Porous geopolymer composites: A review

https://doi.org/10.1016/j.compositesa.2021.106629Get rights and content

Abstract

Porous geopolymers have emerged as one of the most promising inorganic porous materials over the last decade, due to their inexpensive and easy fabrication process, suitable properties, thermal and chemical stability, and extensive applications. To further improve or optimize the properties of porous geopolymers or to endow them with new functionalities, a significant effort has been devoted to the exploitation and application of porous geopolymer composite materials. This review article highlights the current state-of-the-art in the field of porous geopolymer composites manufacturing methods (direct foaming, embedding lightweight (porous) fillers, additive manufacturing, etc.), properties (mechanical properties, thermal properties, adsorption properties, and others), and applications. With the summary and analysis of previous research literature, this review aims to foster further investigations into developing innovative routes for the fabrication of porous geopolymer components with improved properties and to encourage the widespread technological application of these materials.

Introduction

Geopolymers, originally termed and largely developed by Joseph Davidovits in the 1970s, are produced by the polycondensation of aluminosilicate materials in the presence of an alkali or acid activating solution [1]. Geopolymers have been considered to possess a typical polymeric structure, consisting of many repeated subunits with high molecular weight, although it could also be described as akin to that of an alumino-silicate glass, based on a continuous random network possessing only short-range order [1]. Geopolymers (inorganic polymers) have emerged as one of the most promising inorganic non-metallic materials over the past few years, due to their remarkable advantages such as low cost and low CO2 emissions for their production,[2], [3] facile synthesis protocol,[4] good formability and local availability of the raw materials,[3], [5], [6] superior thermal and chemical resistance,[7] lightweight porous structure,[6], [8] rapid hardening at low temperature with an excellent resultant strength,[9] etc. [1], [10] They can also be used for coatings and adhesives,[11], [12], [13] new binders for composites,[14], [15] new cement for concrete [16], [17] and waste encapsulation,[18] new precursors for zeolite[19] and ceramics,[20], [21] new template for carbon,[22] and others [23], [24]. They can be thus used in various applications including: green construction and building materials,[17], [25] repair and strengthening materials for infrastructures and heritage structures,[26] heat-resistant structural components,[27] toxic and radioactive waste containment materials,[28], [29], [30] low-cost ceramics tiles and refractories,[31] artworks and artifacts,[1], [32] etc. The research in geopolymer technology, which encompasses mineralogy, colloid chemistry, modern inorganic chemistry, physical chemistry and most engineering technology fields, has sharply increased in last 30 years, as evidenced by the increasing number of research groups working all over the world on this topic (see Fig. 1).

In last decades, porous geopolymers and porous geopolymer composites (PGCs) have attracted increasing attention by widely expending the application domains where dense geopolymer components cannot meet the demands. There has been a series of reviews providing information on the fabrication, property, and application of porous geopolymers,[6], [8], [10], [24], [33], [34], [35], [36] and geopolymer composites [16], [19], [37], [38]. However, to the best of our knowledge, no review on porous geopolymer composites has been published.

Fillers and reinforcing and/or functional components have been added to improve or optimize the properties of porous geopolymers or to endow them with new functionalities. In particular, hybrid materials or composites can combine the different characteristics or performance of two or more constituents. The interest in porous geopolymer composites has sharply increased in recent years. A content analysis approach was used to identify the literature (only journals based on the science citation index were considered) in this review.

In a broad sense, powder-type materials containing mostly amorphous silica (SiO2) and/or alumina (Al2O3) can be directly used for geopolymer synthesis [39]. Hence, lots of aluminosilicate materials including natural pozzolanic materials and industrial waste by-products have been used for geopolymer synthesis around the world [1], [39]. Except for silica and alumina, other oxides such as TiO2, Fe2O3, MgO, CaO, etc. and residues are more or less present. Normally, there are regarded as a part of the geopolymer matrix. In this review, the impurities deriving from raw materials were considered as a part of the matrix as well. It should be noted that some aluminosilicate materials (zeolite, additional or fiber-type or sphere-type oxides or/and aluminosilicates, aluminosilicates with low reactivity) are categorized as the second phase with respect to the geopolymer matrix.

Due to the large number of publications in the field, this review focuses solely on porous geopolymer composites in the form of granules, monoliths, membranes, etc., discussing their fabrication, main properties, and applications.

