Year: 2026 | Month: October | Volume: 13 | Issue: 10 | Pages: 263-279
DOI: https://doi.org/10.52403/ijrr.20261025
Influence of Omni Processor Ash Incorporation on the Atterberg Limits and Compaction Behaviour of a Laterite from Thicky, Senegal: Physicochemical Characterization and Preliminary Study
Seydou Khoulé Diagne1,2,3, Dame Keindé1,2,3, Cheikh Kaïré Ndiaye1,2,3, Prince Momar Gueye4,2,3
1Materials Laboratory, École Polytechnique de Dakar, Université Cheikh Anta Diop (UCAD), Dakar, Senegal
2PRIMOLAB, Geotechnical Laboratory, Senegal
3SOCOCIM Industries, Rufisque, Senegal
4École Polytechnique de Diamniadio, Senegal
Corresponding Author: Seydou Khoulé Diagne
ABSTRACT
Turning sanitation by-products into construction materials advances circular-economy goals and lowers the environmental footprint of road infrastructure. Here we examine how small additions of ash from an Omni Processor affect the Atterberg limits and compaction response of a lateritic soil sampled at Thicky, Senegal. The raw laterite was characterized by sieve analysis and X-ray diffraction (XRD); the bottom ash (CFOP) was assessed by X-ray fluorescence (XRF), XRD, and SEM-EDS. Six laterite-CFOP blends (0, 1, 1.5, 2, 2.5, and 3% ash) underwent Atterberg limit and Modified Proctor compaction testing. Quartz (55.7%) and kaolinite (27.1%) dominate the laterite, 28.4% of which passes the 0.08 mm sieve. The CFOP contains 33.9% SiO2 and 17.4% CaO; SiO2+Al2O3+Fe2O3 together total 54.7%, short of the 70% ASTM C618 benchmark for some pozzolanic materials. Plasticity evolved non-monotonically with CFOP content: the plasticity index climbed from 12.5% (untreated) to 16.9% at 1% CFOP before falling to 10.8% at 3%. Compaction followed a similar pattern, with maximum measured dry density peaking at 2.093 g/cm3 (from 2.00) at 1% CFOP before declining at higher dosages, while the corresponding water content rose to 14.53% at 2.5% before easing to 12.92% at 3%. All blends met the CEBTP (1984) plasticity threshold for a foundation layer; only the 1% blend exceeded the base-layer limit. Meeting the plasticity criterion alone, however, does not confirm overall fitness for road use. Further testing (particle size, CBR, strength, durability, and leaching of the blends) remains necessary before any conclusion on pavement use.
Keywords: Laterite; Sewage sludge ash; Omni Processor; Atterberg limits; Proctor compaction; Road geotechnics; Circular economy
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