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  9. Inspection & Testing Requirements
    1. IT-1 General Provision
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Infrastructure Development Code

IT-4.2 Testing

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  1. Council shall be advised when testing is being undertaken but may choose not to attend the testing.
  2. All compliance testing is to be carried out by an IANZ Registered testing Company IT-4 - Appendix A – Company Requirements for Pavement Testing.
  3. It is expected that Contractors will carry out their own uniformity testing in addition to the compliance testing. While not acceptable for compliance, copies of all of the Contractor’s uniformity testing results will be made available to Council if requested.

IT-4.2.1 Subgrade Testing Carriageways 

The tests in IT-4.2.1.1 Test Methods shall be completed and accepted before placing any pavement aggregate.

It is the Engineer’s responsibility to ensure soils and bearing testing is undertaken (as may be required) and to identify and carry out any necessary remedial works on the subgrade (not less than 400mm depth) to achieve the required bearing capacity and, where utilised, deflections necessary at subgrade level. 

Testing requirements covered in this section address only the tests required to satisfy Council that the finished subgrade of the pavement is competent in both bearing capacity and deflection to support the road pavement.

IT-4.2.1.1 Test Methods

The test method to be utilised to measure and prove the strength of a completed sub-grade for all soil types is the Insitu CBR test method in accordance with NZS 4402 Methods of Testing Soils for Civil Engineering Purposes

Other test methods can be utilised between Insitu CBR tests to confirm the uniformity of the completed subgrade.

The other test methods that can be used for consistency testing are for:

  1. Cohesive soils: shear vane testing.
  2. Non-cohesive soils: scala-penetrometer testing.

Both methods require calibration against several of the passed Insitu CBR tests.

Benkelman Beam testing is also an acceptable test utilised by the Engineer to test a subgrade for consistency and uniformity of performance. (This is a non-mandatory requirement.)

  1. CBR Testing:

Insitu CBR tests are to be carried out on all completed subgrades. Tests shall be carried out at 15m intervals on alternate lanes. The subgrade CBR’s shall achieve:

  1. CBR =7 for modified ash subgrades. 
  2. CBR =10 for modified sand pumice subgrades.

unless the approved design CBR is different. 

The CBR value used in the design shall be the 10 percentile value of the CBR tests taken on the subgrade material. A selection of tests shall be taken at 150mm, 300mm and 450mm below final subgrade level.

  1. Scala Penetrometer testing (non-cohesive soils only): 

The Scala Penetrometer shall be calibrated by performing tests located adjacent to one or more insitu CBR test that meets the approved design CBR or performance standards referenced in a) above. 

Once calibrated the Scala Penetrometer can be used to check the uniformity of the subgrade. 

Testing with Scala Penetrometer shall be carried out in both wheel tracks of each lane of the pavement at 10m intervals:

The Scala Penetrometer shall only be employed on non-cohesive subgrades where a significant part of the subgrade particles pass a 9.5mm sieve. The penetrometer shall be bedded into the soil with one (or more) blows. The zero point for depth and the number of blows is taken neglecting the bedding blows.

Table 1: Scala Penetrometer vs CBR Approximation sets out the first approximation co-relationship between the Scala Penetrometer readings in non-cohesive soils and equivalent CBR readings.

Refer to IT-4.2.6 Scala Penetrometer CBR Conversion Chart for the California Bearing Ratio (CBR) vs Penetration relationship.

  1. Shear Vane Testing (cohesive soils only): 

The shear vane shall be calibrated by performing tests located adjacent to one or more insitu CBR test that meets the approved design CBR or performance standards referenced in a) above.

Once calibrated the Shear Vane can be used to check the uniformity of the subgrade. 

Testing with Shear Vane is to be carried out in both wheel tracks of each lane of the pavement at 10.0m intervals:

There is no established direct correlation between the Shear Vane and CBR as every soil type has different characteristics, however, by calibrating directly to insitu CBR results as in a) CBR Testing above, a local comparison is useful for uniformity assurance. In general the local ashes for soils close to optimum moisture content (OMC) and 100% maximum dry density, the shear strength should be >150 kPa.

  1. Benkelman Beam Testing: 

Although not mandatory, Benkelman Beam tests for total deflection are encouraged to be carried out on all prepared subgrades. Tests shall be carried out at not less than 15.0m intervals on alternate lanes. It is anticipated that in general subgrade total deflections should be 4mm average and not exceed 6mm. Deflections in excess of 6mm shall require remediation of the subgrade or the Engineer will need to reassess the pavement design to ensure the maximum final pavement deflection is not exceeded:

The Benkelman Beam test shall be as per NZTA Specification T/1 Benkelman Beam Deflection Measurements.

Table 1: Scala Penetrometer vs CBR Approximation

CBR Maximum mm per blow Minimum blows / 100mm
7 32 3
10 23 4
15 17 6

IT-4.2.1.2 Shape of Subgrade

Stringing may be carried out by the Contractor in the presence of the Engineer and shall be at no greater than 20m intervals and within a tolerance of +0mm and -20mm of design subgrade level.

