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TECHNICAL PAPER

Service life estimation (Years)
120 111.8
100
87.5
84.8
80 74.1 75.8
67.6 66.4
60.9
Years 60 50.3 61.6 52.7 58 53.8 52.6
42.6 40.8 44.8 49.1 46.8 43.6 41.5
40 33.2 34.8 37.5 33.8 33.2 40.3 38.4 34.8
25.7 27.7 32.3 29.3 28.3 27.2 30.8
20.4 23.6 24.7 23.5
20.7
20 17.5
0
MIX ID
SCC SCCFRA50 SCCFRA100
HSSCC HSSCCFRA50 HSSCCFRA100
Figure 21: Chemical analysis for determining Chloride concentration

were obtained from the literature and exposure severity: Service life under conditions of severe exposure at
15.98 kg/m³, 23.5 kg/m³ for severe and 55.83 kg/m³ for the 120 cover depths (10 to 50 mm)
extreme exposure conditions, which indicates and matches 99.2
100
[12]
with the findings of Qi et al. (2017) and other similar studies
78
done on chloride penetration in recycled aggregate concrete. 80 75.7
67.9 66.5
Experimental results indicated that the chloride threshold value 54.8 55.5 60.7 59.7
52.4
was 1.18 kg/m , which was taken as the threshold. Also, alkali- Years 60 47.6 47.6 45.5 44.4 48.7
3
40.6 39.4 42.5
36.4
aggregate reaction (AAR) propagation period was assumed 40 33.8 29.8 31.5 37.5 36.8 30.5
34.6
25.5 27.8
to be constant at 6 years, which is in line with generally used 24.5
20 21
design methods of durability. AAR is a significant contributor to
the long term performance of OPC based concrete structures 0
and along with corrosion as a result of chloride, poses a critical SCC SCCFRA50 SCCFRA100 HSSCC
consideration in service life modelling and durability evaluation. HSSCCFRA50 HSSCCFRA100
These parameters adoption is compatible with the existing
design procedures, and the joint analysis of AAR and chloride Figure 23: The service life of all mixes for severe exposure at different
cover depths
threshold requirements offers an extensive context through
which concrete durability should be assessed and structural Service life under conditions of extreme exposure at cover
integrity checked. 90 depths (10 to 50 mm)
79.7
80
The results of service life estimations from LIFE365 for different 70 63.4
cover thicknesses from 0 to 50 mm and for different exposure 60 55.5 54.2 61.6
conditions are shown in Figures 22, 23 and 24. 50 44.9 45.5 49.7 48.8
42.8
Years 38.9 38.8 37.2 36.4 39.8
34.7
33.2
The results of service life estimations from LIFE365 for different 40 27.6 28.3 30.6 30.1 29.7
32.2
24.5
cover thicknesses from 0 to 50 mm and for different exposure 30 20.7 19.8 25.7 24.8
22.7
conditions are shown in Figures 22, 23 and 24. 20 17.3
10
The service life for maximum cover under different exposure 0
conditions decreased up to 30 % for 50 % replacements and SCC SCCFRA50 HSSCC
45 % for 100 % replacement in standard strength mixes and SCCFRA100 HSSCCFRA50 HSSCCFRA100
decreased up to 24 % for 50 % replacements and 40 % for
100 % replacement in high strength mixes. However, the Figure 24: The service life of all mixes for extreme exposure at different
percentage decline and the service life were both lower for cover depths
lesser cover thicknesses. Several researchers have applied are taken into consideration since the thickness of the layer is
[41]
Fick’s second law of diffusion to compute the initiation time small, the reaction terms containing Dc and the time derivative
to corrosion (it) upon exposure to chlorides based on the of Cs, the model can be reduced. Threshold Cl value (Cl th ) and
American Concrete Institute (ACI) 365., and the Cx = 0 at t = Maximum surface Cl concentration (C s ) are known and assuming
0, 0 < x < ∞; Cx = Cs at x = 0, 0 < t < ∞ boundary conditions propagation period = 6 years.

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