A Comprehensive Review on Fly Ash-Based Geopolymer

Abstract

The discovery of an innovative category of inorganic geopolymer composites has generated extensive scientific attention and the kaleidoscopic development of their applications. The escalating concerns over global warming owing to emissions of carbon dioxide (CO2), a primary greenhouse gas, from the ordinary Portland cement industry, may hopefully be mitigated by the development of geopolymer construction composites with a lower carbon footprint. The current manuscript comprehensively reviews the rheological, strength and durability properties of geopolymer composites, along with shedding light on their recent key advancements viz., micro-structures, state-of-the-art applications such as the immobilization of toxic or radioactive wastes, digital geopolymer concrete, 3D-printed fly ash-based geopolymers, hot-pressed and foam geopolymers, etc. They have a crystal-clear role to play in offering a sustainable prospect to the construction industry, as part of the accessible toolkit of building materials—binders, cements, mortars, concretes, etc. Consequently, the present scientometric review manuscript is grist for the mill and aims to contribute as a single key note document assessing exhaustive research findings for establishing the viability of fly ash-based geopolymer composites as the most promising, durable, sustainable, affordable, user and eco-benevolent building materials for the future.

A Review on the Incorporation of Diatomaceous Earth as a Geopolymer-Based Concrete Building Resource

“…This results in sodium aluminosilicate hydrate (N-A-S-H) gel or calcium aluminosilicate hydrate (C-A-S-H) gel products, which trigger the geopolymers’ hardening mechanism and produce materials with exceptional structural integrity and durability with the added benefit of lower greenhouse emissions [ 73 , 74 ]. By creating geopolymer construction composites with a lower carbon footprint, it is hoped that the growing concerns about global warming caused by emissions of carbon dioxide (CO 2 ), a key greenhouse gas, from the ordinary Portland cement industry can be lessened [ 12 , 14 ].…”

“…According to Luhar [ 12 ], a pozzolanic material with properties such as a low calcium content, a high vitreous phase, possessing between 80 and 90% particle sizes that are less than 45 µm, a content of unburned material at less than 5%, a reactive silica content more than 40%, and less than 10% Fe 2 O 3 content results in the optimal binding characteristics. Low-calcium binders are preferable for making geopolymers because the high amount of calcium can hinder the polymerization-setting rate resulting from an alteration of the microstructure [ 131 ].…”

“…This eco-footprint is also expected to rise with the significant population growth anticipated by 2050 [ 3 ]. Currently, CO 2 emissions are to blame for 65% of global warming, with ordinary Portland cement (OPC) production contributing around 8% of all CO 2 -related greenhouse gas emissions [ 12 , 13 ]. The negative impacts of using cement-based concrete and ceramic bricks can be mitigated by adopting sustainable practices.…”

“…Numerous researchers have become interested in cutting-edge geopolymer technology and geopolymer composite production to attain sustainability in the manufacture of concrete. This is because geopolymers may be produced at low temperatures, using little energy, and by using a variety of wastes as either cementitious materials (SCM) or precursors [ 12 ]. Numerous scientists are fascinated by geopolymer concrete because it has the potential to be a more environmentally friendly alternative to ordinary Portland cement concrete [ 16 , 17 , 18 ].…”

The Mechanical Properties of Plant Fiber-Reinforced Geopolymers: A Review

“…The production process of geopolymers is relatively simple compared with traditional cement, which has outstanding advantages in energy saving and carbon emission reduction. Compared with organic polymer materials, geopolymers have the advantages of high hardness, high strength, good thermal stability, and strong antioxidant capacity [ 7 , 8 ].…”