Page 20

2015WinterShotcreteEMag

was ruled out due to the harsh marine environment Shells project, and be carried out in a short time and the threat of anti-social behavior such as frame, thus reducing the site costs further. graffiti and arson. It was decided that a robust The project was built in two distinct stages: material was required that could withstand all the construction of the shells by the Shotcrete possible eventualities. Concrete was chosen as a Group, the specialist sprayed concrete contractor, material that could be dense enough to meet an followed by the integration into the landscaping, acoustic brief and be robust enough to be a match which was by Landbuild. for the environmental conditions. The development of the scheme in three An all-concrete structure had its own problems dimensions was very complex and involved con- and would have to use innovative construction siderable input from the contractor. After having techniques to limit the wastage inherent in shut- developed the form of the building in specialized tering and forming processes. Research was under- software, a digital model of the scheme was taken in the development of thin shell structures. handed to the Shotcrete Group to drive the devel- These can be self-supporting and have structure opment the form. Following the ordering and integrated into the form of the shell. The most delivery of the reinforcement bars, a grid of efficient technique that would suit was that of scaffolding 3.3 x 3.3 x 3.3 ft (1 x 1 x 1 m) was sprayed concrete. With care, this process can set up on the site. A corresponding digital version produce the complexity required by the Acoustic was set up in the architect’s office. Points were taken on the digital model where the form of the shells touched the grid. These were then marked on the scaffold. These points were then checked by digital survey and sent back to the model in the office for review. Once all parties were content with the spatial coordinates, the reinforcing bar mesh could be assembled within the constraints of the marked scaffold, with the confidence that the form of the shells will conform exactly to the shape and specification of the digital version. Following the reinforcing bar assembly, an expanded metal mesh was threaded into the struc- ture. This acted as stay-in-place formwork and enabled the spraying process to take place from both sides. The thickness of the shell was on average 4 in. (100 mm), with the leading edge thickening to 6 in. (150 mm) for structural stability. Once sprayed, the structure was hand-finished with metal trowels, creating a perfectly smooth finish. This was then painted and given an anti- graffiti seal. Since the project’s completion in April 2014, the Acoustic Shells have gone on to become a celebrated local landmark for the Littlehampton community. Available for event hire through the local town council, the stage and shelter are also used on a daily basis for play and rest by Stage (Photo courtesy Flanagan Lawrence) passers-by. On a wider scale, the project has Stage (Photo courtesy Flanagan Lawrence) 18 Shotcrete • Winter 2015


2015WinterShotcreteEMag
To see the actual publication please follow the link above