New Construction Materials: Calcined Paper Sludges as Active Additions

Abstract

This paper shows the possibility of reutilize paper sludge waste as supplementary cementing material for the cement manufacture. This industrial waste consists essentially of a mixture of organic matter (30%) and inorganic compound, such as calcite and clay minerals. The raw paper sludge does not present pozolanic properties, but once calcined at 650°C during 2 hours, exhibits a good pozolanic activity. Calcined paper sludge was used as partial Portland cement replacements of 0 and 10%. It was a sligth increment in compressive strength for 10 % of substitution from 7 days on. Furthermore, calcined paper sludge reduces the initial and final setting times of cement paste.