Utilizing Repeated Load Triaxial Testing in the Assessment of Local Materials on Taihape Napier Road Seal Extension

Transcription

1 Utilizing Repeated Load Triaxial Testing in the Assessment of Local Materials on Taihape Napier Road Seal Extension

2 133 km Taihape to Napier 37km unsealed Alternatives 291km and 275km Strategic Increased usage if sealed Potentially State Highway 21km in Rangitikei District

3 56 km NE from Taihape Mangaohane Rd to Gentle Annie

4 Four sections Existing alignment Minor safety improvements

5 Rotten rock Rock > R2 Varying subgrades Pumice, ash Clay, sand

6 Design Life 25 years AUSTROADS

7 Local rock subbase

8 Local river resourced basecourse

9 Fragile network cu m M4 AP40 basecourse 70km cartage potential $ per year maintenance

10 Pavement Rutting design to avoid

11 Rutting shear in subgrade Aggregate Soil Austroads Pavement Design Guide ensures adequate cover/protection to subgrade

12 Rutting bshear in base Rutting compaction in base b b/3 Aggregate Soil Aggregate Soil Specifications usually ensure aggregates do not fail (but not always! Especially if they get wet) A Repeated Load Triaxial Test (applies 350,000 load cycles): - Will determine the amount of rutting in the aggregate (wet and dry) - To determine suitability of chosen materials

13 Repeated Load Triaxial Testing

14 Repeated Load Triaxial Testing Soaking sample For saturated test

15 Material Sampling Local Aggregate

16 Material Sampling Local Aggregate

17 Repeated Load Triaxial Testing Compaction Local Aggregate After test

18 Repeated Load Triaxial Test Results - DRY 2 Typical Results for TNZ M4 Basecourse Aggregates - Dry/Drained 1.8 Permanent strain [%] Local Agg - M4 middle grading Tests 3 & 5 average TNZ M4 basecourse Test 1 very good TNZ M4 Test 7 Poor TNZ M4 Test 21 Local aggregate Taihape/Napier Number of load cycles [-]

19 Permanent strain [%] Repeated Load Triaxial Test Results - WET Typical Results for TNZ M4 Basecourse Aggregates - Saturated/Undrained 22 Taihape/Napier local agg - M4 middle grading (saturated) Tests 4 & 6 avg M4 Test 2 v. good M4 Test 8 Poor TNZ M4 Test 22 Local aggregate Taihape/Napier (Note : very sensitive to Water) Number of load cycles [-]

20 Traffic Loading Limit - RLT Test Dry/drained Analysis of RLT Results Rutting Dry 3. V. Good - TNZ M4-95%MDD - Dry 5. Avg. TNZ M4 - Dry 7. V. Poor TNZ M4 - Dry 21. Taihape/Napier - middle - 95%MDD - Dry Material Traffic Loading Limit (Million ESAs

21 Traffic Loading Limit - RLT Test Saturated/Undrained Not suitable as a basecourse as failed in stage 6 Analysis of RLT Results Rutting Wet 2. V. Good - TNZ M4-101%MDD - Saturated 6. Avg. TNZ M4 - Saturated 8. V. Poor TNZ M4 - Saturated 22. Taihape/Napier - middle - 95%MDD - Saturated Material Traffic Loading Limit (Million ESAs

22 Repeated Load Triaxial Test Results WET Stabilised Local Aggregate Combinations Test # Source Agg. % Subgrade soil % Hydrated Lime % Cement 24 Taihape/Napier local agg. 33% 2% - 25 Taihape/Napier local agg. - 2% - 26 Taihape/Napier local agg. - 2% 1% 27 Taihape/Napier local agg %

23 Repeated Load Triaxial Test Results - WET Taihape/ Napier Stabilised Aggregates - Saturated/Undrained Permanent strain [%] Taihape - Agg. + 33% Soil + 2% Lime 25 - Taih. Agg. + 2% Lime 26 -Taih. Agg. + 2% Lime + 1% Cement 27 - Taih. Agg % Cement 10 - Fine M4 + 2% Cement 12 - Coarse M4 + 2% Cement 14 - GAP40 + 2% Cement Number of load cycles [-]

24 Traffic Loading Limit - RLT Test Saturated/Undrained Not suitable as a basecourse as failed in stage 7 Analysis of RLT Results Rutting Wet 10. Fine TNZ M4 + 2% Cement 12. Coarse TNZ M4 + 2% Cement 14. GAP40 + 2% Cement 24. Taihape Agg. + 1/3rd Soil + 2% Lime 25. Taihape Agg. + 2% Lime 26. Taihape Agg. + 2% Lime + 1% Cement 27. Taihape Agg. 1.5% Cement Material Traffic Loading Limit (Million ESAs)

25 Durability water for 1 month Agg + 1/3 rd soil + 2% Lime Agg + 2% Lime + 1% Cement Agg + 2% Lime Agg + 1.5% Cement Local Aggregate + 2% Lime Best (lowest cost and performs well in tests)

26 Pavement Design Surfacing Basecourse Insitu 2% lime + local agg. 100 mm Basecourse Consider using 2% Lime and 1% Cement mixture Upper Sub-base Insitu 2% lime +local agg. Lower Sub-base Local aggregate (unmodified) 100 mm 150 mm Upper Sub-base 100mm is sufficient depth to protect underlying layers as any deeper compaction is poor and no cementation Lower Sub-base leave unmodified as there is poor compaction this close to subgrade and no cementation occurs Natural existing subgrade Assumed CBR=5%

27 Spread and crush raw material 150mm sub-base 150mm basecourse Raw materials identical

28 Stabilise 200mm 2% Lime 7% moisture content, modified

29 Reduced maintenance on local network Minimised resource consent costs for materials

30 Client savings $ Efficiencies in construction Innovation, science, practical