A Comparative Study of Aluminum and Steel Culverts: Progress Report No. 4

About the report:

The results of a comparative study of aluminum and steel culverts at six test sites throughout Virginia indicate that satisfactory durability can be expected of aluminum pipe under exposure to most of the soil and water conditions in the state. The performance of the bare aluminum culverts suggests that bituminous coating of the pipes or paving of the inverts would be necessary only under severe site conditions. The performance of the steel culverts in the study demonstrates the effectiveness of coating and paving in prolonging the service life of these pipes. The heavy paving layer in the invert of this type of culvert is subject to cracking soon after installation, but the distress is generally serious only at the ends. The following recommendations are offered. 1. The current policy of the Virginia Department of Highways regarding the use of fully bituminous coated corrugated steel culverts with paved inverts, as stated in Instructional and Information Memorandum LD-68 (R)-11.2 (11/12/68), should be continued. The use of uncoated pipe allowed in the above memorandum is also reasonable. 2. The use of aluminum culvert as an alternate to bituminous coated, corrugated steel culvert with paved invert should be allowed, at least on a number of projects. This action would increase the experience of the Department of Highways and local fabricators and contractors with the product. 3. If desired, paving of the inverts can be required on initial projects, but consideration should be given, whenever possible, to the use of unpaved aluminum culvert, which presents greater economy. Uncoated aluminum should be allowed as an alternate to uncoated steel culvert. 4. A pH of 4.0 should be considered the absolute lower limit for the use of unprotected aluminum culvert. Since the pH value varies with the amount of flow, the suitability of uncoated aluminum culvert should be considered questionable when the pH values range between 4.0 and 5.0.

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