1. Coarse Aggregate Selection for Improved Rigid Pavement Joint and Cracking Performance Jeffery R. Roesler, Ph.D., P.E. and Punya Chupanit, Ph.D. University of Illinois at Urbana-Champaign CEAT Brown Bag Lunch Seminar OMP Chicago, IL – May 5, 2005

2. Concrete Pavement Cracking

3. Concrete Pavement Joint Deterioration

4. RESEARCH OBJECTIVES  Improve concrete material’s mechanical properties for rigid pavements by selecting the appropriate concrete constituents > Maintain high shear load transfer across joints > Increase concrete slab cracking resistance / ductility

5. Joint Load Transfer Efficiency (LTE) Good Load Transfer L = 1 U = 0 Poor Load Transfer L = 1 U LTE = U L

6. LOAD TRANSFER ABILITY  FACTORS AFFECTING THE LOAD TRANSFER  CRACK WIDTH  AGGREGATE TYPE  AGGREGATE SIZE  AGGREGATE SHAPE  AGGREGATE GRADATION  CONCRETE STRENGTH  METHOD & TIMING OF CONCRETE FRACTURE

7. CONCRETE JOINT PERFORMANCE GOOD BAD Strong Aggregate × Weak Aggregate (Nowlen-1968; Colley and Humphrey-1967; Abdel-Maksoud-1999; Wattar-2001; Jensen and Hansen-2001) Large Aggregate× Small Aggregate (White and Holley-1972; Walraven-1980; Laible et al-1977; Sutherland and Cashell- 1945; Abdel-Maksoud-1999; Jensen and Hansen-2001) Gap Gradation× Dense Gradation (Bruinsma et al-1995; Abdel-Maksoud-1999; Wattar-2001) Rough and Strong Surface × Smooth and Weak Surface

8. JOINT SHEAR TESTING EXPERIMENTAL SETUP

9. PREVIOUS JOINT SHEAR TESTING RESEARCH AT UIUC  CONCRETE TEST SPECIMENS BY ABDEL-MAKSOUD(1999) AND WATTAR(2001)

10. JOINT SHEAR STIFFNESS (Abdel-Maksoud-1999;Wattar-2001)

11. CONCRETE MATERIAL COMPOSITION

12. Concrete Mix Design Nomenclature ( 25GRG)  Aggregate Size, e.g., 25 or 38 mm  Gap Graded = G  Dense Graded = D  River Gravel = RG  Limestone = LS  Trap Rock = TR

13. Aggregate Composition

14. CONCRETE MATERIALS Mix Number 25GRG38GRG25DRG25DTR38GTR25DLS Type I Cement (kg/m 3 ) 335.4 Fine/Sand (kg/m 3 ) 741.1 Coarse aggregate (kg / m 3 ) 1198.0 Water Content (kg / m 3 ) 165.2 177.0165.2 171.6 W/C ratio 0.49 0.530.49 0.51 Aggregate Type River Gravel River Gravel River Gravel Trap Rock Trap Rock Limestone Max. Size25mm38mm25mm 38mm25mm Agg.GradationGap Dense GapDense

15. Mix Number 25GRG38GRG25DRG25DTR38GTR25DLS f’c at 10-12 hrs (MPa) 4.03.94.14.03.84.2 f’c at 28 days (MPa) 33.831.733.833.632.238.1 CONCRETE COMPRESSIVE STRENGTH

16. JOINT SHEAR STIFFNESS (Wattar-2001) Mix ID Crack Opening (mm) AVG. Joint Stiffness (MPa/mm) 25GRG2.00.793 38GRG2.01.187 25DRG2.00.708 25DTR2.00.825 38GTR2.01.094 25DLS2.00.616

17. EXPERIMENTAL SETUP OF CRACK SURFACE CHARACTERIZATION

18. CONCRETE CRACK SURFACES

19. NON-CONTACT LASER PROFILOMETER SCANNED SURFACE STEPPING MOTOR SYSTEM FRAME STEPPING MOTOR LASER SENSOR

20. Concrete Surface Re-creation Actual surfaceScanned surface 50mm Trap Rock Surface

21. Concrete Surface Characterization  Roughness Surface Roughness Volumetric roughness  Fractals or degree of irregularity  Power Spectral Area Parameter (PSAP)

22. Surface Roughness Parameter

23. Volumetric Surface Texture Ratio (VSTR) (Vandenbossche-1999)

24.  FRACTAL DIMENSION Mix IDFractal Dimension 25GRG2.247 38GRG2.245 25DRG2.267 25DTR2.264 38GTR2.233 25DLS2.255 SENSITIVITY INDEX = 1.33%

