## 1 Introduction
These emissions from cement production underscore the necessity of adopting innovative approaches, such as alternative materials and recycled components [12; 13; 14; 15]. Furthermore, recent research demonstrates how optimizing concrete properties and utilizing waste materials can mitigate these challenges, as evidenced in studies on autoclaved aerated concrete and ferroaluminate cement [16; 17; 18]. In many industrialized countries, the use of lightweight aggregates (LWAs) has somewhat reduced the depletion of natural resources. Additionally, the production of LWAs from industrial waste materials contributes significantly to sustainability. Using waste materials, such as expanded palletized fly Ash (FA), expanded slag gravel, and blast furnace slag, as LWAs has led to substantial savings in construction [19; 20]. Applying by-products, such as wheat straw (WS) Ash, to geo-polymer beams as an eco-friendly alternative to traditional Portland cement concrete offers advantages like rapid strength gain, excellent mechanical properties, and prevention of water contamination [21]. Numerous studies have been conducted on using AWs in concrete production. An experimental study on the performance of RC beams found that using sustainable PO fuel Ash(POFA) mortar (PM) and normal mortar as a bonding agent between the concrete substrate and glass fiber-reinforced polymer (GFRP) rods, instead of epoxy adhesive, demonstrated that POFA, an AW, could be used in construction [22]. Another study revealed that PO shells increased concrete strength, achieving compressive strengths greater than 40 MPa when used as concrete aggregates [23]. Research has shown that adding steel fibers, an AW, to CS concrete beams increased their ultimate moment capacity by 5-14% and flexural toughness by up to 45%. The span-to-deflection ratio of all fiber-reinforced CS concrete beams was reported to meet the requirements of IS 456:2000 [24] and BS 8110-97 [25; 26]. RHA, an AW, creates a calcium silicate hydrate (C-S-H) gel around cement particles in concrete, resulting in a dense matrix that accelerates early strength development with an average density of approximately 2200-2550 kg/m\({}^{3}\)[15]. This study examines the use of AWs as sustainable materials in the construction sector. The growing global population and limited natural resources make environmental sustainability imperative. Recycling AWs provides both economic and environmental benefits (Figure 1). Accordingly, this study evaluates the existing literature on the potential and challenges of using AWs as construction materials in RC structures (Table 1). In recent years, the construction industry has explored various approaches to mitigate carbon emissions, including the development of low-heat cement. Studies such as \"Hydration and Fractal Analysis on Low-heat Portland cement Pastes Using Thermodynamic-Based Methods\" highlight the energy-saving and carbon-reducing potential of this material. In addition to the utilization of agricultural wastes, these methods demonstrate the industry's efforts to align with global sustainability goals. Incorporating such complementary strategies into concrete production could further enhance the sector's environmental performance [27]. Figure 1: Broader process of sustainable utilization of agricultural waste (own research). Agro-waste recycling is a significant approach to reducing the carbon footprint of construction materials. When considered alongside other carbon-reduction strategies, such as the use of low-heat cement and geo-polymer alternatives, it becomes evident that these approaches collectively contribute to a more sustainable construction industry. This integrative perspective highlights the potential of a multi-faceted approach to achieving carbon neutrality in the sector [28]. This scoping review aims to systematically explore the applicability of AW materials as sustainable, low-carbon alternatives in RC structural systems.