Čerpání lehkého betonu nebylo v době výstavby mostu Raftsundet v Norsku běžně užíváno jako možný způsob ukládání těchto betonů. Pro mostní konstrukce nebylo čerpání vysokohodnotného lehkého betonu povoleno vzhledem k vysokým absorbčním hodnotám expandovaného jílu nebo jílovitých břidlic, z nichž jsou v Evropě lehká kameniva do betonu obvykle vyráběna.
Pumping of High Performance Lightweight Concrete For The Raftsundet Bridge, Northern Norway
Pumping of lightweight concrete is traditionally not used as a means of placing lightweight concrete in Norway. For bridge construction, this procedure has not been permitted for placing high performance concrete due to the high absorption of expanded clay or shale lightweight aggregate normally used in Europe. The recently completed Raftsundet Bridge is a 711- meter long free cantilever concrete bridge spanning the Raftsundet Strait in northern Norway. The main span, with a total length of 298 m and a sailing height of 47 m, is constructed from high performance light weight concrete with a hardened density of 19.75 kN and a 28-day compressive strength of 60 MPa (LC60). In order to obtain permission to pump lightweight concrete for the Raftsundet Bridge, the contractor AS Anlegg developed an elaborate testing programme and documenting of concrete properties. The program was implemented in order to demonstrate that by using a rotary kiln expanded slate lightweight aggregate (LWA), high performance lightweight concrete could be pumped without any measurable adverse affect on concrete properties. This paper discusses the concerns regarding pumping of high performance lightweight concrete, outlines the testing programme developed for the Raftsundet Bridge and reports on results from a parallel testing of both normal weight and lightweight concrete performed during the period of construction.
