ORCID Profile
0000-0003-4371-7178
Current Organisation
University of New South Wales
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Civil Engineering | Construction Materials | Environmental Rehabilitation (excl. Bioremediation) | Building Science and Techniques | Structural Engineering
Cement and Concrete Materials | Climate Change Adaptation Measures | Urban and Industrial Air Quality | Cement Products and Concrete Materials |
Publisher: Rilem Publications SARL
Date: 29-12-2020
DOI: 10.21809/RILEMTECHLETT.2020.123
Abstract: The development of cementless concrete is attracting increasing attention in practice and research to reduce both greenhouse gas emissions and energy consumption of concrete. Alkali-activated materials (AAMs) are one of the viable alternatives to replace Portland cement due to their lower CO2 emissions. This study investigated the evolution of rheological parameters of alkali-activated fly ash/slag pastes as a function of time. Flowability and rheological measurements were carried out to determine the fluidity, plastic viscosity, and yield stress at different time intervals. The effects of the slag content, the concentration of SiO2 in the activator, and the solution/binder ratio were considered. Based on the results, the yield stress and plastic viscosity followed an increasing trend over time coinciding with a reduction in the paste fluidity. The plastic viscosity of AAM pastes was in the range of 1.3–9.5 Pa.s and 2.6–28.9 Pa.s after 5 min and 45 min of mixing, respectively. Given the same alkali activator, the higher content of slag the paste had, the higher yield stress the paste showed. In addition, this paper confirmed that the SiO2/Na2O ratio in the activator had no significant effect on yield stress, but a drastic effect of this ratio was found on the plastic viscosity of the paste.
Publisher: Wiley
Date: 06-07-2022
Abstract: The tensile creep of concrete with supplementary cementitious materials (SCMs) such as fly ash (FA) and ground granulated blast furnace slag (GGBFS) is investigated in this paper. A total of 21 series of tensile creep tests using dog‐bone specimens under uniaxial tensile loading have been carried out. The cement replacement rates considered were 30% fly ash, 40% and 60% GGBFS. The characteristic compressive strength of concrete was ranging from 25 to 100 MPa. The tests were conducted from the age of 2 days until 28 days. It is observed that the tensile creep of fly ash concretes was slightly lower than that of the reference mixtures without SCM. For GGBFS concrete, the higher the GGBFS content, the higher the tensile creep. Existing creep models, originally developed for creep in compression, could not predict the experimental tensile creep results. Thus, a new tensile creep model was proposed including creep prediction for concrete with fly ash and GGBFS. The new model was calibrated only for controlled environmental conditions (23°C and 50% RH) and has been validated by analyzing the development of concrete tensile stress in the restrained ring test.
Publisher: Elsevier BV
Date: 03-2018
Publisher: Elsevier BV
Date: 03-2020
Publisher: American Concrete Institute
Date: 07-2019
DOI: 10.14359/51716676
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D0RA08593F
Abstract: Demonstration of a solar-powered sensor array for remote carbon sequestration and enhanced oil recovery monitoring. An unattended sensor array can collect real-time gas concentrations, allow leak detection, and measure daily concentration cycles.
Publisher: Elsevier BV
Date: 10-2016
Publisher: Elsevier BV
Date: 04-2021
Publisher: Springer Science and Business Media LLC
Date: 13-01-2023
DOI: 10.1617/S11527-023-02099-8
Abstract: This study investigates the shrinkage of two sustainable aluminosilicate blends with fly ash or limestone-calcined clay (LC3). Paste and concrete were prepared using these SCMs for the highest possible replacement of binder without compromising the strength. The chemical and autogenous shrinkage were assessed for paste s les and further investigation were conducted on hydration by thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). Opting for an engineering approach, comparison among different segments of shrinkage i.e., autogenous, drying and total shrinkage of concrete having a specific compressive strength were considered. The initial investigation on paste s les highlighted the dissimilarities in shrinkage and hydration of fly ash and calcined clay. LC3 hydrated faster compared to fly ash leading to greater autogenous shrinkage. The high autogenous shrinkage in the LC3 blend was compensated by a low drying shrinkage for a specific compressive strength. Considering the replacement level of cement, shrinkage, and ecological impact, LC3 proved to be a more sustainable and eco-friendly concrete compared to fly ash.
