Effects of the type of activator on the self-healing ability of fiber-reinforced alkali-activated slag-based composites at an early age

Nguyễn, Huy Hoàng; Choi, Jeong-Il; Kim, Hyeong-Ki; Lee, Bang Yeon

doi:10.1016/j.conbuildmat.2019.07.113

Cited by 30 publications

(9 citation statements)

References 28 publications

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“…Consequently, most of the calcium content is consumed in the gepolymerization process during the first 7 days. Some modifications have been proposed in AAS mixtures to improve the autogenous self-healing property such as partial replacement of AAS by calcium hydroxide [ 53 , 57 ], addition of fiber [ 53 , 54 , 58 , 59 ], and incorporation of an additional calcium source (i.e., calcium lactate) [ 15 , 54 ]. A study conducted by Provis showed that incorporating Ca(OH) 2 in the AAS mix led to higher Ca 2+ concentration due to the low solubility of Ca(OH) 2 at a high pH level before cracking takes place.…”

Section: Self-healing Mechanismsmentioning

confidence: 99%

State-of-the-Art Report: The Self-Healing Capability of Alkali-Activated Slag (AAS) Concrete

2023

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Alkali-activated slag (AAS) has emerged as a potentially sustainable alternative to ordinary Portland cement (OPC) in various applications since OPC production contributed about 12% of global CO2 emissions in 2020. AAS offers great ecological advantages over OPC at some levels such as the utilization of industrial by-products and overcoming the issue of disposal, low energy consumption, and low greenhouse gas emission. Apart from these environmental benefits, the novel binder has shown enhanced resistance to high temperatures and chemical attacks. However, many studies have mentioned the risk of its considerably higher drying shrinkage and early-age cracking compared to OPC concrete. Despite the abundant research on the self-healing mechanism of OPC, limited work has been devoted to studying the self-healing behavior of AAS. Self-healing AAS is a revolutionary product that provides the solution for these drawbacks. This study is a critical review of the self-healing ability of AAS and its effect on the mechanical properties of AAS mortars. Several self-healing approaches, applications, and challenges of each mechanism are taken into account and compared regarding their impacts.

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Section: Self-healing Mechanismsmentioning

confidence: 99%

State-of-the-Art Report: The Self-Healing Capability of Alkali-Activated Slag (AAS) Concrete

2023

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“…Keeping all these parameters constant in the preparation of composite materials, the nature of the reinforcement, basalt fibers, or cellulose fibers in this work, together with the volume or weight fraction (percent) and their aspect ratio, are accounted as effective parameters during the consolidation process. A large number of different types of fibers has already been investigated from the following slag-based inorganic binders: polyethylene fibers [ 17 , 18 , 19 ]; polyvinyl alcohol (PVA) fibers [ 20 ]; carbon fibers [ 21 ]; steel [ 22 , 23 , 24 , 25 ] and alkali-resistant glass fibers [ 26 ], or other functionalizing components [ 27 ]. Since the insertion of the reinforcement is expected to improve the mechanical performance of the matrix, or binder, the majority of the published studies present results that are related to the performance and fracture toughness of these composites.…”

Section: Introductionmentioning

confidence: 99%

“…However, there was a lack of published data in the open literature, investigating whether these reinforcements will affect the reaction in AAMs or not. Only recently [ 17 , 18 , 19 ], some studies are more dedicated to the self-healing properties of alkali-activated slag-based composites, where, in NaOH or Na-silicate activated CaO–(Na 2 O)–Al 2 O 3 –SiO 2 –H 2 O (C–(N)–A–S–H) matrices, CaCO 3 and some amount of Na 2 CO 3 were formed in the fractured areas. Concerning steel-reinforced AASC [ 22 ], it was proved that high-performance fiber-reinforced composites, with respect to Portland cement ones, can be prepared, owing to the alkali-activated matrix, which has superior adherence to steel fiber.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Fibrous Reinforcement on the Polycondensation Degree of Slag-Based Alkali Activated Composites

