Soil Index Property – Definition of Water Content (Moisture Content) In geotechnical engineering, the ratio of the weight of water to the weight of dry solids in a given mass of soil is known as what?

Introduction / Context:
Correctly defining the basic index properties of soils is essential for laboratory testing, quality control, and design calculations in foundation engineering, earthworks, and pavement subgrades. Water content (also called moisture content) directly affects compaction, strength, and compressibility of soils and is therefore measured frequently in practice.

Given Data / Assumptions:

• The question asks for the name of a ratio: weight of water divided by weight of dry soil solids.
• Standard geotechnical terminology is assumed.
• No numerical calculation is required.

Concept / Approach:

By definition, water content w is the mass (or weight) of water divided by the mass (or weight) of dry soil solids, usually expressed as a percentage. It is distinct from porosity n (volume-based) and void ratio e (also volume-based). It is also distinct from specific gravity Gs (ratio of densities) and does not by itself give the phase volumes without additional information.

Step-by-Step Solution:

Verification / Alternative check:

Laboratory methods such as oven-drying at 105–110 °C, the alcohol method, and pycnometer-based methods for coarse soils all determine water content consistent with the same definition.

Why Other Options Are Wrong:

Porosity and void ratio are volume ratios, not weight ratios. Specific gravity compares densities, not water mass to dry mass.

Common Pitfalls:

Confusing volume-based indices with mass-based moisture content; reporting w as a fraction when the specification expects a percentage.

Final Answer:

Water content