Table 2 Chemical oxide composition (% by weight) of RHA, EMS, and OPC.

From: Modeling and optimization of sustainable ternary concrete incorporating rice husk ash and extracted micro silica

Oxide composition (%)

RHA

EMS

OPC

SiO2

91.02

99.47

21.00

CaO

2.22

0.25

61.70

Al2O3

ND

ND

5.04

Fe2O3

2.13

0.06

3.24

P2O5

1.04

ND

ND

MgO

ND

ND

2.56

SO3

0.47

0.11

1.51

K2O

2.78

0.05

0.62

Na2O

ND

ND

0.13

TiO2

0.06

0.007

ND

MnO

0.13

0.006

ND

CuO

0.01

0.008

ND

LOI

ND

ND

1.83

SiO2 + Al2O3 + Fe2O3

93.16

99.53

29.28

ASTM C618

Class N

Class N

NA

  1. Note: ND = Not detected (below XRF detection limit); NA = Not applicable. The sum of SiO2, Al2O3, and Fe2O3 is used for pozzolanic classification in accordance with ASTM C618.
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