Structural Behavior of Fly Ash-Based Geopolymer for Roller-Compacted Concrete Pavement

The environmental concerns associated with the use of portland cement prompted finding an alternative. As a possible solution to this issue, fly ash-based geopolymer concrete has been developed and implemented in roller-compacted concrete pavement. The mechanical and rheological properties of roller-compacted geopolymer concrete were analyzed, accompanied by the chemical characterization through X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDXS) of the optimized samples, which confirmed the formation of geopolymer. The research entailed creating a stepwise mix design to determine the aggregate proportion and particle-size distribution of mixed aggregate that can achieve high packing density, resulting in improved roller-compacted geopolymer concrete properties. The optimized mixture was developed using dry sodium hydroxide (NaOH) to produce roller-compacted concrete, and the mixture characteristics were analyzed in different weather conditions such as humidity and temperature. The compressive strength after 28 days was 58 MPa at ambient curing and 61 MPa at thermal curing conditions. Flexural strength and split tensile strength were 5.5 and 4.2 MPa, and the modulus of elasticity was 33.10 GPa. The designed concrete was tested in the field by filling patches on cement concrete and bituminous pavements and compacting them with a prototype roller developed to test the mutual adhesiveness of the concrete and roller.