Two-lift paving
Design aspects
Luc Rens, C.E.
FEBELCEM – Consulting Engineer
l.rens@febelcem.be
EUPAVE – Managing Director...
Classic continuous reinforced
concrete in Belgium
Belgian standard design for concrete motorways
1 lift - single run of th...
1996 - Herne : Test
sections of low-noise
surfaces
TWO-LIFT PAVING - BELGIAN EXPERIENCE
2002
N511 – Estaimpuis
Double layered CRCP
with different top layers
TWO-LIFT PAVING - BELGIAN EXPERIENCE
E34/N49
Category : main road (at most places transformed into
motorway)
Traffic volume (March 2007):
23 000 vehicles a day...
E34/N49 – Two lift continuously
reinforced concrete
 Construction in two layers: optimum noise reduction at
surface due t...
Recycled aggregates: from existing road –
quality controlled by COPRO
Concrete mix specifications
Specifications for the top layer:
- aggregate 4/6,3 (PSV  50) – no reclaimed material allowed...
Structure of two-layered CRCP
Continuous longitudinal
reinforcement at 8 cm
from surface
Placing of the concrete “wet on wet” by two slipform
pavers (maximum time interval of 2 hours)
EXECUTION
 Surface finishing = fine-grained exposed
aggregate concrete
EXECUTION
RECLAIMED AGGREGATES IN PAVEMENT CONCRETE
Experiences in other countries
 Austria
• Double-layered jointed plain concrete...
N49 : after 3 years in service…
(May 2011)
N49 : after 3 years in service…
(May 2011)
N49 : after 3 years in service…
(May 2011)
Horizontal cracks at the height of
the reinforcement
Shrinkage crack
Over total
depth
Horizontal
crack
Vertical crack
ends...
What is different?
Older realisations with double layered CRCP:
Herne (1996) – Estampuis (2002)
What is different on the ...
Research and investigation
 Inspection of cores
 Bond steel – concrete
 Microscopic examination
 Ultrasonic tomography
Ultrasonic tomography :
measurement at a crack
Concrete properties determined on bottom layer
(after 4 years in service)
Core Volumic density Compressive
strength
1 2350...
We are still looking for the
answers…
How did the horizontal cracks occur?
 Due to the too large opening of the initial t...
Changes in design for recent
worksites of two-lift CRCP
 Changes in design
– No RCA
– No air entrainer in
bottom layer
– ...
Risk for punch-outs
What could be the solutions ?
ACTIVE CRACK CONTROL ?
 Short crack inducer
– At the edge of the pavement
– 40 cm wide
– 3 ...
Test strips of double layered
concrete (JPCP) for industrial areas
 Wet-in-wet
application –
excellent bond
 Recycled ag...
Thank you for your
kind attention
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Two-Lift Paving - Design Viewpoints

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A Two-Lift concrete Paving (2LCP) workshop was organized as a part of the Texas Department of Transportation (TxDOT) project 0-6749: Feasibility Study of Two-Lift Concrete Paving (2LCP). This workshop was conducted at the J. J. Pickle Research Campus (PRC), The University of Texas at Austin, Austin, TX on May 23rd, 2013. Dr. Jiong Hu, Texas State University, Research Supervisor, and Dr. David Fowler, The University of Texas at Austin, Co-Research Supervisor, co-chaired the workshop. The workshop offered the option of attending in person or remotely through webinar. Fifty-one attendees were present remotely or in person; 28 in person and 23 persons remotely.

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Two-Lift Paving - Design Viewpoints

