Lightweight-foamed concretes (LFC) were formulated from cement, natural sand, and foam from a
foaming agent with densities of 600 and 700 kg/m3. The identified mineral phases in the cement are
alite, belite, celite, ferrite, calcite, and gypsum. The obtained foamed concretes have a porosity varying
from 29.17 to 37.14 vol%, a thermal conductivity below 0.2 W/m.K, and a mechanical strength greater
than 2 MPa. At 28 days setting, the relative quantities of crystalline and amorphous phases were
identified by XRD and DTA/TG. These techniques allowed to show the importance of the carbonation
process and hydrated phases formation on the macroscopic strength increase. The microstructural
characterization by image analyses evidences that when the density decreases, growth of both crystalline
and amorphous phases in the bubble walls during setting is a mean of compensating the role of density
in strength.

Foamed concretes, Thermal conductivity, Porosity, Foaming agent, Mechanical strength