Dry-cast concrete is a type of concrete that is commonly used in the production of architectural accents and features such as fire pits, fire tables, planters, water vases, and more. It relies on a low water-cement (w/c) ratio, typically ranging from 0.30 to 0.38, to initiate cement hydration without the need for admixtures. Below are several important facts about dry-cast concrete and its applications in architectural accents and features.
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Increased production: One of the benefits of using dry cast is that it can be consolidated within a form, and the stiffness of the mix allows for the form to be immediately stripped. This means that the product can stand under its own weight to complete the curing process, and the form can be reused to cast another product. This increases production efficiency and reduces downtime.
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Reduced shrinkage and creep, rapid strength increase: Dry-cast concrete has reduced shrinkage and creep compared to traditional wet-cast concrete. This is because all of the aggregate particles in dry-cast concrete are in contact with each other, which helps resist the shrinkage of the cement. As a result, the particles are preloaded, leading to increased compressive strength of the concrete. The rapid strength increase of dry-cast concrete allows for quicker demolding and handling of the finished products.
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Dry-cast concrete ≈ roller-compacting concrete: Dry-cast concrete mix designs and applications are similar to roller-compacting concrete (RCC), which is commonly used for paved surfaces. Both dry-cast and RCC have zero-slump properties, and the batching method for dry-cast concrete is similar to that of RCC. As a result, the use of dry-cast methods is becoming more popular in engineering applications.
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Vibration: not one size fits all: Vibration is a key step in the production of quality dry-cast concrete products. However, due to the stiffness of the mix, traditional internal vibration methods are not effective. Instead, dry-cast products need to be consolidated using external vibration methods such as centrifugal force, mechanically packing the mix into the form jacket with spinning cylindrical heads, or using external vibrators attached to the product form or vibrating table. Different products may require different vibration settings to ensure that the consolidation energy is adequate for the specific product being cast.
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A heavy-duty form, all day long: Heavy-duty forms are required for dry-cast concrete production due to the need to transfer intense external vibration energy to the mixture through the formwork. These forms need to be rigid, yet not overly bulky to maintain consolidation effectiveness. Proper form design is crucial to optimize form stiffness and ruggedness while keeping form weight to a minimum. Dry-cast forms are typically used continuously throughout the day's production, as the process allows for multiple precast concrete sections to be produced using a single form system.
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Let a little out at the bottom: It's important to note that most dry-cast products have slightly tapered wall surfaces to accommodate easy stripping from the forms. Unlike traditional wet-cast precast operations where forms are typically internally vibrated and cured overnight, dry-cast forms are often hinged on the outside or collapsible on the inside to assist with stripping. Some dry-cast forms may be fabricated as a single steel section, requiring physical pulling or sliding of the finished product out of the form. Proper form design and release agent application can help ensure smooth and efficient stripping of dry-cast products.
In conclusion, dry-cast concrete is a specialized type of concrete used in the production of architectural accents and features such as fire pits, fire tables, planters, water vases, and more. It offers advantages such as increased production efficiency, reduced shrinkage and creep, rapid strength increase, and the