Volume 87, Issue 10 (2026), Pages: 70-86;
Received: 11 July 2026 / Resubmitted: 01 September 2026/ Revised: 09 October 2026/ Accepted: 13 October 2026/ Published: 22 October 2026
Research article
Design Optimization of Fly Ash-Stabilized Pavements on Expansive Soil
Vicky Anand1, Amit Kumar Sinha2, Akanksha Kesharwani3, Sakshi Gupta3,4, Ranajeet Kumar3, Suman Kumari5, Shashi Ranjan6, Akash Sharma7, *
1Assistant Professor, Department of Civil Engineering, B.P. Mandal College of Engineering, Madhepura, Bihar, India.
2Assistant Professor, Department of Civil Engineering, Government Engineering College, Munger, Bihar, India.
3Assistant Professor, Department of Civil Engineering, Sershah Engineering College, Sasaram, Bihar, India.
4Research Scholar, National Institute of Technology, Patna, Bihar, India.
5Assistant Professor, Department of Civil Engineering, Rashtrakavi Ramdhari Singh Dinkar College of Engineering, Begusarai, Bihar, India.
6Assistant Professor, Department of Civil Engineering, Nalanda College of Engineering, Chandi (Nalanda), Bihar, India.
7Research Scholar, Department of Civil Engineering, Visvesvaraya National Institute of Technology, Nagpur, Maharashtra, India
Abstract: Expanding water-bound macadam (WBM) or bituminous rural road networks over weak subgrade formations, such as expansive soils, typically compromises structural longevity due to recurring moisture-induced swelling and shrinkage. High maintenance overheads combined with restricted budget allocations call for economic, alternative pavement designs. This research explores the geo-structural stabilization of expansive clay using fly ash sourced from the National Thermal Power Corporation (NTPC) facility in Solapur, Maharashtra, India. Laboratory tests were systematically carried out on soil blended with varying fly ash dosages, spanning 0% to 50% by weight, evaluating index parameters, free swell ratio (FSR), unconfined compressive strength (UCS), and California bearing ratio (CBR). The findings indicate that incorporating an optimum 20% fly ash dosage significantly enhances structural competency. At this threshold, UCS and soaked CBR values improved by 2.98 and 3.92 times, respectively, relative to untreated soil. Using traffic load data (0.251 MSA) collected via an automatic traffic count classifier (ATCC), structural pavement optimization based on IRC: SP:72-2015 guidelines allowed for the complete elimination of the 150 mm sub-base layer. This layer suppression yielded a 1.46-fold structural crust thickness reduction, demonstrating a sustainable, high-efficiency framework for rural road infrastructure.
Keywords: California Bearing Ratio, Unconfined Compressive Strength, Expansive Soil, Fly Ash
Stabilization, Rural Road Design, Automatic Traffic Count Classifier (ATCC).
* Corresponding Author.
Email address: ds19ce006@students.vnit.ac.in
Doi (Journal): 10.1045/2026.Bauingenieur/108805-VDI_008
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