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Depletion of natural aggregates due to extensive use for road construction has triggered the scope of implementing non-conventional materials. The utilization of treated native soil in the subbase course of flexible pavement can largely reduce the consumption of natural aggregates and overall construction cost. The primary objective of this study is to investigate the feasibility of using slag–lime-treated native soil in the subbase course of flexible pavement. Ground granulated blast furnace slag (GGBS) alone, as well as in combination with lime, was intended to stabilize the expansive native soil which poses sizeable complications during the construction and maintenance of road pavements due to its poor strength and high swelling–shrinkage characteristics. The native soil was treated with GGBS (G) at 3, 6, 9 and 12% and GGBS + lime (G + L) at 2 + 1, 4 + 2, 6 + 3 and 8 + 4% by weight of dry soil. On the basis of California bearing ratio (CBR) and unconfined compressive strength tests, native soil treated with 12% G, 6% G + 3% L and 8% G + 4% L bettered the minimum requirement for subbase material based on IRC criteria. In order to assess the service life ratio of flexible pavement constructed with slag–lime-treated native soil as a subbase on the basis of fatigue as well as rutting criteria, finite element analysis using PLAXIS 3D was performed on the pavement crust over the subgrade of 4% CBR for a traffic intensity of 100 million standard axles. Finally, design charts of equivalent thickness of slag–lime-treated expansive soil in relation to conventional granular subbase (GSB) were developed to derive the cost efficiency of utilizing stabilized native soil as a potential alternative for conventional GSB. Pavement with slag–lime-treated native soil in subbase layer exhibited residual life of up to 65% more than that of conventional pavement, subsequently reducing the overall construction cost by 15.5%.

Structural evaluation of road pavement by falling weight deflectometer (FWD) plays a vital role in the maintenance and reinstatement of highways. The load-deflection data from the FWD test is interpreted through back-calculation technique to generate the elastic moduli of individual layers of pavement crust. The main objective of this study is to corroborate the significance of FWD in comparing the field performance and service life of pavement sections constructed with waste materials in the base and subbase layers to that of pavement section constructed with conventional base (WMM – wet mix macadam) and subbase (GSB – granular subbase) layers. Six optimal combinations of waste materials were chosen for the construction of sixteen different test sections (each 3.5 m wide and 50 m long) with different thicknesses of base (150 mm & 250 mm) and subbase (200, 300 & 400 mm) layers with waste mixtures i.e. 40% copper slag + 60% fly ash (CCF), 70% copper slag + 23% fly ash + 7% lime (CFL) & 75% steel slag + 19% fly ash + 6% lime (SFL) as base layers and fly ash + 5% lime (FL), 80% fly ash + 20% GBFS (FG) & 70% copper slag + 30% fly ash (CF) as subbase layers. Based on initial structural evaluation, all the six aforementioned mixtures exhibited lower deflections and higher elastic moduli when compared to conventional material. In particular, SFL base and FL subbase exhibited the highest elastic modulus of 710 MPa and 450 MPa; elastic moduli of WMM and GSB being 138 MPa and 110 MPa. Furthermore, sections with waste mixtures in base and subbase layers exhibited better service life with a cost-efficacy up to 17% when compared to that of conventional section.

The concept of utilizing industrial wastes for road construction can be materialized only by evaluating the field performance of roads constructed with these wastes. The present study encom...

In agriculture-based country like India road network plays a major role. The life and maintenance of roads mainly depend on the strength of both sub-base and subgrade of soil and traffic intensity. In India about 20% of the total area is covered by Black cotton soil. Because of the high swelling and shrinkage characteristics under varying water contents Black cotton soil poses problems in road construction and maintenance. This paper presents experimental results illustrating the behavior of Black cotton soil stabilized with Ground Granulated Blast furnace Slag (GGBS) and GGBS-lime mix. In order to estimate the strength of the stabilized soil, tests such as Unconfined Compressive Strength (UCS) and California Bearing Ratio (CBR) tests were performed. Tests were conducted on soil-GGBS mix for GGBS dosages 3, 6, 9, and 12% by weight of dry soil and soil-GGBS-Lime mix with 2 part GGBS and 1 part Lime for dosages 3, 6, 9, and 12% by weight of dry soil. Tests were conducted on both unsoaked and soaked samples, unsoaked samples were cured for 7 and 28 days whereas soaked samples were cured for 3 days and soaked for 4 days. The effect of binder content, curing period and soaking on the UCS and Elastic modulus were studied and subsequently the effect of binder content on CBR values were also studied. With the increase in binder content and curing period the strength of the treated soil was found to be enhanced. Soaking resulted in the decrement of the strength of the stabilized soil. From the experimental results it is clear that GGBS-lime mix is a superior binder content than GGBS for the improvement of black cotton soil, when used as a sub-base material in flexible pavement.