Measuring the water retention curve of rock fragments: A novel repacked core methodology

We describe a novel suction plate experiment that uses large, repacked soil cores comprising clasts and a fine-textured matrix to accurately measure the water retention curve of rock fragments (RFs) of high and low porosity. The method incorporates a suction plate-core containment system that can be weighed as a unit, to overcome typical core size restrictions. The method relies on analysing the relationship between total core volumetric water content and RF concentration. Cores are packed with a mix of glass and RFs to maintain a uniform volumetric total clast proportion of 30% while RF concentration varies. A constant total clast volume improves accuracy and precision by ensuring the water-holding characteristics of the matrix varies as little as possible among cores. Highlights We determine the water retention curve of greywacke-pumice clasts in large, repacked soil cores. A suction plate-core containment system that is weighed as a unit allows large cores to be used. WRC is determined with cores of varying rock%, but total clast% stays constant by adding glass. By using the above, the WRC of low and high porosity rocks can be measured precisely.