A construction block includes a pair of base members and a pair of side wall assemblies. Each base member defines first and second upper channels and comprises a first plurality of ribs positioned within the first upper channel and a second plurality of ribs positioned within the second upper channel. Each side wall assembly defines a hollow load chamber having an open top and an open bottom and includes a plurality of hingedly interconnected panels, each including a thermoplastic material. A first side wall assembly is releasably engaged with at least some of the first plurality of ribs of a lower one of the base members, and a second side wall assembly is releasably engaged with at least some of the second plurality of ribs of the lower one of the base members. Each side wall assembly is releasably engaged with an upper one of the base members.