RESEARCH PAPER Simplified Method to Predict Compaction Curves and Characteristics of Soils Yes ¸im Gurtug 1 • A. Sridharan 2,3 • Sabriye Banu I ˙ kizler 4 Received: 24 October 2016 / Accepted: 6 January 2018 Ó Shiraz University 2018 Abstract Improvements of the soils in sites are usually necessary to achieve the desired strength, compressibility and hydraulic conductivity of soils. Generally, improvement in compaction is preferred and applied in sites. The compaction curve and associated characteristics, namely maximum dry unit weight and optimum moisture content, should be determined in the laboratory by using Proctor test procedures. However, a number of Proctor tests need to be carried out for projects like earth dams, embankments and highways. In this paper, a simplified and dependable way of obtaining compaction char- acteristics and compaction curves at different compaction energy levels for preliminary designs is introduced. For this purpose, Proctor compaction tests were conducted with different soils and at different compaction energy levels apart from using extensive results found in the literature. It was found out that by only getting the compaction characteristics from plastic limit an approximate compaction curve can be obtained from family curves. The approximate compaction curve compares well with the tested values too. Maximum dry density predicted is 0.986 times the maximum dry density at plastic limit, whereas predicted optimum moisture content is 0.99 times the actual optimum moisture content. Keywords Compaction test Á Ground improvement Á Proctor test Á Mechanical stabilization Á Compaction characteristics 1 Introduction With the increasing population, the demand for the land in construction facilities is also increasing. Earth structures such as earth dams, embankments (highways, railways and canals) and loose foundation soils need to be improved for achieving the desired strength and reduction in compress- ibility, when they do not meet the engineering requirements. In cases where improvement in the con- struction site is necessary, generally compaction is a good and widely used alternative. In fact, compaction is a practical way of improving the engineering properties of soil by means of applying mechanical energy. Before compaction in the field, compaction characteristics of soils should be determined in the laboratory. Most often com- paction characteristics, namely optimum moisture content (OMC) and maximum dry unit weight (c dmax ), are obtained through standard Proctor test. Often a number of Proctor tests should be carried out in projects such as highways, railways, earth dams and embankments. Proctor test not only takes considerable time to carry out, but also needs a vast amount of soil in a number of tests. Since the number of Proctor tests should be carried out for the aforemen- tioned projects, a practical way of obtaining the com- paction characteristics is necessary. In cases where higher strength of soil is required, compaction energy needs to be increased. To accomplish this, modified Proctor com- paction test procedure is used. Thus it can be seen that compaction tests must be carried out in the laboratory at different compaction energy levels also. As a result, & Sabriye Banu I ˙ kizler banuh73@gmail.com Yes ¸im Gurtug yesim.gurtug@marmara.edu.tr A. Sridharan sridharanasuri@yahoo.com 1 Department of Civil Engineering, Marmara University, Istanbul, Turkey 2 Indian National Science Academy, Delhi, India 3 Indian Institute of Science, Bangalore, India 4 Department of Civil Engineering, Karadeniz Technical University, Trabzon, Turkey 123 Iran J Sci Technol Trans Civ Eng https://doi.org/10.1007/s40996-018-0098-z