Defining existence domains in geopolymers through their physicochemical properties

A Sustainable Approach for the Geopolymerization of Natural Iron-Rich Aluminosilicate Materials

“…This amorphous fraction was used from 15-35 wt% on the basis of the literature that describes 3-30 wt% amorphous phase in indurated lateritic blocks [13]. In their work studying the domains of existence of geopolymers, Prud'Homme et al [14] gave similar consideration about the amorphous phase which in their case was between 25 and 40 molar% of soluble silica. They also recognized the impacts of some impurities in the physic-mechanical properties of geopolymers confirming our projection on the use of river sand which here acts as catalytic agents by promoting interfacial reactions and reinforcements.…”

Geopolymer/PEG Hybrid Materials Synthesis and Investigation of the Polymer Influence on Microstructure and Mechanical Behavior

“…The powder was added gradually to an alkaline solution previously prepared by mixing of a sodium silicate solution, with ratio SiO 2 /Na 2 O = 2.5 (Sigma Aldrich, Milano, Italy), and sodium hydroxide pellets (Sigma Aldrich, Milan, Italy) with ratio Na 2 SiO 3 /NaOH = 2.0. The final composition of the geopolymer synthesized can be expressed as Al 2 O 3 3.4SiO 2 0.9Na 2 …”

“…A strong alkaline solution induces the dissolution of those solid raw materials producing aluminate and silicate species which link by means of a polycondensation reaction to form the 3D-cross-linked polysialate structure ([-(Si-O) z -Al-O-] n ) [3,2] . These materials were first introduced as calcium-free inorganic cements by Davidovits in 1978 4 and since then they have been attracting increasing attention due to their promising characteristics.…”

“…Geopolymers are amorphous, three-dimensional alkali aluminosilicate binder materials synthesized by means of the alkaline activation of clays, calcined clays, natural minerals, industrial waste, fly ash and other aluminosilicate sources 1,2 . A strong alkaline solution induces the dissolution of those solid raw materials producing aluminate and silicate species which link by means of a polycondensation reaction to form the 3D-cross-linked polysialate structure ([-(Si-O) z -Al-O-] n ) [3,2] .…”

Microstructural and phase evolution in metakaolin geopolymers with different activators and added aluminosilicate fillers

“…Some studies reported the use of reactive alumina (ρ-Al 2 O 3 ) and fine aerosol silica [17], nano SiO 2 [18,19], pyrogenic silica and sand incorporation [20,21] and incorporation of alumina powder as supplementary Al source [4,22].…”