A methodological framework to determine optimum durations for the construction of soil water characteristic curves using centrifugation

Abstract

During laboratory assessment of the soil water characteristic curve (SWCC), determining equilibrium at various pressures is challenging. This study establishes a methodological framework to identify appropriate experimental duration at each pressure step for the construction of SWCCs via centrifugation. Three common temporal approaches to equilibrium – 24-, 48- and 72-h – are examined, for a grassland and arable soil. The framework highlights the differences in equilibrium duration between the two soils. For both soils, the 24-h treatment significantly overestimated saturation. For the arable site, no significant difference was observed between the 48- and 72-h treatments. Hence, a 48-h treatment was sufficient to determine ‘effective equilibrium’. For the grassland site, the 48- and 72-h treatments differed significantly. This highlights that a more prolonged duration is necessary for some soils to conclusively determine that effective equilibrium has been reached. This framework can be applied to other soils to determine the optimum centrifuge durations for SWCC construction.

Study on Soil‐Water Characteristics of Expansive Soil under the Dry‐Wet Cycle and Freeze‐Thaw Cycle considering Volumetric Strain

“…e commonly used test methods include the pressure plate method, filter paper method, centrifuge method, and tensiometer method. e centrifuge method is widely used because of its simple operation, short time usage, and the ability to measure the SWCC under high matric suctions [1][2][3][4][5]. As a kind of soil with high clay content and a large number of hydrophilic minerals, expansive soil has a series of special properties such as strong water sensitivity, swelling, and shrinkage.…”

Development and validation of the steady state centrifuge experiment for the moisture retention curve of porous building materials

“…Secondly, the literature on soil samples reveals that the moisture content first decreases rapidly after which moisture is expelled during a slow, second stage that can take hours up to days (Vero et al, 2016). Any evaporation stream, no matter how small, therefore influences this second stage and hence the true equilibrium moisture content.…”

“…Sample holders with direct water contact. In soil physics, the evaporation flux is sometimes eliminated by guaranteeing contact between the sample and a fully saturated material (Khanzode et al, 2002;Lozano et al, 2020;Vero et al, 2016). This is replicated by connecting the material of interest with a saturated piece of calcium silicate insulation, which in its turn is in direct contact with a water reservoir.…”

“…By minimizing the difference between measured and simulated variables, the hygric properties of the materials can be inversely characterized (Vereecken et al, 2018). Contrary to steady state tests, it is no longer required to complete the full equilibration process (Vero et al, 2016) which reduces the total measuring time. Additionally, the moisture permeability in materials can be obtained simultaneously (McCartney and Zornberg, 2010;S ˇimu˚nek and Nimmo, 2005).…”

Simulation of Sugarcane Growth and Yield Under Optimized Subsurface Irrigation System

“…We used soil samples from six layers as 0-10, 10-20, 20-30, 30-40, 40-50, and 50-60 cm to estimate the lower limit (LL15, mm/mm), drained upper limit (DUL, mm/mm), soil saturation (SAT, mm/mm), bulk density (BD, g/cm 3 ), particle density (TD, g/cm 3 ) and saturated hydraulic conductivity (KS, mm/day). LL15 and DUL were considered the volumetric water content equilibrium to the -1500 kPa and -33 kPa, respectively, and measured of using the centrifuge method (Khanzode et al 1999;ASTM International 2003;Vero et al 2016). Measured BD and TD values were used to estimate soil saturation.…”