Gunārs Asaris, Oļegs Zakamennijs, Oļģerts Ostenbergs and Ivars Strautmanis
Ļevs Bukovskis, Ya. Zanis and Oļegs Skarainis, Sculptors
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 .
Prestressing is a method that helps increase the strength of reinforced concrete, specifically making it possible to increase the distances between supports. As such, it is very common in bridge construction and for creating large spans without intermediate supports.
These long spans are achieved by subjecting the structural elements to compressive forces in an initial resting position, prior to their use in construction. Once the elements are subject to loading, their capacity to withstand axial tensile stresses is increased and their structural behavior is substantially improved.
Prestress — (1) to place a hardened concrete element or an assembly of units in a state of compression before the application of service loads; (2) the stress developed by prestressing, such as by pre-tensioning or post-tensioning.
Pre-tensioning — method of prestressing reinforced concrete in which prestressing steel is tensioned before the concrete is placed.
Post-tensioning — method of prestressing reinforced concrete in which tendons are tensioned after the concrete has attained a specified minimum strength or a specified minimum age.
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.
- 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 Salaspils concentration camp, built by the Nazi regime, was located a few kilometres outside the Latvian capital, Riga. Officially, it was only a detention camp for Latvians, but Jews who had been deported directly from Germany and the occupied countries were also sent there, and it functioned an extermination camp where nearly 3,000 people died.
In 1967 the memorial was opened – one of the first and the largest of its kind in Europe. The allegorical monument consists of a long wall of exposed concrete and seven monumental sculptures, also made of concrete, representing: the Mother, the Unbroken, the Infamous, Protest, Red Front and Solidarity. To access the enclosure where the sculptures are located, which is also a cemetery, you cross the narrow space left open under the wall: it is slightly suspended in the air, supported only at its ends.
The wall is actually a large reinforced concrete box girder, and the interior can be accessed through a discreet opening. The dramatic interior space – which houses a small exhibition – is lit only by linear skylights that seem to leave the ceiling suspended.
Riga (District) LV-2117 Salaspils
Fundación DOCOMOMO Ibérico