Soil Moisture as a Factor in Subgrade Evaluation

The pretesting treatment is for the purpose of providing soil specimens having moisture conditions similar to those under the pavements. This is a necessary step in the laboratory evaluation of subgrade soils because soil moisture is an important factor affecting the supporting power of the subgrade. Before the development of the method for specimen treatment, field investigations were conducted to determine the variation in the subgrade moisture conditions below existing pavements. Results obtained therefrom indicate that a general correlation can be established between the suction and the moisture content of subgrade soils. For this reason, the developed method is based on the principle of controlling the suction of soil specimens prior to testing. The equipment and procedures involved in the developed method for specimen treatment are relatively simple. This method is, therefore, suitable for use in routine tests for subgrade evaluation purposes.