Sachin Gowda

This study investigates the use of imperial smelting furnace (ISF) slag, a zinc industry by-product, as a sustainable replacement for natural fine aggregate (FA) in concrete pavements. Laboratory specimens were prepared by substituting natural FA with ISF slag from 0-100%. Laboratory specimens were prepared by substituting natural FA with ISF slag from 0 to 100% on volume basis. Results showed that incorporating ISF slag enhances compressive and flexural strength up to 60% replacement at 7 and 28 days, after which strength declines. Additionally, the compressive strength of dry lean concrete (DLC) mixes prepared with an aggregate-to-cement ratio of 10:1 and results indicated that the compressive strength increased with an increase in ISF slag content. Split tensile strength increased from 3MPa at 0% to a peak of 4.54MPa at 80%, before decreasing to 4.16MPa at 100% at 28 days. Thus, ISF slag offers economic and environmental benefits for sustainable pavement construction.

Full-depth reclamation (FDR) is emerging as a sustainable solution for rehabilitating deteriorated pavements, particularly on rural and low-volume roads. However, inconsistent field performance, often attributed to inadequate compaction, has raised concerns about its long-term effectiveness. This study investigates the influence of the degree of compaction (DoC) on the mechanical and fatigue performance of cement-stabilized FDR mixes. Reclaimed pavement materials were blended to achieve the target gradation and stabilized using 5% Ordinary Portland Cement. Specimens were compacted at five DoC levels (94% to 106% of modified Proctor density) and tested for unconfined compressive strength (UCS), ultrasonic pulse velocity (UPV), flexural strength, and flexural modulus. Additionally, fatigue performance was assessed through laboratory beam fatigue testing and mechanistic analysis. Results showed significant gains in strength and fatigue life with increased compaction, UCS improved by up to 154%, UPV (a measure of material quality and homogeneity) by over 50%, and fatigue life rose from 23 million standard-axles (msa) at 94% to 214 msa at 106% DoC. However, achieving 106% DoC may pose practical challenges in the field. The study highlights that a compaction range of 100%–103% is both feasible and sufficient to yield substantial performance benefits, emphasizing the critical need for stringent compaction control in FDR projects.

Despite the growing interest in using Municipal Solid Waste Incinerated – Bottom Ash (MSWI-BA) in road construction, understanding its performance and environmental impact is crucial. With natural aggregates becoming scarce and the need for sustainable waste management increasing, this study examined replacing fine aggregates in Bituminous Concrete (BC-II) mixes with MSWI-BA at levels from 0 to 50%. Results showed that while MSWI-BA requires more binder due to its porosity, up to 20% replacement improved Marshall Stability, stiffness, and moisture resistance. The 20% MSWI-BA mix achieved optimal performance, meeting Ministry of Road Transport and Highways (MoRTH) specifications. Though higher replacement levels (up to 30%) showed slight increases in rutting susceptibility, they still performed satisfactorily. The Toxicity Characteristic Leaching Procedure (TCLP) confirmed the MSWI-BA was non-hazardous and effectively encapsulated. Thus, up to 20% MSWI-BA replacement in BC-II mixes is recommended for a balance of performance and environmental benefits.