Segmental Paving and Retaining Wall Systems

About this course.

Segmental paving and segmental retaining walls are systems built from many small, individually manufactured units that work together rather than as a single monolithic slab or wall. In segmental paving, precast concrete (or sometimes clay or stone) units are laid tightly over a prepared base and bedding layer, with the joints filled so that the units transfer load to one another and behave as a flexible, interlocking surface. In a segmental retaining wall, dry-stacked concrete blocks are laid in courses to hold back a bank of soil, either by their own mass or with the help of soil reinforcement placed in the backfill. Both are modular, unmortared systems whose performance depends heavily on what is beneath and behind them.

Segmental pavements are best understood as flexible pavements made of small elements. Unlike a poured concrete slab or an asphalt surface, a segmental pavement is not a single rigid sheet; it is a mat of units bedded on a thin layer of bedding material over a compacted base. When a wheel or footfall passes over it, load spreads through the interlocked units and down through the layers below. This flexibility is a strength: the surface can accommodate minor movement and settlement without cracking the way a rigid slab might, individual units can be lifted and reinstated to reach services beneath, and a damaged or stained unit can be replaced without patch marks. These qualities are a large part of why segmental paving is so widely specified.