Publisher: Elsevier BV
Date: 11-2016
Publisher: Elsevier BV
Date: 12-2021
Publisher: Elsevier BV
Date: 2015
Publisher: Rilem Publications SARL
Date: 27-12-2022
DOI: 10.21809/RILEMTECHLETT.2022.167
Abstract: The effects of chemical oxides and the surface area (SA) of slags on the initial reactivity of alkali-activated materials (AAMs) are coupled. It is well known that the reactivity of slag in AAMs is impacted by the SA, however, a quantitative measure of this effect was not provided in previous studies. For a proper understanding of the effect of slag chemistry on the reaction kinetics of AAMs, a quantitative description of the slags SA's effect is required. The reaction kinetics in the activated slags were monitored using isothermal calorimetry. The SAs of the pulverised slags were linked to the time-to-reach-the-main-peak (TTRP) of the reaction, the slope of the acceleration part of the main peak, and the total heat at one, three, and seven days. A 100% relative increase in SA caused a ~51%-75% relative decrease in TTRP. The slope of the acceleration stage also considerably increased with the SA of the slags. However, the effect of the SAs on the total heat was only distinct up to three days and then considerably reduced at seven days. The result of this study indicates that the effect of SA on the initial reactivity of AAMs cannot be simply considered using the proportional contribution. The outcome of this study can provide a promising measure to decouple the effects of SAs and the chemical compositions of slags on the reaction kinetics of AAMs by providing quantitative results for the effect SAs.
Publisher: Elsevier BV
Date: 05-2015
Publisher: American Society of Civil Engineers (ASCE)
Date: 08-2019
Publisher: Elsevier BV
Date: 2022
Publisher: American Society of Civil Engineers (ASCE)
Date: 12-2023
Publisher: Thomas Telford Ltd.
Date: 19-08-2023
Abstract: Supplementary cementitious materials (SCMs) are widely used to reduce the cement content to achieve economic and environmental objectives. As a result, understanding the shrinkage of blended cement-based concrete is essential. In total, 21 concrete mixes were produced with type general purpose cement and with cement replacements of 30% by fly ash, 40% and 60% by ground granulated blast furnace slag (GGBFS). The concrete compressive strength ranged from 25 MPa to 100 MPa. Experimental results were also compared with the predictions by models. Additional tests on pastes with the same SCM content were conducted to investigate both autogenous and chemical shrinkage in relation to their time-dependent pore structure refinement. For concretes with strength below 50 MPa, no significant difference in autogenous shrinkage could be observed between the different blends up to 28 days. However, the autogenous shrinkage of GGBFS concrete increased significantly after 28 days, being about 50% higher than all other concretes at 100 days. This late increase in autogenous shrinkage between 28 and 100 days can be attributed to pore refinement processes. No clear difference was observed for GGBFS concretes with strength greater than 50 MPa. Autogenous shrinkage of fly ash concretes was overall equivalent to that of reference concretes.
Publisher: Elsevier BV
Date: 10-2022
Publisher: Elsevier BV
Date: 07-2023
Publisher: Springer International Publishing
Date: 2021
Publisher: Elsevier BV
Date: 02-2023
Publisher: Elsevier BV
Date: 11-2019
Publisher: Wiley
Date: 26-05-2014
DOI: 10.1111/JACE.12992
Publisher: Elsevier BV
Date: 12-2023
Publisher: Wiley
Date: 09-02-2014
DOI: 10.1111/JACE.12830
Publisher: Thomas Telford Ltd.
