Etude préliminaire de la valorisation des boues de papeterie comme matières premières secondaires dans les mortiers de ciment Portland.

The recycling of paper mill sludges is increasing rapidly as far as the economical and positive environmental benefits are realised. The aim of the present work was to show if paper mill sludges could be used as a partial replacement of Portland cement in mortar without affecting their durability. Calcined at temperatures between 650°C and 800°C, the pozzolanic activity of ashes from paper mill sludges is improved because of the transformation of kaolinite in metakaolin. The mechanical characteristics of mortar containing 25% of these ashes appear comparable to standard mortar (containing 100% of Portland cement). The nature of the leaching does not affect the mechanical strength of mortars leached during 64 days. However, there is also a loss of compressive strength of mortars. [ABSTRACT FROM AUTHOR]