Pozzolanic properties of pulverized coal combustion bottom ash

The pozzolanic properties of a coal combustion bottom ash were investigated. Plain pastes containing equal amounts of calcium hydroxide and bottom ash were prepared and analyzed at different ages for their strength and the calcium hydroxide consumption. At early ages, bottom ash does not react with calcium hydroxide. Its pozzolanic reaction proceeds slowly and accelerates gradually to become very interesting after 28 days and especially after 90 days. The strength activity indexes measured on mortars are sufficiently important to allow the use of bottom ash in concrete. When ground for 6 h in a laboratory ball mill, the 28-day strength activity index of bottom ash is increased by 27%. (C) 1999 Elsevier Science Ltd. All rights reserved.