infills

Infills are materials or structures used to fill spaces, voids, or gaps within a system. They can restore volume, provide support, and improve stability, thermal performance, acoustics, or load transfer. The term is widely used across fields such as construction, urban planning, mining, and manufacturing.

In construction and civil engineering, infill works include backfill behind walls, trench fills, grouts, and concrete pours used to fill cavities or stabilize structures. The choice of infill material and method depends on load requirements, drainage, compaction needs, and long-term durability. Proper compaction and testing help prevent settlement, voids, or differential movement.

In urban planning and architecture, infill development describes building within existing urban areas on vacant or underused parcels rather than expanding into undeveloped land. Benefits include higher density, revitalization of neighborhoods, and reduced urban sprawl; challenges involve zoning restrictions, infrastructure capacity, compatibility with surrounding built form, and community engagement.

In mining and geotechnical engineering, infill materials are used to fill mined-out voids or to backfill excavated areas. Cemented backfill or rock paste can stabilize underground openings, reduce surface subsidence, and enable future extraction or site remediation. Material choice reflects availability, cost, environmental impact, and required ground support.

In additive manufacturing, infill refers to the internal lattice or pattern that fills the interior of a 3D-printed object. Infill density and pattern affect part strength, weight, and material use. Common patterns include grid, honeycomb, and gyroid, with higher densities yielding stronger but heavier objects.