This study aims at evaluating synergistic influences of limestone powder (LP) and unground rice husk ash (URHA) utilizations on comprehensive performances of a slag-cement self-compacting concrete (SCC). In addition, the improved strength efficiency of the binders in concretes due to the additives of LP and/or URHA was also explored. Experimental results illustrated that sole addition of LP partially replacing slag in range of 10–30 mass% remarkably increased 28-day compressive strength of the modified SCC at 17.7% in average as compared with the reference SCC. In addition, the modified SCC with LP in range of 10 to 50 mass% had water absorption reduced at 21.2% in average, 28-day drying shrinkage reduced at 15.7% in average, UPV increased at 29.4%, and total Coulomb passed reduced at 11.6%, which implied the better quality concrete than the reference SCC. By using LP to replace slag at 30 mass% for achieving the best 28-day compressive strength of 61.2 MPa, adding URHA as partial replacement for fine aggregate at the values of 10 vol% and 30 vol% led to the modified SCCs with further improvement on resistance to chloride penetration up to 15.47% reduction on total Coulomb passed as compared with the reference SCC and the best early compressive strengths of 17.5, 37.7, and 53.0 MPa at 1, 3, and 7 days, respectively.