Usability of industrial ashes in cement production as pozzolanic materials

In the present study the utilization of coal ashes that appear at the end of firing process of brick production in cement pastes was examined. Ashes with three different particle sizes of 75 gm, 106 pm and 150 gm were used to replace ordinary Portland cement (PC) as 5 % and 15 % by weight. Seven samples were prepared and physical, mechanical, chemical and microstructural analyses were carried out. The compressive and bending strength values of samples were determined at the ages of 2, 7 and 28 days. It was found that cementitious pastes with finer particle sizes possessed the highest compressive and bending strength values at all curing ages. Both values after 2 and 7 days cure increased with an increase in ash content, no matter what the particle sizes of ashes were. However, strength decreased after 28 days cure as a result of ash addition of 15 %, although it was still above that of the PC.