Evaluation of cement-treated ferrochrome slag and quarry dust composites for base and sub-base layers of flexible pavement
CH Ajay, K Durga Rani
Civil Engineering Department, Andhra University, Visakhapatnam, Andhra Pradesh, India.
Ultrasonic pulse velocity;
Unconfined compressive strength
This study explores the use of ferrochrome slag as cement-bound granular layers of flexible pavement. To meet MoRTH design criteria, ferrochrome slag (FS) gradation was improved by incorporating quarry dust (Q) in proportions of 10%, 20%, 30%, 40%, and 50% (by weight). Only FS70Q30 and FS60Q40 composites have satisfied the gradation requirements of cementitious sub-base and base courses of flexible pavement. Unconfined compressive strength (UCS) and ultrasonic pulse velocity (UPV) tests were performed under OMC and MDD conditions on ferrochrome slag and quarry dust composites stabilized with cement in proportions of 2% to 10% (by weight of the aggregate mix) and curing periods of 3, 7, 14 and 28 days. FS70Q30 and FS60Q40 mixes exhibited a significant increase in strength and wave velocities with increasing cement content and curing periods. The UCS of FS60Q40 mixes was 1.03 to 1.62 times that of FS70Q30 mixes, and no significant variation in UPV was observed. An equation with a high regression factor (R-square >0.98) was formulated to correlate UCS and UPV values with cement content. Based on the developed statistical equation, the predicted minimum cement content for FS60Q40 mixes was found to be 12-16% lower than FS70Q30 mixes.
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