Title: The Construction Of Concrete Arches In Allegheny County, Pennsylvania
Author(s): V. R. Covell
Publication: Journal Proceedings
Appears on pages(s): 653-664
Forms for arch ribs and spandrel forms were designed to be transferred practically without modification from one arch to another. Arch forms were built especially tight. Three-ply I/2-in. veneer boards were used to cover 4 x 4-in. lagging and served as the intrados form. 1forms were -in. ton ue-and-groove lumber. All seamsand cracks were fil ed l with sawdust and glue, after which form oil was applied. For winter concreting a 2000-ton bin for the sand and gravel was erected in which I in. perforated steam pipes were placed at an angle of about 45 deg upward.A 230-ton steel bin for measuring and loadmg was erected underneath. The total cost of heating for a daily run of 400 cu yd was about $25. Contractors found it advantageous to use high-early-strength cement in cold weather, which were protected by steam-heated tarpaulins; frequent temperature tests were made by the inspector.