PROCESS FOR THIN-WALLED REINFORCED CONCRETE SHELL STRUCTURES PREFERABLY FOR LARGE SPAN STRUCTURES

摘要

Thin reinforced concrete, stressed-skin structures are prepd. using pref. smooth surface negative and/or positive moulds pref. coated with a mould release agent. Several layers of a mouldable mixt. of cement, water and additives are applied contg. alternate layers of steel-mesh. The assembly is compacted by vibration. The concrete mixt. comprises (all Kg/cu.m): (a) 500-1200 cement (of at least grade 500) (b) additives, namely 1300-2000 ground basalt of following grain distribution: 3-5mm max: 40%; 1-3mm:30-40%; 0.5-1mm:20-30%. 30-85 alkali resistant chopped glass fibre of 8-10 ion dia. and 10-40 min. length 25-60 ground dolomite of 0.005-0.1mm grain size, and (c) 200-450 l/cum softened or deionised water. - Steel mesh insertion is prepd. from wires of 0.8-2mm dia. either twisted or welded together to constitute hexagonal apertures of 30-60mm size. The stressed skin is constructed by applying a 5-8mm thick initial concrete layer to the mould, followed by a mesh and a 8-12 mm thick layer of concrete. This is continued up to a skin thickness of 5-8mm less height than the final thickness. The last steel mesh is put in plce followed by a 5-8mm thick layer of concrete. Concrete laying time is 15 mins. min. and 60 mins. max. for every layer. Total application time should not exceed 200 mins. The third, fifth and any subsequent odd numbered layer is compacted by a surface vibrator pref. for 1-3 mins.