| Title: |
Trends in concrete
technology for offshore and marine structures (SP-144) |
| Author(s): |
G. C. HOFF |
| Publication: |
Special Publication |
| Volume: |
144 |
| Keywords: |
columns (supports);
constructability; curing; ductility; harbor structures; heat of
hydration; high-strength concretes; mechanical couplers; mix
proportioning; offshore structures; reinforcing steels; splicing tests;
thermal gradients; |
| Date: |
March 1, 1994 |
Abstract:
The trend in offshore and marine concrete is to use higher strength concretes (HSC)
than have been used in the past. These concretes provide both additional
strength and improved durability due to their improved microstructure. This is
achieved by using greater cement content, supplementary cementing materials, and
a low water-cementitious material ratio. HSC is more brittle than normal
strength concrete and requires additional confining reinforcement to insure
ductile behavior of the structural members. Higher strength steels and special
methods of confinement, such as the use of T-headed bars, can contribute
to the ductility of the concrete.
The use of HSC creates some constructability
problems such as high concrete temperatures due to a large amount of cement
present and significant thermal gradients. Reinforcing bar congestion in HSC
requires concrete with smaller coarse aggregate sizes and very high slumps to
satisfactorily place the concrete. Lap splicing in HSC can produce problems of
concrete splitting unless the splices are properly confined. The use of
mechanical couplers for splicing has some advantages in HSC. Proper curing with
HSC is essential.
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