| |
Cast Stone and Precast Concrete textures and products
manufactured by Ventura Precast.
Glossary of
textures
Description: Scagliola Texture
(click to enlarge)
| Scagliola texture, made in precast concrete or GFRC product, rich
natural stone texture resembling cut marble. |
| Name is derived from the Italian word "scaglia" meaning "chips of
stone". |
| Ancient secret formula dating from the 15th century, revived and
improved upon by Italian monks in the 17th century, and which had all but
disappeared by the 19th century. |
| Lightweight thin wall GFRC or full weight precast, with smooth
polished surface with many small irregular fissures and swirls. |
| Made from crushed limestone or aggregates, fiberglass reinforcement, cement, and integrated pigment. |
| Hand laid into molds. |
Description: Travertine Texture
(click to enlarge)
| Travertine texture, made in precast concrete or GFRC product,
resembles travertine or cut and polished limestone. |
| Lightweight thin wall GFRC or full weight precast, with smooth regular
polished surface with small irregular fissures. |
| Made from sand or aggregates, fiberglass reinforcement, cement, and integrated pigment. |
| Hand laid into molds. |
Description: Old World Texture
(click to enlarge)
| Old world texture, precast concrete or GFRC product, resembles aged
stone with flashes of color and deep fissures. |
| Lightweight thin wall GFRC or full weight precast, with bright multicolored hand made highlights. |
| Made from sand or special aggregates, fiberglass reinforcement, cement, and integrated pigment. |
| Hand laid into molds.
|
Description: Sanded Texture
(click to enlarge)
| Sanded texture, precast concrete or GFRC product, resembles sandstone,
regular smooth sandy surface. |
| Lightweight thin wall GFRC or full weight precast, with sandstone look
and feel. |
| Made from sand and aggregates, fiberglass reinforcement, cement, and integrated pigment. |
| Hand laid or sprayed into molds..
|
Description: Smooth texture
(click to enlarge)
| Smooth texture, precast concrete or GFRC product, smooth plaster like
finish, with a regular surface. |
| Lightweight thin wall or full weight. |
| Made from sand and aggregates, fiberglass reinforcement, cement, and integrated pigment. |
| Hand laid or sprayed into molds..
|
Glossary of products
Description: GFRC (glass fiber reinforced concrete)
(click to enlarge)
| GFRC product, resembles aged stone at approximately 25% of the
weight. |
| Lightweight thin wall with many different textures available (see
above). |
| Made from sand or aggregates, fiberglass reinforcement, cement, and integrated pigment. |
| Hand laid or machine sprayed into molds..
|
Description: Precast Concrete
(click to enlarge)
(click to enlarge)
| Precast concrete can be made to resemble many natural products. |
| Precast concrete is "full weight" concrete with many
different textures available (see above). |
| Made from sand or aggregates, cement, and integrated pigment. |
| Wet poured or hand laid into molds.
|
Description: Cast Stone
(click to enlarge)
| Cast stone resembles expensive cut limestone at 25% of the cost. |
| Cast stone is usually "full weight" concrete, with sharp
edges and rich texture, more uniform in color and texture than other cast products. |
| Can also be made in lightweight GFRC. |
| Made from limestone sand, white cement and integrated pigment. |
| Dry packed into molds under extreme pressure. |
| More expensive than our other products.
|
Description: GRG (glass fiber reinforced gypsum)
| GRG can be made to resemble many natural products. |
| Recommended for indoor use only (unless modified). |
| Made from gypsum, sand or aggregates, polymers, and integrated pigment. |
| Wet poured, sprayed or hand applied into molds. |
A short lesson on our concrete products.
GFRC (glass fiber reinforced concrete)
We simulate aged stone by hand laying a mix of special aggregates and cement
into molds with special "techniques", making the product look time worn or
aged, resembling the old stone moldings seen at many historical sites or
buildings. The GFRC product is thinwall about 3/4" thick and is extremely strong
and about 25% the weight of solid stone.
Precast concrete can also be sprayed into molds, resulting in a smooth
unblemished surface.
Precast concrete
We also simulate limestone or sandstone by pouring a mix of wet concrete into
molds and when cured are then sand washed,
to remove the fine cured cement particles at the surface of the product, and
hopefully expose the aggregates to give the product the highly desired limestone
"look".
Precast concrete can also be sprayed into molds, resulting in a smooth
unblemished surface.
Cast Stone
Cast stone, used by man since the Egyptian pyramids were constructed, is hand
packed into molds under tremendous pressure, just as in nature when limestone is
made from the extreme pressure on sand, lime and slurry over thousands of years.
This technique of compacting sand, crushed limestone and colored pigment with a
small amount of water ensures a product which closely resembles limestone.
Uniform in color and texture because very little water is used in it's
production, cast stone is used where limestone or sandstone is desired but is
cost prohibitive. The surface of cast stone shows the aggregate naturally at its
surface, simulating limestone or sandstone.
Cost's more than our other products because of the Materials used and the
special molds needed in it's manufacture.
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Copyright © 2002 Ventura Cast Stone.
PO Box 552, Somis, CA 93066 (805) 386-8185 Fax: (805)
386-3002
|
Cast stone
We at
Ventura Precast are pleased to introduce this lightweight GFRC cast stone or lightweight precast concrete if you will, into our line of precast concrete and cast stone. Because lightweight cast stone is made from fiberglass
strand mixed with real limestone which gives it that stone look, it is suitable for fireplace mantle treatments.
Lightweight precast concrete
Lightweight precast concrete is usually called GFRC or glass fiber reinforced concrete, and is manufactured by Ventura cast stone and
installed in the Los Angeles, Ventura and Santa Barbara Counties. Precast concrete usually weights 100 lbs per cubic foot. Gfrc usually weights 10 lbs per lin foot. Precast concrete is a lower end product
and does not simulate limestone as does cast stone. Precast concrete resembles finished concrete and the surface looks like your garage floor. Cast stone resembles limestone or sandstone. Lightweight
GFRC precast concrete is not a new
product but has been used for years, but not in architectural uses.
Our Cast Stone range of products are into two product types:
Dry Cast
The "Dry Cast" method is a two part process, a face material to give
you the similar finish to natural stone. Mechanically compacted to the
rear of this is the backing mix to give the units strength in the terms
of handling ability
Dry cast units are immediately demoulded after casting and are hand
finished to a very high standard.
Wet Cast
Wet Cast as the name suggests produces structural products like heads
and sills but is also used for slabs, beams and other similar products,
that are for high exposure or structural situations where greater loads
are required on the finished unit. The Wet Cast also has the added
advantage of specialist finishes with the use of special sand
aggregates, a massive spectrum of colors can be achieved.
