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TECHNICAL PAPER

Group Category Identifying composition Relevant IS code SCM
I Silicate Si ≥ 85 IS: 15388 (2003) [3] Rice husk ash, Silica fume, Micronized biomass silica,
II Alumina silicate (Si+Al+Fe) ≥ 70, Si ≥ 35 IS: 3812-2 (2013) Calcined clay, Ceramic waste, Glass powder, Fly ash,
[4] Metakaolin, Bagasse ash,
III Calcareous (Si+Al+Fe) ≥ 50, Ca ≥ 10, Si ≥ 25 IS: 3812-2 (2013) Sewage sludge ash, Cupola slag
alumina silicate [4]
IV Slag CaO+MgO+Al 2 O 3 ≥ SiO 2, CaO+MgO+1/3.Al 2 O 3 IS: 12089 (1987) [5] BOF slag, GGBS, Jarrosite slurry, EAF
≥ SiO 2 +2/3.Al 2 O 3
V Calcites MgO+CaO+LoI ≥ 50, CaO ≥ 30 - Marble powder, Lime sludge, Wollastonite
Figure 2: Grouping of SCMs based on elemental oxide composition

2.2 Fast search and selection approach (1)
The elemental composition and specific surface area-based
grouping can be used to identify a suitable SCM based on (2)
[1]
the desired concrete application . The grouping system,
while being able to identify potentially suitable SCMs, did not
indicate optimum substitution or effect on overall sustainability. (3)
In another study, the application of the characterisation-based
approach was further extended by integrating a probability-
[6]
based mathematical model .
(4)
The mathematical model uses the probability of success [r(ϕ)] for
a given degree of substitution (ϕ), as expressed in Equation 1 .
[6]
The expression is derived from the previous trials on optimum Here, ϕ, ϕ p , ϕ 0 , p(ϕ p ), r n (ϕ), k T , V, C cem , C 0 , C i , C test j , n, m, and k,
composition and elemental composition, as shown in represent the degree of substitution for which savings are
[6]
Equation 2 . The probability of success can then be correlated being estimated, and the optimum substitution level based on
with potential savings after accounting for costs related to previous trials for the data set k, current level of SCM usage,
[6]
additional testing, as shown in Equation 3-4 . Here, Equation 3 probability of optimum substitution being ϕ p , the probability
serves as the basis for a fast search and selection approach, of at least one successful exploration across n trials, a factor for
which can help the stakeholders to understand how long to look discounted present value across the time duration T, volume of
for an alternative SCM and when to stop looking. cement to be used, cost of cement, cost of presently used SCM,

68 THE INDIAN CONCRETE JOURNAL | JANUARY 2026