2012 MID- CONTINENT TRANSPORTATION RESEARCH FORUM

Transcription

1 2012 MID- CONTINENT TRANSPORTATION RESEARCH FORUM Sept 6-7, 2012 Madison, Wisconsin By Sriram Aale*, Pavel Beresnev, Sri Sritharan and Ahmad Abu- Hawash

2 Problem Ultra High Performance Concrete (UHPC) Objective and Proposed Solution Laboratory Experimental Program Experimental results and observations Summary and Conclusions 9/11/12 Outline 2

3 Poor rating of Bridges!! Deck Deterioration (Durability) Corrosion of reinforcement Inadequate capacity New Bridges Membranes Exis*ng Bridges Epoxy overlays May Not Improve Capacity! Concrete overlays Deck replacement (use high-performance materials such as UHPC) Increase clear cover Epoxy coated reinforcement 9/11/12 Problem 3

4 Accelerated Bridge Construction and highly durable structures (100 yrs life) Highways for LIFE Program Precast Waffle Deck System UHPC material Capacity > 165 kips Higher cost compared to normal concrete deck!! pi - girder Waffle deck 9/11/12 Waffle Deck 4

5 Cement (27 38%)+ Silica fume (8%)+ Fine sand (39-41%)+ Ground Quartz (0-8%) + Water (5-8%) + super plasticizer + Fibers (5-8%) NO COARSE AGGREGIATE!! Good Structural and durability Properties High Bond Strength Self-Consolidating / Self Leveling Steel Fibers 9/11/12 UHPC 5

6 Develop an Economical Precast Deck System using UHPC (durability, strength and ABC) Create a rehabilitation solution for deteriorated bridge decks A composite bridge deck with a thin layer of UHPC overlaying a Normal Strength Concrete (NC) slab 9/11/12 Proposed SoluAon 6

7 Slant Shear Test to characterize the shear friction behavior between the UHPC and NC surfaces Small-Scale Slab Tests Establish & validate suitable details for UHPC-NC composite deck system. 9/11/12 Experimental Program 7

8 Texture depth = 2 mm Standard Setup using 4 by 6 rectangular specimen Test type Texture (# of specimens) Cas*ng sequence Texture depth Target = 2 mm NC Strength UHPCw- NC5 Factors considered: surface roughness (5 textures) UHPCw- NC7 concrete strength ( 5 ksi, 6.4 ksi and UHPCw- NC ksi) curing condition (Heat treated or Wet UHPCh- NC5 UHPC) Total of 60 tests 5 textures (3 per texture) 5 textures (3 per texture) 5 textures (3 per texture) 5 textures (3 per texture) Wet UHPC over Cured 5 ksi NC P Texture depth = 3 mm Wet UHPC over Cured 6.5 ksi NC Wet UHPC over Cured 7.5 ksi NC Texture depth = 5 mm Wet NC on Heat 5 ksi treated UHPC Texture depth = 6.5 mm 9/11/12 Slant Shear Test 8

9 UHPC UHPC UHPC Crushing of NC Wrap NC with FRP Sliding of the specimens 9/11/12 Slant Shear Test 9

10 2 mm (Broom) 3 mm 5 mm 1.25 in. topping; 5 ksi NC 1.5 in. topping; 5 ksi NC 9/11/12 Slant Shear Test 10

11 Small Scale Slab Tests Three Tests ( 3 different Textures) broom finish, 3 mm, 5.5 mm) 9 ft long, 2 ft wide strip from typical Iowa DOT bridge Deck 1.5 in. thick UHPC overlay Used 4 ksi standard concrete deck mix for Normal Concrete (NC) 9 ^ 2 ^ UHPC NC #6 9/11/12 Slab tests 11

12 Test Setup Single point bending Used 10 x 20 wheel load plate Load plate in Two Configurations State-of-the art 3-D measurement system 10 Config- 1 9/11/12 Test Setup 20 Config- 2 12

13 UHPC-NC Deck (Broom Finish) Typical overlay deck /11/12 Slab Test (Broom Finish) 13

14 Max. load applied = 72 kips (~ 4.5 x service load) Max. moment = 108 kip-ft Specimen failed in Shear, with failure started normal concrete. No delamination of the interface till failure. 9/11/12 Slab test (3 mm) 14

15 Max. load applied = 75 kips (~ 4.7 x service load) Max. moment = kip-ft Specimen failed in Shear, with failure started normal concrete. No delamination of the interface till failure. 9/11/12 Slab test (6 mm) 15

16 Interface shear capacity depends on texture depth and distribution and concrete strength Measured interface shear capacity varied from (f c ) mm 5 mm is appropriate for texture depths to resist the interface stresses expected in decks UHPC-NC composite deck system performed exceptionally well under shear and flexure loading. 9/11/12 Conclusions 16

17 9/11/12 17