Introduction to Cast Stone (wet cast and dry cast)
Cast Stone is known by a variety of
other names including art stone, reconstructed stone, reconstituted
stone, artificial stone and manufactured stone. This defines cast
stone as any material manufactured with aggregate and cementicious
binder and intended to resemble in appearance, and be used in a similar
way to, natural stone. Cast stone is either homogenous through out or
consists of a facing material and backing concrete.
The method of production is split into two categories.
| Semidry mixes |
| Precast concrete or sometimes referred to as 'wet' cast. |
Choice of manufacturing method
The majority of cast stone manufactures use the semi-dry method of
production. And is the more commonly widely used method of manufacture.
Early consultation with us is advisable to ascertain the correct method
of production for your project.
Sizes: Components produced using the semidry
method are limited in size with face dimensions of Ashlar units normally
no greater than 1200x600mm. This is mainly because of the fact a semi
dry mix is used, which require rapid and rigorous compaction with hand
held pneumatic tampers. The semidry method of production is best suited
to traditionally sized ashlars quoins, sills, copings, door and window
surrounds, etc.
Structural requirements: Components requiring
reinforcement which is more complex than a few straight bars or a layer
of fabric reinforcement, must be produced using the wet cast method of
production. This is because it is difficult to achieve thorough
compaction of semidry mixes around congested reinforcement.
Appearance: Cast stone can replicate a variety
of stone colors and finishes. The semidry method of production is used
to simulate limestones and sandstones. Where a component has a
particularly intricate pattern or profile including slender projections,
precast concrete may have to be used in preference to the 'semidry'
method. Good color matching between components can be achieved by both
methods, although textural differences become apparent at close range.
Economics: Rapid production rates with frequent
reuse of moulds are possible with cast stone produced using semidry
mixes. Where as with the Wet Cast process a higher number of concrete molds is
required to achieve the same casting program, but careful thought a
planning stages of the contract can minimize the number of concrete molds. In
Fact an additional 2-3 weeks extra lead-time for standard or semi
standard products can sometimes be all that is needed to achieve the
same casting program.
Comparison between the semidry and wet methods
The production of cast stone using semidry mixes differs from that of
wet method in several ways.
Casting
Semi Dry ~ De-molding takes place immediately after compaction. This
allows a rapid casting cycle with e.g. up to 100 or more basic
components (sills, copings, etc.) a day from a single mould.
Wet Cast ~ Where as to manufacture the equivalent in wet cast it
would not only take longer but you would require 1 mould per cast per
day i.e. to produce 100 units a day you would need 100 moulds.
Semi Dry ~Compaction is carried out by pneumatic tampers rather than
by vibration.
Wet Cast ~ Compaction is carried out by vibration.
Mixes
Semi Dry ~ *Separate facing and backing mixes are often used for
components like ashlars, sills, heads and jambs, where the backing mix
is concealed from view. Separate facing and backing mixes are used
primarily to economize on the facing mix. BS1 217 requires a separate
facing mix to be not less than 20 mm thick at any point, with semidry
cement sand facing mixes and concrete backing mixes each mix is placed
and compacted in immediate succession to ensure that they are
effectively monolithic.
Wet Cast ~ Wet Cast units are manufactured from a through colored
homogenous mix.
Semi Dry ~ Water repellent admixtures are invariably used in facing
mixes to reduce permeability. Giving a water absorption of Grade B. All
constituents are accurately weigh batched with the moisture content
monitored regularly. Mix batches are necessarily small to prevent any
premature drying of the mix. Thorough mixing and compaction are critical
to ensure that the cast stone achieves the required density (typically
between 1850-2100kg/m2), compressive strength and permeability.
Wet Cast ~ superplasticisers and accelerators are used to ensure good
flow of the mix during vibration and compaction to achieve a smooth,
compact and blow hole free finish (where ever possible finish smooth
after dressing) also to give good early strength. Typical cube tests at
7-10 Days are that of the equivalent of that of a semi dry unit at 28
Days
Products are split into three categories.
Standard - Cast stone items that are
manufactured in accordance with our Technical specification sheets.
These items could be stock items or units, which are ready to cast at
the first available production slot, with no moulds to produce. Products
like standard head, sills or pier caps and copings. The cost of
establishing the moulds is not same, thus for small production runs
costs can be kept to the minimum. Also not forgetting lead times can be
much shorter by not having to detail, obtain approval and then construct
moulds.
Semi Standard - Cast stone items, which are
similar to details within our Technical specification sheets. But say
vary in length or require slight mould adaptation or modification.
Purpose Made - Cast Stone items which are
manufactured in accordance with the contract documents. These units are
made from new purpose made concrete molds. These would probably be
specialized units, which are not contained in our brochure. We have our
own in house design department, who will assist you in the process of
your design advising you in Careful thought must be given in the
planning process for purpose made products. Please consider the
following.
| Design and detailing of in house production drawings- Some times
it is of necessity to produce working drawings of Architects details
to enable production of moulds.
This process can some times take any thing from 2 10 days,
dependant on how long it takes to get details approved.
|
| Approval of production drawings.
|
| Production of Patterns- Sometimes it is necessary to produce units
from G.R.P. or Rubber moulds.
|
| This may involve the pattern being produced and before moulds are
manufactured, approval of the pattern may be sort from the Architect
or Client.
|
| Approval of production patterns
|
| Manufacture of concrete molds
|
| Production of Units
|
| Curing of units
|
| Packaging and Transportation to Site
|
Remember adequate time must be allowed for production of concrete
molds.
Colors and Finishes
Natural stone colors are achieved either by reliance on the color of
crushed rock and sands and aggregates or by the addition of pigments.
White cement gray cement and a combination are often used. The use of
pigments can give the cast stone greater scope in the selection of
suitably graded aggregates, which permit good compaction and achieve a
strong, dense mix. Iron oxides based pigments are normally used in small
quantities (e.g. 0.2%-1% yellow iron oxide by weight of cement for
yellow sandstone's and up to 5% red iron oxide for red sandstone). High
proportions of pigment powder (above say 6 - 8% by weight of cement) are
used sometimes to achieve unusual colors like blues and browns but
generally these should be avoided.
A variety of traditional ashlar finishes can be replicated with cast
stone, including plain, boasted, tooled, rockfaced, vermiculated. The
other ashlar finishes are normally produced from latex:sand or concrete mold
liners.
| Semi Dry ~ Plain finishes normally produced using sealed plywood
mould liners or, where the shape, detail or longevity for mould
dictates, fiberglass is used. |
| Wet Cast ~ unlike the semidry method, the wet cast mix produces a
surface laitance which has to be removed after demoulding to reveal
the color and texture of the fines layer. The laitance is removed by
either acid etching or retarding the surface within the mould prior to
curing and washing off after demolding to achieve a smaller large
expose of aggregate. |
Here is where specialist aggregates can be used to achieve some
wonderful and varied finishes and colors.
