Carbonation Characteristics of Alkali-Activated Blast-Furnace Slag Mortar

Song, Keum Il; Song, Jin Ah; Lee, Bang Yeon; Yang, Keun Hyeok

doi:10.1155/2014/326458

Cited by 78 publications

(27 citation statements)

References 16 publications

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“…This explains the increase in compressive strength of mortars/concrete with continued curing when exposed to CO 2 laden environment. Conversely, as shown in (8), continued ingress of CO 2 attacks CSH resulting in its disintegration and subsequent loss of strength in cement based structures [6,21,22,61,62]. This enhanced at low RH.…”

Section: Compressive Strengthmentioning

confidence: 88%

“…Moderate carbonation process occurs on the surface layer of cement based materials leading to the formation of CaCO 3 . The CaCO 3 formed is deposited on the pore network in the hydrated cement matrix resulting in pore refinement of the carbonated layer [6,21,22,61,62]. This is beneficial since pore refinement subsequently results in increased strength, reduced porosity and improved durability of hydrated cement.…”

Section: Compressive Strengthmentioning

confidence: 99%

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Review of Carbonation Resistance in Hydrated Cement Based Materials

Marangu

Thiong’o

Wachira

2019

Journal of Chemistry

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Blended cements are preferred to Ordinary Portland Cement (OPC) in construction industry due to costs and technological and environmental benefits associated with them. Prevalence of significant quantities of carbon dioxide (CO2) in the atmosphere due to increased industrial emission is deleterious to hydrated cement materials due to carbonation. Recent research has shown that blended cements are more susceptible to degradation due to carbonation than OPC. The ingress of CO2 within the porous mortar matrix is a diffusion controlled process. Subsequent chemical reaction between CO2 and cement hydration products (mostly calcium hydroxide [CH] and calcium silicate hydrate [CSH]) results in degradation of cement based materials. CH offers the buffering capacity against carbonation in hydrated cements. Partial substitution of OPC with pozzolanic materials however decreases the amount of CH in hydrated blended cements. Therefore, low amounts of CH in hydrated blended cements make them more susceptible to degradation as a result of carbonation compared to OPC. The magnitude of carbonation affects the service life of cement based structures significantly. It is therefore apparent that sufficient attention is given to carbonation process in order to ensure resilient cementitious structures. In this paper, an indepth review of the recent advances on carbonation process, factors affecting carbonation resistance, and the effects of carbonation on hardened cement materials have been discussed. In conclusion, carbonation process is influenced by internal and external factors, and it has also been found to have both beneficial and deleterious effects on hardened cement matrix.

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Section: Compressive Strengthmentioning

confidence: 88%

Section: Compressive Strengthmentioning

confidence: 99%

Review of Carbonation Resistance in Hydrated Cement Based Materials

Marangu

Thiong’o

Wachira

2019

Journal of Chemistry

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“…Under atmospheric conditions, carbonation and water release from concrete to environment take simultaneously place. Carbonation of AAS-concrete is caused by the reaction between the activator in the pore solution and CO 2 from the air as well as due to decalcification of C-S-H. 43,44 The activators in AAS-concrete, NaOH and sodium silicate, are more reactive than Portlandite (Ca(OH) 2 ) which is significantly participating in the carbonation of Portland cement-based concretes. Hence, AAS-concrete is more susceptible to carbonation than concretes based on Portland cement.…”

Section: Water Loss and Shrinkage In Drying Environmentmentioning

confidence: 99%

Shrinkage and creep behavior of an alkali‐activated slag concrete

Dehn

2017

Structural Concrete

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In this paper, experimental results about the shrinkage and creep behavior of an alkali‐activated slag concrete (AAS‐concrete) are presented. The autogenous shrinkage of AAS‐concrete is pronounced at a relatively high water to binder ratio of 0.41. The ultimate value of autogenous shrinkage is determined to be higher than that of high‐strength concrete (HSC). The observed self‐desiccation at a later concrete age can be one of the reasons for the autogenous shrinkage. In a drying environment of 65% relative humidity AAS‐concrete exhibits a significantly higher total shrinkage compared to normal‐strength concrete composed of Portland cement. In the contrary to normal and HSC carbonation shrinkage must not be neglected for AAS‐concrete in the early concrete age. The sum of drying and carbonation shrinkage develops much more rapidly for AAS‐concrete in the first weeks after the beginning of drying. Based on the experimental results the shrinkage behavior of AAS‐concrete cannot be predicted by conventional models. The creep behavior of the AAS‐concrete was investigated under sealed and unsealed conditions. The creep coefficients for both conditions are higher than those calculated when using conventional models.

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“…When Na 2 SiO 3 was used as the activator, the C-S-H content of the hydration products of ACNCMs was the highest, and it was the lowest when Na 2 SO 4 was used as the activator. C-S-H decomposes at 560 • C [38], CaCO 3 decarburizes at 600 • C [39], and CaCO 3 decomposition reactions occur at 600-784 • C [40,41]. According to the weight loss of CaCO 3 revealed in the figure, it was evident that the content of CaCO 3 in N1 was the highest.…”

Section: Tg and Mip Analysesmentioning

confidence: 92%

Alkali Activation of Copper and Nickel Slag Composite Cementitious Materials

Zhang

Zhi

et al. 2020

Materials

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Alkali-activated copper and nickel slag cementitious materials (ACNCMs) are composite cementitious materials with CNS (copper and nickel slag) as the main materials and GGBFS (ground-granulated blast-furnace slag) as a mineral admixture. In this paper, the activity indexes of CNS with different grinding times were studied using CNS to replace a portion of cement. NaOH, Na2SO4, and Na2SiO3 activators were used to study the alkaline solution of the CNS glass phase. The effects of the fineness of CNS and the type of activator on the hydration of ACNCMs were investigated via physical/mechanical grinding and chemical activation. The hydration products of ACNCMs were analyzed via XRD, SEM, FT-IR, TG, and MIP. The results of the study revealed that the activity indexes of CNS ground with different grinding times (10, 30 and 50 min) were 0.662, 0.689, and 0.703, respectively. When Na2SiO3 was used as the activator, the glass phase dissolved the most Si4+, Al3+, and Ca2+, and the respective concentrations in the solution were found to be 2419, 39.55, and 3.38 mg/L. Additionally, the hydration products of ACNCMs were found to have a 28-day compressive strength of up to 84 MPa.

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Carbonation Characteristics of Alkali-Activated Blast-Furnace Slag Mortar

Cited by 78 publications

References 16 publications

Review of Carbonation Resistance in Hydrated Cement Based Materials

Review of Carbonation Resistance in Hydrated Cement Based Materials

Shrinkage and creep behavior of an alkali‐activated slag concrete

Alkali Activation of Copper and Nickel Slag Composite Cementitious Materials

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