Excavation and Backfill Specifications | Earthwork Inspection Requirement

Excavation and Backfill Specifications or Inspection and Testing Requirements:

In this Article today we will talk about the Excavation and Backfill Specification | Earthwork Inspection Requirements | Earthwork Construction Procedure | Specification for Earthwork in Embankment | Backfilling Soil Specification |  Backfill Material Specifications ASTM

Earthwork Material Specifications:

EARTHWORK or BACKFILL:

1. Fill Material:

Specifications:

• Gravel, sand and/or marl materials-maximum size shall be 75mm (SAES-A-114 Sec. 6.2.1, ASTMC136, Sieve Analysis of Fine and Coarse Aggregates)
• Delivered fill materials shall be free of organic material, trash, or other unsatisfactory materials (SAES-A-114 Sec. 6.2.1, ASTMC136, Sieve Analysis of Fine and Coarse Aggregates) Excavation and Backfill Specifications

Review of Test Reports:

• Retained on 75mm sieve shall be zero.
  • Note 1: If ½ of lift thickness is less than 75mm, max. size shall not  exceed ½ of lift thickness. Earthwork Inspection Requirements
  • Note 2: Atterberg Limits not required for Fill materials. (SAES-A-114, Sec. 6.2.1, ASTM C136) Earthwork Inspection Requirements

2. Select Fill Material:

Specifications:

• Maximum size of sand and gravel materials being received shall be 50mm diameter particles (SAES-A-114 Sec. 6.2.2, ASTMC136, Sieve Analysis of Fine and Coarse Aggregates)
• Delivered fill materials shall be free of organic material, trash, or other unsatisfactory materials (SAES-A-114 Sec. 6.2.2, ASTMC136, Sieve Analysis of Fine and Coarse Aggregates) Specification for Earthwork in Embankment

Review of Test Reports:

• Amount (of material) passing 50mm sieve shall be 100%. (Sec. 6.2.2 ASTM C136)
• Amount (of material) passing #200 sieve shall be between 0-20% (Sec. 6.2.2 ASTM C136)
• Portion passing the #40 sieve, Liquid Limit (LL) shall be between 0 – 35. Note Liquid Limit Tests are not required if material has less than 15% fines (passing #200 sieve). Sec. 6.2.2 ASTM C136 (Sieve Analysis of Fine and Coarse Aggregates)
• Portion passing the #40 sieve, Plasticity Index (PI) shall be 0 – 12%. Note: Plasticity Index Tests are not required if material has less than 15% fines (passing #200 sieve). Sec. 6.2.2 ASTM C136 Specification for Earthwork in Embankment

3. Marl Cap Materials:

Specifications:

• Maximum size of marl materials being received shall be 75mm Delivered fill materials shall be free of organic material, trash, or other unsatisfactory materials (SAES-A-114 Sec. 6.2.1, ASTMC136, Sieve Analysis of Fine and Coarse Aggregates)

Review of Test Reports:

• No material shall be retained on 75mm sieve.
  • Note 1:If ½ of lift thickness is less than 75mm, maximum size shall not exceed ½ of lift thickness. Sec. 6.3.2.10 ASTM C136 (Sieve Analysis of Fine and Coarse Aggregates)
• Amount of passing #200 sieve shall be between 11-35%.
• Liquid Limit (LL) shall be between 0 – 35 & Plasticity Index (PI) shall be between 0-12%.
  • Note: Liquid Limit and Plasticity Index tests are not required if material has less than 15% fines (passing #200 sieve). Sec. 6.3.2.10 ASTM C136 (Sieve Analysis of Fine and Coarse Aggregates) Backfilling Soil Specification

4. Dune Sand:

Specifications:

• Wind-deposited sand consisting of relatively single-sized particles generally passing the #16 sieve (1.18 mm) and usually containing less than 10% soil particles passing the #200 sieve (0.074 mm) (SAES-A-114 Sec 4, ASTM Cl36, Sieve Analysis of Fine and Coarse Aggregates) Backfilling Soil Specification

Review of Test Reports:

• Passing the #16 sieve (1.18 mm) and usually containing less than 10%, soil particles passing the #200 sieve (0.074 mm) Sec 4 ASTM C136 (Sieve Analysis of Fine and Coarse Aggregates)

Earthwork Specification for Construction or Compaction:

The following specification must be follow during earthwork construction:

• Fill material shall be placed in lifts not exceeding 200mm in loose depth. (Sec. 6.3.2.2 ASTM C136)
• Fill material shall be placed in lifts not exceeding 100mm in loose depth for hand-operated compaction. (Sec. 6.3.2.2)
• Compaction shall begin only after the fill or backfill has been properly placed and the material to be compacted is at the proper moisture. content. +/- 3% of the optimum moisture content per ASTM D1557 or ASTM D698, whichever is applicable. (Sec. 6.3.2.7 ASTM D1557)
• Fill or backfill placed beneath footings, grade beams, mats, buildings or process areas shall be compacted to at least 90% of the maximum Modified Proctor density as determined by ASTM D1557. (Sec. 6.3.2.5, ASTM D1557)
• For coheesionlss free draining soils, 70% relative density as determined by ASTM D4253 and ASTM D4254 shall be achieved under footings, grade beams, mats, buildings or process areas. (Sec. 6.3.2.5 ASTM D4253)
• Under foundations with static loads over 320kPa and foundations for vibrating or heavy machinery and pavements, 85% of relative density (ASTM D4253/ASTM D4254) for cohesionless soils or 95% of the maximum density as determined by ASTM D1557 for cohesive materials. (Sec. 6.3.2.5 ASTM D1557, ASTM D4253 & ASTM D4254)
• Contractor’s testing agency shall be a Saudi ARAMCO approved civil testing agency. (Sec. 5.1.1)
• One Modified Proctor Test per ASTM D1557 with corresponding Proctor curve shall be performed for each type of fill material or where there is a change in the type or the source of material. (Sec. 6.3.3.1, ASTM D1557)
• For cohesionless free draining soils, ASTM D4253 Maximum Index Density and Unit Weight of Soils Using a Vibratory Table and ASTM D4254 Minimum Index Density and Unit Weight of Soil and Calculation of Relative Density shall also be performed for each type of cohesionless, free draining material or where there is a change in the type or the source of material. (Sec. 6.3.2.7, ASTM D4253, ASTM D4254)
• In-place density shall be determined using one of the following:
  1. ASTM D-1556 Sand Cone Method;
  2. ASTM D-2167 Rubber Balloon Method;
  3. ASTM D-2922 Nuclear Method; or
  4. ASTM D-2937 Drive-cylinder.
  5. General fill – one test every 5000 ft² (460 m²) of each lift. (Sec. 6.3.3.2, ASTM D-1556, ASTM D-2167, ASTM D-2922, or ASTM D-2937)
• As a minimum, at least one in-place density test must be performed on every lift of fill and further placement shall not be allowed until the required density has been achieved. (Sec. 6.3.3.3)
• Nuclear density gauges, when used, shall have a valid calibration certificate per the requirement of ASTM D2922, (Sec. A1.2. Sec. 3.2 ASTM D2922)
• The depth of the test holes shall be no greater than 300mm (12 inches) deep. (ASTM D 2922, Sec. 1.1) Backfill Material Specifications ASTM

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Conclusion:

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