Journal: Cement and Concrete Research

Abbreviation

Cement Concrete Res

Publisher

Elsevier

Journal Volumes

ISSN

0008-8846
1873-3948

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Publications1 - 10 of 180
  • A reactive-transport framework to model carbonation performance of a hardened cement: the case of alkali-sulfate slag cement pastes
    Item type: Journal Article
    Yue, Zengliang; Dhandapani, Yuvaraj; Provis, John L.; et al. (2025)
    Cement and Concrete Research
    This study introduces a novel reactive transport framework tailored for hardened cementitious materials, applied to a clinker-free sodium sulfate-activated slag cement as a case study. The modelling tool enables the prediction of CO₂-induced alterations in the phase assemblage, transport properties (e.g. diffusivity, permeability, saturation, liquid volume fraction, and capillary pressure) in cementitious materials, pore solution pH, the composition of aluminium-substituted calcium silicate hydrate gel (C-A-S-H), and CO₂ sequestration profiles as a function of cover depth. The framework was applied to simulate one year of accelerated carbonation (1 % CO₂ v/v) and ten years of natural carbonation (0.04 % CO₂ v/v) under controlled temperature and humidity conditions, showing excellent alignment with experimental data. This framework represents a significant step forward in the state-of-the-art for predicting carbonation performance of cementitious materials, enabling calculation and estimation of CO₂ uptake capacity of cement systems, including those containing supplementary cementitious materials (SCMs) or based on alkali-activated binders.
  • 3D crystalline phase and pore structure evolution upon CO₂ exposure in sodium sulfate-activated cement pastes
    Item type: Journal Article
    Yue, Zengliang; Su, Zixian; Paul, Partha P.; et al. (2025)
    Cement and Concrete Research
    The effects of CO₂ exposure on sodium sulfate-activated blast furnace slag cement paste have been characterised by X-ray (attenuation) computed tomography revealing changes in micron-scale pore structure, and X-ray diffraction computed tomography (XRD-CT) elucidating changes in the spatial distribution of crystalline and semi-crystalline phases. Accelerated carbonation reduced ettringite volumes and induced formation of hydrotalcite, demonstrating the critical role of Mg-Al-SO₄-layered double hydroxide phases in the CO₂ uptake of these cements. These changes yield a refinement of small pores and increase the overall porosity, reaching values comparable to those of blended Portland cements. Formation factor values were determined considering the pore solution electrical resistivity, calculated from thermodynamic modelling, and the porosity. A correlation between simulated tortuosity and porosity is proposed to estimate the diffusion tortuosity and formation factor of sodium sulfate-activated slag pastes. This approach represents a significant step forward for assessing carbonation resistance and CO₂ uptake capacity of cementitious pastes.
  • Plastic shrinkage of mortars cured with a paraffin-based compound – Bimodal neutron/X-ray tomography study
    Item type: Journal Article
    Wyrzykowski, Mateusz; Ghourchian, Sadegh; Münch, Beat; et al. (2021)
    Cement and Concrete Research
    Early-age drying (immediately after casting) of mortars and the corresponding plastic shrinkage were studied using bimodal neutron/X-ray computed tomography. This novel, correlative 3D imaging mode enabled studying simultaneously and without any source of spurious perturbation the water migration and loss processes together with the corresponding deformations due to plastic shrinkage. Bimodal imaging opens up new possibilities for studying dynamic processes of coupled water transport and deformations in porous solids. The measurements were carried out on model systems (cylindrical mortar specimens with height of 19 mm). The study focused on the effect of a paraffin-based curing compound. Our results confirm that when the curing compound was applied directly onto the drying surface in a sufficient amount, both the evaporation rate and the rate of vertical displacement (settlement) were substantially reduced. The results shed a new light on the mechanisms of plastic shrinkage and the action of curing compounds.
  • Chloride-induced corrosion of steel rebars in simulated pore solutions of alkali-activated concretes
    Item type: Journal Article
    Mundra, Shishir; Criado, Maria; Bernal, Susan A.; et al. (2017)
    Cement and Concrete Research
    The passivation and chloride-induced depassivation of steel rebars immersed in varying alkaline environments (0.80 M, 1.12 M and 1.36 M NaOH solutions), simulating the pore solutions of low-Ca alkali-activated concretes, were investigated using a range of electrochemical techniques. The passive film on the steel rebars was complex in chemical makeup, composed of Fe–hydroxides, oxy-hydroxides and oxides. An increased degree of passivation of the rebars was observed when exposed to solutions with higher hydroxide concentrations. The critical chloride level ([Cl−]/[OH−] ratio) required to induce depassivation of steel was strongly dependent on the alkalinity of the pore solution, and was found to be 0.90, 1.70 and 2.40 for 0.80 M, 1.12 M and 1.36 M NaOH solutions, respectively. These values all correspond to a constant value of [Cl−]/[OH−]3 = 1.25, which is a novel relationship to predict the onset of pitting, interlinking chloride concentration and the solubility of the passive film.
