THICKNESS HICKN ESS ESI ES G I N A ph a t l Pa P v a em e ents for r Hi way a s y s & & St S ree

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1 Asphalt Institute Lectures of 4., 5., 6. Week 4. Week Week Week (Adha holiday) 7. Week Prof. DR. Eng. Shafik Jendia Islamic University of Gaza Standard and Regulation THICKNESS DESIGN Asphalt Pavements for Highways & Streets MANUAL SERIES NO. (MS-1) FEBRUARY 1991 ١

2 Design Considerations Classifications of Highways and Streets Selection of Design Input Variables Stage Construction Economic comparisons Classifications of Highways and Streets Rural Functional Systems Principals Arterial System Interstate (free ways) Other principal arterials Minor Arterial System Collector System Major collector Minor collector Local System Urban Functional Systems Principals Arterial System Interstate Other freeways & expressways Other principal arterials Minor Arterial Street System Collector Street System Local Street System ٢

3 Rural Functional Systems Urban Functional Systems ٣

4 Relationship Between Road Systems And Their Functions Classifications of Highways and Streets Classifications of Highways and Streets Home work Compare between the American and European classification systems of highways and streets ٤

5 Selection of Design Input Variables All variables used in design should be based on Studies of actual data. The Design Variables are: Subgrade Properties Material Properties Traffic Values Environmental Factors Design Principles Basis for Design Design Criteria Material Characteristics Environmental Considerations ٥

6 Basis for Design The Pavement is regarded as a multi- layered elastic system. The material in each of the layers are characterized by a modulus of elasticity and a Poisson s ratio. Traffic is expressed in terms of repetitions of an equivalent 80 kn (18,000 lb) single- axle load. Basis for Design The subgrade, the lowest layer, is assumed infinite in the vertically downward and in the horizontal directions. ٦

7 Basis for Design Boussinesq Vertical and Horizontal Stresses Boussinesq Vertical and Horizontal Stresses σ z = P 1 ( a 2 z 3 + z 2 ) 3 σ h 3 P 2 ( ) ( 1+ ) µ z z = 1+ 2µ a + z 2 2 ( a + z ) τ v = 2 1 ( σ σ ) z h ٧

8 Boussinesq Vertical and Horizontal Stresses Basis for Design Boussinesq Relationship Contact Pressure (p), Modulus of Soil or Subgrade(E) and Deflection (D) Soil Deflection (mm D a D = 1. 5 P E a semi infinite mass m,e a D a a mass m,e E-Modulus of Soil (MN/m 2 ) ٨

9 Basis for Design Environmental Considerations Subgrade modulus variation for the conditions where freeze-thaw occurs Frozen Subgrade Modulus Normal Subgrade Modulus Thaw (Reduced) Subgrade Modulus Basis for Design The other layers, of finite thickness, are assumed infinite in extent in the horizontal directions. Full continuity ( full friction ) is assumed at the interfaces between each of the layers. ٩

10 Design Criteria In the methodology adopted for this manual, loads produce two strains which, are critical for design purposes. They are: -the horizontal tensile strain on the underside of the lowest asphalt-bound layer. -the vertical compressive strain at the surface of the subgrade. Design Criteria ١٠

11 Material Characteristics All Material were characterized by a modulus of elasticity and Poisson's ratio. Modulus of Elasticity = dynamic modulus for asphalt mixture. = resilient modulus for untreated granular or soil (subgrade) materials. The dynamic modulus of asphalt mixtures is highly dependent upon pavement temperature. Material Characteristics Untreated Granular Materials Resilient Modulus of untreated granular materials vary with stress conditions in the pavement. Values used in developing the design charts given in the Appendix of the manual vary from fewer than 103 MPa (15000 psi) to more than 345 MPa (50, psi) ١١

12 Environmental Considerations Mean Annual Air Temperature (MAAT) Three sets of environmental conditions are selected to represent the range of conditions to which the manual should apply. Mean Annual Air Temp. Less than or equal 7 o C (45 o F) = 15.5 o C (60 o F) Greater than or equal 24 o C (75 o F) Frost Effects yes Possible No Soil Stresses and deflection Home work 1-Calculate the vertical and horizontal stresses at depth 0.1a, 0.3a, 0.5a, a, 5a, 10a. Draw the curves, which show the relationship between all stresses and the depth (z). Where wheel load = 40 kn 2- Calculate the deflection on the surface of soil (subgrade E 30 MN/m 2 ) caused by a wheel load of 40 kn. Plot the relationship between deflection and E-Modulus of different Soils (E = 10, 20, 40, 60, 100, 150,... MN/m 2 ). ١٢

13 Traffic Analysis Traffic Volume Estimates (initial and future traffic volume, analysis period, classification and number of trucks, design lane, design period, traffic growth, etc..) Estimating ESAL Determining Design ESAL Traffic Analysis Traffic Volume Estimates ١٣

