On renovation sites, concrete is the ideal material for creating cast-in-place lintels, door and window jambs, and window sills. Indeed, on such sites, using precast lintels, jambs, or window sills is not feasible. Thus, it is necessary to pour concrete on-site.
Solution
PROMPT natural cement enables rapid formwork removal for lintels, door and window jambs, and window sills. Thanks to its quick setting time, formwork removal can occur as soon as one hour after pouring. Moreover, various textures (smooth, textured, bush-hammered, polished) and different shades are achievable, whether the substrate is new or old.
Technique
Before preparing the PROMPT natural cement mortar, ensure the substrate is properly prepared. Provide suitable metal reinforcement, as with regular cement concrete works. Oil or wax the formwork, as this will affect the appearance of the concrete once it's removed.
For placement, position the reinforcement, pour, and vibrate the PROMPT natural cement concrete prepared in a mixer or concrete mixer (PROMPT natural cement, sand or aggregate, TEMPO, water).
For formwork removal, wait around 1 hour for the sides and 2 hours for the undersides of lintels or window sill formwork.
Quel est le temps de décoffrage des linteaux, jambages et appuis de fenêtres ?
Grâce à son temps de prise rapide, les linteaux, les jambages et les appuis de fenêtres en Ciment Naturel Prompt peuvent être décoffrés rapidement. Cela permet de gagner du temps sur le chantier et d'accélérer le processus de construction.
Vous pourrez ainsi décoffrer les joues dès 1 heure et les sous-faces de linteaux ou les coffrages d'appuis de fenêtres après 2 heures.
Using Vicat PROMPT natural cement concrete to create cast-in-place lintels, jambs, and window sills allows for :
- Quick return to service
- Cost-effective solution
- Suitable aesthetics: color and texture
- Adjustable setting time
L'utilisation du Ciment Naturel Prompt est ici parfaitement adapté pour la réalisation de :
- Linteaux
- Jambages
- Appuis de fenêtres
- Seuils de portes
Yes, reinforcement is essential. A lintel is a load-bearing element subject to bending forces: without steel reinforcement, even a very strong mortar will fail under load. The reinforcement must be sized according to reinforced concrete design rules, taking into account the span and the loads carried. For wide-span lintels or those bearing significant loads, a structural engineering assessment is recommended.
For spans below approximately 1 m, formwork can be removed quickly thanks to the rapid setting of PROMPT natural cement. Beyond 1 m, supporting props must remain in place for at least 3 weeks to allow full hardening before the lintel takes on its design loads. For large spans or heavy loads, a prior structural assessment is required.
Vibration eliminates air bubbles trapped during pouring and ensures uniform filling around the reinforcement. Without vibration, porous zones (honeycombing) form and compromise the steel cover. With PROMPT natural cement, vibration must be carried out immediately after pouring, as the rapid setting does not allow time for subsequent reworking.
These three elements form the frame of a wall opening. The lintel is the horizontal piece above the opening that carries the loads from the masonry above. The jambs are the vertical sections forming the sides of the frame. The window sill is the horizontal piece at the bottom of the opening, slightly inclined outward to ensure rainwater run-off.
dddqsdjgklmqsdgjqgjdfYes, this is one of its preferred applications. The naturally ochre hue of PROMPT natural cement is visually compatible with limestone, tufa and old brick, without creating the aesthetic discontinuity that grey Portland concrete would produce. Its mineral composition is also close to that of most regional stones, promoting compatibility with historic substratesYes, this is one of its preferred applications. The naturally ochre hue of PROMPT natural cement is visually compatible with limestone, tufa and old brick, without creating the aesthetic discontinuity that grey Portland concrete would produce. Its mineral composition is also close to that of most regional stones, promoting compatibility with historic substrates
Yes. The mortar shade can be adjusted by choosing the appropriate sand and adding natural mineral pigments to the mix. The surface texture can also be modified depending on the type of formwork used. A test sample is recommended before on-site production to validate the final shade.
PROMPT natural cement lintel concrete consists of PROMPT natural cement, 0/4 sand, 5/10 or 5/15 aggregate and water, with the addition of TEMPO retarder to facilitate placement. The water/cement ratio must be carefully controlled: excess water reduces the final strength. The online calculator provides precise mix proportions based on the desired consistency and volume.
Yes, provided minimum conditions are met: temperature above 2°C, non-frozen substrate, no risk of frost in the hours following pouring. Below this threshold, setting is inhibited. In extreme heat (above 30°C), it is advisable to use cold water and to work with aggregates stored in the shade.
