XVI Danube - European Conference on Geotechnical Engineering 07-09 June 2018, Skopje, R. Macedonia Paper No. 137 Abstract. The primary objective in soil stabilization is improving on-site materials to create a solid and strong sub-base and base courses for further construction activities. Classic stabilization methods for road structures imply soil mixing with cement or lime, depending on the soil types found on-site. Although widely used, these stabilization methods fail to provide hydrophobic properties for the stabilized layer, thus being vulnerable to road failure from water penetration or heavy frosts by inhibiting the ingress of water into the treated layer. Dorosol© is a hydraulic binder which combines cement and lime in order to improve and consolidate cohesive soils for embankments and subgrade stabilization, providing a superior protection against water penetration. This paper presents the improvement of physical and mechanical parameters of a silty clay from Cluj-Napoca, by using two types of Dorosol©, C30 and C50 suited for treating heavy plastic clayey soils. Percentages of 2.5, 3, 3.5, 4 and 4.5 were used for creating stabilized soil samples for both types of binder. Keywords: clayey soils, soil stabilization, Proctor test, direct shear test, optimal water content 1 INTRODUCTION Soil stabilization process implies improvement of physicochemical and mechanical properties of certain soil types, by adding fixed quantities of hydraulic binder (such as cement, slag or fly ash) and water, followed by compacting operation. With the intense urbanization and development of large cities from Romania, available potential construction sites became more and more scarce. This led investors choosing to acquire properties once ruled out for constructions, due to inadequate bearing capacity of soil. Also large infrastructure projects, such as highway or railway network extensions, have met difficulties of passing through difficult terrains from a constructor’s point of view. Typical soft soils in Transylvania, with low bearing capacity, usually contain large fractions of clay, which can undergo high volume variations, when subjected to moistening-drying cycles. Mixing these soils with modern hydraulic binders increases shearing resistance, reduces permeability and compressibility, bringing them up to ensure functionality and safe exploitation of potential constructions on site. Cement, lime and hydraulic binders are consistently used in road building industry [1, 2]. In the structural layers that form the pavement, cement is used in recycled base courses made with foamed bitumen and bitumen emulsion [3, 4], in base courses made of hydraulically bound mixtures (HBMs) [5] and in subgrades to improve their bearing capacity. In the case of hydraulically bound mixtures, the content of cement, dependent on the gradation and design strength, is typically from 3% to 8% and is calculated relative to the amount of aggregate in the mixture [6]. The amount of road binder in cold deep recycled mix bases is smaller that in HBMs and ranges from 1.5% to 4.0% [7]. Limiting the amount of the binder and adding asphalt emulsion or foamed asphalt reduces the stiffness of the structure [8]. Low content, 2%, of the binder (cement) is a feature of hydrated cement treated crushed rock base [9]. A higher content of the binder is used in the soil stabilization process. Due to high diversification of the soil subgrade and its fine gradation the binder (a mix of cement, hydrated lime, fly ash, etc.) is added in the amounts from 2% to 12% [10]. Combinations of binders are also widely used for stabilizing soils. Many researchers have seen potential in aggregates stabilized with cement- Soil stabilization with modern hydraulic binders. Variations of geotechnical parameters NAGY A.-C. 1 , CÎRCU A.P. 2 , ILIEȘ N.M. 3 , MOLDOVAN D.V. 4 , GHERMAN C.M. 3 , PÉTER A. 5 1 Ph.D. student; Technical University of Cluj-Napoca, Memorandumului Str. No. 28, 400114 Cluj-Napoca, Romania; Andor.Nagy@dst.utcluj.ro 2 Ph.D. student; Romanian Waters, Vânătorului No.17, Cluj-Napoca, Romania; alexandru.circu@mecon.utcluj.ro 3 Associate Professor, Ph.D. Eng.; the same as author 1; nicoleta.ilies@dst.utcluj.ro 4 Lecturer, Ph.D. Eng.; the same as author 1; dorin.moldovan@dst.utcluj.ro 5 Lecturer, Phd. Eng.; the same as author 1; calin.gherman@dst.utcluj.ro 1021 https://doi.org/10.1002/cepa.806 wileyonlinelibrary.com/journal/cepa © Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin · ce/papers 2 (2018), Nos. 2 & 3