US 20 provided a set of specimens that represented the best- and
poorest-performing pavements, concretes with and without fly ash replacement
of the cement, and pavements using a single mix design exhibiting opposite
performance characteristics. Four sampling sites were identified with the
assistance of Iowa DOT to facilitate comparison of poorly-performing with
sound pavements. Materials and properties information (Table 4) was taken from IDOT reports supplied to the Pooled Pavement Study by
Northwestern University [28].
| Table 4. US 20 Location 1, Webster County: Materials
and Properties [28]. |
| Cement: | Type I |
| | 3.5 % SO3,
|
| | 0.77 % equivalent alkali, |
| |
| Coarse Aggregate: | Ft. Dodge Limestone, Gilmore City bed,
ledge 36-42 |
| | 1 % Freeze-thaw loss, 0.9 % absorption., |
| | LA abrasion 28 % loss, durability factor 94 |
| |
| Fine Aggregate: | Yates sand |
| |
| Admixtures: | AEA (air entraining admixture) |
| Fly Ash: | Class C, |
| | 3.23% SO3, |
| | 2.95% equivalent alkali, 0.28% loss on ignition
|
| Concrete Batch Mass / m3
|
| Cement | 274 kg | 0.48 w/s | Slump: 50 mm to 44 mm,
avg. 46 mm |
| Water | 160 | | Air: 7.8 % to 6.0 %, avg. 6.7
% |
| Fly Ash | 46 | |
| C. Agg. | 980 | | slipform paver with
spreader |
| F. Agg. | 821 | | Temp: 31 to 10 (º
C), no precipitation, clear/sunny |
| WR | na | | Mix Characteristics: Harsh |
| AEA no value | | | 31 MPa compressive
strength |
| (IDOT Mix 3 - actual material mass estimated from mass
proportions [28] |
| Completed 5/86, deterioration noted 1990 |
| |