25. Can’t predict joint stiffness Fractal Dimension to Characterize Crack Surfaces

26. SURFACE ROUGHNESS PARAMETERS  FRACTAL DIMENSION  POWER SPECTRAL AREA PARAMETER (PSAP)  BASED ON 2D FOURIER TRANSFORM  DEFINED AS AREA UNDER POWER SPECTRUM (Carpinteri et al-1999)

27. POWER SPECTRAL AREA PARAMETER (PSAP)  BASED ON 2D FOURIER TRANSFORM  DEFINED AS AREA UNDER POWER SPECTRUM Power Spectrum

28. Power Spectral Area Parameter (PSAP) Determination 2D Fourier Transform

29. PSAP Calculation 2D Mean Spectral density (mm 3 /cycles) Radial Wave Number (cycles/mm)

30. PSAP DETERMINATION The cut-off wave number separates the large amplitude surface components from the small amplitude surface components PSAP is defined as the area under the 2D mean power spectrum from non-zero wave number up to 0.0666 cycles/mm.

31.  PSAP Results and Correlation with Joint Stiffness Radial wave number Number of Component * 25GRG38GRG25DRG25DTR38GTR25DLS R 2 -VALUE 0.067316.2220.3917.0417.2920.9616.140.875 0.111520.2725.2221.4721.5626.3220.230.843 0.178824.1328.9425.3325.4830.3723.730.839 0.2221025.6330.3726.9127.0132.0825.140.823 0.2891327.2231.8528.6928.7333.8426.680.797 0.3331527.9932.5729.5829.5734.6927.430.782 0.4001828.8533.4530.5930.5135.6928.330.766 0.5552530.2134.8932.2332.0337.3029.740.742 0.6663030.8935.6233.0532.7838.1230.450.730 1.0664831.0435.1332.9932.3938.4031.000.655 * The PSAP does not include the zero radial wave number component PSAP DETERMINATION

32.  PSAP Results Scale Independent, Better Predict Shear Load Transfer, Valid with Different Aggregates.

33. PSAP predicts load transfer ability across cracks/joints

34. Roughness Parameter Summary Surface Parameter Correlation with Joint Stiffness Unique Sensitivity Index % Rs0.437No5.0 VSTR0.128No27.7 DfDf 0.476Yes1.3 PSAP0.875Yes23

35. How can we characterize concrete surface roughness / shear stiffness? CONCRETE FRACTURE ENERGY

36. Beam Fracture Testing a0a0 D P S t

37. WEDGE SPLITTING TEST (WST) (Linbauer and Tschegg-1986)

38. Fracture Energy (G F ) Definition ftft G F = Area or Work of Fracture Cracked Area

39. G F determination from WST test

40. Fracture Energy Results Mix ID G F at 12 hrs G F at 28 days 38GTR 194.5566.2 38GRG 145.8573.3 25DTR 114.4384.9 25GRG 89.1252.3 25DRG 87.8208.8 25DLS 52.793.7 AVG. Joint Stiffness (MPa/mm) 1.094 1.187 0.825 0.793 0.708 0.616

41. Effect of Concrete Material Properties on Surface Roughness, Crack Resistance and Shear Load Transfer

42.  G F and Shear Load Transfer Shear load transfer depends on G F at 28 days. Concrete with high G F at 28 days provides good shear load transfer across cracks/joints.

43.  AGGREGATE TYPE (25mm) 1) TRAP ROCK 2) RIVER GRAVEL 3) LIMESTONE

44.  AGGREGATE GRADATION Aggregate gradation doesn’t have much impact.

45.  AGGREGATE SIZE LARGE BETTER THAN SMALL (38MM) (25MM)

46. Other significance of G F  G F better characterize the effect of Coarse Aggregate on concrete cracking performance.  f’c (12 hrs) = 3.8 – 4.2 MPa  G F (12 hrs) = 52.7 – 194.5 N/m  f’c (28 days) = 31.7 – 38.1 MPa  G F (28 days) = 93.7 – 573.3 N/m

47. CONCLUSIONS  Power Spectral Area Parameter (PSAP) indicates surface roughness and predicts shear stiffness across crack/joint.  G F at 12 hours and 28 days can represent the concrete cracking resistance at early and mature ages  Aggregate type and size primarily influence joint shear stiffness (PSAP) and concrete cracking resistance (G F ).

48. CONCLUSIONS  Concrete with large, strong aggregates perform better than concrete with small, weak aggregates.  Design of concrete materials should use more than flexural/compressive strength to quantify material behavior (G F ).  Maintain small crack widths (<1.5 mm)

49. Concrete Mix Design Update

50. Concrete Strength Results

51. QUESTIONS /COMMENTS