Table of Contents
Chapter 7
— David Wagner 2007/06/29 15:40
Problem 1.
- Average 7-day maximum pavement design temperature: 58°C
- Minimum pavement design temperature: -10°C
Problem 2.
| Mix Design | Field Mix | ||
|---|---|---|---|
| (cf) | (lb) | ||
| Cement | 0.478 |  | 667 |
| Sand | 1.421 |  | 1768 |
| Gravel | 2.500 |  | 307 |
| Water | 0.865 |  | 227 |
| Total | 5.264 | ||
Excess Water: 
22 lb
Capacity: 34*1.1=37.4 lb; N=7.1 batches
Problem 3.
| Compnonent | Fraction | Total | Rate (dry) | Rate (field) |
|---|---|---|---|---|
| Asphalt | 0.06 | 140 | 8.4 | |
| Aggregate | 0.94 | 140 | 131.6 | 140 |
| — | — | — | ||
| 1.00 | 140 | 140.0 | ||
| Aggregate components (dry weight) | ||||
| Coarse A | 0.50 | 131.6 | 65.8 | 70.0 |
| Coarse B | 0.20 | 131.6 | 26.3 | 28.0 |
| Sand | 0.24 | 131.6 | 31.6 | 33.6 |
| Mineral Filler | 0.06 | 131.6 | 7.9 | |
| — | — | — | ||
| 131.6 | ||||
(Feed rates in tons per hour.)
Problem 4.
| Compnonent | Fraction | Total | Rate (dry) | |
|---|---|---|---|---|
| Asphalt | 0.05 | 3 | 0.15 | |
| Aggregate | 0.95 | 3 | 2.85 | |
| — | — | — | ||
| 1.00 | 3 | 3.0 | ||
| Aggregate components (dry weight) | ||||
| Coarse A | 0.45 | 2.85 | 1.28 | |
| Coarse B | 0.35 | 2.85 | 1.00 | |
| Sand | 0.15 | 2.85 | 0.43 | |
| Mineral Filler | 0.05 | 2.85 | 0.14 | |
| — | — | — | ||
| 2.85 | ||||
(Rate is tons per batch)
Problem 5.
This is a computer programming problem.
Problem 6.
a. w/c=50/94=0.53
| w/c=0.53 |
|---|
b. Lowering the water content makes the mix less workable, so it may not fill forms properly and make voids or honeycombing. Adding plasticizers may help lower water content while maintaining workability.
Problem 7.
To get 100% passing 2½”, use a roller crusher closed side setting of 1¼ or smaller.
| Jaw Setting: 4 | Roll Setting: 1.25 | Total: 150 tph | |||
| Screen | Passing | Sent to Roller | Passing | Output (%) | Output (tph) |
| 2.5 | 48% | 52% | 100% | 100.00% | 150.0 |
| 2 | 39% | 95% | 88.40% | 132.6 | |
| 1.5 | 29% | 82% | 71.64% | 107.5 | |
| 1.25 | 25% | 80% | 66.60% | 99.9 | |
| 1 | 19% | 66% | 53.32% | 80.0 | |
| 0.75 | 15% | 49% | 40.48% | 60.7 | |
| 0.5 | 11% | 32% | 27.64% | 41.5 | |
| 0.375 | 8% | 25% | 21.00% | 31.5 | |
| 0.25 | 6% | 18% | 15.36% | 23.0 | |
| Jaw: 4” | Roller: 1¼” |
|---|
Problem 8.
- Total Screen Load: 37.3 tph
- Passing Screen: 16.1 tph
- Total Feed: 3.9 tph/sf; Passing: 1.95 tph/sf [fig. 7-6]
- DPF: 0.8; HSF: 0.7; OF: 57%; TH: 1.27; Pass: 0.86
Total Feed Capacity: 
2.8 tph/sf
Size Feed: 
13 sf
Passing Capacity: 
0.94 tph/sf
Passing Size: 16.1/0.94=17
| 17 sf |
|---|
Problem 9.
16/4.950=3.23≈3 mixes/batch
| Mix Design | Field Mix | |||
|---|---|---|---|---|
| (lb) | (SG) | (cf) | (lb) | |
 |  |
|||
| Cement | 94 | 3.15 | 0.478 | 282 |
| Gravel | 395 | 2.66 | 2.380 | 1185 |
| Sand | 215 | 2.65 | 1.300 | 645 |
| Water | 50 | 1.00 | 0.801 | 150 |
| Total | 4.95 | |||
Discussion