Jul 303 min read

Prompt Cement

Prompt Cement: The Quick-Setting Solution for Modern and Historic Construction

Vicat Prompt Cement, also known as Prompt Natural Cement, is a type of natural hydraulic binder known for its quick setting time and strength (90 seconds). It is used in various construction and restoration applications.

History:

Prompt is a unique binder produced by the Vicat Company at their Voreppe works near the French Alpine city of Grenoble. Established in 1853 by Joseph Vicat (1821-1902), the Vicat Company was founded on the pioneering work of Joseph's father, Louis Vicat (1786-1861), a French military engineer known for his contributions to artificial cements. Today, the Vicat Company is the third-largest cement producer in France and the only manufacturer of Natural Cement sold under the name Prompt, which is as synonymous with its unique properties as Hoover is with vacuum cleaners.

Prompt is an entirely natural cement, produced from a single geological layer of argillaceous (clayey) limestone, a sedimentary rock formed during the formation of the Alps. It is mined, then fired at the relatively low temperature of 800-1200ºC, and finely ground, with no added additives. While it is fully compatible with other lime binders, Prompt Natural Cement cannot be classified as a lime binder since it contains no free lime (Ca(OH)₂). Its primary uniqueness lies in its rapid set, which can be controlled with the addition of Tempo (citric acid), delaying the set time in a Prompt mortar by 10 to 30 minutes, depending on the ambient temperature.

Applications of Prompt Natural Cement:

Prompt Natural Cement is incredibly versatile and can be used in numerous applications. It can be used on its own, mixed with sand, or combined with traditional lime mortars and plasters, lime putty, or NHL mixes. This makes it ideal for building conservation projects where accelerating or achieving a rapid set is advantageous. Prompt is also the only commercially available and suitable material for repairing Roman Cement applications. Here are just a few examples of its many uses:

Advantages of Vicat Prompt Cement

Quick Setting Time: Sets rapidly, which is beneficial for fast-track projects and emergency repairs.
Hydraulic Properties: Can set and harden underwater, making it suitable for marine and hydraulic engineering applications.
High Early Strength: Provides high early strength, reducing the time needed before structures can be put into service.
Compatibility: Compatible with traditional building materials, making it ideal for conservation and restoration of historic structures.
Durability: Offers excellent durability and resistance to environmental factors, ensuring long-lasting repairs and constructions.

Applications for Quick-Setting 'Prompt Cement'

Waterproofing
Lime renders
Casting
Repairing Roman Cement
DIY and hobby projects
Builders and tradesmen
Fixer masons (stone cladding)
Monumental masonry
Concrete and mortar repair
Shotcreting
Securing fixings and street furniture
Flooring
Road, street, motorway, and runway repairs
Window fitting
Marine and harbour works
Underwater engineering
Agriculture
Water and sewage systems
Soil stabilization
Pond construction
Landscape gardening
Fish farming

Creating a Roman Cement-like Mortar Using Lime and Prompt Cement

Materials Needed:

Prompt Cement: A natural hydraulic binder known for its rapid setting properties.

Natural Hydraulic Lime: A traditional building material that offers breathability and flexibility.

Mixing Ratio:

The exact ratio can vary based on the specific requirements of the project, but a common starting point could be 1 part Prompt Cement to 2-3 parts lime.

The mixture can be adjusted to achieve the desired working time, strength, and setting characteristics.

Mixing Process:

Dry Mixing: Thoroughly mix the Prompt Cement and hydrated lime in the desired ratio in a dry state.

Adding Water: Slowly add water to the dry mix while continuously stirring until you achieve a workable consistency. The amount of water required will depend on the specific project needs and environmental conditions.

Application:

Substrate Preparation: Ensure the surface to be worked on is clean, free of loose materials, and appropriately dampened to prevent rapid water loss from the mortar.

Applying the Mortar: Use the mixture as you would with traditional lime mortars or cements. Prompt Cement will ensure a rapid set, so work efficiently.

Curing:

Protect the freshly applied mortar from rapid drying, extreme temperatures, and direct sunlight to ensure proper curing.

Keep the area damp for several days if necessary, using wet burlap or misting the surface lightly.

System solutions for non-statically relevant concrete repairs

Measures that improve the aesthetic appearance of concrete surfaces, do not impair the structural integrity, but restore them as originally as possible and do not have a statically relevant effect, are commonly described as concrete cosmetics. The so-called quick repair or concrete cosmetics describes the use of repair mortars that cannot be statically calculated, in particular the repair of breakouts, pores and defects.

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