Pohjamateriaali

Pohjamateriaali is a Finnish term that denotes the underlying material on which something rests, is deposited, or is built. The concept is used across several fields to refer to the base layer that supports a structure, product, or process. In geology and civil engineering, pohjamateriaali usually means the bedrock, soil, or other substrate that underlies a construction site. Its characteristics—load-bearing capacity, stiffness, drainage, and stability—help determine foundations, excavation requirements, and potential settlement.

In sedimentology and marine geology, pohjamateriaali describes the substrate at the bottom of a body of water, which affects sediment transport, habitat, and geotechnical properties. In materials science and electronics, pohjamateriaali is the substrate material on which films, coatings, or microstructures are deposited. Common substrates include silicon wafers, glass, and ceramics, chosen for compatibility with the deposited material, thermal properties, and lattice match.

Determining the pohjamateriaali involves geotechnical investigations such as boreholes, sampling, laboratory testing, and geophysical surveys. The results guide design choices, such as foundation type, ground improvement methods, or surface preparation.

The term emphasizes the contrast between the base material and the overlying layers that may be variable or temporary. Etymologically, it combines pohja, base or bottom, with materiaali, material.