Ethio Construction Engineering
👉CALCULATION – Field Density Test (FDT)

📜Example

⚖️ Weight of sand used

= Weight of sand + cylinder before test − Weight of sand + cylinder after test
= 8373 − 2524
= 5849 g

🕳️ Weight of sand in hole

= Weight of sand used − Weight of sand in cone
= 5849 − 1610
= 4239 g

📦 Volume of hole

= Weight of sand in hole ÷ Bulk density of sand
= 4239 ÷ 1.344
= 3154 cc

🪨 Weight of soil passing 19 mm sieve

= Weight of wet material − Weight retained on 19 mm sieve
= 7263 − 1350
= 5913 g

⚙️ Bulk density of soil

= Weight of soil ÷ Volume of hole
= 5913 ÷ 3154
= 1.875 g/cc

💧 Moisture content (Speedy Moisture Tester)

= 7.8 %

📊 Field dry density

= Bulk density ÷ (1 + Moisture content ÷ 100)
= 1.875 ÷ (1 + 7.8 ÷ 100)
= 1.875 ÷ 1.078
= 1.74 g/cc

📈 Percentage of compaction

= Field dry density ÷ Laboratory MDD × 100
= 1.74 ÷ 2.144 × 100
= 96.3 %

✅ RESULT

📌 Field Dry Density = 1.74 g/cc
📌 Laboratory MDD = 2.144 g/cc
📌 Compaction Achieved = 96.3 %

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2 comments

Fekadu 🐐
Why you subtract the weight retained on 19mm sieve from the total weight of excavated soil?
Abdi Boru (QC Engineer)
V.Good info👍