A process for manufacturing set cellular cement, including the steps of: (i) mixing cementitious material, water, foaming agent and optionally additives into a free flowing slurry having a slump of at least 100 mm; subsequently (ii) injecting and distributing air into the slurry of step (i) to form a cellular slurry; subsequently (iii) casting the cellular slurry of step (ii); and finally allowing the cellular slurry to set. And, an apparatus for carrying out the process.