Mechanical performance and capillary water absorption of sewage sludge ash concrete (SSAC)

Figures & data

Table 1 Properties of sewage of a treatment plant of Alborz Industrial City.

Rate	Property
Temperature (°C)	Varies
Colour	Dark green
Ec (μ s/cm)	1800
PH	7.6
Ph^a	7.2
BOD (mg/l)	1200
BOD^a (mg/l)	130
COD (mg/l)	2000
COD^a (mg/l)	195
TSS (mg/l)	1400
Phosphate (mg/l)	60
Nitrate (mg/l)	10
Sulphate (mg/l)	183
Azotes (mg/l)	44
NH4 (mg/l)	28
Suspended solids (SS, mg/l)	40
Detergent (mg/l)	14.2
No2 + No3 (mg/l)	10
TDS (mg/l)	980
^a After digestion.

Table 2 XRF analysis of dry sludge.

Elements	Percentage
LOI^a	21.3
Na2O	0.436
MgO	2.194
Al2O3	8.962
SiO2	54.545
P2O3	1.303
SO3	0.171
K2O	1.79
CaO	7.337
TiO2	0.2
Fe2O3	0.927
Zn	0.149
Br	0.541
Sr	0.031
Zr	0.114

Figure 1 XRD diagram of dry sludge: before and after calcinations.

Table 3 XRD analysis.

Before calcination	After calcination
Quartz (SiO2)	Quartz (SiO2)
Muscovite [KAl2(Si3Al)10(OH,F)2]	Muscovite [KAl2(Si3Al)10(OH,F)2]
Calcite (CaCO3)	Illite [KAl2(Si3Al)O10(OH)2]
Dolomite [CaMg(CO3)2]

Figure 2 Thermal analysis of the dry sludge.

Figure 3 Particle size distribution of aggregates.

Table 4 Concrete mixture proportions per cubic metre of concrete.

						Water (l)
Mixtures	Cement (Kg)	Gravel (Kg)	Sand (Kg)	Sludge (Kg)	Super plasticiser (Kg)	W/C = 0.55	W/C = 0.45
Control	360	861	852	0	3.6	198	162
SSAC-5	360	861	852	18	3.6	198	162
SSAC-10	360	861	834	36	3.6	198	162
SSAC-20	360	861	798	72	3.6	198	162

Figure 4 Density of concrete mixtures.

Figure 5 Compressive strength of concrete mixtures with W/C = 0.55.

Figure 6 Compressive strength of concrete mixtures with W/C = 0.45.

Figure 7 Flexural strength.

Figure 8 Capillary water absorption coefficients of concrete mixtures with W/C = 0.45.