A brief history and review of geopolymer technology is presented with the aim of introducing the technology and the vast categories of materials that may be synthesized by alkali-activation of aluminosilicates. The fundamental chemical and structural characteristics of geopolymers derived from metakaolin, fly ash and slag are explored in terms of the effects of raw material selection on the properties of geopolymer composites. It is shown that the raw materials and processing conditions are critical in determining the setting behavior, workability and chemical and physical properties of geopolymeric products. The structural and chemical characteristics that are common to all geopolymeric materials are presented, as well as those that are determined by the specific interactions occurring in different systems, providing the ability for tailored design of geopolymers to specific applications in terms of both technical and commercial requirements.

Geopolymer technology: the current state of the art

The Role of Inorganic Polymer Technology in the Development of ‘Green Concrete’

Understanding the relationship between geopolymer composition, microstructure and mechanical properties

Carbon dioxide equivalent (CO2-e) emissions: A comparison between geopolymer and OPC cement concrete

Advances in alternative cementitious binders

The geopolymerisation of alumino-silicate minerals

Geopolymerisation of multiple minerals

The development of the pore structure of geopolymers synthesized from class F fly ash was studied using electron microscopy and porosimetry. Fly-ash-based geopolymer can be classified as a mesoporous aluminosilicate material, with a Si/Al composition varying from 1.51 to 2.24. The Si/Al composition and pore structure of fly-ash-based geopolymer vary depending on the curing temperature and the silicate ratio of the activating solutions (SiO2/M2O, M = Na or K). A higher Si/Al ratio and finer pores are obtained in geopolymers synthesized at higher temperature and silicate ratios. Elevating the curing temperature increases the extent and rate of reaction, shown through an increase in mesopore volume, surface area, and an accelerated setting time. The kinetics appears to be temperature-controlled only before the material is hardened. Very high silicate ratios (SiO2/M2O ≥ 2.0) are also believed to slow the reactions. The pore structure of K-based geopolymer is more susceptible to change in temperature than that...

Effect of Curing Temperature and Silicate Concentration on Fly-Ash-Based Geopolymerization

The effect of alkali metals on the formation of geopolymeric gels from alkali-feldspars

Few attempts have been made to understand the effect of the structural and surface properties of source materials on geopolymerization. In the present work, kaolinite, albite, and fly ash have been chosen for a case study to answer this question. X-ray diffraction, X-ray fluoresence, X-ray photoelectron spectroscopy, 27Al and 29Si magic-angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, and scanning electron microscopy (SEM) have been used to characterize the source materials and geopolymers. The fly ash that has an amorphous structure and possesses the lowest binding energies in its structure shows the highest reactivity during geopolymerization. Apart from the reactivity, the desired Si/Al molar ratio in the gel phases and the leaching of the source materials are observed to significantly affect the geopolymerization. The geopolymerization of mixtures of two or three source materials demonstrates the benefits derived from the interaction between the source materials. Such interactions cou...

Hua Xu

Papers

The geopolymerisation of alumino-silicate minerals

Geopolymerisation of multiple minerals

Effect of Curing Temperature and Silicate Concentration on Fly-Ash-Based Geopolymerization

The effect of alkali metals on the formation of geopolymeric gels from alkali-feldspars

Effect of Source Materials on Geopolymerization