Optimization of Arabian-Shield-Based Natural Pozzolan and Silica Fume for High-Performance Concrete Using Statistical Design of Experiments

Table 5

Paired t- and two-sample tests for the predicted and observed results.

Regression method	Variable	Eq.		Result	Mean (MPa)	Std. Dev. (MPa)	95% confidence interval of difference		-value
							Lower	Upper	Mean	Std. Dev.
SLF	Compressive strength	1a	0.25	Observed	91.71	5.25	−2.08	2.08	1.000	0.238
				Predicted	91.71	4.11
		1b	0.40	Observed	64.03	8.39	−2.70	2.70	1.000	0.334
				Predicted	64.03	7.23
	Permeability	2a	0.25	Observed	886.75	1148.50	−78.54	71.70	0.917	0.490
				Predicted	890.38	1139.10
		2b	0.40	Observed	2287.6	2669.2	−126.82	−126.82	−126.82	0.496
				Predicted	2287.6	2667.7
RSD	Compressive strength	3a	0.25	Observed	91.71	5.25	−2.54	2.87	0.895	0.027
				Predicted	91.54	2.55
		3b	0.40	Observed	64.03	8.39	−2.81	3.14	0.905	0.287
				Predicted	63.86	6.90
	Permeability	4a	0.25	Observed	886.75	1148.5	−230.90	82.90	0.322	0.546
				Predicted	960.75	1193.0
		4b	0.40	Observed	2287.6	2669.2	−230.28	224.87	0.980	0.453
				Predicted	2290.3	2576.7