Study on Shrinkage in Alkali-Activated Slag–Fly Ash Cementitious Materials

With rapid infrastructure development worldwide, the generation of industrial solid waste (ISW) has substantially increased, causing resource wastage and environmental pollution. Meanwhile, tunnel engineering requires large quantities of grouting material for ground treatment and consolidation. Using ISW as a component in tunnel grouts provides a sustainable solution to both issues. This paper presented a comprehensive review of the recent advancements in tunnel grouting materials using ISW, focusing on their feasibility, mechanical characteristics, and future development directions. Initially, the concept and classification of ISW were introduced, examining its feasibility and advantages as grouting materials in tunnels. Subsequently, various performances of ISW in tunnel grouting materials were summarized to explore the factors influencing mechanical strength, fluidity, durability, and microstructure characteristics. Simultaneously, this review analyzed current research trends and outlines future development directions. Major challenges, including quality assurance, environmental risks, and lack of standardized specifications, are discussed. Future research directions, including multifunctional grouts, integrated waste utilization, and advanced characterization techniques, are suggested to further advance this field. These findings provided useful insights for the continued development of high-performance and environmentally friendly ISW-based grouting materials.

Section: Other Iswsmentioning

confidence: 99%

A Review on Development of Industrial Solid Waste in Tunnel Grouting Materials: Feasibility, Performance, and Prospects

Jiang,

Wu,

et al. 2023

“…Therefore, it is still not clear how changing the molarity or the activator quantity affects the volume stability of slag when exposed to different RH levels. Finally, it is known that autogenous deformation is a significant part of the total shrinkage of alkali-activated slag at early age [ 11 , 24 ], but it is still unclear how alkali-activated slag behaves in purely drying conditions, that is to say when autogenous deformation can be considered negligible.…”

Section: Introductionmentioning

confidence: 99%

New Experimental Evidence for Drying Shrinkage of Alkali-Activated Slag with Sodium Hydroxide

Sirotti,

Delsaute,

Staquet

2023

Alkali-activated slag (AAS) is emerging as a possible and more sustainable alternative to Ordinary Portland Cement (OPC) in the construction industry, thanks to its good mechanical and chemical properties. Conversely, the effects of its high drying shrinkage are still a concern for its long-term durability. This study aims to investigate the drying shrinkage behaviour of six AAS/sodium hydroxide mortar compositions and the main phenomena affecting their drying shrinkage behaviour. Specifically, the molarity, solution-to-binder ratio (s/b), autogenous shrinkage, creep compliance, microcracking, and carbonation are considered as possible causes of the differences between AAS and OPC. The results show that it is not possible to correlate the shrinkage magnitude with the molarity of the activating solution, while an increase in the s/b increases the drying shrinkage. Concerning the other factors, autogenous deformation remains significant even after a period of 112 days, while the creep compliance is definitely affected by the drying process but does not seem to affect the shrinkage magnitude. Furthermore, the presence of microcracks caused by the drying process definitely influences the drying shrinkage. Finally, carbonation depends on the molarity of the activating solution, even though its effects on the material are still unclear.

“…The combination of slag and fly ash is the most studied binary system [18]. Recently, extended setting time [21], decreased shrinkage [22], and ultra-high strength are reported for this binary system [23].…”

Section: Introductionmentioning

confidence: 99%

The Effects of Partial Replacement of Ground Granulated Blast Furnace Slag by Ground Wood Ash on Alkali-Activated Binder Systems

Teker Ercan,

Cwirzen,

Habermehl-Cwirzen

2023

Cement production contributes significantly to carbon dioxide emissions. Alkali-activated materials offer an environmentally friendly alternative due to their comparable strength, durability and low-carbon emissions while utilizing wastes and industrial by-products. Wood ash is a waste material that shows promising results as a partial replacement for Portland cement and precursors in alkali-activated systems. The aim of this study was to examine the effect of ground wood ash on the mechanical properties of alkali-activated mortars. Wood ash was incorporated as a 0 wt%, 10 wt% and 20 wt% partial replacement for ground granulated blast furnace slag (GGBFS). The wood ashes were ground in a planetary ball mill for 10 and 20 min. Sodium silicate (Na2SiO3), sodium carbonate (Na2CO3), and sodium hydroxide (NaOH) were used as alkali activators. The results demonstrated that ground wood ash improved the mechanical properties of alkali-activated systems compared to untreated wood ash. However, the incorporation of wood ash increased the porosity of the binder matrix.