Effect of rice husk ash on physical, mechanical, and hydric properties of clay-based geopolymer

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Résumé

This study explores the production of geopolymer using a mixture of rice husk ash (RHA), clay and a local
alkaline activator. To emulate previous research, the bricks are formulated for thermal curing at 60
◦
3
C for 24 h.
The formulation of geopolymers incorporates varying mass percentages (0 %, 5 %, 10 % and 15 %) of RHA. The
results of physical, mechanical, and water spray resistance tests carried out on the developed geopolymer adobe
bricks indicate that the formulation containing 5 % RHA performs in accordance with civil construction re
quirements. In particular, it exhibits a maximum linear shrinkage of 8.33 % and an apparent density of 1.72 g/
cm
3
, in line with the limits recommended by standards such as ASTM D560 for shrinkage, and the guidelines of
ASTM C62 or NBR 8492 (Brazil) for stabilized raw earth materials. The formulation in question has an apparent
density of 1.72 g/cm
, a mass loss of 1.63 % following water erosion tests, and a compressive strength of 32.28
MPa. These results reflect high mechanical performance and durability, in line with the requirements of stan
dards applicable to geopolymer construction materials and stabilized earth elements, thereby reinforcing the
potential of this composition for structural applications in aggressive environments. The incorporation of RHA
into geopolymer concretes has been observed to enhance their mechanical strength. The RHA was observed to
exert a filling effect within the clay matrix. The geopolymer reactions between the amorphous mixture (MK
0
+
RHA) and the alkaline solution (c), obtained by leaching the fine sand with a 10 M sodium aqueous solution of
local factory “Faso Chimie”, has been found to produce a hydrated sodium aluminosilicate gel (N-A-S-H).

Mots-clés

Alkaline solutionBricksClayGeopolymerizationRice husk ash