Date: 02-2007
DOI: 10.1680/MACR.2007.59.1.53
Abstract: This paper presents experimental and analytical studies on the long-term behaviour of rectangular concrete-filled steel tubular (CFT) columns under central axial loading. Four loading cases are considered in this study: (a) a load applied simultaneously on both the inner concrete and steel tube (SCE) (b) a load applied only on the inner core concrete (CE) (c) a load applied on the steel tube and three quarters of the inner concrete (SCQ) and (d) a load applied on the steel tube and half of the inner concrete (SCH). The last two loading cases (SCQ and SCH) simulate a diaphragm installed in the steel tube. Specimens measuring 600 mm in length were tested for the first two loading cases (SCE and CE), and specimens of three different lengths, 600, 900 and 1200 mm, were tested for the last two loading cases in order to investigate the effect of the diaphragm size and the length of the specimen on the long-term behaviour of rectangular CFT columns. In addition to the experimental study, three-dimensional finite element models for each specimen were established and verified from a comparison of the test data and the analysis results. From the test and analysis results, a number of conclusions can be drawn. The magnitude of long-term deformation of a CFT column with a diaphragm that covers more than a half of the cross-sectional area of the inner concrete is identical with that of a column under a load applied simultaneously on the entire section of the steel tube and the inner concrete. The diaphragm confines the lateral deformation of the end surface of the column, and its influence range is limited only to the end part of the column, meaning it is limited only from the surface to a depth as long as the width of the CFT column. The confinement effect and stress variation along the longitudinal axis do not occur except in the influence range of the diaphragm. In the case of loading only at the inner concrete, the inner concrete is confined at the corner by the steel tube, and the slip between the inner concrete and the steel tube increases over time.
Publisher: American Society of Civil Engineers (ASCE)
Date: 08-2019
Publisher: Springer Singapore
Date: 2020
Publisher: Elsevier BV
Date: 09-2023
Publisher: Springer Science and Business Media LLC
Date: 06-2022
Publisher: American Society of Civil Engineers (ASCE)
Date: 2020
Publisher: Elsevier BV
Date: 04-2022
Publisher: Elsevier BV
Date: 2021
Publisher: ASTM International
Date: 09-07-2018
DOI: 10.1520/ACEM20180016
Publisher: Elsevier BV
Date: 11-2020
Publisher: Elsevier BV
Date: 11-2020
Publisher: Elsevier BV
Date: 03-2022
Publisher: SAGE Publications
Date: 2012
DOI: 10.3141/2290-02
Abstract: Calcium hydroxide [Ca(OH) 2 ] is one of the major constituents of hydrated portland cement paste. Its content can be used to trace the progress of cement hydration or serve as an indicator of the extent of pozzolanic reaction. The thermogravimetric analysis (TGA) method is often used to determine the Ca(OH) 2 content because it is a relatively easy and fast procedure. However, no universally accepted method exists for the preparation of TGA specimens and for the interpretation of the resulting TGA curves. This paper presents an investigation on the contents of Ca(OH) 2 in s les subjected to different preparation techniques. The results showed that a certain amount of calcium carbonate (CaCO 3 ) was produced as a result of carbonation during the s le preparation process. The degree of carbonation was dependent on the s le preparation, and carbonated Ca(OH) 2 was considered to determine the accurate total Ca(OH) 2 content. In addition, a modified interpretation of the TGA curve for Ca(OH) 2 was suggested. In this interpretation, the mass losses caused by the other hydration products, except for the Ca(OH) 2 and the carbonated Ca(OH) 2 , were considered so that the accurate content of Ca(OH) 2 could be determined. The interpretation technique was verified by comparing the results with those obtained by differential scanning calorimetry. Ultimately, the actual contents of Ca(OH) 2 in pastes undergoing different s le preparation techniques were determined by using the modified interpretation of the TGA curve for the Ca(OH) 2 . The results showed that this interpretation yielded comparable contents of Ca(OH) 2 in most of the s le preparation techniques used in this study.
