The chemical composition of sewage sludge ash (SSA) and their sized fr
actions are studied, some differences in chemical composition are obse
rved. SEM studies show irregular shape of SSA particles and sized frac
tions, this shape has a decisive influence on workability of mortars.
The effect of replacing 15% of portland cement by SSA and their sized
fractions: coarse (SSAC) and medium (SSAM) obtained by sieving on comp
ressive (R(c)) and flexural (R(f)) strength of mortars was investigate
d. The study reveals an enhancement of strength when ashes are used, d
ue to probably, pozzolanic properties of SSA.