PSI - Issue 70

Abhijeet Singh et al. / Procedia Structural Integrity 70 (2025) 611–618

617

Compressive strength (N/mm 2 ) 28 Days Residual Plot

-0.04 -0.02 0 0.02 0.04

Residuals

29 30 31 32 33 34 35 36 37

Compressive strength (N/mm 2 ) 28 Days

Fig. 8. Residual Plot of Compressive Strength at 28 days

28 Days Split tensile Strength (N/mm 2 ) Residual Plot

-0.04 -0.02 0 0.02 0.04

Residuals

2.9

3

3.1

3.2

3.3

3.4

3.5 3.6

28 Days Split tensile Strength (N/mm 2 )

Fig. 9. Residual Plot of Split Tensile Strength at 28 days

4. Conclusion and Recommendations Marble dust addition to concrete mixes affects their workability and mechanical attributes to a considerable extent. The workability decreases as marble dust levels rise since the standard mix without marble dust reaches 90 mm slump while the mix containing 20% marble dust shows only 65 mm slump. The stiffening characteristic of marble dust leads to reduced mix workability because it requires less water to reach its final state. The evaluation of workability represents a crucial element before using marble dust for rigid pavement applications because both handling and surface finishing depend on it. The optimum slump value from the performed experiments is observed in concrete mix containing 16% marble dust, meeting the requirements established by IRC:15-2017 and IRC:58-2015 for rigid pavements. The addition of marble dust enhances mechanical strength performance until the optimal level is achieved. The compressive strength testing revealed that mixes containing 16% marble dust reached their maximum value as 36.15 MPa at 28 days, starting from 20.80 MPa for the reference mix at 7 days. Split tensile strength reaches its maximum value of 3.52 MPa for the mixture containing 16% marble dust. This improvement in compressive strength is mainly attributed to the fine particle size of marble dust, which helps fill micro-pores in the concrete matrix, thereby reducing porosity and enhancing compactness. The enhancement in split tensile strength is due to the formation of dense concrete matrix with marble dust, which improves the internal cohesion and crack resistance of the concrete. However, the compressive and tensile strength values decrease slightly when 20% marble dust exceeds the optimal level, since this threshold leads to a reversal of