In-depth investigation of the long-term strength and leaching behaviour of inorganic polymer mortars containing green liquor dregs
authors Novais, RM; Carvalheiras, J; Senff, L; Seabra, MP; Pullar, RC; Labrincha, JA
nationality International
journal JOURNAL OF CLEANER PRODUCTION
author keywords Green liquor dregs; Biomass fly ash; Geopolymer; Mechanical resistance; Long-term performance; Leaching
keywords ASH-BASED GEOPOLYMER; BIOMASS FLY-ASH; MECHANICAL-PROPERTIES; PAPER-INDUSTRY; RAW-MATERIAL; WASTE GLASS; PULP; SLAG; SPHERES; METALS
abstract Green liquor dregs are the most challenging waste stream coming from the pulp and paper industry. Despite tremendous efforts, there are not currently any viable recycling alternatives for this massively produced waste (2 Mt/year), which inevitably ends up in landfills. Urgent actions must be undertaken to tackle this. In this work, a substantial amount of dregs was incorporated into eco-friendly, waste-based inorganic polymer (geopolymer) mortars as fine filler. Then, and for the first time, the long-term strength performance (up to 270 days) and heavy metals leaching behaviour of the dregs-containing mortars was evaluated. The effect of the mixture composition and dregs incorporation content on the fresh- and hardened-state properties of the mortars was also studied. Dregs were found to increase the initial and final setting time of the slurries, thus extending the open time before their in-situ application. The use of dregs as fine filler effectively enhances the compressive strength of the mortars, and decreases their water absorption levels. These eco-friendly building materials showed excellent long-term performance, as their strength continuously increases up to the 270th day (after mixture), and no signs of efflorescence formation were detected. Moreover, the heavy metals leaching levels of the mortars were well below the contamination limits in soil, which demonstrates the feasibility of this recycling methodology. (C) 2019 Elsevier Ltd. All rights reserved.
publisher ELSEVIER SCI LTD
issn 0959-6526
year published 2019
volume 220
beginning page 630
ending page 641
digital object identifier (doi) 10.1016/j.jclepro.2019.02.170
web of science category Green & Sustainable Science & Technology; Engineering, Environmental; Environmental Sciences
subject category Science & Technology - Other Topics; Engineering; Environmental Sciences & Ecology
unique article identifier WOS:000465509400051
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