Effect of Hybrid Steel-Basalt Fiber on Behaviors of Manufactured Sand RPC and Fiber Content Optimization Using Center Composite Design

Table 13

Model validation for both responses.

Statistical parameters	28-day compressive strength (R1)	28-day flexural strength (R2)	28-day flexural-compressive ratio (R3)
R^2	0.9872	0.9943	0.9928
Adjusted R^2	0.9780	0.9903	0.9877
Predicted R^2	0.9289	0.9836	0.9733
Adeq. precision	33.0126	46.8517	41.7526
Std. dev.	1.08	0.2713	0.1495
Mean	133.81	20.33	15.13
COV (%)	0.8066	1.33	0.9880