Reactivity of Ground Coal Bottom Ash to Be Used in Portland Cement

Abstract

Ground coal bottom ash is considered a novel material when used in common cement production as a blended cement. This new application must be evaluated by means of the study of its pozzolanic properties. Coal bottom ash, in some countries, is being used as a replacement for natural sand, but in some others, it is disposed of in a landfill, leading thus to environmental problems. The pozzolanic properties of ground coal bottom ash and coal fly ash cements were investigated in order to assess their pozzolanic performance. Proportions of coal fly ash and ground coal bottom ash in the mixes were 100:0, 90:10, 80:20, 50:50, 0:100. Next, multicomponent cements were formulated using 10%, 25% or 35% of ashes. In general, the pozzolanic performance of the ground coal bottom ash is quite similar to that of the coal fly ash. As expected, the pozzolanic reaction of both of them proceeds slowly at early ages, but the reaction rate increases over time. Ground coal bottom ash is a promising novel material with pozzolanic properties which are comparable to that of coal fly ashes. Then, coal bottom ash subjected to an adequate mechanical grinding is suitable to be used to produce common coal-ash cements.