Structural Use
Dependant on the situation all cast stone both Wet and Dry Cast can
be used. But there are limitations in the Dry Cast process as opposed to
Wet Cast: -
| Semi Dry ~ Components requiring reinforcement which is more
complex than a few straight bars or a layer of fabric reinforcement
are not possible. This is because it is difficult to achieve thorough
compaction of semidry mixes using a pneumatic tamper in and around the
congested reinforcement. Therefore Wet Cast is the option.
|
| Wet Cast ~ unlike the semidry method, the Wet Cast mix is poured
into the mould as thick liquid mix and compaction is achieved by
vibration. So even the more complex arrangement of bars can be
compacted sufficiently. The added advantage being the need to put any
secondary support like pressed or fabricated steel lintel saving
costs. Also we can manufacture structural beams for larger vehicle
entranceways for example. |
Cast Stone
Cast stone by
Ventura Cast Stone installed in California city's such as
Los Angeles, Beverly Hills, Bel Air, Ventura or Santa Barbara has to be
mechanically fastened to the wood frame of a building usually with
stainless steel or galvanized attachments, this because of earthquake
codes. There are many historical buildings in California with cast
stone as part of their facade. Cast stone in
Los Angeles, Beverly hills, Bel Air, Ventura and Santa Barbara was at it's
most popular in the 1900's. In Santa Barbara, cast stone was used
extensively in the downtown district and also in a primitive form at the
Santa Barbara mission in the form of adobe, a mixture of mud and straw or horsehair
mixed with water and hand shaped into molds. Cast stone in the City
of Ventura was used mainly on churches in the downtown area. Cast
stone in Los Angeles was used in many important buildings including the
famous Los Angeles City hall. In Santa Barbara cast stone and Santa
Barbara stone were used in conjunction in many historical buildings.
Santa Barbara stone also called Santa Barbara sandstone, is found mainly
in Santa Barbara county, is removed from the ground in loose form, the
Santa Barbara stone is then cut and shaped by a stonemason into useable
blocks. Cast stone in Beverly Hills was used in the Beverly Hills
City hall and is now used on many residential buildings.
We also supply and install granite and CDI precast caststone and concrete design product, CDI columns,
Sierra stone caststone columns and balustrade, California precast
products, CDI precast, CDI precast granite moldings and stairs. We also supply and install CDI precast
granite concrete
window and door trim, CDI GFRC columns, Sierra stone products, concrete design, full weight
precast
and granite or limestone products, California precast columns, CDI precast pool coping, CDI precast
or limestone moldings
and CDI fireplace mantles. We manufacture our own concrete molds.
Precast concrete
Precast concrete is
usually used in lower end track homes where budget is a concern, cast
stone is usually used in higher end homes where budget is not a major
concern. The difference between
cast stone and precast concrete is easily seen, and even the novice can
appreciate the high quality limestone like finish on a cast stone product.
Fireplace mantels or as some call them fireplace mantles look beautiful
when constructed from cast stone. Cast stone fireplace mantels are used in
any situation. The fireplace mantels are both strong and fireproof.
Fireplace mantels are
a thing of beauty when made from cast stone or precast concrete. Fireplace
mantels are also made from wood. Fireplace mantels or fireplace chimneys
are the main feature in any room and a fireplace mantel made from cast
stone or precast concrete is a sight to behold.
Cast stone by
Ventura Cast Stone installed in California city's such as
Los Angeles, Beverly Hills, Bel Air, Ventura or Santa Barbara has to be
mechanically fastened to the wood frame of a building usually with
stainless steel or galvanized attachments, this because of earthquake
codes. There are many historical buildings in California with cast
stone as part of their facade. Cast stone in
Los Angeles, Beverly hills, Bel Air, Ventura and Santa Barbara was at it's
most popular in the 1900's. In Santa Barbara, cast stone was used
extensively in the downtown district and also in a primitive form at the
Santa Barbara mission in the form of adobe, a mixture of mud and straw or horsehair
mixed with water and hand shaped into molds. Cast stone in the City
of Ventura was used mainly on churches in the downtown area. Cast
stone in Los Angeles was used in many important buildings including the
famous Los Angeles City hall. In Santa Barbara cast stone and Santa
Barbara stone were used in conjunction in many historical buildings.
Santa Barbara stone also called Santa Barbara sandstone, is found mainly
in Santa Barbara county, is removed from the ground in loose form, the
Santa Barbara stone is then cut and shaped by a stonemason into useable
blocks. Cast stone in Beverly Hills was used in the Beverly Hills
City hall and is now used on many residential buildings.
We also supply and install granite and CDI precast caststone and concrete design product, CDI columns,
Sierra stone caststone columns and balustrade, California precast
products, CDI precast, CDI precast granite moldings and stairs. We also supply and install CDI precast
granite concrete
window and door trim, CDI GFRC columns, Sierra stone products, concrete design, full weight
precast
and granite or limestone products, California precast columns, CDI precast pool coping, CDI precast
or limestone moldings
and CDI fireplace mantles. We also install the products exclusively
manufactured by other company's including,
Sierra concrete design, Sierra stone and Dura art stone, Stone legends,
Moonlight molds, Fineline precast, Concrete design inc. Studio cast
design, Concrete design inc, CDI, Architectural products, Haddonstone.
These products include: cast stone,
limestone, precast concrete, precast, cast, stone, limestone, sandstone,
los angeles, ventura, santa barbara, los angeles precast, los angeles
columns, los angeles cast stone, santa barbara precast, santa barbara cast
stone, santa barbara stone, santa barbara columns, ventura cast stone,
ventura precast, ventura columns, ventura stone. These products include: cast stone,
limestone, precast concrete, precast, cast, stone, limestone, sandstone,
los angeles, ventura, santa barbara, los angeles precast, los angeles
columns, los angeles cast stone, santa barbara precast, santa barbara cast
stone, santa barbara stone, santa barbara columns, ventura cast stone,
ventura precast, ventura columns, ventura stone, concrete molds.
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vi About Ventura
Cast Stone
Cast stone
We are pleased to introduce a new line of Tuscan
moldings, taken from actual moldings from the Villas and grand homes of
the Tuscany region of Italy.
Ventura Cast Stone product, 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.
Cast stone is a highly
refined architectural precast concrete stone manufactured to simulate
natural cut stone. It is a masonry product that provides architectural trim
and ornamentation. Used for centuries in Europe and in the United States in
the 1900s, cast stone has gained widespread acceptance in the architectural
community as a suitable replacement for many masonry materials and for all
types of natural cut building stones. Continental Cast Stone manufactures
cast stone using the VDT (vibrant dry tamp) method. A zero slump mix is
compacted into a rigid mold, resulting in a finish that is virtually
indistinguishable from quarried limestone. The primary advantage of this
method is that it virtually guarantees the absence of air voids (also known
as "bug holes") on the surface. Cast stone made by the company meets the
requirements of ASTM C-1364, the Standard Specification for Architectural
Cast Stone.
