BUILDING A WORKING TABLE WITH LIME

the use of quicklime or hydrated lime for stabilization is discussed with the goal of creating a working table for the pavement structure. Results obtained from lime treatment of a heavy subgrade soil on I-20 east of Dallas, Texas, during the winter of 1954-55 provided a basis for the understanding of improvement due to lime subgrade treatment. First, the lime was mixed and compacted during the wet season of late 1954 and early 1955. At that time Texas was in a critical drought period beginning in 1951 and ending in 1957. It is now apparent that the lime-treated layer formed a moisture barrier and helped maintain a uniform moisture condition below the stabilized layer. On the other hand, the fill sections were constructed with less moisture controls and without adequate subgrade and slope protection and the wet and dry cycles have produced considerable heaving over the 18-year period. Following this illustration, lime stabilization of highly plastic swelling subgrade soils and wet, weak nonswelling subgrade soils is discussed. The remainder of the report deals with design considerations and includes typical pavement sections to assist the engineer in designing a pavement using lime without use of complicated design formulas. The principal factors affecting the pavement design are traffic, subgrade report, and material used in the pavement structure.