1. 2018 Pavement Workshop May 23-24, 2018
Laboratory and Field Performance of Recycled Aggregate Base in a Seasonally Cold Region
Bora Cetin
Assistant Professor
Iowa State University
Tuncer Edil & Ali Soleimanbeigi
Professor Emeritus / Research Associates
University of Wisconsin-Madison
+ 46 Associate Members

2. OUTLINE Problem Statement/Introduction Objectives
Materials & Methodology
Results
Freezing Point Depression & Freezing Temperatures
Resilient Modulus
Frost Depth & Freeze-Thaw Cycle Prediction
Elastic Modulus
Conclusions
Acknowledgements

3. PROBLEM STATEMENT
Heaving
Potholes

4. Frost Action – Alligator Cracking
PROBLEM STATEMENT
Frost Action – Alligator Cracking

5. CLIMATIC ZONES
Six climatic regions in the United States for pavement design

6. OBJECTIVES Primary Goals: Stiffness of recycled and natural aggregates
Base Layer
Primary Goals:
Stiffness of recycled and natural aggregates
Freeze point depression
Freezing temperature
Prediction of freeze-thaw cycles
Prediction of frost depth

7. MATERIALS Recycled Concrete Aggregate (RCA) Natural Aggregate
(Class 5)
Recycled Asphalt Pavement (RAP)

8. MATERIALS

9. MATERIALS

10. Asphalt/Mortar Content (%)
MATERIALS
MATERIAL
Natural Aggregates
RCA
RCA Blend
RAP
Wopt (%)
8.9
11.2 8
6.7
γdmax (kN/m3)
20.1
19.3
21.4
20.7
Absorption (%) - 15
1.8
Asphalt/Mortar Content (%) 55
7.1
Impurities (%)
0.25
0.87
0.36
0.06
USCS
GW-GM SW SP
AASHTO
A-1-b
A-1-a

11. METHODS Materials were compacted at optimum moisture content
Thermocouples

12. FREEZE-THAW PROCEDURE
Freeze-thaw cycles numbers: 0, 5, 10, 20
Freeze-Point Depression Tests:
Determine the freezing temperature
Freeze-Thaw Procedure
1-D

13. RESILIENT MODULUS-AASHTO T-307
Resilient Modulus (MR)
Stiffness
Durability
Test & Compaction Procedure
Vertical
Deformation
Vertical Stress
Confining Pressure
H: 12 inches
D: 6 inches
Resilient modulus test is a repeated-load trixial test. It is a non-destructive test. It is used to characterize the base materials under loading conditions that are not resulted in failure of the pavement system.

14. FALLING WEIGHT DEFLECTOMETER
Parameters
FWD
Number of receivers 9
Receiver spacing (m)
0.15 to 0.31
Total length (m)
1.38
Distance from the source to the first receiver (m)

15. FIELD SENSORS
Thermocouples
Moisture Sensors

16. Freezing Point Depression Tests
RESULTS
Freezing Point Depression Tests

17. RESULTS Summary of Freezing Temperatures
MATERIALS
Freezing Point Depressions (˚C)
Freezing Temperature (˚C)
Natural Aggregate
-5.2
-12
RCA
-10
RAP
Based on the results of freeze-point depression tests, all samples were frozen at -15˚C.

18. Laboratory Resilient Modulus Tests (No Freeze-Thaw)
RESULTS
Laboratory Resilient Modulus Tests (No Freeze-Thaw)

19. Laboratory Resilient Modulus Tests (After Freeze-Thaw)
RESULTS
Laboratory Resilient Modulus Tests (After Freeze-Thaw)

20. RESULTS
Temperature
RCA

21. Freeze-Thaw Cycles/Year
RESULTS
Freeze-Thaw Cycles/Year

22. Cumulative Freeze-Thaw Cycles
RESULTS
Cumulative Freeze-Thaw Cycles

23. Modulus After Freeze-Thaw Cycles
RESULTS
Modulus After Freeze-Thaw Cycles

24. Modulus vs Moisture Content
RESULTS
Modulus vs Moisture Content

25. Laboratory and Field Modulus After Freeze-Thaw Cycles
RESULTS
Laboratory and Field Modulus After Freeze-Thaw Cycles

26. CONCLUSIONS Laboratory Tests
Stiffness changes slightly after 5 freeze-thaw cycles based on the laboratory tests
RCA Modulus Freeze-Thaw Cycles
Total modulus reduction:
RAP ~ 20%
Natural Aggregate ~ 60% over 20 F-T cycles
Read the slides

27. CONCLUSIONS Field Tests
Elastic Modulus Freeze-Thaw Cycles
RCA & RAP > RCA Blend & Natural Aggregate
Elastic Modulus Moisture Content
Laboratory Modulus = Field Modulus except RCA
Read the slides

28. Acknowledgments Minnesota Department of Transportation
MnROAD (Benjamin Worel)
Recycled Materials Resource Center (RMRC) at the University of Wisconsin

29. Thank You

30. RESULTS