Effect of Al anodizing waste on the final properties of porous geopolymers

authors	Buruberri, LH; Senff, L; Seabra, MP; Labrincha, JA
nationality	International
journal	CONSTRUCTION AND BUILDING MATERIALS
author keywords	Al-anodizing sludge; Porous geopolymers; Porosity control; Direct foaming technique
keywords	FLY-ASH; FOAMS; POROSITY; AGENT; WATER; PERMEABILITY; STRENGTH; POWDER
abstract	The Achilles heel in the production of porous geopolymers (PGPs) by the direct foaming technique is the porous coalescence phenomenon. The control of pore size distribution and porosity type (closed or open) is mandatory, although difficult. In most of the published studies, this problem is overcome through the addition of chemical stabilizing agents (surfactants) or thickening agents (fibers or particles). In this work, porous geopolymers were produced by the direct foaming technique using aluminium powder as a chemical foaming agent. The pore size distribution and porosity type was controlled by adding, to the geopolymeric mixture, Al-anodising sludge (AAS), a waste resulting from aluminium surface treatment. The PGPs were characterized in terms of apparent density, porosity, pore morphology, thermal conductivity, water vapour permeability and compressive strength, yielding lightweight materials (0.339 g/cm(3)) exhibiting high total (84%) and open (70%) porosity, low thermal conductivity (0.082 W/mK) and a low water vapour diffusion resistance coefficient. Compressive strength (of about 2 MPa or higher) is enough for the applications (e.g. insulating materials, filters, lightweight structures). (C) 2020 Elsevier Ltd. All rights reserved.
publisher	ELSEVIER SCI LTD
issn	0950-0618
isbn	1879-0526
year published	2020
volume	263
digital object identifier (doi)	10.1016/j.conbuildmat.2020.120160
web of science category	Construction & Building Technology; Engineering, Civil; Materials Science, Multidisciplinary
subject category	Construction & Building Technology; Engineering; Materials Science
unique article identifier	WOS:000582567100057