Infrastructure Engineering - Research Publications
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ItemStrength Development and Thermogravimetric Investigation of High-Volume Fly Ash Binders(MDPI, 2019-10)To address sustainability issues by facilitating the use of high-volume fly ash (HVFA) concrete in industry, this paper investigates the early age hydration properties of HVFA binders in concrete and the correlation between hydration properties and compressive strengths of the cement pastes. A new method of calculating the chemically bound water of HVFA binders was used and validated. Fly ash (FA) types used in this study were sourced from Indonesia and Australia for comparison. The water to binder (w/b) ratio was 0.4 and FA replacement levels were 40%, 50% and 60% by weight. Isothermal calorimetry tests were conducted to study the heat of hydration which was further converted to the adiabatic temperature rise. Thermo-gravimetric analysis (TGA) was employed to explore the chemically bound water (WB) of the binders. The results showed that Australian FA pastes had higher heat of hydration, adiabatic temperature rise, WB and compressive strength compared to Indonesian FA pastes. The new method of calculating chemically bound water can be successfully applied to HVFA binders. Linear correlation could be found between the WB and compressive strength.
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ItemHydration and Strength Evolution of Ternary-Blend High-Volume Fly Ash Concretes(American Concrete Institute, 2019-09-01)The increase of carbon emissions due to the annual growth of portland cement (PC) production has promoted research into the development of sustainable green concrete using a range of readily available industrial waste materials. The present study is focused on developing two high-volume fly ash (HVFA) concretes with cement replacement levels of 65% (HVFA-65) and 80% (HVFA-80). The required lime for both HVFA concrete mixtures was initially determined and the optimized mixture designs identified, based on the 28-day compressive strength, by varying the low-calcium Class F fly ash-hydrated lime composition. The optimized concrete mixtures achieved a compressive strength of 53 and 40 MPa (7.69 and 5.80 ksi) for HVFA-65 and HVFA-80 concretes, respectively. The early-stage strength development is dependent on the matrix produced in the specific HVFA concrete, which is itself dependent on the number of unreacted fly ash spheres. The increase of fly ash and hydrated lime dosage in HVFA concrete increases the rate of hydration of the C3A and C4AF phases, but decreases the hydration of the C3S phase, which resulted in lower early-age strength development than occurs in PC concrete. It was noted that the initial setting time of HVFA concretes increase with an increase of fly ash content. However, addition of hydrated lime accelerates the hydration and decreases the final setting time for HVFA concretes.
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ItemTransforming Municipal Solid Waste into Construction Materials(MDPI AG, 2019-05-09)Rapid urbanisation and the associated infrastructure development are creating a deficit of conventional construction materials and straining the natural resources. On the other hand, municipal solid waste (MSW) disposal poses a serious environmental problem. Landfilling of MSW is both costly and polluting. Incineration of MSW to generate energy is a commonly adopted approach. However, there are concerns associated with micro pollutants emitted from the combustion process. The carbon footprint of the process and the environmental cost–benefit balancing are disputable. There is clearly a need to adopt cost-effective alternatives to treat MSW. This paper proposes the potential application of “treated” MSW as an ingredient for construction materials. The treatment process involves placing MSW in an autoclave at 150 °C with 5 bars (0.5 MPa), followed by the separation of metals, plastics and glass for recycling purposes. The end-product, which is a semi-organic mixture (referred to as ‘biomass’), is passed through a vortex-oscillation system, which makes it more uniform as a material. Compressive testing of Portland cement-based pastes containing 10% and 15% biomass shows consistency in the results, demonstrating the potential use of biomass in construction materials.
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ItemMaintenance of building structural systems(Nethwin Printers, 2016)The aim of this paper is to review the current literature on maintenance of building structural systems. It emphasises the importance of maintenance as an item for consideration from the beginning of the conceptual design stage. Building sustainability concept is generally understood to have better energy efficiency focus and maintenance of structural components ensures they serve their designed service life and beyond. The conventional design approach considers structural maintenance during the “product use” phase. This paper argues that if the accessibility of the building and maintenance (inspection, repair and retrofitting) are considered from the early conceptual design stage, it would save resources and maintenance cost. Case studies of buildings subject to earthquake loading and corrosion and their maintenance are presented.