MTO EMPIRICAL MTO EMPIRICAL PAVEMENT DESIGN PAVEMENT DESIGN The following presentation contains references to The following presentation contains references to Tables 6.02 Tables 6.02 and and 6.03 6.03 , and “ , and “ MTO Empirical Design Examples MTO Empirical Design Examples ”, all of which ”, all of which are posted under subsection 2.6 of the course notes on the are posted under subsection 2.6 of the course notes on the instructor’s website. Viewer discretion is advised as some instructor’s website. Viewer discretion is advised as some scenes contain material of a tabular nature. scenes contain material of a tabular nature.
Transcript
MTO EMPIRICAL MTO EMPIRICAL PAVEMENT PAVEMENT
DESIGNDESIGN
The following presentation contains references to The following presentation contains references to Tables 6.02Tables 6.02 and and 6.036.03, and “, and “MTO Empirical Design MTO Empirical Design ExamplesExamples”, all of which are posted under ”, all of which are posted under subsection 2.6 of the course notes on the subsection 2.6 of the course notes on the instructor’s website. Viewer discretion is advised instructor’s website. Viewer discretion is advised as some scenes contain material of a tabular as some scenes contain material of a tabular nature.nature.
Notes: All AADT Volumes ref er to Present Traffi c
HM: Hot Mix Asphalt & Thickness (mm)
B: Base Thickness (mm)
SB: Subbase Thickness (mm)
GBE: Equivalent Thickness of Granular Base (mm)
( 1 mm HM = 2 mm B = 3 mm SB )
**: Proposed subbase thicknesses may be decreased or increased respectively
f or harder or sof ter subgrade conditions in each category, except f or
varved & leda clay subgrades where exceptionally large ranges are shown
(Af ter: "Pavement Design and Rehabilitation Manual", 1990)
SANDS AND SI LTS
Percent Passing No. 200 Sieve
TABLE 6.03 a
STRUCTURAL DESI GN GUI DELI NES FOR FLEXI BLE PAVEMENTS
- KI NG'S HI GHWAYS AND FREEWAYS
Subgrade Material
So, a) has 5 levels (rows) of traffic (AADT) So, a) has 5 levels (rows) of traffic (AADT) which are different than the 6 for b)which are different than the 6 for b)
The 6 columns for different subgrade types The 6 columns for different subgrade types are the same for bothare the same for both
Each cell has a conventional pavement designEach cell has a conventional pavement design
Gravels
Range of Pavement and Sands Lacustrine Varved &
AADT Structure Suitable as Clays Leda Clays
Elements Gran. Borrow <40% 40 - 55% >55%
HM 90 90 90 90 90 90
2000 - B 150 150 150 150 150 150
3000 SB** --- 300 450 600 450 800
GBE 330 530 630 730 630 865
HM 50 50 50 50 50 50
1500 - B 150 150 150 150 150 150
2000 SB** --- 250 300 450 300 450(300 - 600)
GBE 250 415 450 550 450 550 (450 - 650)
CL 50 50 50 50 50 50
1000 - B 150 150 150 150 150 150
1500 SB** --- 250 300 450 300 450 (300 - 600)
GBE 240 405 440 540 450 540 (450 - 640)
ST* --- --- --- --- --- ---
500 - B 150 150 150 150 150 150
1000 SB** --- 150 250 300 250 350 (250 - 450)
GBE 150 250 315 350 315 385 (315 - 450)
ST* --- --- --- --- --- ---
200 - B 150 150 150 150 150 150
500 SB** --- 150 250 300 250 300
GBE 150 250 315 350 315 350
Gravel --- --- --- --- --- ---
< 200 B 100 100 100 100 100 100
SB** --- 150 250 300 250 300
GBE 100 200 265 300 265 300
Notes: All AADT Volumes ref er to Present Traffi c
HM: Hot Mix Asphalt & Thickness (mm)
B: Base Thickness (mm)
SB: Subbase Thickness (mm)
GBE: Equivalent Thickness of Granular Base (mm)
( 1 mm HM = 2 mm B = 3 mm SB = 1.11 mm CL)
CL: Cold Mixed, Cold Laid or Road Mixed Mulch
ST: Double Surf ace Treatment or Single Surf ace Treatment with Prime
*: Apply surf ace treatments 0.25 m wider that lane width
**: Proposed subbase thicknesses may be decreased or increased respectively
TABLE 6.03 b
STRUCTURAL DESI GN GUI DELI NES FOR FLEXI BLE PAVEMENTS
- SECONDARY HI GHWAYS(Af ter: "Pavement Design and Rehabilitation Manual", 1990)
Subgrade Material
SANDS AND SI LTS
Percent Passing No. 200 Sieve
AADT>200 vpd
Subgrades range from:STRONGEST
to weakest
AADT<3000 vpd
Same old Same old subgradesubgradess
Example Example 11
A 2-lane county road is expected to have A 2-lane county road is expected to have an initial AADT of an initial AADT of 1750 vpd1750 vpd and is to and is to built over a built over a silty sandsilty sand subgrade with subgrade with 30%30% Passing the No. 200 sieve. Passing the No. 200 sieve.
