Opus caementicium was the core of every Roman wall after the 2nd century bc. Mostly walls made in opus caementicium were covered with other materials to make a more robust and workable surface. Opus caementicium is a construction technique using an aggregate, water and a binding agent. The aggragate functioned as a filler like gravel, chunks of bricks or stones and rubble. The binding agent is usually called mortar like lime, gypsum or pozzolana (nowadays (Portland) cement is used).

HOME

Opus craticium Term both used for wattlework and walls of half-timer construction, filled in with stones and/or staw and plastered with mortar
Opus incertum Using irregualar shaped and random placed uncut stones or fist-sized tufa blocks inserted in a core of opus caementicium, used from the beginning of the 2nd century bc, later superceded by opus (quasi) reticulatum
Opus quadratum Walls of cutstone, recangular in form
Opus (quasi) reticulatum Small square tufa blocks placed diagonally to form a diamond-shaped mesh pattern, often supllemented by other materials at frames of windows and doors or at reinforments at corners of buildings with oblong tufa blocks
Opus testaceum / latericium Brickfaced masonry - kiln-backed bricks; the dominant technique throughout the imperial period
Opus (retilatum) mixtum Masonry of reticulated material reinforced and/or intersected by brickbands or interlocked with bricks
Opus vittatum Oblong (or occasionally square) tufa blocks intersected by one or more brickbands at (ir-)regular distances
Opus sectile Decoration patterns and figures at walls (and floors) with precisely cut pieces of polychrome stone, usually marble
Opus spicatum Walls (and floors) made of quite small elongated tiles, laid in a fishbone pattern
Opus signinum Waterproof floor- and wall-revetment of mortar mixed with terracotta sherds and crushed tiles or bricks