et al. 2021

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Alternative cementitious binders, based on industrial side streams, characterized by a low carbon footprint, are profitably proposed to partially replace Portland cement. Among these alternatives, alkali-activated materials have attracted attention as a promising cementitious binder. In this paper, the chemical stability of the matrix, in fiber-reinforced slag-based alkali-activated composites, was studied, in order to assess any possible effect of the presence of the reinforcement on the chemistry of polycondensation. For this purpose, organic fiber, cellulose, and an inorganic fiber, basalt, were chosen, showing a different behavior in the alkaline media that was used to activate the slag fine powders. The novelty of the paper is the study of consolidation by means of chemical measurements, more than from the mechanical point of view. The evaluation of the chemical behavior of the starting slag in NaOH, indeed, was preparatory to the understanding of the consolidation degree in the alkali-activated composites. The reactivity of alkali-activated composites was studied in water (integrity test, normed leaching test, pH and ionic conductivity), and acids (leaching in acetic acid and HCl attack). The presence of fibers does not favor nor hinder the geopolymerization process, even if an increase in the ionic conductivity in samples containing fibers leads to the hypothesis that samples with fibers are less consolidated, or that fiber dissolution contributes to the conductivity values. The amorphous fraction was enriched in silicon after HCl attack, but the structure was not completely dissolved, and the presence of an amorphous phase is confirmed (C–S–H gel). Basalt fibers partly dissolved in the alkaline environment, leading to the formation of a C–N–A–S–H gel surrounding the fibers. In contrast, cellulose fiber remained stable in both acidic and alkaline conditions.

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“…It also has high ductility, of over 3%, under a tensile load. In particular, unlike fly ash-based geopolymers, alkali-activated slag-based binding materials have been shown to develop strength even without high-temperature curing [12,13,14,15,16,17]. Previous studies have also reported that electric arc furnace slag can be used as a recycled aggregate [18,19,20].…”

Section: Introductionmentioning

confidence: 99%

“…Nguyễn et al (2019) investigated the self-healing performance of alkali-activated slag-based composites, prepared using calcium hydroxide, sodium hydroxide, and sodium silicate alone. They reported that the material prepared with calcium hydroxide as the activator had the highest self-healing performance and the best tensile behavior after self-healing [13].…”

Section: Introductionmentioning

confidence: 99%

Strain-Hardening and High-Ductile Behavior of Alkali-Activated Slag-Based Composites with Added Zirconia Silica Fume

et al. 2019

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This paper presents an experimental study on the effects of zirconia silica fume on the composite properties and cracking patterns of fiber-reinforced alkali-activated slag-based composites. Four mixtures were prepared with added zirconia silica fume and varying water-to-binder ratio. Polyethylene fiber was used as a reinforcing fiber for all the mixtures at a volumetric ratio of 2.0% cubic specimens and uniaxial tensile specimens were prepared to evaluate their density, compressive strength, and tensile behavior. The test results demonstrated that the compressive strength, tensile strength, and tensile strain capacity of the composite can be simultaneously improved by incorporating zirconia silica fume. A mixture incorporating zirconia silica fume showed high-ductile behavior of 26.5% higher tensile strength, and 13.7% higher tensile strain capacity than the mixture without zirconia silica fume. The composite with added zirconia silica fume also showed excellent cracking patterns, i.e., narrow crack spacing and crack width.

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Effects of the type of activator on the self-healing ability of fiber-reinforced alkali-activated slag-based composites at an early age

Cited by 30 publications

References 28 publications

State-of-the-Art Report: The Self-Healing Capability of Alkali-Activated Slag (AAS) Concrete

State-of-the-Art Report: The Self-Healing Capability of Alkali-Activated Slag (AAS) Concrete

The Effect of Fibrous Reinforcement on the Polycondensation Degree of Slag-Based Alkali Activated Composites

Strain-Hardening and High-Ductile Behavior of Alkali-Activated Slag-Based Composites with Added Zirconia Silica Fume

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