Optimized Design Aspects of Low-Volume Traffic Roads on Expansive Soil Stabilized with Fly Ash

Abstract

A significant portion of villages in India has been built with water-bound macadam (WBM) or bituminous roads. Rural roads typically experience low traffic volume, usually less than 0.50 MSA, primarily consisting of light transport vehicles with infrequent heavy traffic. If a pavement is constructed over a weak subgrade soil, such as expansive soil, and is unable to sustain the prevailing traffic load, it could lead to various issues and pavement failures. Maintenance of these roads is often neglected due to limited budgetary allocations, leading to deterioration of the road assets. There is an urgent need to examine alternative pavement designs to construct sustainable, enduring rural road infrastructure. In this research, a traffic survey was conducted between Undargaon–Wakav-Londhewadi village road block Madha, district Solapur, Maharashtra, India, to assess the traffic count of three days by an automatic traffic count classifier (ATCC). This research explores the strength characteristics of expansive soil near Undargaon–Wakav-Londhewadi village road block in the Madha, district of Solapur, Maharashtra, India. Fly ash utilized in this research was sourced from coal fired facility operated by National Thermal Power Corporation Ltd. (NTPC) in Solapur, Maharashtra, India. This study assessed the impacts of fly ash on the index properties and strength-related parameters of soil, including an unconfined compressive strength (UCS) and california bearing ratio (CBR). Tests were executed using expansive soil blended with varying proportions of fly ash in increments of 10%, ranging from 0% to 50% by weight. The findings indicate that incorporating 20% fly ash markedly enhanced the engineering behaviour of the expansive soil.  UCS and CBR values improved by approximately 2.98 and 3.92 times, respectively, compared with untreated soil. Overall, the inclusion of fly ash produced favourable outcomes by strengthening the soil and allowing a reduction in pavement thickness by about 1.46 times relative to the natural soil condition. The study determines that fly ash as an effective additive is suitable for road construction, particularly in rural areas. The development of predictive systems using linear regression and nomographs based on the study results delivers practical tools for field engineers to guide road construction projects.