Field evaluation of road pavement constructed with waste materials through nondestructive testing

Abstract

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.