Section snippets

Fabrication of porous geopolymer composites

Generally, porous geopolymers can be obtained by four main methods, which are: 1) direct foaming, 2) the replica route, 3) the sacrificial filler route and 4) additive manufacturing, as indicated in a previous review [6]. Due to the excellent rheological properties of an aluminosilicate polymer paste, which are analogous to those of cement and organic resins, fillers forming a second-phase or acting as reinforcement can be added directly to the slurry; i, e., the synthesis methods used to

Properties and applications of porous geopolymer composites

In this section, the current progress on the mechanical, thermal, adsorption, and other properties of porous geopolymer composites is reported. Factors affecting the properties of the PGGs obtained by different processing routes and/or different additives were addressed. Applications such as water purification, membrane support, thermal insulation materials, lightweight parts, etc. were summarized and discussed as well.

Future perspectives and challenges

Many fabrication routes (direct foaming, embedding lightweight (porous) fillers, additive manufacturing, immersion and impregnation method, reactive emulsion templating-based method, particle compaction method, post-grafting method, etc.) and their corresponding pore forming mechanisms have been successfully employed for the manufacturing of porous geopolymer composite components. In summary, every approach has its pros and cons, which in turn offers important research opportunities and

Conclusions

To summarize, this article systematically reviews research papers concerning porous geopolymer composites published until the end of 2020. It presents an overview of the main manufacturing strategies (direct foaming, embedding lightweight (porous) fillers, additive manufacturing, immersion and impregnation method, reactive emulsion templating-based method etc.), properties (mechanical, thermal, adsorption etc.) and corresponding applications (thermal insulation, adsorption, filtration, etc.).

A

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This work was supported by the National Natural Science Foundation of China [52002090], the Heilongjiang Postdoctoral Science Foundation Funded Project (LBH-Z19051), the Scientific Research Foundation for the Returned Overseas Chinese Scholars of Heilongjiang Province (2019QD0002) and the Fundamental Research Funds for the Central Universities [3072020CF1001, 3072019CFJ1003]. The authors are grateful to Prof. Joseph Davidovits (Geopolymer Institute, 02100 Saint-Quentin, France) for kindly

References (200)

  • A. Hassan et al.

    Use of geopolymer concrete for a cleaner and sustainable environment – A review of mechanical properties and microstructure

    J Clean Prod

    (2019)
  • P. He et al.

    Interplay between storage temperature, medium and leaching kinetics of hazardous wastes in Metakaolin-based geopolymer

    J Hazard Mater

    (2020)
  • P. Rożek et al.

    Geopolymer-zeolite composites: A review

    J Clean Prod

    (2019)
  • Y.J. Zhang et al.

    Geopolymer-based catalysts for cost-effective environmental governance : A review based on source control and end-of-pipe treatment

    J Clean Prod

    (2020)
  • S.A. Rasaki et al.

    Geopolymer for use in heavy metals adsorption, and advanced oxidative processes: A critical review

    J Clean Prod

    (2019)
  • M. Nawaz et al.

    Geopolymers in construction - recent developments

    Constr Build Mater

    (2020)
  • M. Lahoti et al.

    A critical review of geopolymer properties for structural fire-resistance applications

    Constr Build Mater

    (2019)
  • B.D. Williams et al.

    Mineral assemblage transformation of a metakaolin-based waste form after geopolymer encapsulation

    J Nucl Mater

    (2016)
  • B.I. El-Eswed et al.

    Stabilization/solidification of heavy metals in kaolin/zeolite based geopolymers

    Int J Miner Process

    (2015)
  • A.R.G. Azevedo et al.

    Potential use of ceramic waste as precursor in the geopolymerization reaction for the production of ceramic roof tiles

    J Build Eng

    (2020)
  • M. Clausi et al.

    Metakaolin as a precursor of materials for applications in Cultural Heritage: Geopolymer-based mortars with ornamental stone aggregates

    Appl Clay Sci

    (2016)
  • Z. Zhang et al.

    Geopolymer foam concrete: An emerging material for sustainable construction

    Constr Build Mater

    (2014)
  • T.H. Tan et al.

    Current development of geopolymer as alternative adsorbent for heavy metal removal

    Environ Technol Innov

    (2020)
  • N. Ranjbar et al.

