Low-Density Concrete Backfills for Lined Tunnels.
Abstract
Low-density concretes having an oven-dry unit weight of 50 pounds per cubic foot or less have been successfully used as backfills for lined tunnels. The most satisfactory technique for backfill placement is by pumping. Information on lift heights, cold joints, temperature problems, and water saturation problems which are unique to these types of concretes is included. Lift heights should not exceed those which cause an increase in density over the desired density by more than a stipulated amount in the lower portion of the lift. Horizontal cold joints do not appear to be a problem area. Temperatures over about 120 F tend to cause collapse of the structure of unhardened low-density cellular concrete. Because of the permeable nature of these concretes, free water contact situations should be avoided. Suggestions for avoiding most problem areas are provided. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1970
- Accession Number
- ADA029820
Entities
People
- George C. Hoff