Paper • open access

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IOP Conference Series: Materials Science and Engineering
PAPER • 
OPEN ACCESS
Setting time and standard consistency of Portland cement binders
blended with rice husk ash, calcium carbide and metakaolin admixtures
To cite this article: M Babako and JA Apeh 2020 IOP Conf. Ser.: Mater. Sci. Eng. 805 012031
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Nanotechnology Applications in Africa: Opportunities and Constraints
IOP Conf. Series: Materials Science and Engineering 805 (2020) 012031
IOP Publishing
doi:10.1088/1757-899X/805/1/012031
1
Setting time and standard consistency of Portland cement binders blended with rice husk 
ash, calcium carbide and metakaolin admixtures 
 
M Babako and JA Apeh 
Department of Building, Federal University of Technology, Minna. 
[e-mail] 
Abstract 
The use of pozzolanic materials to reduce carbon dioxide (CO
2
) emissions and enhanced 
properties of mortar and concrete has received increased interests in the last decades. In this 
study, admixtures such as metakaolin (MK), rice husk ash (RHA) and calcium carbide waste 
(CCW) partially replaced Portland cement (PC) at 5, 10, 20 % in multiple combinations of 
aforementioned admixtures as binders and the effect of setting times (initial and final) and 
standard consistency on the binders were evaluated. The Department of Environment (DOE) 
approach for mix proportions was employed. The mixes are in six groups consisting of control 
PC, each admixture replaced PC at 5, 10 and 20 % replacement level in binary mixes, then two 
of the admixtures replaced PC at same replacement level in ternary and the three admixtures 
replaced PC in quaternary mixes respectively. Results indicated that RHA significantly 
influenced the standard consistency of the binders incorporating the three admixtures as 
compared with CCW and MK. The requirement of water in the binder increased with increase in 
percentage replacement level of RHA within the binder due to its porous nature. At 5 % 
replacement level, it was 9 % above control value, 21 % and 39 % at 10 and 20 % replacement 
level subsequently. Similarly, setting times at the aforementioned replacement levels are 27 % 
and 6 % above the control value for initial and final setting time. For 20 % replacement level, it 
was 24 % and 38 % above the control value for the initial and final setting time respectively. 
This is due to reduction in PC content leading to less content of Tricalcium silicate aluminate 
(C
3
A) and amount of carbon content within the pozzolanic materials which retard the rate of 
reactions. By and large, the admixtures retard the setting times of quaternary binder, and 
increased its water of consistency which can be overcome by activation. However, they are 
useful in the construction of concrete structural elements or structures that requires longer time 

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Nanotechnology Applications in Africa: Opportunities and Constraints
IOP Conf. Series: Materials Science and Engineering 805 (2020) 012031
IOP Publishing
doi:10.1088/1757-899X/805/1/012031
2
for placement. Furthermore, it will be worthwhile to investigate same properties at the nanoscale 
since these have been established at the micro level.