Feasibility assessment of porous granules from lateritic soil and sawdust as partial cement replacement under seawater immersion

This study developed porous granules from lateritic soil and sawdust as an innovative approach to valorizing waste for use as a partial cement replacement. The study focused on two aspects: first, identifying suitable composition ratios and chemical agents for producing porous granules, and second, evaluating the feasibility of using granules in a cement-granule paste or as a partial cement replacement to achieve sufficient strength under seawater immersion. The findings showed that the optimal granule composition consisted of 70 wt% lateritic soil, 30 wt% sawdust, and 0.50 wt% sodium silicate, producing granules with a maximum porosity of 34% and a pore structure characterized by isolated (closed) internal pores, as indicated by qualitative observations of 3D tomographic images. When incorporated into cement paste at 20 wt% replacement with a size range of 1–2.36 mm, compressive strengths of 31–36 MPa were achieved after 7 days, meeting the standard requirements. The relationship between pore volume, granule size, and compressive strength was non-linear. Under seawater curing, samples with a 20 wt% replacement maintained strength comparable to plastic-wrapped samples, indicating stable mechanical performance during seawater immersion. These results present the feasibility of using lateritic soil-sawdust porous granules as a partial cement replacement under seawater immersion, using a simplified laboratory assessment rather than direct simulation of real marine environments. However, transport-related durability properties, such as permeability, water absorption, and ion ingress (e.g., chloride, sulfate, and magnesium ions), were not evaluated. Therefore, durability-related interpretations remain preliminary and require further validation.