Evaluating the Laboratory Based Polishing of New Zealand Greywackes in Comparison to Melter Slag

Transcription

1 Evaluating the Laboratory Based Polishing of New Zealand Greywackes in Comparison to Melter Slag Authors: Speaker: Ashkan Tatari Seosamh B. Costello Douglas J. Wilson David Hutchison Adelia D. Nataadmaja Ashkan Tatari 1

2 Outline Introduction Purpose of Research Laboratory Tests Test Results Conclusion 2

3 Factors Affecting Skid Resistance Surface aggregate factors Surface microtexture and macrotexture, chip size and shape, and type of surfacing Load factors Traffic loading, traffic intensity and road geometry Environmental factors Water film thickness, surface contamination, temperature, seasonal and short term rainfall effects Vehicle factors Vehicle speed and suspension system, angle of tyres, wheel slip ratio and tyre characteristics 3

4 Textural wavelength analysis Skid resistance on the surface layer decreases continuously with time due to polishing from traffic volume. Microtexture: wavelengths < 0.5 mm felt by one s fingertips Macrotexture: 0.5 mm < dimensions < 50 mm felt by a hand Simplified general pavement polishing model (Prowell et al., 2003) 4

5 Objective Comparison between resistance of Greywacke aggregate and Melter Slag against polishing Compare all the results by New Zealand (Glenbrook) steel mill Investigation Level (IL) NZTA T/10 Wellington Kiwi Point quarry 5

6 Laboratory Tests Polishing samples: Auckland Pavement Polishing Device (APPD) Measuring the coefficient of friction: Dynamic Friction Tester (DFT) Measuring mean profile depth: Circular Track Meter (CTM) 6

7 Laboratory Tests Auckland Pavement Polishing Device The APPD was developed by Wilson (2006) It was adapted from the Three Wheel Polishing Device (TWPD). (NCAT) Three rubber tyres with 20 psi constant pressure Tyres rotate on a diameter of 284mm Assembly weight from this machine is around 57 kg over the rubber tyres Auckland Pavement Polishing device (APPD) (Wilson, 2006) 7

8 Laboratory Tests Dynamic friction Test(DFT) Measure the dynamic coefficient of friction Three rubber mounted slider pads Lateral rotary disk with a diameter of 284 mm Each slider in loaded to 11.8 N Rotating speed set at 60 km/h for all samples 8

9 Laboratory Tests Circular Track Meter (CTM) Measures the Mean Profile Depth (MPD) Circle with a 284 mm diameter Divided into eight equal size segments MPD is reported as the average of all eight segments 9

10 Investigation Level (IL) Investigatory Levels for Skid Resistance (ILs): Investigatory Levels for Macrotexture (ILM): According to NZTA T/10,

11 Historical Results (SCRIM) Historical results of coefficient of friction based on SCRIM measurements on Kiwi point quarry aggregate at Dowse since 2009 (SH2/58 Haywards): 11

12 Test Results Melter Slag Test Results: Coefficient of Friction 0.94 µ 0.77 µ 0.70 µ 0.52 µ 0.74 µ 0.46 µ 0.85 µ 0.53 µ 0.72 µ 0.50 µ 0.51 µ 0.51 µ 30 % 43 % 43 % 12

13 Test Results Melter Slag Results: Mean Profile Depth (Macrotexture) 13

14 Test Results Greywacke Aggregate Test Results: Coefficient of Friction 0.71 µ 0.63 µ 0.43 µ 0.42 µ 35 % 0.82 µ 0.70 µ 0.46 µ 0.46 µ 39 % 0.67 µ 0.64 µ 0.44 µ 0.46 µ 31 % 14

15 Test Results Greywacke Aggregate Test Results: Mean Profile Depth (Macrotexture) 15

16 Skid Resistance (DFT 20), µ Conclusion Polishing Rime (hour) Melter Slag, Sample 1 Melter Slag, Sample 2 Melter Slag, Sample 3 Greywacke Aggregate, Sample 4 Greywacke Aggregate, Sample 5 Greywacke Aggregate, Sample 6 16

17 Skid Resistance (DFT 40), µ Test Results Polishing Time (hour) Melter Slag, Sample 1 Melter Slag, Sample 2 Melter Slag, Sample 3 Greywacke Aggregate, Sample 4 Greywacke Aggregate, Sample 5 Greywacke Aggregate, Sample 6 17

18 Test Results International Friction Index (IFI) SFC 50 F60 By referring to ASTM E-1845 and ASTM E1960: 0.36 µ < F60 18

19 Test Results Converting DFT 20 results to F60 for comparing them with IFI 0.36 µ < F < DFT20 < mm < MPD < 1.5 mm 19

20 Thank You 20