A sustainable method for partially substituting fine aggregate in concrete with marble dust and rice husk ash is described. This approach focuses on the utilization of these materials to minimize environmental impact while maintaining the integrity of the concrete structure. In this study, the fine aggregate was partially substituted with marble dust and rice husk ash. Additionally, sisal fiber was incorporated as secondary reinforcement for concrete at percentages of cement by weight. Concrete has good compressive strength but is weak in tension and bending. Thus, sisal fibers were added to enhance the mechanical properties. Sisal fibers were included at 0.1% and 0.2% of cement weight for varying percentages of mineral admixture substitution. 30% of cement was replaced with mineral admixtures, with replacement levels of 0%, 10%, 15%, 20%, and 30% of marble dust and rice husk ash. The slump cone and compaction factor tests were performed on fresh concrete mixes to determine workability. Standard cubes, cylinders, and prisms were cast to evaluate the compressive, split tensile, and flexural strengths of the hardened concrete. The results show that the replacement of cement with marble dust and rice husk ash with sisal fiber as an additional reinforcing material shows considerable improvement in tensile and flexural strength. The material properties and test results are presented graphically.