IT-4.2.2 Sub-base Testing

All sub-bases shall be constructed from GAP65 aggregate. The GAP65 shall be well-graded crushed rock, free from silt or clay lumps, organic and other non-mineral matter. Unless otherwise approved, Representative samples shall be tested for compliance with the following:

  1. Table 2: Table 2: GAP65 RequirementsGAP65 Requirements.
  2. Grading Limits: When wet sieved in accordance with NZS 4402 Test No. 2.8.1. The grading shall lie within the envelope of values given in Table 2: GAP65 Requirements.
  3. Sand Equivalent: When tested in accordance with NZS 4407 Test No. 3.6 the sand equivalent shall not be = 40.
  4. Crushing Resistance: When tested in accordance with NZS 4407 Test No. 3.10 the percentage of fines produced from a 110 kN load shall be =10%.
  5. CBR: The minimum CBR shall not be = 80% when laboratory tested.
  6. Stringing: Stringing, which may be carried out by the Contractor in the presence of the Engineer, shall be at no greater than 20m intervals and within the tolerance +20 or -20 mm of design subgrade level.

 

Table 2: GAP65 Requirements

Test Sampling and Testing Frequency (based on TMZ M/4)
Grading Limits Minimum of 2  
Test Sieve Aperture % Passing by mass samples less than 2 months old at date of delivery.
Actual number dependant on volume required as follows:
< 400m³ - 2 tests
400-1500m³ - 3 tests
1500-4000m³ - 4 tests
> 4000m³ - 1 test per 1000m³ or part thereof
 
70mm Minimum 100%
19mm Minimum 40%
9.5mm Maximum 70%
425um Maximum 10%
Sand equivalent >40%
Crushing Resistance With 110kN load < 10% fines Minimum of 2 samples less than 6 months old at date of delivery.
Actual number dependant on volume required.
       
Laboratory Soaked CBR >80% 1 Sample per project

 

IT-4.2.2.1 Compaction of Sub-Base

Nuclear Densometer: The degree of compaction shall be tested at 15m intervals on alternate sides of the pavement at the completion of primary compaction. Compaction testing shall be undertaken by a calibrated Nuclear Densometer in Backscatter Transmission mode. Target results for density are an average of 95% of MDD and a minimum of 92% of MDD.

 

IT-4.2.2.2 Shape of Sub-Base

Stringing at not more than 20m intervals and within a tolerance of +0mm and -20mm of design sub-base level.

 

IT-4.2.3 Basecourse Testing

All basecourse aggregate shall be either GAP40 or AP40 (TNZ M4) metal meeting the following test requirements:

  1. Aggregate for construction of basecourse layers shall be crushed rock, free from silt or clay lumps, weathered or disintegrated rock, organic and other non mineral matter.
  2. Unless otherwise approved, the following tables shall be used:
    1. Table 3: GAP40 Requirements (based on NZS 4404).
    2. Table 4: AP40 Requirements (based on TNZ M/4).
  3. Grading Limits: When wet sieved in accordance with NZS 4402 Test No. 2.8.1. The grading shall lie within the envelope of values given in Table 3: GAP40 Requirements (based on NZS 4404) and Table 4: AP40 Requirements (based on TNZ M/4).
  4. Sand Equivalent: When tested in accordance with NZS 4407 Test No. 3.6 the sand equivalent shall not be = 25 for GAP40 or 40 for AP40.
  5. Crushing Resistance: When tested in accordance with NZS 4407 Test No. 3.10 the percentage of fines produced from a 110 kN load shall be =10%.
  6. CBR: The minimum CBR shall not be less than 100% when laboratory tested.

 

Test

Sampling and Testing Frequency (based on TNZ M/4)

Grading limits

 

Minimum of 2 samples less than 2 months old at date of delivery.

 

Actual number dependant on volume required as follows:

< 400m³ - 2 tests

400-1500m³ - 3 tests

1500-4000m³ - 4 tests

> 4000m³ - 1 test per 1000m³ or part thereof

 

Test Sieve Aperture

% Passing by mass

37.5mm

100%

19mm

61–81%

9.5mm

38–57%

4.75mm

23–43%

2.36mm

14–33%

1.18mm

7–25%

600um

2–19%

300um

0–14%

150um

0–10%

75um

0–7%

Sand equivalent

> 25%

Crushing resistance

With 110 kN load
< 10% fines

Minimum of 1 sample less than 6 months old at date of delivery.
Actual number dependant on volume required.

Weathering resistance

AA, AB, AC, BA, BB, BC, CA or CB

Minimum of 1 sample less than 6 months old at date of delivery.

Actual number dependant on volume required.

 

Test

Sampling and Testing Frequency (based on TNZ M/4)

Grading limits

 

Test Sieve Aperture

% Passing by mass

Minimum of 2 samples less than 2 months old at date of delivery.

