The study reported in this paper was undertaken to investigate the physico-mechanical properties of aerated cement composite with rubber waste particles, in order to produce usable materials in cellular concrete applications. The material, containing different amounts of rubber particles as replacement to cement by volume, was aerated by artificially entrapping air voids by means of a new proteinic air-entraining agent. Results from tests performed on fresh composite have shown many attractive properties, such as improvement in workability and air-entrained with high stability of air-bubbles in the matrix. A study conducted on hardened composite properties has indicated a significant reduction in sample unit weight, thereby resulting in a level of compressive strength compatible with a load-bearing wall. The reduction in flexural strength was lower than that in compressive strength. The results have shown that the presence of air voids and rubber particles in the matrix reduces the elasticity dynamic modulus, which indicates a high level of sound insulation of the composite. This study has also highlighted the effect of the proteinic air-entraining agent on the cement matrix/rubber interaction system, as regards the composite’s mechanical strength.