About Ventura Cast Stone
We now offer concrete molds for precast concrete and cast stone to the
public. These are not "Garden Ornament" concrete molds,
but are professional architectural concrete molds, the same molds we use in our
own production.
Cast stone
We at Ventura cast stone 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.
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