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

New cements for the 21st century: The pursuit of an alternative to Portland cement

Composition and Microstructure of Alkali Activated Fly Ash Binder: Effect of the Activator

To reduce greenhouse gas emissions, efforts are needed to develop environmentally friendly construction materials. This paper presents the development of fly ash-based geopolymer concrete. In geopolymer concrete, a by-product material rich in silicon and aluminum, such as low-calcium (ASTM C 618 Class F) fly ash, is chemically activated by a high-alkaline solution to form a paste that binds the loose coarse and fine aggregates, and other unreacted materials in the mixture. The test results presented in this paper show the effects of various parameters on the properties of geopolymer concrete. The application of geopolymer concrete and future research needs are also identified.

On the development of fly ash-based geopolymer concrete

In recent years, both industrial and academic world are focussing their attention toward the development of sustainable composites, reinforced with natural fibres. In particular, among the natural fibres (i.e. animal, vegetable or mineral) that can be used as reinforcement, the basalt ones represent the most interesting for their properties. The aim of this review is to illustrate the results of research on this topical subject. In the introduction, mechanical, thermal and chemical properties of basalt fibre have been reviewed. Moreover, its main manufacturing technologies have been described. Then, the effect of using this mineral fibre as reinforcement of different matrices as polymer (both thermoplastic and thermoset), metal and concrete has been presented. Furthermore, an overview on the application of this fibre in biodegradable matrix composites and in hybrid composites has been provided. Finally, the studies on the industrial applications of basalt fibre reinforced composites have been reviewed.

A review on basalt fibre and its composites

Synthesis and characterisation of materials based on inorganic polymers of alumina and silica: sodium polysialate polymers

The purpose of this work was to investigate the influence of the volumetric fraction of the fibers on the fracture toughness of geopolymeric cement concretes reinforced with basalt fibers. The values of fracture toughness, critical stress intensity factor and critical crack mouth opening displacement were measured on 18 notched beams tested by three-point bending. The a 0 / h (notch height/beam height) ratio was equal to 0.2 and the L 0 / h (distance between the supports/beam height) ratio was equal to 3. According to the experimental results, geopolymeric concretes have better fracture properties than conventional Portland cement. They are also less sensitive to the presence of cracks.

Fracture toughness of geopolymeric concretes reinforced with basalt fibers

Surface phenomena and polymer miscibility of PVC/EVA blends

In this work, equilibrium data in the (Sm-Gd)Cl3-HCl-H2O-1 M saponified and nonsaponified HEHEHP–isoparaffin system were determined. The total and individual effects of rare earth (RE) concentrations on the separation factor were obtained. Based on the equilibrium data, five mathematical models describing the extraction of Sm and Gd under equilibrium conditions were developed. The models cover wide ranges of various parameters such as the total RE concentration in equilibrated aqueous phase from 0.045 to 0.6 M; acidity in equilibrated aqueous phase from 0.09 to 0.65 M; and mole fraction of Sm from 0.008 to 0.991 with small average relative errors( <3.5%). These models describe the extraction behavior of Sm and Gd, including the distribution of rare-earth concentrations in both the aqueous and the organic phases, the effects of acidity, RE concentration, and the mole fraction of Sm in aqueous phase and the RE concentration in the organic phase. A solvent extraction simulation and experiment were performed ...

Extraction behavior and simulation of rare earths in phosphonic acid systems

The existence of a miscibility window in the PVC/EVA system was investigated using a binary approach. The miscibility window was observed for 45 or 50% to 80% acetate content depending on thermodynamic parameters used. Experimental data on PVC/PVA system give no evidence for the existence of miscibility. The cloud point curves indicated a lower critical solution temperature (LCST) for the PVC/EVA system. This behavior was corroborated using equation of state analysis.

Clelio Thaumaturgo

Papers

Synthesis and characterisation of materials based on inorganic polymers of alumina and silica: sodium polysialate polymers

Fracture toughness of geopolymeric concretes reinforced with basalt fibers

Surface phenomena and polymer miscibility of PVC/EVA blends

Extraction behavior and simulation of rare earths in phosphonic acid systems

A miscibility window in PVC/EVA system