Hd. Zhou et al., Characterization and use of pulp mill fly ash and lime by-products as roadconstruction amendments, CAN J CIV E, 27(3), 2000, pp. 581-593
Fly ash and lime by-products are the two main waste streams generated by th
e pulp and paper industry. Traditionally, these wastes are disposed of eith
er in surface impoundment or landfills. Greater environmental concerns and
limited land availability have made these disposal practices increasingly u
nacceptable and costly. Thus, the objective of this study was to determine
the feasibility of beneficial utilization alternatives with emphasis on the
ir use as road construction amendment materials based on technical, economi
cal, and environmental considerations. The experiments were conducted to co
mprehensively characterize the chemical, physical, engineering, and environ
mental properties for both waste samples and their mixtures prepared with l
ocal soils at different curing conditions. Field road tests were then condu
cted to verify and assess the performance of the mixtures in terms of load
bearing capacity, serviceability, and compaction. The results showed that p
ulp mill wastes would have little adverse environmental impact and could be
used as road construction amendments to improve soil strength and reduce d
eformation. This improvement was significantly affected by soil types, mois
ture contents, and waste addition rates. During waste-soil amendment, the m
etal leachability would be further reduced by the occurrence of solidificat
ion processes.