Colosseum Park Office
High performance LWAC is seldom used in Norway for house constructions and high rice buildings. There are several reasons for this: Few high rice buildings, good ground conditions, no pumping tradition and somewhat higher price on LWAC compared to NDC. For normal strength LWAC as LC 25 there is several examples of utilisation in buildings. For bridges and offshore oil platforms high performance LWAC is frequently in use. Colosseum Park has for long time been a not utilised open area in the attractive Majorstua area in Oslo. The first construction phase started in 1991, and a four-floor underground garage was completed, but the construction was stopped due to the bank crises in Norway.
Why Expanded Clay:
New requirements above the basements from the user forced the engineers to redesign the building. This involved that the vertical loads had to be replaced and increased. To avoid overloads on the existing basement 3 alternatives were studied: 1) precast slabs with NDC, 2) prestressed NDC slabs and 3) on site cast LWAC. Alternative 1 and 2 were rejected because of less flexibility during construction and particularly reduced flexibility when building is in use. The client meant that changes of the design of the floor structure were impossible with alternative 1 and 2 after the building was finished. The architect demanded to use an on-site cast solution to be able to achieve the geometric design of the floors. Alternative 3 was therefore chosen.
The reduced weight is achieved by replacing the natural coarse aggregate with lightweight materials made of expanded clay. The other constituents are the same as used for normal density (ND) concrete of high strength. To comply with the LWAC specifications LC45, density 1750 kg/m3, Norsk Leca had do develop and produce a LWA with bulk density 670 kg/m3 corresponding to a particle density at 1200 kg/m3. Two trial productions were. During the construction time the mix design was changed once when polymers were used as a superplasticizer.