E XPERIMENT (1) WATER CONTENT OF SOIL By: Eng. Othman Tayeh. Eng. Doaa Safi. 1

INTRODUCTION 2 ASTM: American Society for Testing and Materials AASHTO: American Association of State Highway and Transportation Officials Test Designation ASTM D-2216; AASHTO T-265

Water content : the ratio of the weight of free water on the soil surface or between soil particles to the weight of dry soil solids. D EFINITIONS : 3

P URPOSE : To determine the water content of soil, by determining the weight of water removed by drying the moist soil to the solid particles. The clay soil is the most important soil for determining water content to it because its expanding & shrinkage and it has high water content and small voids between particles. 4

1- Sensitive balance. 2- Drying oven (105 o C o C). 3- Cans. A PPARATUS : 5

P ROCEDURES : 1. Determine the mass (g) of the empty moisture can plus its cap (W1), and also record. the number. 2. Place a sample of representative moist soil in the can. Close the can with its cap to avoid loss of moisture. 6

3. Determine the combined mass (g) of the closed can and moist soil (W2). 4. Remove the cap from the top of the can and place it on the bottom (of the can). 5. Put the can (Step 4) in the oven to dry the soil to a constant weight. In most cases, 24 hours of drying is enough. 6. Determine the combined mass (g) of the dry soil sample plus the can and its cap (W3). 7

C ALCULATIONS Calculation 1. Calculate the mass of moisture = W2 - W3 2. Calculate the mass of dry soil = W3 – W1 3. Calculate the water content. 8

A sample calculation of water content is given in the following Table: 9 Average moisture content, W=16.2 %

Notes : 1- For soil containing significant amounts of gypsum or organic materials, keep the oven temperature at 60 – 80 o C, for longer period, to avoid oxidation and loss of water of crystallization. 2- Most natural soils, which are sandy and gravelly in nature, may have water contents up to about 15 to 20%. In natural fine-grained (silty or clayey) soils, water contents up to about 50 to 80% can be found. 10

3- Typical values of water content for various types of natural soils in a saturated state are shown in the following Table: 11