Whatever the type of construction project, one of the fundamental choices you have to make is selecting the ideal material. Should you choose cast stone or other natural building stones? There are many to choose from, each with advantages and disadvantages.
One construction material that has been in use since around 1138 is cast stone. It’s a more affordable option than other natural building stones. In addition, it’s designed to replicate natural stone.
Three words sum up the popular use of cast stone compared to natural cut building stones:
Its popularity grew due to its ability to be versatile while maintaining durable physical properties. It is often used to simulate natural cut stone in many applications.
What is Cast Stone?
The official definition of cast stone is as follows:
A refined architectural concrete building unit manufactured to simulate natural cut stone, used in unit masonry applications.
It’s one of the oldest known types of concrete. Since the early 1920s, it has gained widespread acceptance as a more than suitable replacement for a range of masonry materials, all-natural cut building stones, to replicate natural stone and simulate natural cut stone.
Compared to natural-cut building stones, cast stone has advantages but a few disadvantages too. Keep reading for more information about cast stone, including the different types, benefits of using it, applications, and much more.
But let’s start with a quick history lesson on how this material came about.
History of Cast Stone
The history of cast stone goes back centuries, even thousands of years. Cast stone dates back to Ancient Rome. Cast stone was made using pozzolanic cement and other aggregates, including natural limestone and well-graded natural gravels. This exciting new building material was used to create magnificent buildings such as the gateways and vaulted arches of Rome’s Colosseum. Athens’ Pantheon is another fine example with its large span dome.
Cast stone was also used in the Middle Ages, mainly by artists. It allowed them to create molded ornaments with the finest and most accurate details. These cast stone ornaments were used in churches and castles. There are many fine examples of cast stone fortifications in Europe. Another benefit for these artists was that they could mass-produce the decorations. Each cast would produce precisely the same detail and quality.
The first recorded commercial production process of a cast stone, cement-based material in the format familiar today, was in the late 1820s. Felix Austin started a stone-making business in New Road, London. He made the cast stone using Portland cement, broken natural stone, coarse sand and pounded marble.
In America, cast stone became widely accepted around the beginning of the 1900s. At the beginning of the new millennium, it enjoyed a massive comeback.
Nowadays, it has a variety of uses, from reinforcing or building houses and other structures to being used as an architectural feature such as elegant pillars and fireplaces.
When was Cast Stone Invented?
Cast stone was first used in Ancient Rome. At that time, pozzolanic cement was used along with aggregates such as lightweight pumice, natural limestone, other popular natural stones, and bricks from buildings that had been demolished.
What is Cast Stone Made Of?
Cast stone is a material consisting of cementitious binder and natural aggregates. It resembles natural stone very closely and is used in many similar ways.
Several other names are used for the same composite material, such as reconstituted stone, reconstructed stone, synthetic stone, art stone, manufactured stone, and artificial stone.
It is made using Portland cement, manufactured or natural sands, and carefully selected crushed stone. If color is needed, mineral coloring pigments are usually added.
The end product is made by setting the mixture in a specific mold. The mixture flows into the molded shape and is allowed to dry. Once dry, the result is cast stone.
Cast stone is stronger than simple architectural precast concrete or cement and is popularly used as a building material. The qualities that have made it such a popular construction material are its strength and lightweight, an advantage when transporting it. It’s also highly customizable, multipurpose, non-combustible, and easily maintained. It is also considered a natural material, and environmentally sustainable, an appealing feature in the modern world.
Cast stone can be made in one of three ways: semi-dry, wet-cast, or fiber reinforced.
- Semi-Dry Cast: This method uses low amounts of water or an “earth moist” mix. This casting approach allows large numbers of products to be produced relatively quickly. Generally, casting is face down in a wooden mold. The aggregate is then compacted using electric sand or pneumatic rammers. Steel hand molding machines can also be used.
- Wet-Cast Method: This method produces a grain pattern on the cast stone and is commonly used for stone cast structural elements, larger units, and complex reinforcements. More water is used in casting this type of product. The wet-cast mix is poured into a mold and compacted using vacuum casting, a vibrating table, or, more commonly, by using self-compacting additives. Wet casting takes longer.
