Table 1 Summary of different ML models used for predicting concrete strength incorporated with FS and CBA.

From: Ensemble machine learning models for predicting strength of concrete with foundry sand and coal bottom ash as fine aggregate replacements

References

Model used

Input variables

Output variables

Waste materials used

Dataset size

Key findings

Gaps identified

44

Neural network & support vector regressor

Slump, WFS%, w/c, cement, aggregate content, curing age

Compressive, split, and flexural strength

FS

137

Neural network outperformed support vector in predicting compressive, tensile, and flexural strength; curing time was identified as the most influential parameter. High R2 and low RMSE were achieved for all strength properties

Single-waste material (FS only); no ensemble learning methods used; no dual-waste interaction (e.g., FS + CBA); limited generalizability due to no external validation on a heterogeneous dataset

49

Hybrid neural network

w/c, cement, cement class, WFS%, aggregate content, curing age

Compressive strength

FS

340

Optimised neural network gave co-relation = 0.9971, lowest error range (± 1.5 MPa); w/c ratio and cement content were most influential

Only FS; no ensemble models; no feature interpretability; no dual-waste modeling; compressive strength only

45

Artificial neural network

FS/cement, w/c, fine to total aggregate ratio, coarse aggregate to cement ratio, FS/fine aggregate, curing age

Compressive, split tensile, and flexural strength

FS

397

The models accurately predicted multiple concrete properties, better than multi-layer regressor model

Only FS used; no ensemble/hybrid models; no feature importance; interpretability and external validation not discussed

50

Hybrid gradient boosting

Cement, FS%, aggregate content, w/c, curing age

Compressive strength

FS

430

The optimised technique outperformed in prediction strength

Only FS used; no dual-waste modeling; lacks interpretability (feature importance); limited benchmarking vs. ensemble models

46

Artificial neural network

Cement, aggregate content, fly ash%, CBA%, w/c

Compressive strength

CBA, fly ash

111

ANN predicted compressive strengths at multiple ages using literature

Focused only on CBA and Fly Ash; no ensemble or hybrid ML; no dual-waste approach; limited interpretability beyond input ranking

48

Hybrid support vector regressor

Cement, aggregate content, CBA%, w/c, curing age

Compressive strength

CBA

156

Hybrid model outperformed; showed sand, curing age, and cement most influential; 25–50% CBA improved compressive strength at 90 days

Only CBA considered; no dual-waste or ensemble ML; no benchmarking vs. other models; dataset size not detailed; limited external validation

47

Artificial neural network

Fly Ash, CBA, water to binder ratio, aggregate content

Compressive strength

CBA, fly ash

46

The model achieved best performance for compressive strength prediction of geopolymer concrete

No ensemble/hybrid ML; interpretability not addressed;

51

Random forest & gradient boosting

Density, w/c ratio, fly ash%, CBA%

Compressive strength

CBA, fly ash

93

compressive strength regression co-relation ≈ 0.85

Prediction less accurate; no hybrid optimization; dataset size not specified; no detailed cross-model comparison