Actual number dependant on volume required as follows:

< 400m³ - 2 tests

400-1500m³ - 3 tests

1500-4000m³ - 4 tests

>4000m³ - 1 test per 1000m³ or part thereof

 

37.5mm

100%

19mm

66–81%

9.5mm

43–57%

4.75mm

28–43%

2.36mm

19–33%

1.18mm

12–25%

600um

7–19%

300um

3–14%

150um

0–10%

75um

0–7%

Shape Limits

 

19 mm - 4.75 mm

28–48%

 

9.5 mm - 2.36 mm

14–34%

 

4.75 mm - 1.18 mm

7–27%

 

2.36 mm - 600 um

6–22%

 

1.18 mm - 300 um

5–19%

 

600 um - 150 um

2–14%

 

Sand equivalent

>40%

 

Crushing resistance

With 130 kN load
< 10% fines

Minimum of 1 sample less than 6 months old at date of delivery.

Actual number dependant on volume required.

Weathering resistance

AA, AB, AC, BA, BB, BC, CA or CB

Minimum of 1 sample less than 6 months old at date of delivery.

Actual number dependant on volume required.

 

IT-4.2.3.1 Compaction of Basecourse

  1. Nuclear Densometer: The degree of compaction shall be tested at 15m intervals on alternate sides of the pavement at the completion of primary compaction. Compaction testing shall be undertaken by a calibrated Nuclear Densometer in Backscatter Transmission mode. Target results for density are an average of 98% of MDD and a minimum of 95% of MDD.
  2. Tolerances shall meet the requirements of NZTA specification B/2 Construction of Unbound Granular Pavement Layers.
  3. Benkelman Beam tests for total deflection and D250/D0 are to be carried out on all prepared basecourse surfaces. Tests shall be carried out at not less than 15m intervals on alternate lanes. The basecourse total deflections shall be about 3mm average and not exceed 4.5mm. D250/D0 ratios are required to meet the following:
    1. Chip Seal and 25 mm asphalt >0.54
    2. 40 mm Asphalt >0.65
    3. >50mm Asphalt >0.70
    4. The beam test shall be as per NZTA Specification T/1 Benkelman Beam Deflection Measurements.
  4. The Engineer shall provide the results from the Benkelman Beam tests (specified above) to show that the pavement complies with the requirements detailed. The organisation carrying out the tests shall be IANZ accredited.
  5. Acceptance of pavements with deflections exceeding the target figures will be at the discretion of the Council.

 

IT-4.2.3.2 Shape of Basecourse 

Stringing, which may be carried out by the Contractor in the presence of the Engineer, shall be at not more than 20m intervals and within a tolerance of +5mm and -5mm of design basecourse level.

 

IT-4.2.4 Surface Texture

The method for determining surface texture shall be TNZ Specification T/3 Sand Circle Surface Texture measurements.

 

IT-4.2.5 Sealed Surface Roughness

This shall only apply to designated collector, arterial and strategic arterial roads.

  1. The target maximum values for roughness of sealed surfaces shall be 60 for asphalt and 70 for chipseal.
  2. Roughness measurements shall normally, but not exclusively, only be taken on surfacing applied to areas on new or reworked road surface or as directed by the Engineer.
  3. In addition to the shape requirements of TNZ B/2, TNZ P/9, TNZ P/9P and TNZ P/11 notes, National Association of Australian State Road Authorities (NAASRA) roughness readings shall be recorded in each lane at 20m intervals.
  4. A minimum of 3 runs for roughness measurements shall be taken in each direction. Roughness measurements taken through rotary intersections shall not be considered as part of the average roughness.
  5. The moving 100m average of those 20m readings (in each lane including tie ins) shall be determined and none of those 100m averages shall exceed a value of 70 NAASRA counts/km.
  6. Where the finished surfacing is asphaltic concrete, the maximum 100m moving average lane roughness requirement is reduced to 60 NAASRA counts/km.
  7. Roughness readings are not required on lengths 100m or less, as the shape requirements of the above TNZ specifications are expected to be sufficient to control isolated bumps over this short length.
  8. The average roughness value shall be taken to be the arithmetic mean of all recorded readings excluding readings taken through rotary intersections.
  9. For the purposes of comparing with the specified Average Construction Roughness, the average roughness obtained shall be rounded to the nearest whole number.
  10. The Contractor shall be responsible for all costs in arranging and carrying out the testing and informing the Engineer of the results.
  11. The Contractor shall provide the Engineer with all the Certified Test results. The Certification shall include that the testing has been carried out in accordance with this clause.

 

IT-4.2.6 Scala Penetrometer CBR Coversation Chart

Scala Penetrometer CBR Conversion Chart

 

 


Definitions in this section

Approved design

Cohesive soil

Contractor

Council

Design

Engineer

NZTA

Pavement

Road

 

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