Use of a three-dimensional scanner for shrinkage curve tests

Abstract

A procedure is proposed for conducting shrinkage limit tests using a three-dimensional (3D) scanner. Shrinkage limit tests were conducted on 27 different soils of varying plasticity. In this study only eight of the shrinkage curves were determined using 3D scanning techniques, while the remaining 19 were taken from literature. An individual specimen was scanned between 30 and 50 times to produce a high-resolution shrinkage curve. Shrinkage curves for each material were obtained by curve fitting a shrinkage model to the measured dataset. The primary intent of the research was to relate the shrinkage curve equation to the plasticity of a given soil. Using linear regression analysis, an empirical correlation was developed to reasonably relate parameter csh from the shrinkage model to the ratio of the plastic and liquid limits. The shrinkage curves produced based on the model have an average difference of ∼1.2% in terms of measured void ratio and predicted void ratio. The method was demonstrated to be robust for materials of low, medium, and high plasticity. The proposed methodology also presents a means of estimating a shrinkage curve in its entirety based solely on the volume of an air-dried sample, the specific gravity, and Atterberg limits of the specimen. This effectively reduces the amount of work needed to derive the shrinkage curve and could potentially reduce the time for a shrinkage limit test by half or more.