a)a) Determine a conventional flexible Determine a conventional flexible pavement design.pavement design.
b)b) A couple of subsections require the use A couple of subsections require the use of a deep strength design using cement of a deep strength design using cement treated base and no subbase. Give the treated base and no subbase. Give the appropriate layer thicknesses.appropriate layer thicknesses.
• for AADT of 1750 for AADT of 1750 use second rowuse second row
• for silty sand with for silty sand with 30% passing no. 30% passing no. 200 use second 200 use second columncolumn
• And the winning And the winning design is:design is:
HM: 50 mmHM: 50 mm B: 150 mmB: 150 mm SB: 250 mmSB: 250 mmGBE: 415 mmGBE: 415 mm
Gravels
Range of Pavement and Sands Lacustrine Varved &
AADT Structure Suitable as Clays Leda Clays
Elements Gran. Borrow <40% 40 - 55% >55%
HM 90 90 90 90 90 90
2000 - B 150 150 150 150 150 150
3000 SB** --- 300 450 600 450 800
GBE 330 530 630 730 630 865
HM 50 50 50 50 50 50
1500 - B 150 150 150 150 150 150
2000 SB** --- 250 300 450 300 450(300 - 600)
GBE 250 415 450 550 450 550 (450 - 650)
CL 50 50 50 50 50 50
1000 - B 150 150 150 150 150 150
1500 SB** --- 250 300 450 300 450 (300 - 600)
GBE 240 405 440 540 450 540 (450 - 640)
ST* --- --- --- --- --- ---
500 - B 150 150 150 150 150 150
1000 SB** --- 150 250 300 250 350 (250 - 450)
GBE 150 250 315 350 315 385 (315 - 450)
ST* --- --- --- --- --- ---
200 - B 150 150 150 150 150 150
500 SB** --- 150 250 300 250 300
GBE 150 250 315 350 315 350
Gravel --- --- --- --- --- ---
< 200 B 100 100 100 100 100 100
SB** --- 150 250 300 250 300
GBE 100 200 265 300 265 300
Notes: All AADT Volumes ref er to Present Traffi c
HM: Hot Mix Asphalt & Thickness (mm)
B: Base Thickness (mm)
SB: Subbase Thickness (mm)
GBE: Equivalent Thickness of Granular Base (mm)
( 1 mm HM = 2 mm B = 3 mm SB = 1.11 mm CL)
CL: Cold Mixed, Cold Laid or Road Mixed Mulch
ST: Double Surf ace Treatment or Single Surf ace Treatment with Prime
*: Apply surf ace treatments 0.25 m wider that lane width
**: Proposed subbase thicknesses may be decreased or increased respectively
TABLE 6.03 b
STRUCTURAL DESI GN GUI DELI NES FOR FLEXI BLE PAVEMENTS
- SECONDARY HI GHWAYS(Af ter: "Pavement Design and Rehabilitation Manual", 1990)
Subgrade Material
SANDS AND SI LTS
Percent Passing No. 200 Sieve
For a county road with For a county road with an AADT of 1750 vpd, an AADT of 1750 vpd, try Table 6.03btry Table 6.03b
LayerLayerLayer Layer
Thickness Thickness (mm)(mm)
Hot MixHot Mix 5050
BaseBase 150150
SubbaseSubbase 250250
EquivalencEquivalency Factory Factor
2.002.00
1.001.00
0.670.67
100100
150150
Granular Granular Base Base
Equivalency Equivalency
(mm)(mm)
167.5167.5
Total Granular Base Equivalency Total Granular Base Equivalency (mm):(mm):
417.5417.5
Lets Lets calculate calculate the the GBEGBE for this for this design:design:
The tabulated GBE was The tabulated GBE was 415415..
The tabulated GBE’s have been rounded The tabulated GBE’s have been rounded to the nearest 5 mm.to the nearest 5 mm.