    Fiber-reinforced geopolymer composites: A review

    Cem Concr Compos

    (2020)
  • V. Medri et al.

    Alkali-bonded SiC based foams

    J Eur Ceram Soc

    (2012)
  • Y. Ge et al.

    Preparation of geopolymer-based inorganic membrane for removing Ni2+ from wastewater

    J Hazard Mater

    (2015)
  • E. Papa et al.

    Geopolymer-hydrotalcite composites for CO2 capture

    J Clean Prod

    (2019)
  • R. Bendoni et al.

    Geopolymer composites for the catalytic cleaning of tar in biomass-derived gas

    Renew Energy

    (2019)
  • Y.J. Zhang et al.

    A novel electroconductive graphene/fly ash-based geopolymer composite and its photocatalytic performance

    Chem Eng J

    (2018)
  • N. Lertcumfu et al.

    Influence of graphene oxide additive on physical, microstructure, adsorption, and photocatalytic properties of calcined kaolinite-based geopolymer ceramic composites

    Colloids Surfaces A Physicochem Eng Asp

    (2020)
  • S. Yan et al.

    Mechanical properties of geopolymer composite foams reinforced with carbon nanofibers via modified hydrogen peroxide method

    Mater Chem Phys

    (2020)
  • L. Liu et al.

    Experimental physical properties of an eco-friendly bio-insulation material based on wheat straw for buildings

    Energy Build

    (2019)
  • V. Medri et al.

    The influence of process parameters on in situ inorganic foaming of alkali-bonded SiC based foams

    Ceram Int

    (2012)
  • W.D.A. Rickard et al.

    Performance of fibre reinforced, low density metakaolin geopolymers under simulated fire conditions

    Appl Clay Sci

    (2013)
  • L. Senff et al.

    Eco-friendly approach to enhance the mechanical performance of geopolymer foams: Using glass fibre waste coming from wind blade production

    Constr Build Mater

    (2020)
  • G. Roviello et al.

    Lightweight geopolymer-based hybrid materials

    Compos Part B J

    (2017)
  • S. Wang et al.

    Experimental research on a feasible rice husk/geopolymer foam building insulation material

    Energy Build

    (2020)
  • S. Zou et al.

    Experimental research on an innovative sawdust biomass-based insulation material for buildings

    J Clean Prod

    (2020)
  • R.M. Novais et al.

    Pyrolysed cork-geopolymer composites: A novel and sustainable EMI shielding building material

    Constr Build Mater

    (2019)
  • A.T. Akono et al.

    Influence of pore structure on the strength behavior of particle- and fiber-reinforced metakaolin-based geopolymer composites

    Cem Concr Compos

    (2019)
  • A.K. Singh et al.

    A review of porous lightweight composite materials for electromagnetic interference shielding

    Compos Part B Eng

    (2018)
  • M.R. Wang et al.

    Microstructural and mechanical characterization of fly ash cenosphere/metakaolin-based geopolymeric composites

    Ceram Int

    (2011)
  • N.N. Shao et al.

    Fabrication of hollow microspheres filled fly ash geopolymer composites with excellent strength and low density

    Mater Lett

    (2015)
  • L. Zhang et al.

    Novel sustainable geopolymer based syntactic foams: An eco-friendly alternative to polymer based syntactic foams

    Chem Eng J

    (2017)
  • S. Yan et al.

    Green synthesis of high porosity waste gangue microsphere / geopolymer composite foams via hydrogen peroxide modi fi cation

    J Clean Prod

    (2019)
  • B. Nematollahi et al.

    Thermal and mechanical properties of sustainable lightweight strain hardening geopolymer composites

    Arch Civ Mech Eng

    (2017)
  • P. Rożek et al.

    Lightweight geopolymer-expanded glass composites for removal of methylene blue from aqueous solutions

    Ceram Int

    (2020)
  • A. Hajimohammadi et al.

    High strength/density ratio in a syntactic foam made from one-part mix geopolymer and cenospheres

    Compos Part B Eng

    (2019)
  • F. Colangelo et al.

    Mechanical and thermal properties of lightweight geopolymer composites

    Cem Concr Compos

    (2018)
  • V. Medri et al.

    Production and characterization of lightweight vermiculite/geopolymer-based panels

    Mater Des

    (2015)
  • Cited by (119)

    View all citing articles on Scopus
    View full text