Which soil type relates to primary consolidation settlement?

Primary consolidation settlement is primarily associated with clayey soils. This phenomenon occurs when saturated clay soils undergo compression due to an increase in load, leading to a reduction in voids and the expulsion of pore water. The process is characterized by the gradual decrease in water content over time, during which the soil structure adjusts and compacts under constant effective stress.

Clayey soils, due to their fine-grained nature and significant plasticity, exhibit these characteristics prominently. They have a high moisture retention capacity and low permeability, which means that the dissipation of pore water pressure takes time, resulting in a slower consolidation process. The primary consolidation is a critical factor in geotechnical engineering, as it can lead to significant and time-dependent settlement in structures built on clayey substrates.

Gravel and sandy soils do not typically undergo primary consolidation in the same manner because they consist of larger particles, allowing for quicker drainage of pore water and less volume change under loads. Loamy soil, while it contains clay, sand, and silt, does not behave identically to pure clay in terms of consolidation characteristics due to mixed grain sizes that contribute to faster drainage and less consolidation-related settlement.