Browsing by Author "Yogarajah, E"

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item: Conference-Abstract
Enhancing concrete sustainability through carbonated recycled cement powder: a review
(Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024) Mylvaganam, N; Yogarajah, E; Iresha, H; Elakneswaran, Y; Dassanayake, A; Jayawardena, C
Concrete is a vital construction material, but the rapid urbanization has led to a significant accumulation of demolished concrete, especially in developing countries. Despite efforts, only a small fraction of this concrete is recycled, leading to environmental challenges. However, countries like Japan have successfully recycled a large portion of their demolished concrete, primarily for use in road subbase and as Recycled concrete aggregate (RCA) which is typically yields lower quality compared to natural aggregate (NA). Additionally, during RCA production, a significant amount of cement powder is generated, which has the potential to be used as a supplementary cementitious material (SCM). Recent research has explored various valorisation methods for recycled cement powder (RCP), with carbonation emerging as the most sustainable option. Carbonated RCP not only stores CO2 but also improves concrete properties such as compressive strength and durability. Considering the environmental impact of traditional cement manufacturing, the utilization of SCMs, such as carbonated recycled cement powder (cRCP), has emerged as a promising strategy. This approach promotes sustainable recycling practices and contributes to ecological conservation efforts, aligning with the circular economy philosophy. This review highlights recent findings on the accelerated carbonation treatment of RCP, exploring its benefits and applications as a sustainable building material
item: Conference Full-text
Impact of Ca/(Si+Al) ratio of calcium aluminosilicate hydrate (C-A-S-H) gel on chloride adsorption for evaluating durability of reinforced concrete
Kobayashi, H; Yogarajah, E; Nawa, T; ; Abeysinghe, AMKB; Dassanayake, ABN; Elakneswaran, Y
Cement-based materials have been using in various application of reinforced concrete structural components as well as in nuclear waste repositories. The ingress of detrimental ions and consequent chemical reactions pose severe threat to the durability of cementitious materials. The chloride-induced corrosion in concrete structures is one of serious durability problems. In the penetration of chloride into concrete, it is necessary to consider both binding and diffusion of chloride. The adsorption of chloride on the surface calcium silicate hydrate (C-S-H) gel, main hydration product of cement, controls the binding of chloride in cement-based materials. It has been reported that a partial substitution of Portland cement by ground granulated blast furnace slag(GGBFS) increase the chloride adsorption and form C-A-S-H gel. The physicochemical and surface electrical properties of C-A-S-H gel are significantly different from the properties of C-S-H gel. Therefore, in this study, chloride adsorption behavior on C-A-S-H gel is analyzed by experimental techniques. The C-A-S-H gel with different Ca/ (Si+Al) ratios was synthesized and their structure and active surface site were analyzed by 29Si MAS-NMR and 27Al MAS-NMR. And zeta potential of C-A-S-H gel in various suspensions were measured and the chloride adsorption experiment was conducted on C-A-S-H gel.