However,
contrary to the normal trend of increasing drying shrinkage with increasing paper sludge addition to
Portland cement matrices, the corresponding geopolymer drying shrinkage decreased by 34% and 64%.
Equally important, the water absorption of hardened geopolymer mortar decreased with increasing
paper sludge content at ambient temperatures, providing good prospects of overall potential for
wastepaper sludge incorporation in the production of building and masonry elements. The results
indicate that, despite its high moisture absorbance due to the organic matter and residual cellulose fibre
content, wastepaper sludge appears compatible with geopolymer chemistry, and hence serves as
a potential supplementary additive to geopolymer cementitious masonry products.