uhpc - 1 Creep of U ltra- H igh P erformance C oncrete (...

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Unformatted text preview: 1 Creep of U ltra- H igh P erformance C oncrete ( UHPC ) Victor Y. Garas CEE 8813 04/13/2007 School of Civil and Environmental Engineering Georgia Institute of Technology Atlanta, GA, 30332 Presentation Organization Ultra-High Performance Concrete- Definition- Developing- Advantages- Applications Creep of Concrete- Definitions- Mechanisms Creep of Ultra-High Performance Concrete- Compressive- Tensile (Motivation)- Tensile (Background)- Tensile (Test Setups)- Tensile (Key Results) Concluding Remarks 2 ACI Committee 116 A concrete meeting special combinations of performance and uniformity requirements that cannot always be achieved routinely using conventional constituent materials and normal mixing, placing, and curing practices. The Federal Highway Administration (FHWA) HPC can be specified not only by the strength , but by also the following: freeze-thaw durability, scaling resistance, abrasion resistance, chloride penetration, creep , shrinkage, and modulus of elasticity. UHPC (Definitions) Collepardi et al. 1997 UHPC can be defined as an ultra-high strength and high ductility concrete with advanced mechanical properties. Shah and Weiss, 1998 Ultra-High Strength Concrete (UHSC) is defined as a mixture with compressive strength greater than 22 ksi (150 MPa) . UHPC (Definitions) 3 1- Decreasing Permeability- Reducing the water-cement ratio (typically < 0.2)- Providing proper compaction (vibration)- Eliminating Coarse aggregates Image from: Mehta and Monteiro, 2005 UHPC (Developing) 2- Densification with micro-fine particles- Filling remaining void space - Denser material- Stronger and more durable material Image from: http://techalive.mtu.edu/meec/module06/Packing.htm UHPC (Developing) 4 3- Macro-defect free (MDF) Materials- Cement + Water-soluble polymer @ low w/c (typically less than 0.2). - Increase in strength arises as a result of the cross-linking between cement and polymer (Poyola et al. 1990). 4- Using Fibers 5- Temperature Curing Image from: Shah and Weiss, 1998 UHPC (Developing) 0.18 0.18 0.18 0.18 0.18 W/CM 341 341 341 341 341 Water 60 60 60 60 60 Glenium (HRWR) 1,590 1,590 1,590 1,590 1,590 BB (150-600) Sand 98 196 295 393 Metakaolin - 235 320 320 320 320 320 Class C Fly Ash 360 270 180 90 Grace Silica Fume 1,200 1,200 1,200 1,200 1,200 P. Cement Type I SF/MK-INF lb/yd 3 SF/MK- 300 lb/yd 3 SF/MK- 100 lb/yd 3 SF/MK - 33 lb/yd 3 SF/MK - 0 lb/yd 3 Material UHPC (Developing) 6- Example 5 750 (but nothing 750 (but nothing after heat curing) after heat curing) 400 400 - 800 800 Total Shrinkage @ 180 of drying Total Shrinkage @ 180 of drying ( ) (in/in x 10 ) (in/in x 10-6 ) 0.039 0.039 0.21 0.21 0.52 0.52 Specific Total Creep in Specific Total Creep in Compression @ 180 ( Compression @ 180 ( /psi psi ) 18 18 Negligible if < 100 Negligible if < 100 800 800 3,000 3,000 Chloride Permeability Chloride Permeability (coulombs) (coulombs) 98 98...
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uhpc - 1 Creep of U ltra- H igh P erformance C oncrete (...

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