bids are invited for custom bid for services - terrace fabrication of shed work in nhdc office - demolishing cement concrete manually/ by mechanical means including disposal of material within 50 metres lead as per direction of engineer - in – chargenominal concrete 1:3:6 or richer mix (including equivalent design mix) , 1:3:6 (1 cement : 3 manufactured sand derived from recycled concrete aggregate (rca) : 6 graded stone aggregate 20 mm nominal size recycled concrete aggregate (rca) ) , structural steel work riveted, bolted or welded in built up sections, trusses and framed work, including cutting, hoisting, fixing in position and applying a priming coat of approved steel primer all complete.