Modified Ohio's Curves: A Rapid Estimation of Compaction Curves for Coarse- and Fine-Grained Soils

Compaction curves from 16 coarse- and 9 fine-grained soils, which cover all soil types classified by the Unified Soil Classification System are analyzed to develop the Modified Ohio's curves. For all soils, the relationships between water content and degree of saturation on both the dry and the wet sides of optimum are represented by power functions. Their compaction curves under standard Proctor energy follow the Ohio's curves. Optimum degree of saturation, ODS, of coarse-grained soils is lower than that of fine-grained soils. However, for a given soil, the ODS is practically the same for different compaction energies, E. Even though compaction characteristics (optimum water content, OWC, and maximum dry unit weight, gamma(d max)) are different for different soils, their relationship between normalized OWC/OWCst and E is practically the same, where OWCst is the OWC at standard Proctor energy. Based on this finding, the Modified Ohio's curves are introduced under compaction energy levels of the half standard, half modified, and modified Proctor energies. The verification of the Modified Ohio's curve is also illustrated in this paper. These curves are useful in rapid estimation of laboratory compaction curves from a single set data of dry unit weight and water content.