Swansea's coastal position on the Bristol Channel means one thing for construction: fine-grained soils that change behavior with every rainfall. Glacial till blankets the northern suburbs while estuarine alluvium fills the Tawe valley. Both materials contain silt and clay fractions that swell when wet and shrink when dry. That movement cracks foundations, heaves pavements, and destabilizes embankments. The Atterberg limits test quantifies exactly when a soil transitions from solid to plastic to liquid. Liquid limit, plastic limit, and the resulting plasticity index tell the design team what to expect as groundwater fluctuates through Swansea's wet winters. Without these numbers, a site investigation is guessing. With them, you get a defensible classification under Eurocode 7 that informs every foundation decision from Sketty to SA1.
Plasticity index tells you how much water a soil can absorb before it becomes structural mush.
