating glass and stone together,
is pre-assembled in a fabrication plant. This results
in easier and faster installation at the site.
The Precast system consists in cutting the granite
panels to size, and shipping them to a Precast Plant,
where they will be set in concrete. At first glance,
this seems to be the most economical system. However,
granite producers are not too keen on the idea,
because of the very high risk of breakage attributed
to handling, and also because the panels are often
put together without consideration to the order
in which they should be installed.
The steel frame — or truss system —
is commonly used on high-rise buildings or in areas
known for seismic activity. It might be economical
if the building is more than five stories high.
Design complexity, building height, and availability
of specialized installation firms usually determine
installation methods.
• Project scheduling
and financing
It goes without saying that
a tight delivery schedule will also entail additional
costs. Project scheduling must be planned by alert
administrators who also have realistic expectations.
Granicor can help you to reduce the overall cost
of a project, by offering value engineering or by
helping you to select a more economical granite.
TOP |
| |
|
• Why is the color
of the installed granite different from the samples
provided ?
There are many possible answers
to this question. Yet, the most frequent are:
• The sample did not come from the same
quarry as the installed product. Either the specification
was not sufficiently explicit, or it was not followed.
• The order was sent in so late, that
it was impossible for the producer to extract blocks
specific to the project. And, in order to meet deadlines,
the producer had to work with what blocks or slabs
were available on the market, even if they did not
match the architect’s choice.
• Someone found a cheaper product and
is trying to substitute the specified granite with
the cheaper material.
• The selection was made from samples
that did not show the complete color range and markings
typical of the granite.
• The necessary steps of the selection
process were not entirely observed. The specifier
did not entirely understand the nature of the product.
TOP |
| |
|
• How
to choose a granite producer ?
Any granite project may not
turn out successfully, if your producer has not
been as minutely researched as your granite. Although
companies who specialize in transforming marble
and granite may have significantly increased in
number over the last few years, most of them labor
in the fabrication of interior design items, such
as kitchen countertops. They have a limited production
capacity and cannot transform blocks into slabs.
Consequently, they have no control over raw materials,
or on primary transformation. There are, in fact,
only a few firms that can supply — within
required lead-times — cladding panels for
medium and large-scale buildings.
Their List of Equipment
should help you see through their real production
capacity. This list should include:
• Primary saws
that allow primary transformation of raw blocks
into slabs. They are known as gangsaws, which are
used in making 20 to 50mm thick slabs, and radial
saws (minimum 3 meters in diameter) that are used
to cut thicker slabs. The following formula can
help you to approximate the primary transformation
capacity of a fabricator:
Loading capacity X [1000mm ÷ (nominal slab thickness
+ 10mm)]
Ex.: if you wish to produce 20mm slabs and the average
loading charge of the saws is 11 cubic meters, this
would correspond to the following quantities:
11 cubic meters X [1000mm ÷ (20mm + 10mm)] = 366.63
M2 per descent.
Multiply this result by the number of descents in
one week (±1.5) and by the number of gangsaws, and
you will have the approximate weekly capacity of
the company. Many factors can influence the production
capacity, namely: quality, dimensions and shape
of the blocks. However, this formula — though
approximate — enables you to compare the primary
production capacity of different companies.
• Surface finish is the second step of
the transformation process; it should also be taken
into consideration during your analysis. Polish,
hone and flamed (or thermal) are the most often
seen finishes. The first two are achieved with a
multi-head automatic polisher and the third, with
an automatic flaming machine fit with an automatic
flaming torch and a continuous belt. This equipment
is used for surface finishing only, not for edge
work.
• The third step is to cut the pieces
down to size. There are a large number of equipment
brands that can carry out this task; each of them
has characteristics that influence production capacity.
Yet, it takes more than one machine to produce medium
and large-scale projects within reasonable lead-times.
• Subsequent steps vary considerably
from one project to another. Consequently, it is
necessary to look at architectural details specific
to each project, such as anchor types, polished
or flamed edges, and non-angular cuts. If there
are many repeating details in the project, then
it is preferable that they should be done with automatic
machinery in order to cut down on their fabrication
time (and cost). You will find in a well-organized
fabrication plant: automatic edge polishers, anchor
hole drilling equipment (for either backs or edges),
contour machines, equipment for drilling holes of
different diameters, etc. All these details could
also be executed by hand, using basic fabrication
tools. But it is a time-consuming process, which
often produces pieces of questionable quality or
uniformity.
