Peat is a renowned problematic soil and needs stabilization to enhance its engineering properties. Silica fume (SF) and Ordinary Portland Cement (OPC) were extensively adopted to increase the mechanical properties of peat; however, their microstructural analysis is lacking. Investigated herein is the microstructural evolution caused by the OPC and SF implementation in peat soil stabilization. Initially, the compositional analysis (elements and oxides) of peat and binders was carried out via energy-dispersive X-ray (EDX) and X-ray fluorescence (XRF). Subsequently, the microstructural changes that occurred in the stabilized peat were examined through a series of microstructural analyses. The analysis includes scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), and thermogravimetric analysis (TGA) for morphological, mineralogical, functional group analysis, and bond thermal analysis, respectively. The SEM micrographs evidence the transformation of loosely packed with large micropores of untreated peat into a compact dense peat matrix. This transformation is due to the formation of newly developed minerals, i.e., calcium hydrates (CH), calcium silicate hydrates (C-S-H), calcium aluminate hydrate (CAH), ettringite (Aft) caused by the pozzolanic reaction of binders as recorded by the XRD. Similarly, different molecular functional groups were found in the FTIR analysis with the incorporation of SF and OPC. Finally, the percentage of mass loss was assessed through TGA analysis revealing the decomposition of stabilized in the second and third stages.
Effects of different surface textures on the interface shear strength, interface slip, and failure modes of the concrete-to-concrete bond are examined through finite element numerical model and experimental methods in the presence of the horizontal load with 'push-off' technique under different normal stresses. Three different surface textures are considered; smooth, indented, and transversely roughened to finish the top surfaces of the concrete bases. In the three-dimensional modeling via the ABAQUS solver, the Cohesive Zone Model (CZM) is used to simulate the interface shear failure. It is observed that the interface shear strength increases with the applied normal stress. The transversely roughened surface achieves the highest interface shear strength compared with those finished with the indented and smooth approaches. The smooth and indented surfaces are controlled by the adhesive failure mode while the transversely roughened surface is dominated by the cohesive failure mode. Also, it is observed that the CZM approach can accurately model the interface shear failure with 3-29% differences between the modeled and the experimental test findings.