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.
Cast
Stone is a highly refined architectural building stone, usually
made up of white cement and a combination of various sizes aggregates of
white marble, quartz, or other durable white stone. The aggregates are
numerous and are meticulously graded by sieve analysis to produce a material
that is dense and lack voids.
The cast material is impervious to
moisture, and will test in compression to 6,000 psi and not over 5% water
absorption. The surface skin of the cement on cast stone is removed to
expose the white stone (or other) aggregates, which reflect and sparkle over
the matrix.
Since cast stone is a type of
architectural precast stone, the question is often asked: "What is the
difference between cast stone and architectural precast concrete?" The short
answer is that cast stone is used in place of natural stone. As a type of
building stone, cast stone is specified under the masonry division 04720. It
is usually set by a masonry contractor using standard building stone
anchors. Perhaps most important, and unless otherwise specified, cast stone
looks like natural stone, dimensional, cut building stone. Upon close
examination, the finish of cast stone looks like limestone.
To distinguish its appearance from the
"pebbly with voids" appearance normally associated with concrete. This dense
finish is more resistant to weather and dirt, and the fine aggregates retain
the granular texture through decades of exposure to the elements. The
character of Cast Stone, made as described above, is similar in color,
texture, and appearance to a good grade of natural cut limestone, but is
stronger, since strength can be controlled through the manufacturing process
and is more impervious to water, weather, and dirt. By controlling the
proportion of white and /or gray cement, manufactured or natural sands,
carefully selected crushed stone or well-graded natural gravel, and mineral
coloring pigments, cast stone can be made to simulate perfectly many other
natural cut building stones, such as brownstone, sandstone, bluestone,
granite, slate, keystone, travertine, and others.
Our Cast Stone range of products are into two product types:
Dry Cast
The "Dry Cast" method is a two part process, a face material to give
you the similar finish to natural stone. Mechanically compacted to the
rear of this is the backing mix to give the units strength in the terms
of handling ability
Dry cast units are immediately demoulded after casting and are hand
finished to a very high standard.
Wet Cast
Wet Cast as the name suggests produces structural products like heads
and sills but is also used for slabs, beams and other similar products,
that are for high exposure or structural situations where greater loads
are required on the finished unit. The Wet Cast also has the added
advantage of specialist finishes with the use of special sand
aggregates, a massive spectrum of colors can be achieved.
Introduction to Cast Stone (wet cast and dry cast)
Cast Stone as is in the British Standard is known by a variety of
other names including art stone, reconstructed stone, reconstituted
stone, artificial stone and manufactured stone. BS 1217 defines cast
stone as any material manufactured with aggregate and cementicious
binder and intended to resemble in appearance, and be used in a similar
way to, natural stone. Cast stone is either homogenous through out or
consists of a facing material and backing concrete.
The method of production is split into two categories.
| Semidry mixes |
| Precast concrete or sometimes referred to as 'wet' cast. |
Choice of manufacturing method
The majority of cast stone manufactures use the semi-dry method of
production. And is the more commonly widely used method of manufacture.
Early consultation with us is advisable to ascertain the correct method
of production for your project.
Sizes: Components produced using the semidry
method are limited in size with face dimensions of Ashlar units normally
no greater than 1200x600mm. This is mainly because of the fact a semi
dry mix is used, which require rapid and rigorous compaction with hand
held pneumatic tampers. The semidry method of production is best suited
to traditionally sized ashlars quoins, sills, copings, door and window
surrounds, etc.
Structural requirements: Components requiring
reinforcement which is more complex than a few straight bars or a layer
of fabric reinforcement, must be produced using the wet cast method of
production. This is because it is difficult to achieve thorough
compaction of semidry mixes around congested reinforcement.
Appearance: Cast stone can replicate a variety
of stone colours and finishes. The semidry method of production is used
to simulate limestones and sandstones. Where a component has a
particularly intricate pattern or profile including slender projections,
precast concrete may have to be used in preference to the 'semidry'
method. Good colour matching between components can be achieved by both
methods, although textural differences become apparent at close range.
Economics: Rapid production rates with frequent
reuse of moulds are possible with cast stone produced using semidry
mixes. Where as with the Wet Cast process a higher number of moulds is
required to achieve the same casting program, but careful thought a
planning stages of the contract can minimize the number of moulds. In
Fact an additional 2-3 weeks extra lead-time for standard or semi
standard products can sometimes be all that is needed to achieve the
same casting program.
Comparison between the semidry and wet methods
The production of cast stone using semidry mixes differs from that of
wet method in several ways.
Casting
Semi Dry ~ De-molding takes place immediately after compaction. This
allows a rapid casting cycle with e.g. up to 100 or more basic
components (sills, copings, etc.) a day from a single mould.
Wet Cast ~ Where as to manufacture the equivalent in wet cast it
would not only take longer but you would require 1 mould per cast per
day i.e. to produce 100 units a day you would need 100 moulds.
Semi Dry ~Compaction is carried out by pneumatic tampers rather than
by vibration.
Wet Cast ~ Compaction is carried out by vibration.
Mixes
Semi Dry ~ *Separate facing and backing mixes are often used for
components like ashlars, sills, heads and jambs, where the backing mix
is concealed from view. Separate facing and backing mixes are used
primarily to economize on the facing mix. BS1 217 requires a separate
facing mix to be not less than 20 mm thick at any point, with semidry
cement sand facing mixes and concrete backing mixes each mix is placed
and compacted in immediate succession to ensure that they are
effectively monolithic.
Wet Cast ~ Wet Cast units are manufactured from a through colored
homogenous mix.
Semi Dry ~ Water repellent admixtures are invariably used in facing
mixes to reduce permeability. Giving a water absorption of Grade B. All
constituents are accurately weigh batched with the moisture content
monitored regularly. Mix batches are necessarily small to prevent any
premature drying of the mix. Thorough mixing and compaction are critical
to ensure that the cast stone achieves the required density (typically
between 1850-2100kg/m2), compressive strength and permeability.
Wet Cast ~ superplasticisers and accelerators are used to ensure good
flow of the mix during vibration and compaction to achieve a smooth,
compact and blow hole free finish (where ever possible finish smooth
after dressing) also to give good early strength. Typical cube tests at
7-10 Days are that of the equivalent of that of a semi dry unit at 28
Days
Products are split into three categories.
Standard - Cast stone items that are
manufactured in accordance with our Technical specification sheets.
