Application of eco-friendly alternative activators in alkali-activated materials: A review

Mendes, Beatryz Cardoso; Pedroti, Leonardo Gonçalves; Vieira, Carlos Maurício Fontes; Marvila, Markssuel Teixeira; Azevedo, Afonso Rangel Garcez de; Carvalho, José Maria Franco de; Ribeiro, José Carlos Lopes

doi:10.1016/j.jobe.2020.102010

Cited by 101 publications

(41 citation statements)

References 118 publications

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“…The great thermal shrinkage and increased micro cracking in both AAS and OPC contribute to the strength loss [ 3 ]. However, the dehydration of calcium hydroxide (CH) is thought to be the main reason for the thermal shrinkage of OPC paste, while less or no formation of CH in AAS is a reason for its higher fire resistance [ 13 ]. AAS cured at room temperature shows slightly increased compressive strength when exposed to 200 °C, which is due to the further hydration of unreacted raw materials [ 14 ].…”

Section: Introductionmentioning

confidence: 99%

Influence of Elevated Temperatures and Cooling Method on the Microstructure Development and Phase Evolution of Alkali-Activated Slag

Wang

et al. 2022

Materials

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The performance of alkali-activated slag (AAS) under thermal treatment has received particular attention. In this study, the effect of five elevated temperatures (25, 200, 400, 600, and 800 °C) and two cooling methods (air cooling and water spraying) on the mechanical and durability properties, microstructure, and phase evolution of AAS was investigated. The results show that AAS mortars exhibit higher resistance to thermal attack than OPC in terms of strength and durability. AAS samples cooled in air show higher residual strength than those cooled by spraying water, which is mainly attributed to fewer cracks formed in the former. The resistance to carbonization of exposed AAS mortars depends on the pore size distribution, while that to chloride ion penetration depends on the porosity. Cooling methods show a minor effect on the phase evolution of reaction products, suggesting that the microstructure degradation is mainly responsible for the damage of AAS structures. This study provides fundamental knowledge for the thermally induced changes on AAS which contributes new ideas for the development of construction structures with higher fire resistance.

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Section: Introductionmentioning

confidence: 99%

Influence of Elevated Temperatures and Cooling Method on the Microstructure Development and Phase Evolution of Alkali-Activated Slag

Wang

et al. 2022

Materials

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“…Additionally, varying viscosities and alkaline silicates of different cations may impact processes throughout the geopolymerization process, resulting in diverse microstructures and mechanical properties. The microstructure of GPC materials made with potassium silicate was much denser (less porous) than that of sodium silicate matrixes [54,84].…”

Section: Modulus Of Elasticity (Moe)mentioning

confidence: 94%

Optimization of Alkaline Activator on the Strength Properties of Geopolymer Concrete

et al. 2022

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This study investigates the effects of red mud on the performance of geopolymer concrete in regard to fresh and mechanical properties. Red mud was used as a binder, and GGBS replaced the binder. Different proportions of red mud ranging from 0 to 30% with an interval of 2% and activator agents such as KOH and K2SiO3 for various alkaline-to-binder ratios such as 0.30, 0.40, and 0.50 were used; their effect on the fresh and mechanical properties of geopolymer concrete were the focusing parameter on the current study. Fresh properties such as setting time, slump, compaction factor, and vee-bee consistometer test, and mechanical properties such as compressive strength, split tensile strength, flexural strength, modulus of elasticity, and impact energy were studied. ANOVA and radar plot analysis were studied for various alkaline to binder (A/B) compressive strength results tested for 7 to 90 days. The increase of red mud quantity caused the decline of workability, but there was continuous enhancement of mechanical properties of GPC up to a specific limit. An alkaline-to-binder ratio of 0.4 shows excellent results compared with other ratios at ambient conditions for strength properties. ANOVA and radar plot reveal that A/B of 0.40 for 90 days shows excellent results compared with other ratios, and CS values vary in a linear manner.

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“…Later, in 2006 Fernandez-Jimenez et al [32] studied engineering properties such as Fig. 1 Representation of synthesis of alkali-activated materials [81] mechanical properties, modulus of elasticity, bond strength, and shrinkage of alkali-activated concrete.…”

Section: Historical Background Of Aacmentioning

confidence: 99%

Fresh mechanical and durability properties of alkali-activated fly ash-slag concrete: a review

Abhishek

Prashant

Kamath

et al. 2021

Innov. Infrastruct. Solut.

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This paper describes a review of the state-of-the-art research carried on the fresh and hardened properties of Alkali Activated Binders and Concretes. Though, many research have been carried out in the recent times on alkali activated binders, few key parameters still remain unattended, that restricts the commercial application of AAMs to the general construction activities. Fresh properties, mechanical strength and durability performance of Alkali activated concrete with various Alumino silicates as base materials is mentioned. An essential parameter of Alkali activated concrete is the concentration of alkaline solution on which various properties like mechanical strength, setting time and durability depends. Influence of wide range of concentrations from 6 to 16 M on these properties are studied and reported in this paper. This paper mainly concentrates on properties of readily available base materials such as Fly ash and Slag and the means to improve their performance through the use of various industrial and agro-based byproducts as additives. Problems pertaining to practical applicability of AAMs to general construction activities are also highlighted.

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Application of eco-friendly alternative activators in alkali-activated materials: A review

Cited by 101 publications

References 118 publications

Influence of Elevated Temperatures and Cooling Method on the Microstructure Development and Phase Evolution of Alkali-Activated Slag

Influence of Elevated Temperatures and Cooling Method on the Microstructure Development and Phase Evolution of Alkali-Activated Slag

Optimization of Alkaline Activator on the Strength Properties of Geopolymer Concrete

Fresh mechanical and durability properties of alkali-activated fly ash-slag concrete: a review

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