14 Traffic Analysis Traffic Volume Estimates Percentage of Total Truck Traffic in Design Lane Number of Traffic Lanes (Two Directions) or more Percentage of Trucks in Design Lane (35-48)* 40 (35-48)* * Probable range Traffic Analysis Traffic Volume Estimates ١٤

15 Traffic Analysis Estimating EAL Traffic Analysis Estimating EAL ١٥

16 Traffic Analysis Estimating EAL Traffic Analysis Estimating EAL ١٦

17 Traffic Analysis Estimating EAL Traffic Analysis Estimating EAL Example of U.S. axleload distribution (based on truck count and weight data for typical U.S. Interstate rural highways) ١٧

18 Traffic Analysis Estimating EAL Traffic Analysis Determining Design EAL Example worksheet for traffic Analysis 2000 ١٨

19 Traffic Analysis Home work In the previous Table 1-How can you determine / calculate the number of vehicle per year. 2-Classify the road according to its average truck factor. Material Evaluation Subgrade Soils Improved Subgrade Evaluation Methods Sampling and Testing Selection of Design Subgrade Resilient Modulus Subgrade Compaction ١٩

20 Improved Subgrade An improved subgrade is any course or courses of improved material between the native subgrade soil and the pavement structure. It may be a treated inplace material, or an imported material. Evaluation Methods A subgrade resilient modulus can be determined from a laboratory test in accordance with procedures described in the Asphalt Institute's Soils Manual (MS-10). The resilient modulus may be approximated from the CBR test values according to the relationship Mr (MPa) =10.3 CBR or Mr (psi) = 1500 CBR. The resilient modulus may be approximated from the Resistance R-value test results according to the relationship Mr (MPa) = (R-value) or Mr (psi) = (R-value). ٢٠

21 Subgrade Soils Tests and Sample Sizes Selection of Design Subgrade Resilient Modulus ٢١

22 Selection of Design Subgrade Resilient Modulus Selection of Design Subgrade Resilient Modulus ٢٢

23 Selection of Design Subgrade Resilient Modulus From the graph, determine the design subgrade Mr value for the different design EAL values. EAL Design Percentile Value Design Subgrade Mr. Mpa PSi , Material Evaluation Untreated Aggregate Base and Subbase Quality Requirements ٢٣

24 Material Evaluation Untreated Aggregate Base and Subbase Quality Requirements Material Evaluation Home work U- Tubes 1-Sand Equivalent Test 2-Field Density Test 3-R-Value Test 4-Resilient Modulus Test ٢٤

25 Structural Design Procedure Design Procedure Select or determine input data - traffic value, EAL, - subgrade resilient modulus, Mr, -surface and base types. Determine design thicknesses for the specific conditions described by the input data. Prepare stage construction design, if appropriate. Make an economic analysis of the various solutions arrived at the design problem Select final design. Design Procedure ٢٥

26 Minimum Thickness of Asphalt concrete Material Characteristics Emulsified Asphalt Mixes The emulsified asphalt mixes included in this manual are characterized by three types, depending on the type of aggregate. They are: -Type I: made with processed, dense-graded aggregates. -Type II: made with semi-processed, crusher-run, pit-run or bank-run aggregates. -Type III: made with sand or siltysands. ٢٦

27 Thickness Determination For Full-Depth Asphalt Concrete Pavements Example 1 ٢٧

28 Example 1 Thickness Determination For Emulsified Asphalt Base Pavements ٢٨

29 Example 2 Example mm ٢٩

30 Minimum Thickness of Asphalt concrete Example 2 ٣٠

31 Thickness Determination For Pavements with Asphalt concrete Over Untreated Aggregate Base Example 3 ٣١

32 Example mm Example mm ٣٢

33 Minimum Thickness of Asphalt concrete over Untreated Aggregate Base Pavement Design Home work 1- Design a pavement with full depth asphalt concrete Subgrade Modulus: Mr. = 50 MPa (7140 PSI) MAAT = 7 o C, 15,5 o C and 24 o C ESAL = 5x10 6 Comparison is required 2- Design a pavement with emulsified asphalt base Subgrade Modulus: Mr. = 50 MPa (7140 PSI) MAAT = 7 o C, 15,5 o C and 24 o C ESAL = 5x10 6 Comparison is required 3- Design a pavement with untreated aggregate base Subgrade Modulus: Mr. = 50 MPa (7140 PSI) MAAT = 7 o C, 15,5 o C and 24 o C ESAL = 5x10 6 Comparison is required ٣٣

34 Thickness Determination For Pavements with Emulsified Asphalt Mixes Over Untreated Aggregate Base Thickness Determination For Pavements with Emulsified Asphalt Mixes Over Untreated Aggregate Base ٣٤

35 Example 4 Example 4 ٣٥

36 Pavement Design Home work 1-Design a pavement with: - an asphalt concrete surface - an emulsified asphalt base and - an untreated aggregate base Given: Subgrade Modulus: Mr. = 50 MPa (7140 PSI) MAAT = 7 o C, 15,5 o C and 24 o C ESAL = 5x10 6 Comparison is required ٣٦