63814 2025 eng lecture 0 -- -- -- The construction sector accounts for 40% of global carbon emissions, and its impact is set to rise as growing populations drive increased construction activity, particularly in the Global South. In Africa, where cement is expensive and urban growth is rapid, innovative, locally tailored solutions are urgently needed. To address this environmental challenge, a common approach is to use limestone-calcined clay cement (LC3), which allows for approximately 50% clinker reduction with equivalent performance to OPC. However, LC3 often presents challenges in terms of fresh concrete properties due to its influence on rheological properties. This paper proposes the use of gum Arabic (GA), a polysaccharide biomass abundant in Africa, as a rheology modifying admixture. These local admixtures would provide access to chemical admixtures for a wider range of concrete users, including the informal sector, and create local value chains while minimising dependence on global supply streams. Rheometer, 1H nuclear magnetic resonance (1H NMR) and heat flow calorimetry (HFC) techniques were used to understand the influence of GA on both OPC and LC3 systems by monitoring their early hydration. Rheological results reveal that GA affects the fresh paste rheology of OPC and LC3 systems differently, requiring different dosages to achieve optimal performance. Heat flow and NMR analyses further confirm that GA retards the hydration reactions in both systems. Sustainable Construction in Africa 2025 Nairobi, Kenya 20.05.2025 0 publish 22.05.2025 false true Renata Lorenzoni eng uncontrolled Polysaccharide-based admixture eng uncontrolled Early hydration eng uncontrolled LC3 eng uncontrolled OPC Ingenieurbau 7 Bauwerkssicherheit 7.4 Baustofftechnologie 8 Zerstörungsfreie Prüfung Infrastruktur Datei im Netzwerk der BAM verfügbar ("Closed Access") Präsentation 8.0 Abteilungsleitung und andere Green Intelligent Building