Study on improvement of carbonation resistance of alkali-activated slag concrete

He, Jie; Gao, Qie; Wu, Yonghua; He, Jian; Pu, Xiaolin

doi:10.1016/j.conbuildmat.2018.04.117

Cited by 46 publications

(16 citation statements)

References 21 publications

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“…As carbonation age increases, pore volume of AAS paste increases, but average pore diameter decreases. In addition, as carbonation age increases, the volume of carbonation products, which are calcium carbonate variants, such as aragonite and vaterite increases [60,61].…”

Section: Durability—carbonation Of Alkali-activated Slag Concretementioning

confidence: 99%

“…He et al [61] reported that Ca(OH) 2 and CaSO 4 ·2H 2 O each decreased carbonation depth in AAS concrete. Figure 11 shows the effect of Ca(OH) 2 on carbonation depth after various ages of carbonation.…”

Section: Durability—carbonation Of Alkali-activated Slag Concretementioning

confidence: 99%

“…Effect of Ca(OH) 2 dosage on carbonation depth of 100 × 100 × 100/300 mm 3 AAS paste compared to reference AAS sample without Ca(OH) 2 [61]. …”

Section: Figurementioning

confidence: 99%

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A Review of Durability and Strength Characteristics of Alkali-Activated Slag Concrete

Mohamed

2019

Materials

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Alkali-activated slag (AAS) is a promising alternative to ordinary Portland cement (OPC) as sole binder for reinforced concrete structures. OPC is reportedly responsible for over 5% of the global CO2 emission. In addition, slag is an industrial by-product that must be land-filled if not re-used. Therefore, it has been studied by many investigators as environmentally friendly replacement of OPC. In addition to recycling, AAS offers favorable properties to concrete such as rapid development of compressive strength and high resistance to sulfate attack. Some of the potential shortcomings of AAS include high shrinkage, short setting time, and high rate of carbonation. Using ground granulated blast furnace slag (GGBS) as an alternative to OPC requires its activation with high alkalinity compounds such as sodium hydroxide (NaOH), sodium sulfate (Na2SO3), sodium carbonate (Na2CO3), or combination of these compounds such as NaOH and Na2SO3. The mechanism of alkali-activation is still not fully understood and further research is required. This paper overviews the properties, advantages, and potential shortcomings of AAS concrete.

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Section: Durability—carbonation Of Alkali-activated Slag Concretementioning

confidence: 99%

Section: Durability—carbonation Of Alkali-activated Slag Concretementioning

confidence: 99%

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A Review of Durability and Strength Characteristics of Alkali-Activated Slag Concrete

Mohamed

2019

Materials

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“…AASC offers favorable properties, some of which include durability in aggressive and acidic environments [4,17]. Numerous studies have been performed to investigate the diverse characteristics of AASC, such as the mechanical properties [7,[18][19][20], shrinkage [21,22], carbonation [23,24], and elevated temperature endurance [25]. The main hydration product of AASC is calcium aluminum silicate hydrate (C-A-S-H) gel, with a quite quick setting time and a low Ca/Si ratio compared with OPC concrete [13,20].…”

Section: Introductionmentioning

confidence: 99%

Mix Design Effects on the Durability of Alkali-Activated Slag Concrete in a Hydrochloric Acid Environment

2021

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Because of its high strength, energy reduction, and low environmental impact, researchers have encouraged considering alkali-activated slag concrete (AASC) as a potential alternative to conventional concrete. In this study, the impact of mix design parameters on the durability of AASC, made with ground granulated blast furnace slag and activated with different alkaline solutions (NaOH, KOH, and Na2SiO3) immersed up to six months in a hydrochloric acid bath with pH = 3, has been investigated. A total of 13 mix designs were made in a way that, in addition to the type of alkaline solution, considered three other parameters, namely the molarity of alkaline solutions, the weight ratio of alkaline solutions to slag, and the weight ratio of alkaline solutions to sodium silicate. Visual inspections displayed that the AASC samples almost remained intact after exposure to an HCl acid solution with pH = 3 for up to 6 months, while the OPC sample experienced deleterious deterioration. The results clearly show that AASC outperformed OPC concrete when it comes to durability in an HCl acid solution. The strength reduction and weight loss of AASC compared with OPC concrete were approximately one-tenth and one-fifth, respectively. The AASC samples containing potassium hydroxide showed a higher strength reduction and weight loss in the HCl acid solution than the samples made with sodium hydroxide.

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“…This is affirmed by Awoyera & Adesina 24 in their recent overview on AAS. The carbonation resistance of AAS concrete can be enhanced by admixing some chemical agents or synthesizing slag in synergy with another precursor 25 . For instance, it was reported that BFS‐based AABs performed better than ferrochrome slag‐based AABs beside abundance of CaO content in the former 26 .…”

Section: Introductionmentioning

confidence: 99%

Sodium sulfate resistance of alkali/slag activated silico–manganese fume‐based composites

Nasir

Johari

Maslehuddin

et al. 2020

Structural Concrete

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The durability of alkali‐activated silico–manganese fume (SMF)‐based mortar specimens was investigated by immersing them in 5% Na2SO4 solution and water (controlled environment) for up to 40 weeks. The effect of blast furnace slag (BFS) content [R = BFS/(BFS + SMF) = 0 and 0.3] and alkali concentration (4 and 10 M NaOHaq) was studied. Visual appearance, variation in alkalinity, mass loss, compressive strength, and microstructural changes were recorded. The maximum strength of 49.4 MPa was noted in BFS‐blended high‐alkaline binder system while the ultimate residual strength and mass loss were 88.8% and − 2.4%, respectively. The high sulfate‐resistance of this binder is attributed to the dense matrix resulting from the formation of C─S─H, K─A─S─H, and C─Mn─H. BFS‐blended mild‐alkaline system exhibited incomplete precursor dissolution thereby gaining a moderate strength of 39.6 MPa with the residual strength and mass loss of 74.1%and − 4.4%, respectively. The decomposition of the specimens on exposure to Na2SO4 may be ascribed to high pH differential from the mobility of Na+, SO42−, and OH− in and out of the mortar leading to formation of additional gypsum and calcite. The BFS‐free system displayed excellent stability under sulfate environment owing to the dearth of Ca in SMF. This was notably aided by increased precipitation of quartz together with the formation of degradation products and despite that still attained low strength of about 20 MPa. It is postulated that Ca/Si, Ca/Mn, Si/Mn, Ca/K, and Si/K ratios are the controlling factors influencing the sulfate‐resistance of the developed binders.

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Study on improvement of carbonation resistance of alkali-activated slag concrete

Cited by 46 publications

References 21 publications

A Review of Durability and Strength Characteristics of Alkali-Activated Slag Concrete

A Review of Durability and Strength Characteristics of Alkali-Activated Slag Concrete

Mix Design Effects on the Durability of Alkali-Activated Slag Concrete in a Hydrochloric Acid Environment

Sodium sulfate resistance of alkali/slag activated silico–manganese fume‐based composites

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