# DETERMINATION OF QUANTITY OF WATER ADDED , FOR REQUIRED COMPACTION OF SUB GRADE & EMBANKMENT Example: A soil in the borrow pit is at a dry density of 17 kN/  with a moisture content of 10%. The soil is excavated from this pit and compacted in a embankment to a dry density of 18 kN/  with a moisture content of 15%. Compute the quantity of soil to be excavated from the borrow pit and the amount of water to be added for 100   of compacted soil in the embankment.

Ans :Volume of compacted soil = 100  m³ & Dry density of compacted soil = 18 kN/m3

Weight of compacted dry soil = 100 × 18 = 1800 kN. This is the weight of dry soil to be excavated  from the borrow pit.

Weight of wet soil to be excavated = 1800 (1 + w) = 1800 (1 + 0.10) = 1980 kN.

Wet density of soil in the borrow pit = 17 (1 + 0.10) = 18.7 kN/ m³

Volume of wet soil to be excavated = 1980 / 18.7  = 105.9  m³

Moisture present in the wet soil, in the borrow pit for every 100  m³ of compacted soil

= 1800 × 0.10 = 180 kN

Moisture present in the compacted soil of 100  m³ = 1800 × 0.15 = 270 kN

Weight of water to be added for 100  m³ of compacted soil = (270 – 180) kN = 90 kN

= 90/ 9.81   m³  = 9.18 kl