  • Influence of fly ash on the hydration of calcium sulfoaluminate cement
    Item type: Journal Article
    Martin, Lukas H.J.; Winnefeld, Frank; Tschopp, Elsa; et al. (2017)
    Cement and Concrete Research
  • Do superplasticizers work the way we think? New insights from their effect on the percolation threshold of limestone pastes
    Item type: Journal Article
    Sha, Shengnan; Mantellato, Sara; Weckwerth, Stefanie Anne; et al. (2023)
    Cement and Concrete Research
    Superplasticizers are polymeric dispersants that play a major role in concrete technology. Despite their ubiquity and much research on their working mechanisms, many questions remain about the effects of their molecular structures on their working mechanism, in particular their ability to lower the yield stress of particulate suspensions. It is generally recognized that superplasticizers decrease attractive interparticle forces, thereby reducing or eliminating yield stress. It is also often assumed that changes in yield stress should be proportional to changes in interparticle forces. This paper takes a fresh look at this question, revisiting Yodel (YD) and modified shifting factor (MSF) models that not only incorporate interparticle forces, but also percolation thresholds. This leads us to conclude that a major impact of superplasticizers is to modify the percolation threshold in direct relation to their adsorption.
  • Surface properties of clinker phases and clay minerals characterized by inverse gas chromatography (IGC) and their link to reactivity
    Item type: Journal Article
    Zunino, Franco; Palacios, Marta; Bowen, Paul; et al. (2024)
    Cement and Concrete Research
    This paper presents a preliminary study of the characterization of the surface energy properties of clinker phases (C3S and C3A), kaolin and metakaolin by Inverse Gas Chromatography (IGC). For this, a reliable measurement methodology was developed. By looking at changes in the whole series of results (dispersive surface energy, specific polar interaction parameter, acid and base constants, morphology index, nanoroughness and adsorption energy distribution function), it is possible to discern changes between the same powders with different surface treatments. A promising correlation between surface properties and the reactivity of studied materials have been found. However, based on the IGC characterization, the increased reactivity of metakaolin compared to the raw kaolinite seems to be strongly linked to the change in local order rather than significant changes in the surface energetics, although a change in the acid/base nature of the surface has been observed.
  • Application of neutron imaging to investigate fundamental aspects of durability of cement-based materials: A review
    Item type: Review Article
    Zhang, Peng; Wittmann, Folker H.; Lura, Pietro; et al. (2018)
    Cement and Concrete Research
  • Alkali silica reaction in concrete - Revealing the expansion mechanism by surface force measurements
    Item type: Journal Article
    Leemann, Andreas; Góra, Michał; Lothenbach, Barbara; et al. (2024)
    Cement and Concrete Research
    Alkali-silica reaction (ASR) is a major cause for concrete deterioration worldwide. However, the mechanism leading to cracking has not been identified yet. In this study, the extended Surface Force Apparatus (eSFA) has been used to determine the surface forces of alkali-silica solutions between two atomically smooth mica surfaces. The setup imitates the situation present in reactive concrete aggregates with negatively charged silicate surfaces and negatively charged polynuclear silica in solution. The distance of strong electrostatic repulsion increases with increasing concentration of dissolved silica, leading to the buildup of pressure up to 6 MPa. When the precipitation of ASR products in confined conditions is triggered by the addition of CaCl₂ to the alkali-silica solution, the resulting solidification pressure forces the mica platelets apart and reaches 6–13 MPa. The eSFA experiments shows that solidification pressure is the mechanism leading to aggregate cracking and expansion of ASR-affected concrete.
  • 4D quantification of C-(A)-S-H and Mg-Al LDH phase alterations and microstructural evolution during accelerated carbonation of alkali-activated slag pastes
    Item type: Journal Article
    Su, Zixian; Yue, Zengliang; Marsh, Alastair T.M.; et al. (2025)
    Cement and Concrete Research
    In situ synchrotron X-ray diffraction computed tomography (XRD-CT) and micro-tomography (μCT) are used to determine the effects of accelerated carbonation on sodium silicate- and carbonate-activated slag cement pastes, focusing on changes in crystalline and semi-crystalline phases, and pore structures. Accelerated carbonation leads to decalcification of the interlayer of aluminium-substituted calcium silicate hydrate (C-(A)-S-H), resulting in reduced interlayer distance, volume shrinkage, and increased porosity with larger pore volumes. The hydrotalcite-like Mg-Al LDH phase acts as a CO₂ sink, mitigating the increased concentration of CO₃²⁻ in pore solution via interlayer anion exchange of OH⁻ for CO₃²⁻, playing a more significant role in sodium silicate slag cement paste. Additionally, sodium silicate-activated slag cement is found to have a finer, more tortuous pore distribution and higher carbonation resistance than sodium carbonate-activated slag cement, as evidenced by a smaller degree of carbonation-induced C-(A)-S-H shrinkage, and a smaller increase in porosity volume during carbonation.
Publications1 - 10 of 180