Kalevan kirkko [Kaleva Church]
Religious/centre of worship
Religious/centre of worship
Reima Pietilä, Raili Pietilä
Concrete by reinforcement
Concrete is a relatively brittle material that is strong in compression but less so in tension.
To increase its overall strength, steel rods, wires, mesh or cables may be embedded in concrete before it sets. This reinforcement, often known as rebar, resists tensile forces. By forming a strong bond, the two materials are able to resist a variety of applied forces, effectively acting as a single structural element .
In this case, the concrete can be made by mixing the components directly on site, or it may be transported from a production plant in concrete-mixer trucks.
This method has the disadvantage of leaving the concrete exposed to the elements while it is setting. Whereas, with other methods, the environmental conditions can be controlled during setting, providing greater control over the outcome, with cast-in-place concrete a series of tests and protocols are necessary to verify its final strength.
PRECAST ON SITE:
In larger and more complex construction projects, a concrete production plant may be installed on the construction site or nearby. The precast elements are moved into place once they have reached their maximum strength. This reduces transportation costs and ensures the concrete will set in the same environmental conditions as the building site. This may be more necessary with structures that combine cast-in-place concrete with prefabricated elements.
PRECAST IN FACTORY, WORKSHOP:
Any concrete element can be manufactured ahead of time and transported to the site once it has set. In this case, the control over geometry, appearance, finish and strength can be as strict as necessary. It can also be ensured that the pieces will be exactly identical to one another.
Prefabricated elements can be of any type: from façade panels and pavements to decorative elements (such as cornices or capitals) and structural elements (columns, slabs, beams, etc.).
These elements may be part of a commercial catalog or specially designed for a specific project. A series of pieces may also be sold as a coordinated and interconnected system to build a complete structure or even an entire building.
- textured walls
- wooden formwork finish
- stamped concrete
- exposed aggregate concrete, colored concrete, etc.
Trussed beams are the cheapest solution for the execution of large spans, in other words, when there are large distances between vertical supports. In reality, this type of beam is a kind of lattice, made up of a series of shorter braces (posts and struts).
Trussed beams are usually made of steel or wood, since some of the elements of the structure will be subject to compression and others to traction. As such, it is unusual for structures of this type to be built only with concrete. Using a combination of concrete for compression and steel to absorb traction results in better structural performance.
State of Conservation
The architects Reima Pietilä and Raili Paatelainen won the competition to build a new parish church in Tampere. The design for the church is articulated in plan. A series of slender exposed concrete walls, curved and independent of one another, close off the volume of the nave with their convex sides facing the interior. A series of long vertical cracks between the walls let in light from outside. The beams above and the flat roof, also made of exposed concrete, round out the space, with a section that punctuates the interior. The program of parish premises is located under the nave and extends beyond it like a calligraphic exercise: it follows the outline of the curved walls. An exterior bell tower – which sits above the volume almost like an independent element – completes the building.
The vertical proportions of the interior space, where, in contrast to the exterior, the concrete walls are bare and uncovered, are characterized by the suggestive effects produced by natural light as it slides across the varying curves of the walls. The scarce decorative elements and furniture – cross, pulpit, altar, pews, organ – all exquisitely designed, mark a contrast in their warmth, from the use of wood, with the coldness and bulk of the concrete architectural elements.
The work by Reima Pietilä and Raili Paatelainen falls in line with the organicist tradition of Erik G. Asplund, Arne Jacobsen and Alvar Aalto, with an architecture that incorporates curves and warmth, connecting with the surroundings and shifting away from early rationalism and the uniformity of functionalism.