SHRINKAGE OF MORTAR CONTAINING RICE HUSK ASH

Through this work, different amount of Rice Husk Ash (RHA) was employed as a
partial replacement of cement with percentages of 2.5%, 5%, 7.5%, 10%, 12.5%,
15%, 17.5% and 20% in mortar mixes. The physical properties of control cement
mortar, and Rice Husk Ash (RHA) mortar were tested to determine the effect of this
material on mortar properties. Mortar specimens were cured in water for certain days,
through which, shrinkage were tested at ages 4, 11, 18, 25, 28 and 60 days, while
porosity test were determined at age 7, 28 and 60 days. All the specimens were
immersed in lime saturated water for certain period. The obtained results show that
the shrinkage and porosity of the mortar containing rice husk ash was better than that
of the control cement mortar and the optimum amount ofRHA got from this research
was 7.5%. One of the main reasons for the improvement of concrete properties upon
addition of RHA possibly may be attributed to the formation of more C-S-H gel and
94- less portlandite in concrete due to the reaction occurring between RHA and the Ca ,
OH" ions, or Ca(OH)2 in hydrating cement.