Reconstituted soil is a soil specimen prepared in the laboratory by breaking down natural soil, mixing it thoroughly with water to form a slurry or remolded mass, and then reconsolidating it under controlled conditions. The purpose of reconstitution is to eliminate natural soil structure so that intrinsic soil properties can be studied independently of structure effects.
A reconstituted clay is one that has been thoroughly mixed at between 1 and 1.5 times the liquid limit and preferably consolidated one-dimensionally.
In geotechnical engineering, reconstituted soils are widely used to investigate compressibility, consolidation behavior, and shear strength characteristics of clays without the influence of natural bonding or fabric.
Purpose of Preparing Reconstituted Soil
The main objectives of preparing reconstituted soil samples are:
- To study intrinsic compressibility characteristics of clay.
- To eliminate natural structure and bonding effects.
- To compare structured and destructured soil behavior.
- To establish reference compression lines (e.g., Intrinsic Compression Line).
Preparation Methods of Reconstituted Soil
According to Liu et al. (2016), the following laboratory methods have been developed for preparing reconstituted soil specimens:
- Moist Tamping (Compaction): Soil is compacted at a controlled moisture content in layers to achieve desired density.
- Water Pluviation: Soil particles are allowed to settle through water to simulate sedimentation.
- Air Pluviation: Dry soil particles are allowed to fall through air into a mold to obtain uniform density.
- Slurry Deposition: Soil-water slurry is poured into a mold and allowed to settle under gravity.
- Slurry Consolidation: A high water content slurry (usually 1–1.5 times liquid limit) is consolidated under one-dimensional loading to form a uniform specimen.
As per Yin and Miao (2015), reconstituted soil sample preparation is mainly categorized into two fundamental approaches:
- Preparation by Compaction Method
- Preparation by Consolidation of Slurry
Among these methods, slurry consolidation is widely used for clay soils because it ensures uniform fabric and minimizes entrapped air.
References
- Burland, J.B. (1990), “On the Compressibility and Shear Strength of Natural Clays”.
- Liu, M.D. and Carter, J.P. (1999), “Virgin Compression of Structured Soils”.
- Yin, J. and Miao, Y.H. (2015), “An Oedometer-Based Method for Preparing Reconstituted Clay Samples”.
- Kausar Alam Anik, Md. (2019), "Shear strength and compressibility characteristics of reconstituted clays".