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Year: 2026 | Month: October | Volume: 13 | Issue: 10 | Pages: 399-409

DOI: https://doi.org/10.52403/ijrr.20261036

Spent Coffee Grounds from Touba Coffee (Senegal): Physico-Chemical Characterization and Effect of Partial Cement Replacement on the Mechanical and Thermal Properties of Cement-Based Composites

Amadou Macka DIOUF^1,2, Allé DIOUM^1,2, Kharouna TALLA^1,2

¹Groupe de Physique du Solide et Sciences des Matériaux, Department of Physics, Faculty of Sciences and Technology, University Cheikh Anta Diop of Dakar, BP 5005, Dakar, Senegal.
²Matériaux, Systèmes Composites et Applications (MASCA), Department of Physics, Faculty of Sciences and Technology, University Cheikh Anta Diop of Dakar, BP 5005, Dakar, Senegal.

Corresponding Author: Amadou Macka DIOUF

ABSTRACT

Spent coffee grounds from Touba coffee, widely consumed in Senegal, are usually landfilled. This study characterized spent coffee grounds collected in Dakar and evaluated the replacement of cement by these grounds, from 5 to 35 % by mass. The grounds had a bulk density of 438 ± 7 kg/m³, an absolute density of 650 ± 27 kg/m³, a natural water content of 15.2 % and a water absorption of 91.7 ± 4.5 % (both relative to the dry mass), and sieving showed a uniform, poorly graded material. Specimens (4 × 4 × 16 cm, three per content) were tested at 28 days. The specimen mass decreased from 493 ± 12 g to 217 ± 6 g between 0 and 35 % replacement. The flexural strength decreased from 7.10 ± 0.41 MPa to 2.23 ± 0.21 MPa at 5 % and was not measurable from 15 %. The compressive strength decreased from 57.3 ± 2.2 MPa to 32.8 ± 0.6 MPa at 5 % and 16.3 ± 0.2 MPa at 10 %, and was nil at 35 %. The thermal conductivity fell from 0.94 to about 0.14 W/m·K. The loss of strength exceeded the reduction of the cement mass, which points to effects other than binder dilution, such as water absorption by the grounds. Raw spent coffee grounds therefore suit non-structural insulating uses rather than load-bearing ones, unless pretreated.

Keywords: Spent coffee grounds; Touba coffee; cement replacement; mechanical strength; thermal conductivity; lignocellulosic biomass; Senegal

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