Chamberlin, Powell and Bon (Geoffry Powell, Peter "Joe" Chamberlin, Christoph Bon)
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.
In its design, the element should account for aspects such as modulation, finishes, transportation, anchoring, installation on site, junctions between panels, the creation of openings and the relationship between the panels and joinery. The element may also be given characteristics that can improve the thermal insulation of the façade, for example. In that sense, they are often part of an industrialized system that offers a variety of responses to different construction situations and maximum versatility in terms of architectural solutions.
The aesthetic possibilities of concrete in prefabricated façade panel systems are endless in terms of size, shape, color, texture, hardness and a wide range of features.
To achieve a more noticeable effect, surface treatments can be applied to the concrete after it has set to expose the aggregates and create texture, shine or roughness.
Some examples include terrazzo pavements and many types of prefabricated façade panels.
There are various exposure methods contractors can choose from, depending on the desired look and the size of the project:
- brushing and washing
- using a surface retarder
- abrasive blasting
Beams are the horizontal load-bearing elements of the frame. Columns are the vertical elements of the frame and act as the building’s primary load-bearing element. They transmit the beam loads down to the foundations.
State of Conservation
In an area of central London devastated by bombings during World War II, the architects Chamberlin, Powell and Bon built a utopian urban vision in one of the most emblematic parts of the City of London, a paradigm of 1970s post-war urban planning.
The heart of the complex is a large artistic and cultural center. The rest is occupied by residential buildings of different types, configurations and volumes; all this surrounds a large central void with carefully designed gardens and ponds, generating an exquisite spatial quality.
The monumental scale of the building and public spaces combines perfectly with the domestic sphere, through elevated access walkways that are more like pedestrian streets than simple distribution corridors. The urban quality of the whole is remarkable and much appreciated by Londoners, contrasting sharply with other examples from the same period that have suffered a slow decline.
The characteristic appearance of the concrete used for the Barbican is the result of a careful choice of sands and aggregates, and an extremely complex and precise final treatment, in which the craftsmen first exposed the aggregate and then manually brushed the surface to obtain the desired shine and color. This treatment was applied to more than 200,000 m2 of prefabricated concrete façade panels, an area equivalent to more than 40 football fields.
London EC2Y 8DS London
Fundación DOCOMOMO Ibérico