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Sewage sludge ash 127

Figure 5.3 SEM micrographs of SSA particles (Monzo ´ et al., 2003). SSA, Sewage sludge ash.

Table 5.4 Chemical composition of sewage sludge ash from Pinedo (Spain)
Oxide (%) Reference
Pe ´rez-Carrio ´n et al. (2014) Baeza et al. (2014a)

SiO 2 19.2 16.98
Al 2 O 3 8.9 9.48
Fe 2 O 3 10.0 8.38
CaO 30.6 29.73
MgO 2.7 3.17
Na 2 O 0.8 0.92
K 2 O 1.4 1.26
1.0 0.90
TiO 2
12.3 14.01
P 2 O 5
Cl 2 -- 0.15
11.1 8.80
SO 3
Others 0.56
LOI 5.1 4.55

the characterisation of the ash was somewhat different than in previous studies
(Table 5.4). In the X-ray pattern, various crystalline compounds [quartz SiO 2 , anhy-
drite CaSO 4 , calcite CaCO 3 , forsterite Mg 2 SiO 4 , Magnetite, Fe 3 O 4 , lime CaO and
whitlockite, β-Ca 3 (PO 4 ) 2 ] were identified, more so than an amorphous material.
2
Ash particles had a specific Blaine surface of 3000 cm /g.
Moreover, Baeza et al. (2014a) studied binary and ternary combinations of SSA
with marble dust (MD), FA and RHA as a replacement for PC pastes. The chemical
composition of the SSA was collected in Table 5.4. For this work, the ash used had
a very small mean particle diameter (16.67 μm).
Pan et al. (2003) investigated the effect of SSA fineness on mortar properties.
This ash was taken from a wastewater treatment plant in Taipei City (Taiwan) and
it was obtained from a typical sewage treatment plant using a primary process. The