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<< Click to Display Table of Contents >> Layer stiffness |
  
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<< Click to Display Table of Contents >> Layer stiffness |
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Layer stiffness is measured in MPa and it should best be determined directly through laboratory testing or it can be back-calculated from deflection measurements (FWD). However CBR, UCS and DCP values can also give an indication of the stiffness values provided the environmental condition and the density of the layer is taken into account:
Material code |
Description of material |
Range of stiffness (MPa) |
Suggested average (MPa) |
Ag, AC & AS |
New hot mix asphalt |
2 500 - 8 000 |
4 000 |
Ag, AC & AS |
Old cracked asphalt |
800 - 1 200 |
1 000 |
C1 |
New cemented G1 & G2 |
2 500 - 4 000 |
2 800 |
C1 |
Old cracked C1 |
200 - 1000 |
500 |
C2 |
New cemented G3 |
2 000 - 3 000 |
2 400 |
C2 |
Old cracked C2 |
180 - 800 |
400 |
C3 |
New cemented G4 & G5 |
1 000 - 2 500 |
1 800 |
C3 |
Old cracked C3 |
120 - 500 |
300 |
C4 |
New cemented G6 & G7 |
500 - 2 000 |
1 500 |
C4 |
Old cracked |
80 - 400 |
180 |
G2 |
Crushed stone |
150 - 800 |
280 |
G3 |
Crushed stone |
100 - 700 |
250 |
G4 |
Base quality gravel |
80 - 5 000 |
210 |
G5 |
Excellent quality gravel |
70 - 300 |
170 |
G6 |
Subbase quality gravel |
60 - 200 |
130 |
G7 |
Good quality gravel (CBR>15) |
50 - 180 |
100 |
G8 |
Natural gravel (CBR>10) |
40 - 140 |
75 |
G9 |
Sandy soil (CBR>7) |
30 - 190 |
50 |
G10 |
Clayey soil (CBR>3) |
15 - 50 |
30 |