Effect of natural carbonation on the pore structure and elastic modulus of the alkali-activated fly ash and slag pastes

Nedeljković, Marija; Šavija, Branko; Zuo, Yibing; Luković, Mladena; Ye, Guang

doi:10.1016/j.conbuildmat.2017.12.005

Cited by 84 publications

(22 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The SEM-image analysis was performed based on the images obtained from environmental scanning electron microscope (ESEM). The vacuum dried samples were impregnated using a low viscosity epoxy resin and then polished down to ¼ μm [ 31 ]. Then, the polished samples were examined by ESEM (Philips XL30, Eindhoven, The Netherland) with backscattering electron (BSE) mode at an acceleration voltage of 20 kV under low vacuum mode.…”

Section: Methodsmentioning

confidence: 99%

Pore Structure Characterization of Sodium Hydroxide Activated Slag Using Mercury Intrusion Porosimetry, Nitrogen Adsorption, and Image Analysis

Zuo

2018

Materials

Self Cite

View full text Add to dashboard Cite

The pore structure of alkali-activated slag has a significant influence on its performance. However, the literature shows insufficient studies regarding the suitability of different techniques for characterizing the pore structure and the influences of Na2O and curing age on pore structure development. In pursuit of a better understanding, the pore structure of sodium hydroxide activated slag paste was characterized by multiple techniques, e.g., mercury intrusion porosimetry (MIP), nitrogen (N2) adsorption, and scanning electron microscopy (SEM) image analysis. The sodium hydroxide activated slag pastes were prepared with three different contents of Na2O (Na2O/slag = 4, 6, and 8%) and cured for different times up to 360 days. The microstructure observation reveals that outer C–(N–)A–S–H and inner C–(N–)A–S–H grow successively around the reacting slag grains, along with crystalline reaction products which are formed in the empty coarse pore space. The increase of Na2O content and curing age lead to a finer pore structure. The MIP measurements show that the total porosity drops about 70% within the first day, and that one peak at most, corresponding to gel pores, was identified in the differential curves of all the investigated samples from 1 to 360 days. On the contrary, only one peak, corresponding to capillary pores, was identified by SEM-image analysis. The differential curves derived from N2 adsorption generally reveal two peaks, and the trend that the pore diameters of those two peaks vary with curing age depends on the content of Na2O. Compared to Portland cement, sodium hydroxide activated slag has a higher pore space filling capacity (χ, Vproducts/Vslag-reacted), while the capacity decreases with increasing Na2O content and curing age.

show abstract

Section: Methodsmentioning

confidence: 99%

Pore Structure Characterization of Sodium Hydroxide Activated Slag Using Mercury Intrusion Porosimetry, Nitrogen Adsorption, and Image Analysis

Zuo

2018

Materials

Self Cite

View full text Add to dashboard Cite

show abstract

“…The carbonation of AAMs has been shown to be strongly dependent on binder microstructure, and particularly the degree of microstructural evolution and pore network refinement achieved prior to the start of carbonation exposure, which can be influenced by curing, as well as various mix design parameters such as the activator dose [204][205][206][207]. The presence of hydrotalcite-type LDH phases has been identified as being particularly crucial in enabling carbonation resistance, whether these are produced directly as a result of activation of an Mg-containing precursor, or due to the addition of a supplemental Mg source (or calcined LDH as a seeding/templating agent) [208] [15,209,210].…”

Section: Durabilitymentioning

confidence: 99%

Recent progress in low-carbon binders

Shi

Provis

2019

Cement and Concrete Research

490

131

View full text Add to dashboard Cite

The development of low-carbon binders has been recognized as a means of reducing the carbon footprint of the Portland cement industry, in response to growing global concerns over CO2 emissions from the construction sector. This paper reviews recent progress in the three most attractive low-carbon binders: alkali-activated, carbonate, and belite-ye'elimite-based binders. Alkali-activated binders/materials were reviewed at the past two ICCC congresses, so this paper focuses on some key developments of alkali-activated binders/materials since the last keynote paper was published in 2015. Recent progress on carbonate and belite-ye'elimite-based binders are also reviewed and discussed, as they are attracting more and more attention as essential alternative low-carbon cementitious materials. These classes of binders have a clear role to play in providing a sustainable future for global construction, as part of the available toolkit of cements.

show abstract

“…Afterwards, as shown in Fig. 14c, these five different phases can be further identified based on the literature of typical elastic modulus ranges for alkali-activated materials [23,33,98], where the typical order of elastic modulus for different phases is N-A-S-H < N-C-A-S-H < C-A-S-H < slag < fly ash. Finally, the mean values of elastic modulus and volume fraction of each phase can be characterised based on the Gaussian distribution curves (see Fig.…”

Section: Quantitative Analysismentioning

confidence: 99%

“…Moreover, the existing research on micromechanical properties of the blended AAM (i.e. AAFS) is limited to the analysis of carbonation effects on its elastic modulus [33]. Up to now, a systematic understanding of the microstructure and micromechanical properties of individual phases within AAFS and the corresponding relationship with the macro-scale mechanical properties is still lacking.…”

Section: Introductionmentioning

confidence: 99%

Multiscale micromechanical analysis of alkali-activated fly ash-slag paste

Fang

Zhang

2020

Cement and Concrete Research

147

View full text Add to dashboard Cite

Current demand for highly sustainable concrete, e.g. alkali-activated fly ash-slag (AAFS) concrete, urges understanding the links between microstructure and micromechanical properties of this binder. This paper presents a systematic investigation into the microstructure and micromechanical properties of AAFS paste from nanoscale to micro-scale. Nanoindentation was used to evaluate the micromechanical properties, while the microstructure was characterised using 29 Si nuclear magnetic resonance, Fourier transform infrared spectroscopy, backscattered electron microscopy, and mercury intrusion porosimetry. The results indicate that N-AS -H gels have a relatively low elastic modulus due to their high level of structural disorder and gel porosity, while the C-AS -H gels and N-C-AS -H gels with a low level of structural disorder and gel porosity have a relatively high elastic modulus. The elasticity of reaction products and their relative volumetric proportions mainly determine the macroscopic elasticity of AAFS paste, while the porosity and pore size distribution primarily condition its macroscopic strength.

show abstract

Effect of natural carbonation on the pore structure and elastic modulus of the alkali-activated fly ash and slag pastes

Abstract: Effect of natural carbonation on the pore structure and elastic modulus of the alkaliactivated fly ash and slag pastes Nedeljkovic, M.; Savija, B.

Cited by 84 publications

References 58 publications

Pore Structure Characterization of Sodium Hydroxide Activated Slag Using Mercury Intrusion Porosimetry, Nitrogen Adsorption, and Image Analysis

Pore Structure Characterization of Sodium Hydroxide Activated Slag Using Mercury Intrusion Porosimetry, Nitrogen Adsorption, and Image Analysis

Recent progress in low-carbon binders

Multiscale micromechanical analysis of alkali-activated fly ash-slag paste

Contact Info

Product

Resources

About