Residuo

Journal of Chemical Technology and Biotechnology

J Chem Technol Biotechnol 77:331±335 (online: 2002) DOI: 10.1002/jctb.583

Advantages in the use of fly ashes in cements containing pozzolanic combustion residues: silica fume, sewage sludge ash, spent fluidized bed catalyst and rice husk ash†
´,* ´, ´s, J Paya J Monzo MV Borrachero, F Amahjour, I Girbe ´zquez and LM Ordo ˜ez ´n S Vela
´n ´n, ´n ´ ´ Grupo de Investigacio en Quımica de los Materiales de Construccio GIQUIMA, Departamento de Ingenierıa de la Construccio ´cnica de Valencia, Camino de Vera s/n, E-46071 Valencia, Spain Universidad Polite

Abstract: The enhancement in the workability of Portland cement concrete when coal ¯y ashes are added to the mix is well-known. This behaviour has been attributed to the spherical shape and the smooth surface of the ¯y ash particles. On the other hand, when other combustion residues with pozzolanic properties are added to concrete mix formulations, a loss in workability is observed, and an increase in water content may be necessary for obtaining a satisfactory plastic consistency of the concrete, or alternatively chemical additives may be used (plasticizers and superplasticizers). The effect of the combination of ¯y ash with other mineral admixtures in respect of the effect on the workability of mortars has been studied. The pozzolanic combustion residues examined were: silica fume, sewage sludge ash, spent ¯uid catalytic cracking catalyst and rice husk ash. Additionally, and due to the pozzolanic properties of coal ¯y ash and these residues, the strength developments of Portland cement mortars containing ¯y ash and the selected admixtures have also been measured. # 2002 Society of Chemical Industry

Keywords: combustion residues; pozzolans; concrete admixtures; silica fume; sewage sludge ash; spent ¯uid catalytic cracking catalyst; rice husk ash
INTRODUCTION

Fly ashes from thermoelectric power plants generally present a typical spherical or spheroidal shape