Efficiency of Eucalyptus Pulps for Internal Curing

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Title: Efficiency of Eucalyptus Pulps for Internal Curing

Author(s): Passarin Jongvisuttisun, Camille Negrello, and Kimberly E. Kurtis

Publication: Special Publication

Volume: 290

Issue:

Appears on pages(s): 1-12

Keywords: Autogenous shrinkage, chemical shrinkage, early age, pulping, wood fiber

Date: 9/14/2012

Abstract:
Cellulosic or wood pulp fibers, like pre-wetted lightweight aggregates and superabsorbent polymers, can be used as internal curing agents in cementitious materials to mitigate autogenous shrinkage. While the internal curing abilities of different types of cellulose fibers have been demonstrated in mortar and concrete, relatively little fundamental research has examined the influence of fiber processing or “pulping” on their efficacy as internal curing agents. This is an important topic because even for fibers derived from the same type of wood, the morphology and composition of its pulp can be altered by processing, and these alterations can have important effects on the fibers’ internal curing capacity. This research examines the effect of variations in pulping process on the internal curing performance of eucalyptus pulp fibers grown in Southeast Asia. Variations in processing produced three fibers – unbleached soda pulp, unbleached kraft pulp, and semi-chemical pulp –which were compared as internal curing agents through standard autogenous shrinkage testing. These data were then compared based on fiber composition and morphology, using results from thermogravimetric analysis (TGA) and scanning electron microscopy, to better understand the complex roles of these factors – as influenced by processing – in providing internal curing to cement-based materials.