Jim Welter, Ohio Department of Transportation
In response to House Bill 163 of the Ohio State General Assembly, the Ohio Department of Transportation (ODOT) established warranty specifications for various items of work in highway construction projects. Warranties are to guarantee the quality and durability of selected items of work for a specific period of time after construction, resulting in lower life-cycle costs. Supplemental Specification 894 was originally written in October 1999 requiring contractors to warrant new bridge decks with high performance concrete (HPC). There were also supplemental specifications for Quality Control/Quality Assurance Concrete and ODOT Class S (superstructure) Concrete for New Bridge Decks with Warranty. The original specification was written for the HPC to be warranted for 7 years. This warranty period was reduced to 2 years in 2005 due to a change in the state law.
The Supplemental Specification 894 applies to the structural bridge deck concrete for the entire deck. The warranty items include scaling, spalling, and alligator or map cracking. Meeting the minimum requirements and guidelines of the applicable specification are not to be construed as a warranty, expressed or implied, as to the material properties and workmanship efforts required to meet the performance criteria. The intent of the contract is for the contractor to provide a maintenance free bridge. The contractor may perform routine maintenance during the warranty period. The design of the superstructure and the design of the concrete mix are not part of the warranty. The contractor is required to mix and place the HPC per normal specifications.
Review Process and Remedial Actions
According to Supplemental Specification 894, High Performance Concrete For New Bridge Decks With Warranty, dated April 15, 2005, at least two reviews performed by an ODOT District Review Team (DRT) are required as follows for the 2-year warranty:
- At the end of the first year, a review for alligator or map cracking.
- Final review, 1 month before the end of the warranty period for scaling and spalling only.
Supplemental Specification 894 lists the following thresholds and required remedial actions for alligator or map cracking, scaling, and spalling.
| Defect Found during Review | Required Remedial Action |
| Alligator or map cracking on 20% or less of deck area | Apply high molecular weight methacrylate resin (HMWM) |
| Alligator or map cracking on greater than 20% of deck area | Hydrodemolition of the surface of the entire deck, 1 in. (25 mm) deep and the placement of nominal 1 in. (25 mm) inlay with either latex modified concrete (LMC) or microsilica modified concrete (MSC). |
| Scaling less than 1/4 in. (6 mm) deep but greater than 1/8 in. (3 mm) deep and no more than 20% of deck area | Grind the defective area, saw cut transverse grooves, and seal the surface with a non-epoxy sealer. |
| Scaling greater than 1/4 in. (6 mm) deep or spalling less than 32 yd2 (27 m2) | Diamond saw cut perimeter, hydrodemolition 1 in. (25 mm) deep, patch with LMC or MSC, and seal edges with HMWM. |
| Scaling is more than 20% of deck area or spalling greater than 32 yd2 (27 m2) | Hydrodemolition of the entire deck 1 in. (25 mm) deep and place LMC or MSC. |
Alligator or map cracks in bridge decks are often due to improper curing of the concrete. In our experience, scaling in bridge decks is caused by water added to the surface of the deck to aid in finishing, or the uncured concrete was allowed to freeze. Spalling can occur in bridge decks because the concrete was not mixed properly and the cementitious materials formed into balls.
Maintenance Bond and Appeal Process
In addition to the normal performance and payment bonds, the contractor furnishes a maintenance bond for 50% of the total price bid for the HPC for a period of 2 years. The contractor may appeal the DRT’s bridge deck review findings within 15 days after receiving the written review results. The ODOT District Construction Engineer (DCE) will evaluate the contractor’s appeal and inform the contractor of his determination within 45 days. If the contractor disagrees with the DCE’s determination, the contractor may appeal.
Experience
Since January 2000, ODOT has let 149 projects with pay items for a total of 227 individual HPC bridge decks with warranty. There have been 41 decks that required corrective work for alligator or map cracking. There have been two decks that required corrective work for major spalling. According to the ODOT Division of Construction Management, 2006 Status Report of the Warranty Program, the warranty program has declined in recent years.
Feedback concerning warranty work from the ODOT Districts was that contractors, while being more conscientious about their work, were not producing significantly better products. Warranties do not necessarily reduce the need for inspection, in that extensive documentation of preexisting conditions and construction methods were required by both parties. Some contractors voiced concerns about issues over which they had no control during the warranty period.
These included the design of the bridges, overloads traveling on the bridges, and salt applications for snow and ice control. ODOT has experienced mixed results in effecting warranty repairs. At this time, ODOT is limiting the use of warranties on its projects. A cost comparison showed warranty concrete bridges cost about 5.6% more than non-warranty concrete bridges. ODOT has found that its basic contract provisions provided essentially the same rights of recovery for defective work as are provided by warranty.
ODOT will continue to use HPC in their bridge decks but not in HPC with Warranty Items.
More Information and References
The supplemental specifications are available at www.dot.state.oh.us. or contact the author at 614-444-6628. Further information is available in the ODOT Innovative Contracting Manual, dated 4/10/06 and the ODOT 2006 Status of the Warranty Program, dated 2/1/07.