These items could be stock items or units, which are ready to cast at
the first available production slot, with no moulds to produce. Products
like standard head, cills or pier caps and copings. The cost of
establishing the moulds is not same, thus for small production runs
costs can be kept to the minimum. Also not forgetting lead times can be
much shorter by not having to detail, obtain approval and then construct
moulds.
Semi Standard - Cast stone items, which are
similar to details within our Technical specification sheets. But say
vary in length or require slight mould adaptation or modification.
Purpose Made - Cast Stone items which are
manufactured in accordance with the contract documents. These units are
made from new purpose made moulds. These would probably be specialised
units, which are not contained in our brochure. We have our own in house
design department, who will assist you in the process of your design
advising you in Careful thought must be given in the planning process
for purpose made products. The following points should be bore in mind
before hand.
| Design and detailing of in house production drawings- Some times
it is of necessity to produce working drawings of Architects details
to enable production of moulds.
This process can some times take any thing from 2 10 days,
dependant on how long it takes to get details approved.
|
| Approval of production drawings.
|
| Production of Patterns- Sometimes it is necessary to produce units
from G.R.P. or Rubber moulds.
|
| This may involve the pattern being produced and before moulds are
manufactured, approval of the pattern may be sort from the Architect
or Client.
|
| Approval of production patterns
|
| Manufacture of molds
|
| Production of Units
|
| Curing of units
|
| Packaging and Transportation to Site
|
Remember adequate time must be allowed for all of the above to be in
accordance with B.S.1217
Colors and Finishes
Natural stone colors are achieved either by reliance on the color of
crushed rock and sands and aggregates or by the addition of pigments.
White cement gray cement and a combination are often used. The use of
pigments can give the cast stone greater scope in the selection of
suitably graded aggregates, which permit good compaction and achieve a
strong, dense mix. Iron oxides based pigments are normally used in small
quantities (e.g. 0.2%-1% yellow iron oxide by weight of cement for
yellow sandstone's and up to 5% red iron oxide for red sandstone). High
proportions of pigment powder (above say 6 - 8% by weight of cement) are
used sometimes to achieve unusual colors like blues and browns but
generally these should be avoided.
A variety of traditional ashlar finishes can be replicated with cast
stone, including plain, boasted, tooled, rockfaced, vermiculated. The
other ashlar finishes are normally produced from latex:sand mould
liners.
| Semi Dry ~ Plain finishes normally produced using sealed plywood
mould liners or, where the shape, detail or longevity for mould
dictates, fiberglass is used. |
| Wet Cast ~ unlike the semidry method, the wet cast mix produces a
surface laitance which has to be removed after demoulding to reveal
the color and texture of the fines layer. The laitance is removed by
either acid etching or retarding the surface within the mould prior to
curing and washing off after demolding to achieve a smaller large
expose of aggregate. |
Here is where specialist aggregates can be used to achieve some
wonderful and varied finishes and colors.
Structural Use
Dependant on the situation all cast stone both Wet and Dry Cast can
be used. But there are limitations in the Dry Cast process as opposed to
Wet Cast: -
| Semi Dry ~ Components requiring reinforcement which is more
complex than a few straight bars or a layer of fabric reinforcement
are not possible. This is because it is difficult to achieve thorough
compaction of semidry mixes using a pneumatic tamper in and around the
congested reinforcement. Therefore Wet Cast is the option.
|
| Wet Cast ~ unlike the semidry method, the Wet Cast mix is poured
into the mould as thick liquid mix and compaction is achieved by
vibration. So even the more complex arrangement of bars can be
compacted sufficiently. The added advantage being the need to put any
secondary support like pressed or fabricated steel lintel saving
costs. Also we can manufacture structural beams for larger vehicle
entranceways for example. |
|
|
Since its introduction in 1969, GFRC has
matured and today's designer has available to him, depending upon his
performance requirements, and a range of matrix modifiers such as
acrylic polymers, rapid set cements and additives to improve the
long-term stability of the material. Extensive independent test and
performance data are available on all aspects of matrix formulation.
This environmentally friendly composite, with its low consumption of
energy and natural raw materials, is being formed into a great variety
of products and has won firm friends amongst designers, architects,
engineers and end users for its flexible ability to meet performance,
appearance and cost parameters.
With GFRC, architects and designers have the ability to create and
innovate totally integrated projects, not only in the buildings they
design, but also with the surroundings in which they are located. The
lightness of GFRC relative to many other cladding materials is a factor
well worth taking into account in the initial calculations. This aspect
is brought into even sharper focus when considering site carnage
particularly on multi-story buildings in congested city centers. GFRC
panels can cover 3 or 4 times the area of precast concrete panels of the
same weight, or permit lower capacity cranes the necessary outreach to
handle units of economical size throughout the whole 3600. GFRC has the
ability to provided shape, color and textures desired by specifiers and
architects alike, with in the unit. Thus eliminating the need to paint
any of the surfaces and in turn reducing the life cycle cost of the
façade. Usually the only routine maintenance necessary is periodic
washing and cleaning. Carefully constructed moulds in metal, timber,
plastics or synthetic rubber can provide the means of achieving an
almost limitless variety of surface textures, from highly disciplined
patterns to freeform art, heraldry and ornamental detail.
Glass fiber reinforced cement, generally referred to as G.F.R.C. is a
combination of alkali resistant drawn glass fiber (A.R.G.) and a cement
based matrix. |
|
Glass reinforced concrete is a tough cement-based
material with a high strength to weight ratio. It can be molded into a
variety of complex shapes to accommodate an immense range of
Architectural and Engineering applications, such as wall claddings for
multi-stored reinforced concrete or structural steel frames, sound
absorption barriers for main roads, flyovers and piping etc. etc. The
applications are endless.
Cast
Stone is comparable to natural stone as a building material in both
appearance and performance, yet it is readily available and provides a
cost effective alternative on projects from simple domestic housing to
complicated schemes such as commercial buildings and cathedrals. It can
be formed to almost any shape and size the designer wishes and can
equal, or even surpass, the technical capabilities of natural stone in
terms of strength, moisture penetration and coloring. It is ideal for
both new build and refurbishment work particularly in areas of sensitive
planning constraints or where stone is a predominant building material.
Cast Stone is any product manufactured with aggregate and cementitious
binder intended to resemble and be used in a similar way to natural
stone. Cast Stone is either homogenous throughout or consists of a
facing and backing mix.
It is produced either as a semi-dry process which gives components a
slightly open textured face, similar to sawn natural stone, or as a wet
cast process which gives a much closer face texture and allows large
components and those with complex reinforcement to be produced. Our cast
stone process continues manufacturing traditions dating back to before
the turn of the century whilst incorporating modern production
techniques to both reduce costs and provide a superior product. Many
units are hand crafted to ensure a high quality finish.
