The functional purpose of edging for a concrete block walkway is twofold. First, it is used as a rigid border to keep the concrete blocks, and the aggregate substrate on which they rest, from shifting outward. Second, the edging keeps the soil, vegetation and/or mulch adjacent to the path from migrating into the path. In a cosmetic sense, the edging frames the path and can be used to accentuate its presence in the landscape. Edging materials should be chosen to complement the color, texture and style of the path's concrete block material.
Flexible edging can be made of plastic, metal or wood and is usually the easiest edging to install for a concrete block path. This kind of edging is installed vertically and staked into place. It easily molds to the shape of a curved walkway. After installed, flexible edging is nearly invisible, with just a narrow edge of it appearing between the path and adjacent landscape. That factor could be considered an aesthetic advantage or a loss, depending on personal preference. The main disadvantage of flexible edging is that it may not be firm enough to keep the concrete blocks from moving over time.
Rigid edging materials include poured concrete, bricks, cobblestones, natural stone and other pavers. Pouring a narrow concrete lip along the edge of installed concrete blocks is a simple option for edging and a sure way to keep the blocks from moving. Bricks and cobblestones can be laid in mortar along the path for an edging that is very stable and considered attractive. Pavers also are used as decorative edging for concrete block walkways. Using pavers that are smaller or darker than the path's concrete blocks usually makes a good visual combination.
Rigid edging should rest on the same bed of compacted soil and aggregate base material as the concrete block walkway. The soft topsoil needs to be excavated down to a solid subsoil layer, which should be compacted further with a tamping tool. Then a 3- to 4-inch-deep layer of aggregate must be spread as a base, and about a 1-inch-deep layer of leveling sand goes on top of the aggregate.
Depending on its height, flexible edging may need to be installed after topsoil has been excavated but before the walkway's base material has been spread. Otherwise, a trench will have to be made after the concrete block walkway is place, and the flexible edging will have to be installed in the trench, a process that can destabilize the concrete blocks.