<![CDATA[The utilization of local aggregates is pivotal for promoting sustainable and cost-effective construction, yet their mechanical viability requires rigorous assessment. This study aims to evaluate the mechanical characteristics and flexural strength of concrete beams formulated with aggregates from Bundubela, East Sumba, to determine their suitability under Indonesian National Standards (SNI). The research employed a laboratory-based experimental method following SNI procedures. Two concrete mixtures were tested: a standard mix designed for a compressive strength (fc') of 21.7 MPa and a second mix enhanced with additives, targeting an fc' of 45 MPa. Results indicated that both mixtures failed to achieve their designed strengths. The standard mix only reached an average compressive strength of 18.15 MPa, while the additive-enhanced mix achieved 28.79 MPa. Furthermore, in flexural strength tests on concrete beams, both configurations exhibited excessive deflection, surpassing the maximum limits allowed by SNI. The beam without additives deflected 4.635 mm under a 1500 Kg maximum load, and the additive-enhanced beam deflected 6.145 mm under a 2100 Kg maximum load. These findings conclude that despite enhancement with additives, the Bundubela aggregate is unsuitable for structural concrete applications that must comply with current SNI requirements. This highlights a critical challenge in reconciling the use of local materials with stringent national construction codes, pointing to the need for material modification or specific-standard development]]>