• You should not hesitate to ask questions
concerning equipment, to producers who wish to submit
pricing. Compare their production capacity, and
make sure that they can supply your granite within
required lead-times.
The Support Team is another critical element
in choosing a producer. Projects require in-depth
comprehension of architectural plans, of construction,
as well as efficient project and production management.
For a producer, a project begins when a request
for information is received. The producer must be
competent to provide technical assistance (value
engineering) to architects and contractors; it must
also have the ability to provide all necessary information
pertaining to granite selection and to make suggestions
on some design elements. The support team should
comprise of experienced draftsmen, engineers, senior
estimators as well as proficient managers.
Experience — without it being a guarantee
— can also indicate a producer’s competence.
Why not look at its portfolio and study its achievements?
Ask for a list that not only shows the project names,
but also the names of architects, general contractors
and masons. This will enable you to substantiate
the producer’s reputation.
Easy Access to Quarries is often the key
to a successful granite project. Even with the most
advanced equipment and most accomplished stone-crafters,
a producer cannot do anything if it cannot control
the source of raw materials. The producer must have
access to the quarry at all times, or have excellent
business relations with the quarrier. Proper block
selection is paramount.
TOP |
| |
|
• Why can’t
I substitute a similar granite to the granite selected ?
Occasionally,
you will find very similar granites in completely
opposite areas of the globe. Then, why would you
worry about the origin of the sample or granite ?
• For practical reasons: You have already
confirmed the quarry’s production capacity,
the possible color variations of the stone, etc.,
in order to ensure color uniformity and availability
of sufficient quantities to fabricate the project,
according to your production schedule. You should
then know that the other quarry, which produced
such a similar sample, could hide significant disparities.
There can be faults that hinder the capacity to
extract blocks of acceptable size; the quarry may
not have the proper equipment to provide the required
number of blocks within its quarrying season; there
can be environmental restrictions that obstruct
quarry operations, etc. If you happen to find an
acceptable sample from another quarry, you must
start the selection process all over again, because
you will be choosing the quarry as much as you are
the sample.
• For humanitarian reasons: Perhaps
not as compelling as substantial financial savings
can be, you should nevertheless be aware that in
some countries, young children and abused workers
toil in quarries and fabrication plants. Some building
owners might wish to avoid any possible controversy,
as it could seriously impede their marketing efforts.
TOP |
| |
|
• What do I do
with similar granites that have different names?
Ask the firms that provided
you with the samples to confirm the quarries’
exact location. Establish who is the quarrier. This
will enable you to find if the samples are of the
same origin. Be cautious: there may be more than
one quarry, which produce very similar granites
within a limited geographic area. In such case,
each quarry must be evaluated individually, as both
can have totally different characteristics and production
capacities.
TOP |
| |
|
• How can I be
sure to select the right granite ?
Each
selection process should allocate a significant
amount of time to testing. Though color and aesthetical
qualities are important, physical properties should
be the predominant factor in the final selection
of your granite. ASTM is the norm in North America.
Tests most often performed are:
| • Absorption
by weight % |
C97 |
| • Density
|
C97 |
| • Compressive
strength |
C170 |
| • Abrasion
resistance, hardness |
C241 |
| • Flexural
strength |
C880 |
These tests will help you to establish if certain
granites are suitable for a specific application
and environment. They also help in determining panel
dimensions and/or thickness constraints.
The proper granite should be selected for a particular
project, only once you have identified the primary
criteria that it should satisfy. For this, you must
take into consideration the following:
• Frost and thaw cycles
• Salt water proximity (saline air and
permanent humidity)
• Polluting agents (proximity to factories)
• Application of deicing products
• Windshield factor
• Acid rains, smoke, etc.
• With horizontal surfaces: traffic density,
maintenance vehicle circulation, etc.
Of course, granite is resistant to corrosion, polluted
atmosphere, as well as to frost and thaw. However,
you need to compare the geological definition against
the commercial definition to really understand the
importance of testing. Let us not forget that granites
are made of diverse mineralogical aggregations,
which composition varies from one to another.
Testing is expensive to producers. To avoid that
this cost be added to the producer’s quote,
make sure the granite you are interested in has
already been tested for previous projects. In general,
serious producers will test all their new granites
systematically.
For more information on ASTM Testing Methods, you
may click to http://www.astm.org/.
TOP |
| |
|
|
| |
|
|
|
|
