Due to increasing long haul air traffic, the Vancouver Airport required expansion to their runway systems. This project included a 1,000 ft. runway extension as well as a run-up pad that would be used as a bypass for taxing aircraft and to allow aircraft to do engine run-ups - running their engines above idle after maintenance. Due to the noise, this pad is situated as far away from the community as possible.
The Vancouver Airport Authority needed a solution that would perform under high volumes of traffic and heavy loads and also provide impermeable, uniform, and strong support for the concrete pavement to be constructed over it. A minimum 4.0 MPa cement treated base (CTB) was chosen as the solution that could meet the demands of the project.
- The cement treated base thickness was 300 mm on the runway and taxiway extension and it was 200 mm on the run-up pad.
- The cement treated base material was mixed in a central mixing plant that was only a few minutes haul from the construction.
- The portland cement concrete pavement thickness was 380 mm.
- The cement treated base was placed with tandem trucks and then graded and compacted in place.
- Approximately 11,000 m3 of cement treated base and 17,000 m3 of portland cement concrete pavement were utilized on this project. Total project area was 63,000 m2.
What Is Cement Treated Base?
Cement Treated Base (CTB) is a mixture of aggregate material and/or granular soils combined with measured amounts of portland cement and water that hardens after compaction and curing to form a durable paving base. A bituminous or portland cement concrete wearing course is placed on the CTB to complete the pavement structure. CTB is widely used as a pavement base for highways, roads, streets, parking areas, airports and materials handling and storage areas.
The Key to Success
In CTB construction the objective is to obtain a thorough mixture of an aggregate/granular material with the correct quantity of portland cement and enough water to permit maximum compaction. The completed CTB must be adequately cured to let the cement hydrate and to harden the cement-aggregate mixture. The fundamental control factors for quality CTB are:
- Proper cement content
- Adequate moisture content
- Thorough mixing
- Adequate compaction
- Proper curing
A central mixing plant is used to mix together the aggregate/granular material, cement and water. Central plants can either be continuous-flow or batch-type pugmill mixers. Alternatively, CTB can also be mixed-in-place using transverse-shaft pulver mixers or traveling mixing machines.
Uses Less Raw Materials for Base
CTB thicknesses are less than those required for granular bases carrying the same traffic, because CTB is a cemented, rigid material that distributes the load over a large area. Its slab-like characteristics and beam strength are unmatched by granular bases that can fail when interlock is lost.
Durable, Ongoing Strength
Hard, rigid CTB is practically impervious. It resists cyclic freezing, rain and spring weather damage. As well, CTB continues to gain strength with age, even under traffic. This reserve strength accounts in part for CTB's known performance.
|Engineering Consultant||Acres International Ltd.|
|Cement Treated Base Contractor
||Dufferin Construction Ltd.
||Vancouver Airport Authority