- Fiber Reinforced Cast Stone: Fiber reinforcement is incorporated into a high water mix and then sprayed or poured into a mold. The inclusion of the fiber means the tensile strength is considerably increased.
Industry standards relating to the constituent raw materials and physical properties ensure a consistent level of quality.
In the US, the standard is ASTM C 1364, the Standard Specification for Architectural Cast Stone.
In the UK and across Europe, the more common standard used is BS 1217 – Cast Stone – Specification. By mid-2013, CE marking was mandatory for any Cast Stone items sold in Europe.
What is the Density of Cast Stone?
The standard density of cast stone is approximately 135 PCF. It should also have a maximum moisture absorption of 6% and a minimum compressive strength of 6500 psi.
What are the Different Types of Cast Stone?
There are three different types of cast stone. Each relates to a different manufacturing process.
Dry Cast Stone
The end product of the dry cast stone manufacturing method resembles the strength and surface texture of natural cut limestone. The main components used for this type of cast stone are natural cut limestone, sand, and white cement. When it’s mixed, it feels like damp earth or sand.
The mixture is packed into a mold and pressed into the mold by hand or using a pneumatic rammer. No finishing is required, and the end product looks like natural quarried stone. It also weathers well, much like natural cut stone.
West-cast stone is a little denser than dry cast stone. It is manufactured using larger particles and also has high water content. Plasticizers are used to improve the density of this type of cast stone. In addition, they reduce the curing time.
In order to obtain a high-quality finished product, wet-cast stone requires additional finishing.
Wet-cast stone is ideal for fireplaces, flooring and paving, and large architectural feature products such as columns. It’s also used for contemporary designs and other applications that don’t require a weathered finish. This type of cast stone is also easy to clean.
Check our comparison page for more information on dry vs wet cast stone and their differences.
Fiber Reinforced Cast Stone
Glass fiber is added to the cement-based and aggregate mixture, and the result is a cast stone in appearance that is two-thirds the weight compared to other types of cast stone.
GFR cast stone has a high strength-to-weight ratio and is perfect for retro-fit, new builds, and timber frame projects.
What are the Benefits of Using Cast Stone?
- Lightweight: Typically, cast stone is much lighter than natural cut stone
- Easy to manufacture
- Easy to install
- A vast range of shapes and sizes
- Available in a range of colors thanks to mineral coloring pigments
- Durable physical properties
- Superior in strength
- More cost-effective building material
- No variations or imperfections
- Improved thaw/freeze durability compared with natural building stones
- Requires minimal maintenance
- Steel components such as fixings and reinforcement can be included as part of the manufacturing process
What are the Different Applications of Cast Stone?
- Structural components
- Internal and external stone features
- New builds
- Refurbishment projects
- Window heads
- Stone mantels
- String courses
- Architectural features
- Door & window surrounds
How Long Does Cast Stone Last?
Cast stone can easily rival natural stone in terms of longevity. Many cast stone installations of good quality from the early 20th century are still in excellent condition and require minimal repair.
However, like natural cut stone and other building materials, cast stone can deteriorate over time. Deterioration can be the result of:
- The core and facing layers separating
- The aggregate deteriorating
- The cementing matric deteriorating or eroding
- Steel or iron reinforcements deteriorating
- Anchors and cramps used in the cast stone installation can also deteriorate
Does Cast Stone Require Any Maintenance?
While cast stone is typically low-maintenance, some upkeep is required if you want to increase its longevity.
Cast stone that contains limestone or marble aggregates needs to be cleaned from time to time. First, remove the build-up of grime, dust, and dirt using a soft brush. Then use an alkaline pre-wash/after-wash cleaning agent, the same as you would for any calcareous natural stone. If there is no limestone or marble aggregate in the cast stone, use an acidic cleaner, like you would for natural sandstone and granite.
Any remaining stains on the cast stone may require other methods to remove them. Micro-abrasive techniques are one option, but this type of cleaning should only be done by a skilled cleaning professional under controlled circumstances.
Under no circumstances should you use wet grit or sand-blasting, as this will seriously damage the cast stone surface.
Repointing is another maintenance task that may be required in certain circumstances. When repointing, it is critical to match the color and character of the manufactured or natural sands and the color of the cement, particularly in historic masonry.
