Prediction of Compressive Strength of Concrete Using the Spearman and PCA-Based BP Neural Network

Table 3

Analysis of correlation between factors of 9 inputs.

Factors	Cement (kg)	Crushed stone 1 (kg)	Crushed stone 2 (kg)	Crushed stone 3 (kg)	Sand (kg)	Fly ash (kg)	Cementitious material (kg)	Four aggregates (kg)	Water-cement ratio
Cement (kg)	1.00	-0.86	-0.81	-0.90	-0.78	0.90	0.68	-0.86	-0.40
Crushed stone 1 (kg)	-0.86	1.00	0.93	0.97	0.85	-0.77	-0.60	0.96	0.10
Crushed stone 2 (kg)	-0.81	0.93	1.00	0.95	0.82	-0.72	-0.58	0.95	0.07
Crushed stone 3 (kg)	-0.90	0.97	0.95	1.00	0.88	-0.81	-0.65	0.97	0.22
Sand (kg)	-0.78	0.85	0.82	0.88	1.0z0	-0.76	-0.59	0.95	0.15
Fly ash (kg)	0.90	-0.77	-0.72	-0.81	-0.76	1.00	0.67	-0.79	-0.35
Cementitious material (kg)	0.68	-0.60	-0.58	-0.65	-0.59	0.67	1.00	-0.63	-0.51
Four aggregates (kg)	-0.86	0.96	0.95	0.97	0.95	-0.79	-0.63	1.00	0.13
Water-cement ratio	-0.40	0.10	0.07	0.22	0.15	-0.35	-0.51	0.13	1.00