The building industry has slowly started to adapt to eco-friendly changes by focusing on resource management, improving the environment, and meeting the increasing expectations for ecofriendly infrastructure. The aim is to design and assess the performance of structural concrete made with fly ash lightweight aggregate. To achieve this, a mix of M35 grade concrete was designed and developed, incorporating supplementary materials such as sugarcane bagasse ash, following IS 10262:2019 standards. A lightweight aggregate sintagg was created during the sintering process of fly ash and expanded clays. This particular material was a special variety of high-strength lightweight aggregate which was useful in the making of concrete. The structural characteristics of LWAC, including its split tensile and compressive strengths, were assessed in laboratory tests. To obtain the required strength, the study also aims to ascertain the ideal percentage of lightweight aggregate (LWA) substitution with normal aggregate. Additionally, the study assessed the environmental impacts of using LWA, and microstructural analysis was performed to examine its behavior under various temperatures ranging from 100 ℃ to 300 ℃. This research investigated the advantages of LWA in relation to dead load reduction and enhanced sustainability. The findings of this paper indicated that LWAC could play a key role in promoting sustainable construction.