No abstract

A salt-saturated concrete proportioned with Class H oilwell cement, Class F fly ash, and a shrinkage compensating component was developed to meet performance requirements for mass placement as seal components at the Waste Isolation Pilot Plant. Target properties of the concrete included 8-in. slump 3 hr after mixing, no aggregate segregation, heat rise of <25°F 4 hr after mixing, compressive strength of 4,500 psi at 180 days, minimal volume change, and probable geochemical stability for repository conditions. Thermal and mechanical properties of promising candidate concrete mixtures were measured. Modulus of elasticity and creep behavior were similar to those of ordinary portland cement mass concretes. Thermal expansion for the salt-saturated concrete developed here was typical of ordinary concrete with similar silicate aggregates. Thermal conductivity, diffusivity, and specific heat approximated values measured for other mass concretes and were similar to values of the host salt rock.

Public reponing burden for this collection of information is estimated to average t hour per rerponse including the time for reviewing Instructions searching existing data sources. gathering and maintaining the data needed,and completing and reviewing the collection of informatlbn. Send commenls r arding this burden es6mate or any other aspect Of this collection of Information, including suggestions for reducing this burden. to Washington Headquarters Services, Directoratc?or Information Operations and Repom. 1215 Jeffenon DIUIS Hiahwav. Suite 1204, Arlington, VA 222024302. and to the Office of Management and Budget, Papemork Reduction Project(0704-0188). Washington, DC 20503.

Recent innovations by the Arizona Department of Transportation (DOT) in the use of design—build procurement for highway construction are presented. Explosive population growth in Arizona has pushed its DOT to the limits of its capacity and has challenged the department to develop innovative ways to stretch its resources to meet its constituents’ needs. In 1996 the department spearheaded the passage of a pilot design–build law aimed at completing public-sector construction projects more rapidly than could be done by traditional methods. An evaluation of the material quality program used in the second design–build project in this program is described. The project reconstructed an extremely congested 7-mi segment of Interstate 17, a primary artery carrying 180,000 vehicles per day through the city of Phoenix, widening it from 6 to 10 lanes. The design–build contract was awarded after A+B bidding, which considered the bid price to do the work and the time required to complete the project, and was the largest ever awarded at the time. It was won by a design–builder who implemented a very aggressive schedule that required double-shift work for nearly 2 years. In another contracting first, the agency also assigned the design–builder responsibility for the quality control and quality assurance functions on the project, with Arizona DOT providing verification sampling and testing only. The concrete compressive strength and material density for the project are examined and are compared to statewide averages for traditional design-bid-build projects in which Arizona DOT performed the quality assurance function. Analysis of the data shows that despite a highly compressed schedule, the quality of the material on the project exceeded the project specifications and was similar to the quality of work completed for the state under traditional contracting methods with an Arizona DOT—operated quality assurance program.

No abstract