Mechanistic performance evaluation of cement concrete pavements in PMGSY rural road networks of Jharkhand: distress mechanisms, NDT assessment and multi-objective design optimisation

Rural cement concrete (CC) pavements built under the Pradhan Mantri Gram Sadak Yojana (PMGSY) in Jharkhand operate under difficult conditions, including high-plasticity CI/CL subgrades, monsoon-driven thermo-hygral loading and variable manual construction quality. This study evaluates 25 rural CC pavement sections across nine districts using functional indicators (PCI and estimated IRI from MERLIN D-value), structural parameters (rebound hammer, UPV and core strength) and subgrade properties (CBR, DCP and Atterberg limits). IRIest ranged from 6.00 to 10.50 m/km, exceeding IRC: SP:16-2004 poor-condition thresholds at all sections, while PCI varied from 10.00 to 74.00. In situ compressive strength was 9.80–25.50 MPa, below the PMGSY 30 MPa requirement, and 19 sections had slab thickness below 150 mm, indicating execution deficiencies. Distress mechanisms were grouped as structural-mechanical fatigue, thermo-hygral deterioration due to infiltration and subgrade softening, and material-chemical weakening from poor compaction, laitance and carbonation. UPV and dynamic modulus correlated strongly with dry density but only moderately with strength, showing limitations of laboratory-based NDT interpretation. NSGA-II optimisation identified slab thickness, joint spacing, shoulder support and drainage as dominant performance drivers, enabling PCI ≥ 75 and IRIest ≤ 4.00 m/km through improved design and construction control for humid rural road networks.