Freeze-Thaw Cycling Effect on the Constrained Modulus and UCS of Cementitiously Stabilized Materials Zhipeng Su 1 , James M. Tinjum 2 , P.E., Ahmet Gokce 3 , Tuncer B. Edil 4 , P.E., D.GE, Dist. M. ASCE 1 Associate engineer, Shanghai Shenyuan Geotechnical Engineering Co., Ltd., Xian Dai Architectural Design Group, Shanghai, China (Formerly Research Assistant, Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, WI 53706. USA), suzhipeng1987@gmail.com 2 Assistant Professor, Engineering Professional Development, University of Wisconsin-Madison, Madison, WI 53706. USA, tinjum@epd.engr.wisc.edu 3 Assistant Professor, Faculty of Civil Engineering, Yildiz Technical University, Istanbul, Turkey (Formerly Research Associate, Civil and Environmental Engineering, University of Wisconsin- Madison, Madison, WI 53706. USA), agokce@yildiz.edu.tr 4 Professor Emeritus, Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, WI 53706.USA, tbedil@wisc.edu ABSTRACT: This study evaluates the effect of freeze-thaw (F-T) cycling on the mechanical properties of cementitiously stabilized materials (CSM). Ultrasonic testing was applied to monitor the P-wave velocity (constrained modulus) change during the F-T cycling. Unconfined compression strength (UCS) test was performed at the end of F-T cycling. It was found that F-T cycling could be detrimental to CSM as the constrained modulus decreased to 7% to 96% depending on the CSMs. The residual UCS was 35% to 84% of the initial UCS at the end of the test. It was found that the greater the cement content, the stronger the anticipated durability. Clay-lime and silt-fly ash showed limited resistance to F-T cycling. INTRODUCTION Due to shortages of aggregates and high cost of petroleum resources, stabilization of the subgrade or subbase/base layers began gaining acceptance since 1960s and ‘70s. Stabilization is a valuable alternative as global demand for raw materials, fuel, and infrastructure continues to increase. Stabilization of subgrade or subbase/base layers involves blending and mixing additives to the host materials to improve the engineering properties. The process includes mixing of commercially available additives, which may alter the gradation, texture or plasticity, or act as a binder for cementation, and the soils (Department of Army, Navy, and Air Force 1994). 364 Pavement Materials, Structures, and Performance GSP 239 © ASCE 2014