Creep, shrinkage and permeation characteristics of geopolymer aggregate concrete: long-term performance
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(2020) 20:140
ORIGINAL ARTICLE
Creep, shrinkage and permeation characteristics of geopolymer aggregate concrete: long‑term performance Charitha Seneviratne1 · Chamila Gunasekara1 · David W. Law1 · Sujeeva Setunge1 · Dilan Robert1 Received: 19 June 2020 / Revised: 10 August 2020 / Accepted: 10 September 2020 © Wroclaw University of Science and Technology 2020
Abstract The long-term impact on creep, drying shrinkage, and permeation characteristics of an innovative concrete produced with manufactured geopolymer coarse aggregate (GPA) has been investigated and compared with quarried Basalt aggregate concrete. Microstructure and pore-structure development up to 1 year were examined through scanning electron microscopy, nanoindentation, and X-ray computed tomography. Compressive strength and elastic modulus of GPA concrete varied from 34.6 to 50.8 and 18.5 to 20.5 GPa, respectively, between 28 and 365 days. The 1-year creep strain of GPA concrete was 747 microstrain while the calculated creep coefficient was 0.97, which is significantly lower than the creep coefficient predicted by AS 3600 and CEB-FIP models. Moreover, the 365-day drying shrinkage is 570 microstrain, which is also lower than the maximum permissible limit specified by AS3600. The GPA concrete displayed high water absorption, but lower air and water permeability compared to Basalt aggregate concrete. This is attributed to a porous surface layer with large number of capillaries increasing the water absorption of GPA concrete through capillary suction. The discontinuity in the pore network coupled with a condensed interfacial transition zone formed in GPA concrete could be the reason for lower permeability. Overall, the long-term performance of the GPA demonstrates a potential as a lightweight coarse aggregate for concrete, with the added advantage of reducing the environmental impact utilizing fly ash from coal-fired power generation. Keywords Sustainability · Fly ash · Geopolymer aggregate · Creep · Shrinkage · Microstructure · Nanoindentation
1 Introduction Concrete is considered to be the most widely used material on earth. Various sources estimate the production of concrete to be in the range of 9–16 billion metric tonnes per year [1, 2] with predicted exponential growth in the next decade. Aggregate in concrete is a vital component of concrete occupying 60–80% of the volume of concrete and * Chamila Gunasekara [email protected] Charitha Seneviratne [email protected] David W. Law [email protected] Sujeeva Setunge [email protected] Dilan Robert [email protected] 1
School of Engineering, RMIT University, Melbourne, VIC 3000, Australia
providing volume stability. Concrete also has a significant carbon footprint due to its widespread application. Furthermore, the production and transportation of aggregates contribute 12.8–17.9% of the total carbon footprint of concrete [3]. Recent studies estimate the embodied carbon of crushed aggregates as 4.32 kg/CO2/ton [4]. In Australia, the carbon footprint of t
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