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Welcome to a pt! The table template
that accompanies this set is variable width, and will adjust to full screen
vi PART 1 - GENERAL
1.1 FABRICATOR: The Fabricator shall have a minimum of 5 years
successful experience in fabrication of integrally colored architectural
Cast Stone units, similar to units required for this project.
- Steps Plus, Inc., 6375 Thompson Rd., Syracuse, NY 13206, web:
steps-plus.com, ph.: 315-432-0806, fax: 315-432-0612.
- Any fabricator that can submit literature and test reports showing
that they can meet the requirements of this specification.
1.2 SUBMITTALS:
- Fabricator information as listed above under section 1.1-B if the
proposed fabricator is not already listed as a qualified manufacturer
above.
- Shop Drawings showing layout, dimensions, and identification of each
Cast Stone unit corresponding to sequence and procedure of installation.
The Fabricator shall submit the shop drawings to the General Contractor
who shall verify all drawing dimensions and coordinate the shop drawings
with field conditions and other trades. The General Contractor shall
submit the shop drawings to the Architect for approval.
- Samples: Minimum size - 6" x 6" x 2" to illustrate the quality,
color, and surface finish texture. Fabricator must develop a custom
colored mix to match a colored sample provided by the Architect. The
color sample to match would either be an earthtone color shade (such as:
Indiana limestone color, off-white, buff, brown, brick orange, brick red,
light gray, dark gray, dull yellow) or pure white. Painted, stained, or
coated Cast Stone is not acceptable. Unless otherwise noted, all the Cast
Stone units on the project will be the same color and of the same mix
design. Smooth, dense, fine-grained texture achieved by acid etching or
lightly sandblasting to thoroughly remove all surface cement paste.
PART 2 - PRODUCTS
2.1 MATERIALS
- Portland Cement: ASTM C 150, Type I or Type III, Color to be white or
gray as required to achieve proper color as determined by the Architect.
- Coarse Aggregate: ASTM C 33, Color to be white. Darker aggregates may
be used as long as the proper color mix is achieved as determined by the
Architect.
- Fine Aggregate: ASTM C 33, Color to be white. Darker aggregates may
be used as long as the proper color mix is achieved as determined by the
Architect.
- Pigments: ASTM C 979; Inorganic, nonfading, resistant to lime and
other alkalis. Pigments not to exceed 10% of the cement weight.
- Water: Drinkable, free from foreign materials in amounts harmful to
concrete or cast in steel.
- Air-Entraining Admixture: ASTM C 260.
- Water-Reducing, Retarding, or Accelerating Admixtures: ASTM C 494,
type as selected by Fabricator and containing not more than 0.1 percent
chloride ions.
- Reinforcement: New billet steel reinforcing bars, as necessary for
safe handling, setting and structural stress. Size of the reinforcing
shall be specified with a minimum area of steel equal to one quarter of
one percent of the cross section area. If the surfaces are to be exposed
to the weather, the reinforcement shall be galvanized or epoxy coated
when covered with less than 2 inches of material for bars larger than 5/8
inch and 1-1/2 inches for bars 5/8 inch or smaller. The material covering
in all cases shall be at least twice the diameter of the bars.
- Reinforcing Bars: ASTM A 615, Grade 60, deformed.
- Epoxy-Coated Reinforcing Bars: ASTM A 775.
- Galvanized Reinforcing Bars: ASTM A 767, Class II (2.0 oz. zinc psf),
hot-dip galvanized after fabrication and bending.
- Welded Wire Fabric: ASTM A 185.
- Anchorages: The Setting Contractor is to provide all loose hardware
(dowels, anchors, plates, etc.) necessary for securing Cast Stone units
to supporting and/or adjacent members. Anchors to be non-corrosive;
galvanized, brass or stainless steel type 304.
2.2 MIX PROPERTIES: Minimum 6000 psi compressive strength at 28 days
using 6" x 12" cylinders per ASTM C39-86; Total Air Content not less than
4% nor more than 7%; Water Absorption is not to exceed 5% by weight when
tested per ASTM C 642.
2.3 SURFACE FINISH: Remove all surface cement paste by means of acid
etching or lightly sandblasting to provide a smooth, dense, fine-grained
texture with no streaks or blotches. Texture and quality of finish to be
generally equal to the approved sample when viewed in direct daylight at a
10 foot distance.
PART 3 - EXECUTION
3.1 INSTALLATION
- Anchorages: The Setting Contractor is to provide loose steel plates,
clip angles, seat angles, anchors, dowels, cramps, hangers, and other
miscellaneous loose steel shapes not provided by other trades, necessary
for securing Cast Stone units to supporting and/or adjacent members.
- Do not install any Cast Stone units that have any defects that exceed
the acceptable PCI MNL-117 tolerances for dimensions and color if
installation would result in unsatisfactory performance or appearance in
the opinion of the Architect.
- Install Cast Stone concrete members plumb, level, and in alignment in
accordance with PCI MNL-117 erection tolerances and the contract
documents Provide temporary supports and bracing as required to maintain
position, stability, and alignment as members are being permanently
connected.
- Protect the Cast Stone units from discoloration and staining when
washing down the surrounding masonry by covering the Cast Stone units
with plastic sheeting and/or by thoroughly soaking them with clear water
to prevent dirty washdown water from being absorbed into them. If dirty
washdown water gets on the Cast Stone, hose it off immediately with clear
water.
- Patching: The repair of chipped or damaged Cast Stone shall be done
with materials and instructions furnished by the Fabricator. The Cast
Stone shall show no obvious repairs or imperfections other than minimal
color variations when viewed with the unaided eye under good typical day
lighting at a 20 foot distance.
- Cleaning: Before pointing and/or caulking, the face of all Cast Stone
shall be scrubbed with a fiber brush, using mild detergent and water and
shall then be thoroughly rinsed with clean running water. Any mortar on
the face of the Cast Stone shall be removed. No acids or prepared
cleaners shall be used without the approval of the Cast Stone Fabricator.
3.2 PERFORMANCE REQUIREMENTS
- Applicable standards for inspection and quality control shall be PCI
MNL - 117 "Manual for Quality Control for Plants and Production of
Architectural Precast Concrete Products" and PCI's "Architectural Precast
Concrete Design Manual, 2nd Edition".
- The Architectural Cast Stone units shall show no obvious repairs or
imperfections other than minimal color variations when viewed with the
unaided eye at a 20 foot distance in good typical daylight illumination.
- Any unacceptable Cast Stone units that can not be repaired to the
Architect's satisfaction in accordance with the aforementioned criteria
are deemed unacceptable and are to be replaced by the Contractor.
|
Ventura Cast Stone product, 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.