Now on to part b)Now on to part b)
Example 1 Example 1 b)b)
Part b) calls for a deep Part b) calls for a deep strength designstrength design
This would require This would require that the base and that the base and subbase be replaced subbase be replaced by a cement treated by a cement treated base layer base layer (CTB)(CTB)
The strength of the The strength of the base and subbase is base and subbase is 150150 + + 167.5167.5 = = 317.5317.5 mm of new Granular Amm of new Granular A
The Equivalency The Equivalency Factor for CTB is…Factor for CTB is…
Note: For design purposes OFC and Surface Treatment, because of their thickness, are assumed to have no structural value and
TABLE 6.02
GRANULAR BASE EQUI VALENCY FACTORS(Af ter: "Pavement Design and Rehabilitation Manual", 1990)
NEW PROJ ECTSEquivalency
Material Factor
New or Recycled HL 2.00Granular A in Base 1.00
Granular B in Subbase 0.67Cement Treated Material in Subbase (with Gr. A base) 1.40
Cement Treated Material in Base (no subbase) 1.80Bituminous Treated Material in Base (with Gr. A subbase) 1.50
Crushed RBM* (in base) 1.00Bituminous Treated Crushed RBM* 1.50
Crushed RBM* Blended with New Granular A 1.00Pulverized Bituminous Surface Mixed with Existing Base 1.00
Old HL 1.25Old Granular Base 0.75
Old Granular Subbase 0.50
RECONSTRUCTI ON PROJ ECTSEquivalency
Material Factor
Granular A Layer 1.00Old HL 1.00
Old Granular Base 0.60Old Granular Subbase 0.40
1.801.80
If the required thickness of CTB isIf the required thickness of CTB is TTCTBCTB, , then the GBE of the CTB is then the GBE of the CTB is 1.80T1.80TCTBCTB == 317.5 mm317.5 mm
Solving,Solving, TTCTBCTB == ≈≈ So the deep strength design would be:So the deep strength design would be:
Granular Base Granular Base Equivalency Equivalency
(mm)(mm)
100100
324324
Total Granular Base Equivalency Total Granular Base Equivalency (mm):(mm):
424424
Example Example 22
A 12 km stretch of Highway 99 has A 12 km stretch of Highway 99 has 75 mm75 mm of of hot mixhot mix over over 180 mm180 mm of of granular granular basebase over over 300 mm300 mm of of granular subbasegranular subbase. . If the If the AADTAADT has grown to has grown to 2500 vpd2500 vpd, , the the sandy subgradesandy subgrade has has 22% passing 22% passing the No. 200 sievethe No. 200 sieve and the and the hot mix has hot mix has lost 65% of its strengthlost 65% of its strength, , what minimum what minimum thickness of hot mix overlay will restore thickness of hot mix overlay will restore the pavement to its required strength?the pavement to its required strength?
• for AADT of 2500 for AADT of 2500 use third rowuse third row
• for silty sand with for silty sand with 22% passing no. 22% passing no. 200 use second 200 use second columncolumn
• The required design The required design is:is:
HM: 90 mmHM: 90 mm B: 150 mmB: 150 mm SB: 300 mmSB: 300 mmGBE: 530 mmGBE: 530 mm
For a highway with an For a highway with an AADT of 2500 vpd, try AADT of 2500 vpd, try Table 6.03aTable 6.03a Gravels
Crushed RBM* (in base) 1.00Bituminous Treated Crushed RBM* 1.50
Crushed RBM* Blended with New Granular A 1.00Pulverized Bituminous Surface Mixed with Existing Base 1.00
Old HL 1.25Old Granular Base 0.75
Old Granular Subbase 0.50
RECONSTRUCTI ON PROJ ECTSEquivalency
Material Factor
Granular A Layer 1.00Old HL 1.00
Old Granular Base 0.60Old Granular Subbase 0.40
1.351.35
0.750.75
0.500.50
Example Example 22
Extra Strength Extra Strength Required =Required =531531 – – 386.25 =386.25 =144.75 mm144.75 mm of new Granular A of new Granular A
Since overlay will be with new Hot Mix, Since overlay will be with new Hot Mix, only only halfhalf of this thickness of new hot mix will be of this thickness of new hot mix will be needed.needed.Overlay Thickness Overlay Thickness Required =Required =144.75144.75/2/2 == 72.37572.375 ≈≈ 80 mm80 mm of new Hot of new Hot MixMix
