Multi-scale petrographic and geotechnical characterization of Kuldana formation limestone and implications for asphalt concrete stiffness and fatigue design.

Authors

Hassan Ayaz, Jiancong Xu, Muhammad Fahad Ullah, Sohail Ahmad, Adnan Khan, Mahmood Ahmad, Zia Ullah, Zsolt Tóth

Published in

Scientific reports. Jul 13, 2026. Epub Jul 13, 2026.

Abstract

This study evaluates the suitability of Kuldana Formation limestone from Nammal Gorge, Salt Range-Potwar Basin, Pakistan, for construction and asphalt pavement applications through integrated petrographic, geotechnical, durability, statistical, and pavement-performance analyses. Fresh, unweathered limestone blocks were collected from intact outcrops and examined using optical microscopy and SEM-EDS to identify mineralogical composition, calcite veining, pore structure, vuggy porosity, and microfracture characteristics. Standardized EN/ISRM/ASTM-aligned laboratory tests were performed to determine mechanical properties, including unconfined compressive strength, unconfined tensile strength, point load index, shear strength, and Schmidt rebound, as well as physical and durability indicators such as specific gravity, bulk density, porosity, water absorption, crushing strength, Los Angeles abrasion coefficient, and freeze-thaw resistance. The limestone showed considerable variability, with UCS ranging from 25 to 98 MPa, UTS from 20 to 80 MPa, water absorption from 0.30 to 0.72%, specific gravity from 1.67 to 2.88, porosity from 1.13 to 2.78%, LA coefficient from 10.31 to 35.20, and freeze-thaw resistance from 14.2 to 60.5. This variability is mainly related to calcite veining, pore-fracture connectivity, vuggy porosity, and microcrack density. Pearson correlation and regression analyses identified coherent relationships among selected physical, mechanical, and durability parameters, while scattered data points reflected defect-controlled responses. Pavement-performance assessment of limestone-aggregate high-stiffness asphalt concrete mixtures showed that the mixtures can satisfy KR7 fatigue requirements and may support limited asphalt-layer thickness optimization, subject to field validation and production quality control. Overall, Kuldana Formation limestone shows promising potential as a construction and asphalt pavement aggregate.

PMID:
42437804
Bibliographic data and abstract were imported from PubMed on 13 Jul 2026.

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