Cast stone is a highly
refined architectural precast concrete stone manufactured to simulate natural
cut stone. It is a masonry product that provides architectural trim and
ornamentation. Used for centuries in Europe and in the United States in the
1900s, cast stone has gained widespread acceptance in the architectural
community as a suitable replacement for many masonry materials and for all types
of natural cut building stones. Continental Cast Stone manufactures cast stone
using the VDT (vibrant dry tamp) method. A zero slump mix is compacted into a
rigid mold, resulting in a finish that is virtually indistinguishable from
quarried limestone. The primary advantage of this method is that it virtually
guarantees the absence of air voids (also known as "bug holes") on the surface.
Cast stone made by the company meets the requirements of ASTM C-1364, the
Standard Specification for Architectural Cast Stone.
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.
Cast Stone is a highly refined architectural
building stone, usually made up of white cement and a combination of various
sizes aggregates of white marble, quartz, or other durable white stone. The
aggregates are numerous and are meticulously graded by sieve analysis to produce
a material that is dense and lack voids.
The cast material is impervious to moisture, and will test in
compression to 6,000 psi and not over 5% water absorption. The surface skin of
the cement on cast stone is removed to expose the white stone (or other)
aggregates, which reflect and sparkle over the matrix.
Since cast stone is a type of architectural precast stone,
the question is often asked: "What is the difference between cast stone and
architectural precast concrete?" The short answer is that cast stone is used in
place of natural stone. As a type of building stone, cast stone is specified
under the masonry division 04720. It is usually set by a masonry contractor
using standard building stone anchors. Perhaps most important, and unless
otherwise specified, cast stone looks like natural stone, dimensional, cut
building stone. Upon close examination, the finish of cast stone looks like
limestone.
To distinguish its appearance from the "pebbly with voids"
appearance normally associated with concrete. This dense finish is more
resistant to weather and dirt, and the fine aggregates retain the granular
texture through decades of exposure to the elements. The character of Cast
Stone, made as described above, is similar in color, texture, and appearance to
a good grade of natural cut limestone, but is stronger, since strength can be
controlled through the manufacturing process and is more impervious to water,
weather, and dirt. By controlling the proportion of white and /or gray cement,
manufactured or natural sands, carefully selected crushed stone or well-graded
natural gravel, and mineral coloring pigments, cast stone can be made to
simulate perfectly many other natural cut building stones, such as brownstone,
sandstone, bluestone, granite, slate, keystone, travertine, and others.
Precast concrete
Precast concrete is
usually used in lower end track homes where budget is a concern, cast
stone is usually used in higher end homes where budget is not a major
concern. The difference between
cast stone and precast concrete is easily seen, and even the novice can
appreciate the high quality limestone like finish on a cast stone product.
Fireplace mantels or as some call them fireplace mantles look beautiful
when constructed from cast stone. Cast stone fireplace mantels are used in
any situation. The fireplace mantels are both strong and fireproof.
Fireplace mantels are
a thing of beauty when made from cast stone or precast concrete. Fireplace
mantels are also made from wood. Fireplace mantels or fireplace chimneys
are the main feature in any room and a fireplace mantel made from cast
stone or precast concrete is a sight to behold.
Cast stone by
Ventura Cast Stone installed in California city's such as
Los Angeles, Beverly Hills, Bel Air, Ventura or Santa Barbara has to be
mechanically fastened to the wood frame of a building usually with
stainless steel or galvanized attachments, this because of earthquake
codes. There are many historical buildings in California with cast
stone as part of their facade. Cast stone in
Los Angeles, Beverly hills, Bel Air, Ventura and Santa Barbara was at it's
most popular in the 1900's. In Santa Barbara, cast stone was used
extensively in the downtown district and also in a primitive form at the
Santa Barbara mission in the form of adobe, a mixture of mud and straw or horsehair
mixed with water and hand shaped into molds. Cast stone in the City
of Ventura was used mainly on churches in the downtown area. Cast
stone in Los Angeles was used in many important buildings including the
famous Los Angeles City hall. In Santa Barbara cast stone and Santa
Barbara stone were used in conjunction in many historical buildings.
Santa Barbara stone also called Santa Barbara sandstone, is found mainly
in Santa Barbara county, is removed from the ground in loose form, the
Santa Barbara stone is then cut and shaped by a stonemason into useable
blocks. Cast stone in Beverly Hills was used in the Beverly Hills
City hall and is now used on many residential buildings.
We also supply and install granite and CDI precast caststone and concrete design product, CDI columns,
Sierra stone caststone columns and balustrade, California precast
products, CDI precast, CDI precast granite moldings and stairs. We also supply and install CDI precast
granite concrete
window and door trim, CDI GFRC columns, Sierra stone products, concrete design, full weight
precast
and granite or limestone products, Malibu California precast columns, CDI precast pool coping, CDI precast
or limestone moldings
and CDI fireplace mantles. We also install the products exclusively
manufactured by other company's including,
Sierra concrete design, Sierra stone and Dura art stone, Stone legends,
Moonlight molds, Fineline precast, Concrete design inc. Studio cast
design, Concrete design inc, CDI, Architectural products, Haddonstone. These products include: cast stone,
limestone, Malibu precast concrete, precast, cast, stone, limestone, sandstone,
Malibu CA, los angeles, ventura, santa barbara, los angeles precast, los angeles
columns, los angeles cast stone, santa barbara precast, santa barbara cast
stone, santa barbara stone, santa barbara or Malibu columns, ventura cast stone,
ventura or Malibu precast, ventura columns, ventura stone.
These products include: cast stone,
limestone, precast concrete, precast, cast stone,precast concrete,los angeles precast,
ventura,santa barbara precast,los angeles columns,los angeles cast stone,santa barbara precast,
santa barbara cast stone,santa barbara stone,santa barbara columns,ventura cast stone,
ventura precast,ventura columns,ventura stonecast, stone, limestone, sandstone,
los angeles, ventura, santa barbara, los angeles precast, los angeles
columns, los angeles cast stone, santa barbara precast, santa barbara cast
stone, santa barbara stone, santa barbara columns, ventura cast stone,
ventura precast, ventura columns, ventura stone,
Malibu precast, Malibu stone, Malibu columns
Ventura Precast Concrete
Colors
Precast
concrete and GFRC colors
Ventura precast concrete colors are integral, the pigments are added to the cast
stone or precast concrete mix as the aggregates are being mixed. this
means the product can be cut or carved and the cut surface will be the
same color as the rest of the product. With cast stone, the color and also
the texture of the product will be very similar to the rest of the
product. We use white cement which produces clean, bright colors
Color is one
of the most important aspects of architectural precast concrete and cast
stone. At Ventura cast stone we can design mixes to match items such as
existing precast concrete and weather-stained limestone. We can also
develop mixes with the correct color tone to match closely, existing cast
stone or precast. This means we can reproduce almost any cast stone
product, even 200 year old stone, limestone or sandstone. The color chips
on this page represent just a small sampling of the colors we can achieve
with our standard materials and pigments. We do not charge extra for
standard colors or texture. Non-earthtone colors that require special
pigments (such as blue and green) or non-stock aggregates do cost extra.
