Preparation and Properties of Alkali Activated Metakaolin-Based Geopolymer

Abstract

The effective activation and utilization of metakaolin as an alkali activated geopolymer precursor and its use in concrete surface protection is of great interest. In this paper, the formula of alkali activated metakaolin-based geopolymers was studied using an orthogonal experimental design. It was found that the optimal geopolymer was prepared with metakaolin, sodium hydroxide, sodium silicate and water, with the molar ratio of SiO2:Al2O3:Na2O:NaOH:H2O being 3.4:1.1:0.5:1.0:11.8. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) were adopted to investigate the influence of curing conditions on the mechanical properties and microstructures of the geopolymers. The best curing condition was 60 °C for 168 h, and this alkali activated metakaolin-based geopolymer showed the highest compression strength at 52.26 MPa. In addition, hollow micro-sphere glass beads were mixed with metakaolin particles to improve the thermal insulation properties of the alkali activated metakaolin-based geopolymer. These results suggest that a suitable volume ratio of metakaolin to hollow micro-sphere glass beads in alkali activated metakaolin-based geopolymers was 6:1, which achieved a thermal conductivity of 0.37 W/mK and compressive strength of 50 MPa. By adjusting to a milder curing condition, as-prepared alkali activated metakaolin-based geopolymers could find widespread applications in concrete thermal protection.

Role of Heat-Treated Laterite on the Strengthening of Geopolymer Designed with Laterite as Solid Precursor

“…Geopolymers have attracted interest in the last three decades. Many research papers on the synthesis of geopolymers have focused in the use of different aluminosilicates such as recycled industrial wastes [12,13] metakaolin [14][15][16][17], meltquenched aluminosilicates [18], grinded mineral resources such as volcanic scoria [19,20] and mixtures of two or more of these materials [21][22][23].…”

La activación alcalina de diferentes aluminosilicatos como una alternativa al Cemento Portland: cementos activados alcalinamente o geopolímeros

“…Among these alternative materials are those coming from the alkaline activation of aluminosilicates, either as natural products (clays) (Chen et al, 2016) or industrial byproducts, such as blast furnace vitreous slags and/or fly ash (Neupane, 2016), where different binders are obtained following the (Deventer et al, 2010 (Davidovits, 1991;Davidovits, 1982;Davidovits, 2008). (Provis and van Deventer, 2014) Figure 1 shows a diagram of the distinction between these classifications (Provis, 2014 (Caicedo Casso et al, 2015), demolition waste (Asensio et al, 2016), glass waste ; Puertas and Torres-Carrasco, 2014;Torres-Carrasco and Puertas, 2015), rice husk ash (J. M. Mejía et al, 2013) Bakharev, 2005a;Puertas et al, 2002), acid environments Bakharev, 2005b), less expansion problems derived from the "aggregate-alkali" reaction produced, under certain conditions, in the case of Portland cement mortars and concretes García-Lodeiro et al, 2007;Puertas et al, 2009 (Donatello et al, 2012;Shi and Fernández-Jiménez, 2006).…”

Fabrication of interconnected macroporosity in geopolymers via inverse suspension polymerization

“…The FTIR spectrum of GS4‐3 (Figure ) shows characteristic geopolymer bands, located between 900 and 1100 cm −1 , attributed to asymmetric stretching of Si‐O or Al‐O . The bands at 600 cm −1 and 700 cm −1 correspond to Al–O–Si stretching vibrations and bending vibrations, respectively …”