Shrinkage Performance of Fly Ash Alkali-activated Cement Based Binder Mortars

Kheradmand, Mohammad; Abdollahnejad, Zahra; Pacheco-Torgal, F.

doi:10.1007/s12205-017-1714-3

Cited by 25 publications

(9 citation statements)

References 28 publications

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“…Among the measures to improve the volume stability of cementitious materials, adding a shrinkage compensation component is a common method. The components of compensating shrinkage can be divided into three categories: Calcium oxide, calcium sulphoaluminate and MgO [25]. Calcium oxide and calcium sulphoaluminate react violently and are not easily controlled in a high alkali environment, thus they cannot achieve a good compensating shrinkage effect in geopolymer [26,27,28,29].…”

Section: Introductionmentioning

confidence: 99%

Effects of Reactive MgO on the Reaction Process of Geopolymer

Zhang

Wang

et al. 2019

Materials

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In order to compensate for the shrinkage of geopolymer pastes uniformly, reactive MgO powders are evenly dispersed in the geopolymer. The deformation performance, mechanical properties, microstructure and components of geopolymer pastes with reactive MgO are characterized. The effects of the content and the activity of MgO are discussed. The results indicate that the chemical shrinkage, autogenous shrinkage and drying shrinkage decrease with the addition of reactive MgO. MgO reacted with water, and fine Mg(OH)2 crystals forms as a geopolymer paste. Mg(OH)2 produces uniform expansion, which refines the pore size of pastes and the compressive strength increases. The shrinkage of the geopolymer pastes is thus effectively compensated.

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Section: Introductionmentioning

confidence: 99%

Effects of Reactive MgO on the Reaction Process of Geopolymer

Zhang

Wang

et al. 2019

Materials

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“…In order to minimize the problems, different methods have been proposed. The methods include using thermal curing, different additives, and fibers [24][25][26][27][28][29][30][31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Effects of Activator Properties and Curing Conditions on Alkali-Activation of Low-Alumina Mine Tailings

Falah

Obenaus-Emler

Kinnunen

et al. 2019

Waste Biomass Valor

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The mining industry generates a notable amount of mine tailings (MTs). Disposal of MTs creates environmental impacts such as air pollution and the release of heavy metals into surface and underground water. The European Union (EU)-funded project "Integrated mineral technologies for more sustainable raw material supply" (ITERAMS) includes an effort to produce eco-friendly backfill materials to enhance operation and mine safety and covers for surface deposits of tailings based on geopolymerization technology. This paper investigates the effects of activator concentration, curing temperature and time on alkali-activated materials based on low-alumina MTs from the Cu/Ni mine in Northern Finland. Alkaline activators containing sodium silicate solution (Na 2 SiO 3) at different concentrations were used and two different curing temperatures, 40 °C and 60 °C, for periods of 7, 14, and 28 days were considered. Scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS) and X-ray diffraction (XRD) were performed to investigate the structure, morphology and phase compositions of the alkali-activated products. The effect of curing temperature and alkaline solutions on mechanical strength and water absorption were investigated. The results indicate that the alkalinity and curing temperature affect the mechanical and microstructural properties of the compositions of alkali-activated MTs. The 30 wt% Na 2 SiO 3 addition enables the alkali activated MT to improve the compressive strength with a highest value of 6.44 and 15.70 MPa after 28 days of curing at 40 °C and 60 °C, respectively. The results of this study deliver useful information for recycling and utilization of MTs as sustainable material through the alkali activation.

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“…However, it may cause slight surface tension cracking of the concrete, which would allow water ingress. The conservation protocol suggested includes regular inspection of the concrete, described by the University of Sydney research into automated systems, in collaboration with the use of Engineered Cementitious Composites, using the composites ductility to seal surface abrasions, protect against corrosion of embedded steel and provide a strain hardening effect on the existing concrete [19][20][21].…”

Section: Discussion Of Creep and Shrinkage Analysismentioning

confidence: 99%

Numerical Analysis of the Creep and Shrinkage Experienced in the Sydney Opera House and the Rise of Digital Twin as Future Monitoring Technology

Tahmasebinia

Fogerty

et al. 2019

Buildings

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This paper presents a preliminary finite element model in Strand7 software to analyse creep and shrinkage effects on the prestressed concrete ribs of the Sydney Opera House as remarkable heritage. A linear static analysis was performed to investigate the instantaneous impacts of dead and wind loads on the complex concrete structure which was completed in 1973. A quasistatic analysis was performed to predict the effects of creep and shrinkage due to dead load on the structure in 2050 to discern its longevity. In 2050, the Sydney Opera House is expected to experience 0.090% element strain due to creep and shrinkage and therefore suffer prestress losses of 32.59 kN per strand. However, given that the current time after prestress loading is approximately 50 years, the majority of creep and shrinkage effects have already taken place with 0.088% strain and 32.12 kN of prestress losses. The analysis concludes that very minor structural impacts are expected over the next 30 years due to creep and shrinkage, suggesting a change in conservation focus from large structural concerns to inspection and maintenance of minor issues of surface cracking and water ingress. The analysis is the first step in the application of more complex finite element modelling of the structure with the integration of complex building information models. The main motivation to undertake the current numerical simulation is to determine a cost-effective solution when it comes to the long-term time-dependent analysis. The paper also will suggest future directions for monitoring unique historical buildings, including ‘digital twin’.

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Shrinkage Performance of Fly Ash Alkali-activated Cement Based Binder Mortars

Cited by 25 publications

References 28 publications

Effects of Reactive MgO on the Reaction Process of Geopolymer

Effects of Reactive MgO on the Reaction Process of Geopolymer

Effects of Activator Properties and Curing Conditions on Alkali-Activation of Low-Alumina Mine Tailings

Numerical Analysis of the Creep and Shrinkage Experienced in the Sydney Opera House and the Rise of Digital Twin as Future Monitoring Technology

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