Whether the goal is to match existing materials or to simply complement
new stucco color, we are the company to turn to whenever high quality
architectural precast concrete or cast stone items are required.
White Portland cement used
in our product. It has essentially the same properties as gray cement,
except for color, which is a very important quality control issue in
the industry.
The color
of white cement depends on raw materials and the manufacturing
process. It is the metal oxides (primarily iron and manganese) that
influence the whiteness and undertone of the material. White cement is
manufactured to conform to ASTM C 150, Specification for Portland
Cement. Although Types I, II, III, and V white cements are produced,
Types I and III are the most common.
White cements produce clean,
bright colors, especially for light pastels. Many different colors can
be created by adding pigments to concrete made with white portland
cement. Two or more pigments can be combined to achieve a wide range
of colors. White cement (or a mixture of white and gray cement) can be
specified to provide a consistent color of choice. An even greater
variety of decorative looks can be achieved by using colored
aggregates and varying the surface finish treatment or texture.
Mix designs for white or
colored concrete are formulated based on each ingredient's effect on
cast stone and precast concrete color:
| Type and color of cement
|
| Type and dosage of pigment
|
| Type and dosage of
admixtures |
| Type, gradation, color,
and cleanliness of fine and coarse aggregates |
| Consistent proportions,
especially maintaining a uniform water-cement ratio |
For every architectural
project, once a mix design has been developed, sample panels should be
built at the job site. These mockups serve as references for color and
overall surface appearance.
White High-Performance
Concrete (White HPC)
High-performance white
concrete (such as high-strength or very low permeability concrete)
adds high-tech appeal by incorporating materials like calcined clay
(such as metakaolin), slag, or white silica fume into white cement
concrete. Applications for HPC may include high-rise buildings,
bridges, and parking structures.
Supplementary cementing materials
may slightly alter the color of hardened concrete. Color effects are
related to the color and amount of the material used in concrete. Many
supplementary cementing materials resemble the color of Portland cement and
therefore have little effect on color of the hardened concrete. Some silica
fumes may give concrete a slightly bluish or dark gray tint and tan fly ash
may impart a tan color to concrete when used in large quantities. Ground
slag and metakaolin can make concrete whiter. Ground slag can initially
impart a bluish or greenish undertone.
Natural and synthetic materials are used to color concrete for aesthetic
and safety reasons. Red concrete is often used around buried
electrical or gas lines as a warning to anyone near these facilities.
Yellow concrete safety curbs are used in paving applications. Generally,
the amount of pigments used in concrete should not exceed 10% by mass of
the cement. Pigments used in amounts less than 6% generally do not affect
concrete properties.
Unmodified carbon black substantially reduces air content. Most carbon
black for coloring concrete contains an admixture to offset the effect on
air. Before a coloring admixture is used at a project, it should be tested
for color fastness in sunlight and autoclaving, chemical stability in
cementing materials and effects on concrete properties. Calcium chloride
should not be used with pigments to avoid color distortions. Pigments
should conform to ASTM C 979.
The Romans referred to concrete as
liquid stone. It was cement that allowed the most famous monuments and
constructions of the ancient world to be completed, marking the most
significant change in building design the world has ever seen. With the
use of cement, architects were freed from the constraints of the past,
from the limitations of quarried stone and its limited strength to size,
from wood and the diminutive stature its buildings always possessed.
Cement enabled the ancient architects to design with their imaginations,
instead of their restrictions.
As anyone in the construction
business surely knows, cement has not yet stopped evolving. The science
of cement manufacture and production is continuing to make great strides,
enabling new and imaginative processes to be invented.
Decorative concrete is on the
forefront of this growth. With such techniques as dry pack cast stone,
homeowners and designers can create an unlimited array of outdoor and
textured surfaces and flooring options. These all enable the designers to
escape the one flaw seen with concrete: as a finish material, its
starkness can be downright plain. For instance, the durability of
concrete makes it perfect for a driveway, patio, sidewalk or floor, so a
means to "dress up" or disguise concrete without sacrificing any of the
versatility is the goal of many of these manufacturers.
Integral color
One of the first ways to
transform concrete is through integral coloring. This is where pigment,
usually iron oxides, is added directly to the mixer. The mix is then
poured normally, producing a colored slab of concrete that will not fade
because the color is literally a part of the mix. These colors can range
from subtle pinks and browns to deep blues and greens.
This is usually done by adding a
precisely measured bag of pigment to the concrete, taking into
consideration the amount of cement, total yardage of the truck and
individual properties of the chosen pigment. The drawback of this dry
add-mix is apparent when trying to attain the same color for different
amounts of cement. Because the pigment attaches to the cement, the same
pigment added to a five-sack mix will be much darker than that of an
eight-sack mix.
"By using four distinct liquid
pigments, added together in the correct ratio (similar to a four-color
printing process), a huge variety of color is available," then we measure
and test the resulting pigment for accuracy.
Integral color has many uses for
the concrete industry. Concrete roof tiles, garden accessories and pre-fab
concrete pipe are all starting to use integral coloring.
Other methods of coloring
concrete are more appropriate for different applications. For instance,
many companies make both dry and liquid color hardeners that can be
scattered or sprayed on top of newly poured concrete, and once worked
into the surface, strengthen the concrete while allowing the use of any
color.
Acid staining
One of the most popular methods
for decorating concrete today is with the use of acid staining. Many
residential and commercial customers are using this method for obtaining
a durable, beautiful and relatively inexpensive way to decorate their
floors.
While this concept is not new
(Frank Lloyd Wright used some acid stains), innovative ideas are
expanding the range of the acid stained look. Multiple stains may be used
to enhance the depth of the color, grout lines may be cut into the
concrete to resemble tile, or highly detailed murals or rosettes may be
stained for any surface outside or inside the home.
Coupled with staining and
stamping, a number of options are available for designing decorative
concrete. Indeed, all of the processes described here can be mixed and
experimented with, limiting designers to only what they can imagine.
There are a few places for the curious designer to experiment with these
options.
Master Builders (www.masterbuilders.com)
may be widely known for manufacturing concrete materials, but they have
recently helped produce an interactive online test grounds (www.concretelifestyles.com).
The site allows the user to swap patterns and colors to see different
styles.
The most impressive thing in
outdoor and indoor concrete today may be what has yet to be constructed.
Home
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About Ventura Cast Stone
● Cast Stone Catalog ●
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