Optimizing industrial waste in road construction: a response surface methodology approach

This research explores the sustainable use of fly ash, glass fiber, and ground granulated blast furnace slag (GGBS) as stabilizing agents in the base and subbase layers of flexible pavements. Utilizing Design Expert 13 software and Response Surface Methodology (RSM), we identified optimal mixtures that satisfy technical specifications. Our analysis found that a composition of 88% fly ash, 3% glass fiber, and 9% GGBS meets the required Unconfined Compressive Strength (UCS) of over 3 MPa at 28 days, ideal for subbase layers, while 83% fly ash, 5% glass fiber, and 12% GGBS achieve UCS values as high as 6.76 MPa, suitable for base layers. Modified Compaction, UCS, and California Bearing Ratio (CBR) tests, alongside ANOVA, grounded our statistical methodology. Specifically, blends with higher glass fiber content demonstrated significant improvements in UCS and CBR, with the 88% fly ash, 3% glass fiber, and 9% GGBS mix achieving a notable CBR of 67.20%, well above the minimum 30% required for heavy-traffic pavements. These findings underscore the potential of such industrial waste materials to enhance mechanical properties and sustainability in road construction.