Eco-friendly geopolymer materials: A review of performance improvement, potential application and sustainability assessment

On the rheology of using geopolymer for grouting: A comparative study with cement-based grout included fly ash and cold bonded fly ash

Many alkali-activated materials (AAMs) exhibit poor workability in mixing owing to great viscosity of the paste and fast setting. Chemical admixtures commonly used in Portland cement-based materials, such as rheology control additives and superplasticizers, show lower efficiency in AAM systems. Understanding the rheological features of various AAMs and their control can lead to a valuable guidance for their application in large-scale, especially in the field of pumping and placement, grouting and 3D printing, etc. This paper aims to deliver a comprehensive review of the effects of composition factors including activators, precursors, admixtures, additions, aggregates and fibers on the rheology of AAMs, as well as models for describing their rheological behavior. The current progress has shown that the large knowledge gap needs substantial research from scientific mechanisms to robust formulations of paste, mortar and concrete to meet both workability and mechanical requirements.

Rheology of alkali-activated materials: A review

Rheology of fly ash-based geopolymer: Effect of NaOH concentration

Stability of a new geopolymer grout: Rheological and mechanical performances of metakaolin-fly ash binary mixtures

Alkali-activated grouts based on slag-fly ash mixtures: From early-age characterization to long-term phase composition

Geopolymers have gained much interest recently as a promising alternative to cementitious materials in some applications. However, research is still needed to use this technology for soil reinforcement grouts. The specifications of grouts mainly consist in rheological properties, strength and permeability. Grouting actually requires a low viscosity, and thus higher water content. The influence of relatively high water content on the other properties of the material, i.e. strength and microstructure, has been investigated. This effect highly depends on the concentration of the activator (sodium silicate solution) and the precursor (metakaolin, fly ash or blast furnace slag) associated with the activator. This paper deals with the main effects of high water content on the microstructure and mechanical properties of the materials, looking at physical and chemical aspects. Scanning electron microscopy and chemical phase analysis were used to highlight the nuances that are related to the precursors used, espec...

Design of geopolymer grouts: the effects of water content and mineral precursor

The nanostructure of alkali-activated materials is now better understood. However, very few studies have been carried on grouts. These highly diluted systems are used to improved soil properties for instance. In this study, the evolution of their local structure was monitored via 29Si and 27Al NMR to understand the formation of the binding phase and its evolution at long-term. The results of this analysis were used to question the relationship between the evolution of the chemistry of binding phases and the observed changes in the mechanical properties at material scale. Metakaolin and slag were used, with the partial incorporation of fly ash to study its effects and the potential benefits of its use. The results show that while metakaolin-based systems are very stable at both scales (local and macroscopic), the structure of slag-based grouts tends to evolve, with a negative impact on their mechanical performance.

Anass Cherki El Idrissi

Papers

Stability of a new geopolymer grout: Rheological and mechanical performances of metakaolin-fly ash binary mixtures

Alkali-activated grouts based on slag-fly ash mixtures: From early-age characterization to long-term phase composition

Design of geopolymer grouts: the effects of water content and mineral precursor

Alkali-activated grouts with incorporated fly ash: From NMR analysis to mechanical properties

Resistance of alkali-activated grouts to acid leaching