This study investigates the influence of wood pellet fly ash blended binder (WABB) on the mechanical properties of typical weathered granite soils (WS) under a field and laboratory tests. WABB, composed of 50 % wood pellet fly ash (WA), 30 % ground granulated blast furnace slag (GGBS), and 20% cement by dry mass, was applied at dosages of 200-400 kg/m3 to four soil columns were constructed at a field site deposited with WS. After 28 days, field tests, including coring, standard penetration tests (SPT), and permeability tests, revealed enhanced soil cementation and reduced permeability, indicating a denser soil matrix. Unconfined compressive tests (UCT) and free-free resonant column (FFRC) tests on field cores at 28 and 56 days, compared with laboratory specimens and previously published data, demonstrated strength gains 1.2-2.1 times higher due to field-induced stress. The presence of clay minerals influenced the WABB's interaction and microstructure development. Correlations between seismic waves, small-strain moduli, and strength were developed to monitor in-situ static and dynamic stiffness gain of WABB-stabilized weathered granite soils.

Deep soil mixing (DSM) is a widely used ground improvement method to enhance the properties of soft soils by blending them with cementitious materials to reduce settlement and form a load-bearing column within the soil. However, using cement as a binding material significantly contributes to global warming and climatic change. Moreover, there is a need to understand the dynamic behavior of the DSM-stabilized soil under traffic loading conditions. In order to address both of the difficulties, a set of 1-g physical model tests have been conducted to examine the behavior of a single geopolymer-stabilized soil column (GPSC) as a DSM column in soft soil ground treatment under static and cyclic loading. Static loading model tests were performed on the end-bearing (l/h = 1) GPSC stabilized ground with Ar of 9 %, 16 %, 25 %, and 36 % and floating GPSC stabilized ground with l/h ratio of 0.35, 0.5, and 0.75 to understand the load settlement behavior of the model ground. Under cyclic loading, the effect of Ar in end-bearing conditions and cyclic loading amplitude with different CSR was performed. Earth pressure cells were used to measure the stress distribution in the GPSC and the surrounding soil in terms of stress concentration ratio, and pore pressure transducers were used to monitor the excess pore water pressure dissipated in the surrounding soil of the GPSC during static and cyclic loading. The experimental results show that the bearing improvement ratio was 2.28, 3.74, 7.67, and 9.24 for Ar of 9 %, 16 %, 25 %, and 36 %, respectively, and was 1.49, 1.82, and 2.82 for l/h ratios of 0.35, 0.5, and 0.75 respectively. Also, the settlement induced due to cyclic loading was high under the same static and cyclic stress for all the area replacement ratios. Furthermore, the impact of cyclic loading is reduced with an increase in the area replacement ratio. Excess pore water pressure generated from static and cyclic loads was effectively decreased by installing GPSC.

The soil-cement deep soil mixing (DSM) technique has been widely used to improve the bearing capacity of the soft soil under embankment loading. However, utilizing ordinary portland cement (OPC) releases a tremendous carbon footprint. Industrial waste-based geopolymer has emerged as a sustainable and environmentally friendly solution for stabilizing soft soils. This work investigates the behavior of embankment models constructed on geopolymer-stabilized soil columns (GPSCs) under static and cyclic loading conditions similar to transportation routes. A series of static and cyclic loading tests were carried out on the reduced-scale designed embankment model resting on soft soil (cus = 5 kPa) reinforced with end-bearing (l/h = 1) and floating (l/h = 0.75) GPSCs with area replacement ratios (Ar) of 12.7%, 17%, and 21.2% to analyze the vertical stress-settlement behavior of the improved ground. Earth pressure cells were used to measure the vertical stress on the column and the adjacent surrounding soil under static and cyclic embankment loading. A pore-pressure transducer was used to monitor the excess pore-water pressure generated during the loading process. The results indicate that the ultimate bearing capacity (qult) improvement for end-bearing GPSCs was 246.92%, 344.56%, and 418.8%, whereas the improvement for floating GPSCs was 126.9%, 151%, and 181.64% for Ar values of 12.7%, 17%, and 21.2%, respectively. Furthermore, the stress concentration ratio increases and excess pore-water pressure decreases with increasing Ar and l/h ratios. A mathematical equation was also derived to determine the qult value with Ar and l/h ratios. End-bearing GPSCs were more effective than floating GPSCs at the same Ar under static and cyclic loading. For installing floating GPSCs, a higher area replacement ratio is required for better load bearing under static and cyclic loading. In addition, a life cycle assessment of the geopolymer compared to OPC was performed, showing that the geopolymer is a sustainable and eco-friendly construction material.