Effect of wetting and drying on the resilient modulus and permanent strain of a sandy clay by RLTT
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International Journal of Pavement Research and Technology Journal homepage: www.springer.com/42947
Effect of wetting and drying on the resilient modulus and permanent strain of a sandy clay by RLTT Frank Siaw Ackah, Nie Zhuochen, Feng Huaiping* State Key Laboratory of Mechanical Behavior and System, Safety of Traffic Engineering Structures, Shijiazhuang Tiedao University, Shijiazhuang, 050043, China Received 27 March 2020; received in revised form 30 August 2020; accepted 1 September 2020
Abstract
Water content is one of the significant factors that affect the stability and stiffness property of the subgrade soils. Under changing environmental conditions such as raining and drought, the water content becomes more variable and is known to facilitate many of the subgra de-related problems such as rutting and swelling. As a result, the compaction moisture and post-compaction moisture changes on the resilient modulus (MR) and permanent strain (εp) of a subgrade soil were investigated. The effect of the bulk stress, octahedral shear stress, wetting, and drying was analyzed using test results and has important consequences on the existing and design of new pavements. MR was higher for soil samples subjected to drying than wetting. Higher MR did not show lower εp. The correlation between MR and εp suggests that MR was not a satisfactory soil property to explain εp of the soil in the Ciyaowan station in Bao-shen. Models used to predict the effect of the moisture content, and stress state showed better performance for MR. Keywords: Resilient modulus; Permanent deformation; Water content; Subgrade soil
1. Introduction The moisture content and its variation are among the several relevant factors that compromise the performance of the subgrade. The moisture content of the subgrade layer varies with the rate of infiltration of rainwater, the variation of the level of groundwater table, the migration of moisture between the layers due to temperature variations, evapotranspiration, seasonal variation and the use of inadequate moisture content during compaction, etc. The effect of the moisture content and its variation on MR have been well researched and documented [1-3]. From the aforementioned, it is evident that moisture content and its variations must be taken into consideration when selecting MR for pavement design. MR is broadly defined as the elastic modulus (stress divided by recoverable strain) after the material has sustained some level accumulated εp It is the significant property for the characterization of repeated loading behaviours of subgrade, subbase, and base course materials in pavement structures. MR represents the mechanical property of the material’s ability to resist deformation under stress. The American Association of State Highway and Transportation Officials (AASHTO) software, AASHTOWare, Mechanistic-empirical pavement design guide (MEPDG), requires
* Corresponding author E-mail address: [email protected] (F. Huaping). Peer review under responsibility of Chinese Society of Pavement Engineering.
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