Any repairs necessary can be done using a pointing mix.
What is the Cost of Cast Stone?
The price you pay for cast stone depends on several factors, such as size, design, ornamentation, and desired color.
- Size: The cost of cast stone is typically given in terms of cubic feet per piece.
- Design: Costs are much lower if one side of the mold design is flat. Such profiles include water tables, banding, headers, coping, sills, and bases. The cost of cast stone increases if one side of the mold is designed in an L-shape or U-shape. This is because more complex pieces require a more intricate mold and additional time for production. Costs become even higher for stone pieces requiring two-sided molds.
- Repetition: The production cost is lower when a mold can be used for more than one piece.
- Rustication and Profiles: Curved and beveled profiles are more cost-effective to make than flat pieces that have a more defined edge.
- Ornamentation: Manufacturing a highly intricate piece requires a specific mold which adds to the cost. This is often the case with historic buildings.
- Color: Natural-colored cast stone is standard. More chromatic colors cost more.
Is Cast Stone Expensive?
While cast stone shares similar properties with natural cut stone, it doesn’t come with the same price tag. Cast stone is far less expensive than natural stone.
How to Choose a Cast Stone Supplier?
You should consider several things when looking for a cast stone supplier.
Word of mouth is one of the best forms of recommendation. Ask friends or family if they or anyone they know has recently bought cast stone and where they sourced it. If their experience was positive, the chances are they’ll happily recommend the supplier.
What type of cast stone do you need? Look for cast stone suppliers that offer the cast stone products you require. Find out whether there is a catalog you can look at and if they provide fabrication or custom cast stone services.
If you want cast stone for a large-scale project, you need a supplier able to provide the amount of cast stone you need.
You don’t want to choose a supplier that offers the lowest prices as they may be cutting corners that will cost you more in the long run. Ask for quotes and look into the companies quoting average prices.
Experience and Credentials
Don’t make your decision based on cost alone. Also, look into the history of a company and its professional background. And check whether the company is a member of the Cast Stone Institute.
Premier Precast is a company that manufactures a high-quality cast stone product thanks to its celebrated group of expert craftsmen that work in the precast mold department. They have earned multiple industry awards.
Premier Precast’s quality control department also ensures all manufactured cast stone products meet recognized quality standards.
Every project that Premier Precast undertakes is assigned a project manager who oversees every part of the process, from first contact to installation.
How is Cast Stone Different From Natural Stone?
Natural stone is what it sounds like – stone that has been formed over millions of years with the help of natural forces.
Cast stone, on the other hand, is a type of concrete designed to look and behave like natural stone but is less expensive. There are, of course, several other benefits.
Cast stone is also lighter in weight, which makes it much easier and quicker to install. However, it is also less dense and not quite as strong as natural stone.
So what about natural stone? It lasts a long time, is strong, durable, and has timeless appeal. Natural stone also requires minimal maintenance, the same as cast stone.
One significant downside to using natural stone is that no piece of natural stone is exactly the same as another. It’s therefore difficult to create slabs and architectural elements that match exactly. While coloration and graining give the natural stone character, they also prevent duplication.
Let’s not forget the price is another downside. Natural stone can be expensive. However, for many people, natural stone is worth the extra cost.
Whether natural stone or cast stone is better for your project depends on your budget and personal taste. If cost is a key factor and the design is simple, cast stone may tick all the right boxes. However, if aiming for a more one-of-a-kind look and quality is higher on your list of priorities than price, nothing is better than natural stone.
1. Cast stone vs natural stone: which is heavier?
Cast stone is not as heavy as natural stone and is easier to work with and transport. It’s also more affordable and better for the environment.
2. Cast stone vs natural stone: which is more durable?
Cast stone is more durable, so much so that US Cast Stone standards provide for a product of – infinite life – meaning it should last longer than 100 years.
3. Is cast stone fireproof?
Cast stone is fire resistant and passes fire codes.
4. Is cast stone frostproof?
Yes, cast stone is frostproof.
5. Is cast stone the same as precast concrete?
Cast stone is not the same as precast concrete. The most significant difference to architectural precast concrete is that cast stone doesn’t contain air voids or bug holes.
As with all construction materials, you must consider the cast stone pros and cons before deciding to use it on a project.