Concrete for lining
The composition, physical properties and mechanical characteristics of concrete for in–situ pressed lining should meet some specific requirements, determined by the technology of works, apart from structural design of the lining. The technology of casting requires that the placement of concrete be mechanized, with concrete mix being pumped through pipes. The strength of concrete at removal of formwork is specified by the design in terms of the loads acting on the lining at the times of formwork removal and incomplete growth of concrete strength. Concrete composition is selected by control characteristics taking into account operational requirements— feasibility of mix delivery through pipes and workability in forming and pressing. Pumpability means the capability of concrete mix to be pumped at a preset speed without formation of plugs. The mobile concrete mixing plant comprises concrete mixer, a unit with fixed concrete pneumatic placer or concrete pump on a platform and auxiliary equipment for transfer of aggregate and cement, delivered in containers.