It is possible to determine the preconsolidation stress that the soil had experienced. The soil sample is to be loaded in the laboratory so as to obtain the void ratio - effective stress relationship. Empirical procedures are used to estimate the preconsolidation stress, the most widely used being Casagrande's construction which is illustrated.

The steps in the construction are:

•  Draw the graph using an appropriate scale.

•  Determine the point of maximum curvature A.

•  At A, draw a tangent AB to the curve.

•  At A, draw a horizontal line AC.

•  Draw the extension ED of the straight line portion of the curve.

•  Where the line ED cuts the bisector AF of angle CAB, that point corresponds to the preconsolidation stress.