PSI - Issue 70

K. Navin Balaji et al. / Procedia Structural Integrity 70 (2025) 295–302

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1. Introduction Concrete stands as the leading construction material worldwide because it offers versatility and durability combined with extensive availability. The requirement for external vibration for conventional concrete results in deteriorated surface finish as well as honeycombing and insufficient concrete consolidation within dense reinforcement areas. In the late 1980s Japan became the birthplace of SCC as described by Okamura and Ouchi (2003). Under its weight alone SCC functions as a flowable non-segregating concrete material that successfully fills and compacts complex formwork without external vibration thereby boosting productivity and durability (Ashish & Verma, 2019; Murthy 2012; Dahal et al.,2020). To achieve the flowability and stability of SCC as well as reach its design requirements operators need to apply increased amounts of powder content together with optimized usage of chemical admixtures. The addition of RHA and LSP in concrete allows better rheological control and decreases cement needs alongside environmental benefits. The high reactivity of RHA as a pozzolan which contains abundant amorphous silica leads to increased compressive strength and lower porosity when used as a cement partial substitution (Ganesan et al.,2008; Tran et al.,2024; Habeeb et al.,2010). LSP enhances the particle packing of SCC mixes along with reduced bleeding and improved viscosity and stability because it remains inert while being finely divided (Bonavetti et al.,2003). Similarly, LSP acts as a micro filler, refining the pore structure and enhancing the packing density of the matrix, which contributes to the overall performance of SCC (Sobuz et al.,2022). The use of CSA alongside other lightweight aggregates gives builders two sustainability benefits through lightweight concrete construction. Researchers have discovered that CSA demonstrates suitable properties to substitute regular coarse aggregates in low to medium strength concrete solutions (Gunasekaran et al.,2011; Olanipekun et al.,2006). Using CSA in SCC helps reduce concrete density which results in valuable applications for precast construction and seismic frameworks and buildings that need decreased dead loads. Alengaram et al. (2012) proved that CSA reduces the weight of concrete compared to traditional aggregate concrete. According to Ahmed et al. (2014) coconut shell creates benefits for economy and sustainability while causing deterioration of concrete strength and durability. The tensile strength showed decreases in both strength criteria with larger CSA replacements and increased particle sizes according to Taha et al. (2017) According to Adewuyi et al. (2018) higher proportions of CSA resulted in compressive strength deterioration but tensile strength retained its initial values. Madurwar et al. (2013) confirmed that adding CSA together with plastic waste materials resulted in lower compressive strength values but other mechanical properties remained unaltered. The study by Abdullahi et al. (2019) showed how CSA decreased weight while consuming waste yet it produced materials that were both porous and weak. The study by Akinyemi et al. (2020) revealed strength reductions which increased proportionally with CSA concentration so they suggested adding admixtures or fibres as an improvement method. Islam et al. (2016) proposed the application of CSA at maximum level reached at 50% because of sufficient strength maintenance. Jayasree et al. (2019) showed decreasing strength levels as the content of CSA increased although workability performance remained unaffected. 1.1 Research Significance The construction industry encounters increasing difficulties because of sustainability requirements and resource exhaustion and environmental protection needs. The research supports sustainable development by adding of admixtures and alternative aggregates in SCC. The research investigates the potential of using RHA and LSP as cement replacements and CSA as NCA replacements to decrease conventional material usage. The utilization of agricultural and industrial waste through this method helps reduce cement production carbon emissions while promoting sustainable waste management. The research outcomes show how to make sustainable SCC while maintaining performance standards which supports environmentally friendly construction methods and waste reduction.