RESEARCH NEEDS/ IDEAS FOCUSED ON BRIDGE DECK CRACKING, HOT MIX ASPHALT (HMA) PAVEMENT, PCC PAVEMENT, AND LANE MARKING
Suggested by the Pavement Design & Management/ Materials Technical Advisory Group (TAG); Contact is TAG Leader David Lippert (e-mail David.Lippert@illinois.gov)Bridge Deck Cracking
A number of possible approaches to help reduce bridge deck cracking are noted. IDOT believes bridge deck cracking is partly due to the composite design of modern bridge decks. Many past studies have focused on the improving shrinkage of the concrete. This may be a flawed approach as the design may be the main cause of cracking. For example, Wacker Drive in Chicago used post tensioning in both directions on the deck and no cracking is apparent. IDOT has constructed a few post-tensioned beam structures and little or no cracking has been found. Some work has been done in the area for IDOT: See: http://www.ict.uiuc.edu/Publications/report%20files/TES-126.pdf
1. Design, construction and monitoring of a deck “lightly” post tensioned over the beams to prevent transverse deck cracking without a significant increase in beam design.
2. Parametric/Systematic Investigation and Development of High Creep Properties for HPC IDOT Bridge Deck Concrete for Crack Mitigation. Includes restrained and unrestrained concrete investigations.
3. Coalesced Recommendations of “Best Practices” for Production, Pouring, and Curing of HPC for IDOT Bridge Deck Concrete.
4. Parametric/Systematic Investigation of Non-Rapid Strength Gain (e.g. Low-Crack) Cements for Use in HPC IDOT Bridge Deck Concrete for Crack Mitigation. Includes Restrained and Unrestrained Concrete Investigations.
5. Parametric/Systematic Investigation of Local Materials (Aggregate, Cement, and SCM) on the Cracking Behavior of Typical IDOT Bridge Deck Concrete. May Include Restrained and Unrestrained Concrete Investigations.
6. Investigation of Improved and Refined Methods for Detailing Reinforcement in Typical IDOT Bridge Decks for Crack Mitigation.
7. Investigation of the Causes and Recommendations for Mitigation of Extensive Cracking in Bridge Approach Slabs.
8. Calculation of the cracking potential of freshly placed concrete for decks on long span bridges as it relates to beam deflection.
9. Investigate the benefits of shrinkage reducing and shrinkage compensating admixtures to reduce bridge deck cracking.
10. Investigate the benefits of precast, post- tensioned parapets for bridge construction for reduction of deck cracking, reduced construction time of the deck and parapets, and increase durability of the parapets.
11. Investigate the use of textured epoxy coated rebar to reduce bridge deck cracking.
Hot Mix Asphalt (HMA) Pavement
Hot Mix Asphalt (HMA) Material durability issues and longitudinal joint performance are the primary driver in pavement performance. The following research needs are suggested:
1. Early performance monitoring and mix property requirements for Warm Mix Asphalt (WMA).
2. Determine the value of PG + tests for various polymers in ensuring quality HMA.
3. Study the benefits of vibratory, rubber tired rollers for achieving density of HMA.
4. Study the damage to the existing, aged HMA layers when an overlay is compacted on top.
PCC Pavement
PCC Pavement issues are center around reducing cost of the section and productive construciton. The following research ideas are offered on this subject:
1. What is the optimum embedment length and size of a PCC pavement tie bar for lane-to
lane and lane-to-shoulder with monolithic and staged construction?
2. Laboratory investigation of simulated tie bar insertion from a slipform paver.
3. Laboratory investigation of simulated dowel bar insertion.
Lane Marking
Alternative reflector design is needed which does not require the large metal castings for snowplow mounting. The following need is identified:
1. Investigation of recessed pavement markers in lieu of raised pavement markings in metal castings.