  1. 1. Two-lift paving Design aspects Luc Rens, C.E. FEBELCEM – Consulting Engineer l.rens@febelcem.be EUPAVE – Managing Director May 23, 2013, Two-Lift Paving Workshop, Austin, Texas
  2. 2. Classic continuous reinforced concrete in Belgium Belgian standard design for concrete motorways 1 lift - single run of the slipform paver Simple and reliable construction method Exposed aggregate concrete surface Stones : PSV ≥ 50 - no recycled materials
  3. 3. 1996 - Herne : Test sections of low-noise surfaces TWO-LIFT PAVING - BELGIAN EXPERIENCE
  4. 4. 2002 N511 – Estaimpuis Double layered CRCP with different top layers TWO-LIFT PAVING - BELGIAN EXPERIENCE
  5. 5. E34/N49 Category : main road (at most places transformed into motorway) Traffic volume (March 2007): 23 000 vehicles a day in the direction from Antwerp to Zelzate 25% heavy traffic  Construction in 2 phases: Direction from Antwerp: 2007 Direction to Antwerp: 2008
  6. 6. E34/N49 – Two lift continuously reinforced concrete  Construction in two layers: optimum noise reduction at surface due to fine exposed aggregate concrete in top layer  Continuously reinforced concrete  Recycled aggregates in the lower course – aggregates from existing concrete road
  7. 7. Recycled aggregates: from existing road – quality controlled by COPRO
  8. 8. Concrete mix specifications Specifications for the top layer: - aggregate 4/6,3 (PSV  50) – no reclaimed material allowed - coarse sand – no reclaimed material allowed - CEM III/A 42,5 N LA  425 kg/m³ - W/C  0,45 - air entrained – air void content  5% Specifications for the bottom layer: - aggregate 4/6,3 : no reclaimed material allowed - aggregate 6,3/20 – 20/32 : reclaimed crushed concrete,60 to 100% - coarse sand – no reclaimed material allowed - CEM III/A 42,5 N LA  375 kg/m³ - W/C  0,45 - air entrained – air void content  3 %
  9. 9. Structure of two-layered CRCP Continuous longitudinal reinforcement at 8 cm from surface
  10. 10. Placing of the concrete “wet on wet” by two slipform pavers (maximum time interval of 2 hours) EXECUTION
  11. 11.  Surface finishing = fine-grained exposed aggregate concrete EXECUTION
  12. 12. RECLAIMED AGGREGATES IN PAVEMENT CONCRETE Experiences in other countries  Austria • Double-layered jointed plain concrete since 1990 • 21 cm + 4 cm • Motorway programme (A1 – A2) • Reuse in the lower course of 65 % of recycled crushed concrete from the old pavement • Asphalt layer between base and concrete pavement  Germany • Has taken over the Austrian technique • Geotextile between base and concrete pavement • The Netherlands, Belgium…
  13. 13. N49 : after 3 years in service… (May 2011)
  14. 14. N49 : after 3 years in service… (May 2011)
  15. 15. N49 : after 3 years in service… (May 2011)
  16. 16. Horizontal cracks at the height of the reinforcement Shrinkage crack Over total depth Horizontal crack Vertical crack ends at the reinforcement
  17. 17. What is different? Older realisations with double layered CRCP: Herne (1996) – Estampuis (2002) What is different on the E34/N49? - Rebars are higher in the concrete layer: 8 cm from surface at the N49 and 13 cm in Herne? - Traffic intensity is much higher and the concrete has been exposed to traffic much sooner - Time of execution: warm summer for the N49, normal spring in Herne - Use of recycled aggregates in the bottom lift
  18. 18. Research and investigation  Inspection of cores  Bond steel – concrete  Microscopic examination  Ultrasonic tomography
  19. 19. Ultrasonic tomography : measurement at a crack
  20. 20. Concrete properties determined on bottom layer (after 4 years in service) Core Volumic density Compressive strength 1 2350 kg/m³ 80,32 N/mm² 2 2360 kg/m³ 82,55 N/mm² 3 2360 kg/m³ 88,45 N/mm²
  21. 21. We are still looking for the answers… How did the horizontal cracks occur?  Due to the too large opening of the initial transverse cracks?  Due to the use of reclaimed aggregates in the bottom layer of the concrete? (because of additional shrinkage and/or lower strength)  Due to the two layers? Differential shrinkage?
  22. 22. Changes in design for recent worksites of two-lift CRCP  Changes in design – No RCA – No air entrainer in bottom layer – Induced cracking – Long. steel 1cm lower
  23. 23. Risk for punch-outs
  24. 24. What could be the solutions ? ACTIVE CRACK CONTROL ?  Short crack inducer – At the edge of the pavement – 40 cm wide – 3 cm deep – Spaced at 1,20 m (4 ft)
  25. 25. Test strips of double layered concrete (JPCP) for industrial areas  Wet-in-wet application – excellent bond  Recycled aggregates in base layer  TiO2 in top layer
  26. 26. Thank you for your kind attention
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