What would you see on a construction site in 1956?
Set up: The general contractor's office was a job-built wooden structure equipped with a pot-belly stove. On one side there was a plan table and the super's desk, on the other side was the timekeeper and tools. One hard-wired phone. The G.C. self-performed all concrete operations. The work force was all union. Layout, lines, and levels were usually run by the super or the carpenter foreman. Layout tools were dumpy level, transit, plump bob, 100-foot tape, and string.
Forms: Concrete forms were job-built in a form yard where a man with a DeWalt saw in a shed sawed tongue-and-groove lumber. Ply form was just beginning to come into use but was expensive and often delaminated. A few 10-inch Porter Cable saws were in use on form deck, but most sawing was by hand. Saws got dull quickly on reused form boards so most jobs had a saw filer. Columns were clamped with two piece Roos-Type column clamps. Wall forms were T & G lumber with double 2x4 wales and pig-foot wedges. Forms and metal pans were mopped with form oil, creating some interesting moments particularly on the metal pans—some of the gyrations should have been filmed. Nox-Crete was a timely solution.
Reinforcing steel: Rebar was fabricated by the supplier and delivered to the jobsite. Most bars were 40 ksi. The iron worker had a coil of tie wire around his shoulder and used wire pliers to tie steel and cut wire. All rebar was hand set and tied. Bars were all lap spliced.
Hoisting: Mobile cranes were not readily available and were expensive but were beginning to be used to hoist steel bundles and pour columns. Two metal towers were in general use, using a three-drum gasoline hoisting engine. One line was for the material platform, one for the concrete bucket, and one for the boom. The boom was used for items too long to get onto the material platform.
Concrete: Delivered to the jobsite in a 3- or 4-yard rear discharge drum or bathtub mixer trucks, ready-mix was available up to 4000 psi. A few remote location jobs still were job mixing concrete with skip mixers. No admixtures were in general use.
Concrete placement: Chutes, Georgia buggies, wheelbarrows, single conveyors, and an occasional mobile crane and bucket were used. Most deck concrete was placed from Georgia buggies on wooden runways. Buggies were loaded at the steel hoisting tower from a hopper. Concrete pumps were new and unreliable.
Concrete finishing: Finishers used jitter bugs to knock rocks down, pipe screeds to strike concrete, wood drags, and wood bull floats. Round headed vibrators were gasoline engine powered, with the engine mounted on a low-slung metal type wheelbarrow frame. Troweling machines were 3-foot Whiteman walk-behinds. Curing was mostly with burlap and water, occasionally sisal kraft paper.
Look around—the wonderful changes we see today
Set up: Prefabricated office and shed with central heat, AC, and toilets. Portable phones and radios. Computerized transits. Laser levels and lines.
Forms: Panel form systems. Single wales. Bolt ties. High density overlaid plywood. Form liners. Flying forms. Strickland shores. Aluminum beams. Scaffold forming. Jump forms. Metal column forms. Climbing forms. Metal wall forms. Battery power tools. Carbide saws and drills. Gang forms. Slip forms. Tunnel forms and skip joist pans.
Reinforcing steel: 60 ksi steel. Wire reels. Mechanical splices. Cad welds. Metal fibers. Post-tensioning cable. Many mats and column cages pre-tied and crane set. Epoxy-coated rebar. Fiberglass bars.
Hoisting: Tower cranes. Reliable concrete pumps. Man lifts. Electric material and manholes. OSHA. Forklifts. Mobile scissor platform lifts.
Concrete: 10-yard ready-mix trucks. Front-end unloading concrete trucks. All kinds of ready mixes up to 14,000 psi. All kinds of admixtures. Integrally colored concrete. Fibers in concrete. Self-consolidating concrete.
Concrete placement: Concrete pumps. Crane and bucket. High cycle vibrators. Conveyor on concrete truck. Long metal chute.
Concrete finishing: Vibrating screeds and floats. Laser screeds. Magnesium tools. Riding trowling machines. Diamond tools and grinders. Soff-Cut saws. Scarifying machines. All kinds of architectural concrete. Color and stain work. Polyethylene. Curing compounds. Curing blankets. “F” numbers. Diamond floor polishers.
Man, what improvements in 50 years! We all hope the future bodes well for much more.