Swelling Characterization of Natural and Chemically Stabilized Clays using Centrifuge Technology

US Transportation Collection2019PDFTech ReportBlake, CalvinSummerlin, KarlyZornberg, Jorge G.University of Texas at Austin. Center for Transportation ResearchTexas Department of Transportation. Research and Technology Implementation OfficeUnited States. Department of Transportation. Federal Highway AdministrationUniversity of Texas at Austin. Center for Transportation ResearchUnited StatesTexasExpansive claysCalcium hydroxideCentrifugesSoil stabilizationSwelling soilsFHWA/TX-19/5-6048-05-15-6048-05November 2016\u2013August 2019Expansive clays, which are common throughout Texas, may cause severe damage to pavements and other lightweight structures. Methods of direct quantification of soil swelling potential may be time-consuming, while indirect methods based on correlations to soil index parameters (e.g., plasticity and grain size distribution) rely on relatively scant empirical data. Also, indirect methods may fail to capture the effects of site-specific conditions, presence of distinct clay minerals, and pore-water composition. Also, indirect methods may not be accurate to optimize the design of chemical stabilization techniques aimed at minimizing the swelling of natural clays. Furthermore, indirect methods may require performing several additional tests in addition to plasticity and grain size distribution, in order to accurately characterize the clay composition, organic content, and sulfate minerals present in the natural soil deposits. Hence, in engineering practice, the design of a chemical stabilization program may involve measurement of a number of parameters except the most important one: the actual soil swelling. This is mainly because of the prohibitively long duration of soil swelling quantification using conventional techniques. The purpose of this report is to develop an accurate, yet expeditious approach to measure directly the swelling of expansive soils either in their native state, or after modification with chemical stabilizers. This is achieved by using centrifuge techniques, which have proven to be a reliable and swift approach to quantify clay swelling. Focus of this report is on the use of hydrated lime as a chemical stabilizer, although the procedures and findings discussed herein are expected to be also applicable to other stabilization techniques.140