Turkish J. Eng. Env. Sci. 32 (2008) , 201 – 209. c  T ¨ UB ˙ ITAK Investigation of Parameters of Compaction Testing Selim ALTUN Ege University, Department of Civil Engineering, 35100 Bornova, ˙ Izmir-TURKEY e-mail: selim.altun@ege.edu.tr A. Burak G ¨ OKTEPE Kolin Construction Co., Akkoy Dam and HEPP Cons., K¨ urt¨ un, G¨ um¨ u¸ shane-TURKEY Alper SEZER Ege University, Department of Civil Engineering, 35100 Bornova ˙ Izmir-TURKEY Received 03.01.2008 Abstract Compaction is one of the most efficient and practical soil improvement techniques that can be applied to earthworks. In the field, compaction control is commonly carried out by sand-cone and nuclear gauge tests. Whether conducted in the field or in the laboratory, these tests are intended to determine optimum water content and dry unit weight parameters, information required for design specifications. In this study, the parameters of field soil densification obtained by various testing methods performed in the same region are compared: unit weight, water content, and densification percentage are measured by nuclear density and sand cone tests. The variations in the outcomes of nuclear density and sand cone tests, namely unit weight, water content, and densification percent, are recorded. It is well-known that the nuclear density test has the advantage of rapid application; nevertheless, this method gives approximate results that should be correlated with a more precise technique, such as sand cone testing. The data at hand are first subjected to statistical analyses. Next, several techniques are used to identify the correlation between the results of the 2 tests. Finally, susceptibility and reliability concepts are considered in evaluating the combined usage of the tests in civil engineering practice. Key words: Compaction control, Nuclear density test, Sand cone test, Correlation Introduction Soil is extensively utilized as a basic material of construction, as witnessed by the existence of earth structure such as dams and road embankments. In these cases, it is desirable that the soil used as in- place material possess reliable properties. The soil should have sufficient strength, be relatively incom- pressible so that future settlement will not be exces- sive, maintain a constant volume change against vari- able water content or other factors, be resistant to deterioration, and possess proper permeability. The requirements can best be achieved by a precise se- lection of fill material type and proper placement application. The essential properties of a fill can be checked independently, however, desirable charac- teristics, such as high strength, low compressibility, and stability, are normally associated with density (or unit weight) values that can be fastened through good compaction. When soil is used for construction purposes, ei- ther in embankments or in pavement subgrades, it is distinctively layered to form the final shape. Obvi- ously, each layer is compacted before being covered with the following layer. After proper placement and compaction, the resulting soil mass has the strength and bearing capabilities that are as good as or bet- ter than many natural soil formations. To evalu- ate the degree of compaction, it is common to check soil zones using the in-situ density (or in-situ unit weight) test procedure. Typically, each compacted layer is checked at random locations. Placement 201