Axioms in Roadway Soil Mechanics

In the proper design and construction of roadways, the detailed study of soil mechanics in all of its phases is complicated by the many items that must be understood and taken into consideration. Many different types of soils must be investigated; their characteristics must be predetermined; and they must be properly used in the roadway. The mechanics of the different types of soils as placed in the roadway are different. Practical methods of designing and constructing different parts of the roadway are not the same. Topographical and climatic conditions in different localities vary and also must be taken into account. There is no panacea, and rules of thumb cannot be established which will fit all conditions. Those who design, construct, and maintain the highways must know the fundamentals of soil mechanics, and use their knowledge to fit each individual situation properly. On the other hand, there are many axiomatic facts, thirteen of which are presented in this paper for detailed examination and comment. These axioms pertain mostly to volumetric changes in soils due to fluctuations in moisture content caused directly by alternate seasons of slow rains and droughts.