Application of Extreme Gradient Boosting Based on Grey Relation Analysis for Prediction of Compressive Strength of Concrete

Table 3

Mathematical forms for the construction of the reference matrix and the comparative matrix.

Compressive strength: X0 (k) = X0 (1), X0 (2), X0 (3), …, X0 (600)	Reference matrix
Cement type: X1 (k) = X1 (1), X1 (2), X1 (3), …, X1 (600)	Comparative matrix
W/B : X2 (k) = X2 (1), X2 (2), X2 (3), …, X2 (600)
Sand ratio: X3 (k) = X3 (1), X3 (2), X3 (3), …, X3 (600)
Dosage of water-reducing agent: X4 (k) = X4 (1), X4 (2), X4 (3), …, X4 (600)
Curing age: X5 (k) = X5 (1), X5 (2), X5 (3), …, X5 (600)
Slag content: X6 (k) = X6 (1), X6 (2), X6 (3), …, X6 (600)
Fly ash content: X7 (k) = X7 (1), X7 (2), X7 (3), …, X7 (600)
MK content: X8 (k) = X8 (1), X8 (2), X8 (3), …, X8 (600)
Si/Al of MK : X9 (k) = X9 (1), X9 (2), X9 (3), …, X9 (600)