Publisher: Elsevier BV
Date: 04-2023
Publisher: Elsevier BV
Date: 09-2019
Publisher: Elsevier BV
Date: 06-2023
Publisher: Elsevier BV
Date: 11-2022
Publisher: Elsevier BV
Date: 03-2016
Publisher: Elsevier BV
Date: 2016
Publisher: Elsevier BV
Date: 11-2021
Publisher: Elsevier BV
Date: 2021
Publisher: Wiley
Date: 11-10-2021
DOI: 10.1111/JACE.18150
Abstract: Geopolymers, as a potentially environmentally friendly alternative to Portland cement, are increasingly attracting attention in the construction industry. Various methods have been applied for customizing the properties of geopolymers and improving their commercial viability. One of the promising methods for refining the properties of geopolymers such as their toughness is the use of short fibers. The effectiveness of a high‐strength short fiber in the geopolymer matrix is largely dependent on the interfacial bonding between the fiber and its surrounding matrix. While the importance of this interfacial chemistry is highlighted in the literature, the characteristics of this bonding structure have not been fully understood. In this paper, we aim to investigate the bonding mechanism between the carbon fiber and metakaolin‐based geopolymer matrix. For the first time, the existence and nature of the chemical bonding at the interfacial region (interphase) between carbon fiber and geopolymer matrix has been revealed. X‐ray pair distribution function computed tomography (PDF‐CT), field emission‐scanning electron microscopy imaging, and nanoindentation techniques are employed to discern the chemo‐mechanical properties of the interphase. PDF‐CT results show the emergence of a new atom–atom correlation at the interfacial region (around 1.82 Å). This correlation is a characteristic of interfacial bonding between the fiber and its surrounding matrix, where the existence of chemical linkages (potentially V Al‐O‐C) between fibers and the matrix contributes to the adhesion between the two constituents making up the composite. Due to such chemical bonding, the nanomechanical properties of the interfacial region fall between that of the carbon fiber and geopolymer. The combination of advanced techniques is proved useful for enhancing our understanding of the interfacial chemistry between fibers and the binding matrix. This level of knowledge facilitates the engineering of composite systems through the manipulation of their nanostructure.
Publisher: Elsevier BV
Date: 04-2018
Publisher: American Society of Civil Engineers (ASCE)
Date: 12-2023
Publisher: Springer Science and Business Media LLC
Date: 29-06-2022
DOI: 10.1617/S11527-022-01989-7
Abstract: With the potential for a decline in fly ash (FA) production over time, due to the phasing down of coal fired power plants, alternative supplementary cementitious materials need to be identified. The efficiency of pulverised glass powder (PGP) was studied for its reactivity and its capacity for inhibiting alkali-silica reaction (ASR) that results from utilisation of recycled glass as a fine aggregate (sand) replacement. Characterisations of pastes containing PGP reveal that PGP may possess latent hydraulic properties, resulting in a more than 75% strength activity index, together with better strength gain than FA-blended pastes. PGP also offered increased heat of hydration compared to FA, from a combination of the dilution effect, filler effect and early-age reactions of PGP. A comparable efficiency of PGP and FA in ASR expansion mitigation was confirmed with mortar bar expansions of less than 0.10% at cement replacement levels of at least 10%. Both PGP and FA provided alkali dilution and reduced the mass transport in hydrated cement paste from the refinement of larger pores to below 60 nm. The FA mix consumed calcium hydroxide and, thus, performed marginally better than the PGP mix in mitigating ASR. This pozzolanic reactivity is not evident for PGP, whereas in the literature glass powders are often regarded as pozzolanic. Microscopic images confirm that PGP and FA significantly limit the occurrence of ASR gels without altering its composition. It was concluded that PGP is a comparable ASR inhibitor to FA, despite the underlying differences in their mechanisms. The result of this research support the utilisation of recycled glass both as an aggregate, and as an ASR-inhibiting SCM in cementitious systems.
Publisher: Elsevier BV
Date: 06-2021
Location: United States of America
Location: Korea, Republic of
Start Date: 2022
End Date: 12-2024
Amount: $220,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 10-2021
End Date: 10-2024
Amount: $230,636.00
Funder: Australian Research Council
View Funded Activity