Mechanical Properties of Wood Dust and Iron Dust Incorporated Concrete

Abstract

This research examines the physical and mechanical behaviour of concretes incorporating two industrial by-products waste wood powder (WD) used as a partial replacement of fine aggregate and waste iron dust (ID) introduced as a micro-filler additive with the objective of identifying pragmatic mix solutions that combine resource valorization, manageable workability and acceptable structural performance. Mixtures were prepared on a fixed volumetric proportion (cement : fine aggregate : coarse aggregate = 1 : 2.31 : 3.02) at a water–cement ratio of 0.60; WD replaced fine aggregate at 5 %, 10 % and 15 % by mass, ID was dosed at 1 %, 2 % and 3 % by mass of cement, and a special formulation combining 7 % WD with 10 % ID was also evaluated. In total, 84 standard 100 × 200 mm cylinders were cast, water-cured and tested at 28 days for compressive strength (ASTM C39), splitting tensile strength (ASTM C496) and fresh workability (slump, ASTM C143). Fresh-state measurements demonstrate a pronounced, replacement-dependent loss of workability with WD: the control mix exhibited a slump of 135 mm while replacements of 5 %, 10 % and 15 % produced slumps of 96 mm, 50 mm and 12 mm, respectively. Hardened-state testing revealed a clear, dose-dependent reduction in compressive capacity for WD-only mixes (control = 21.81 MPa; 5 % WD = 13.38 MPa; 10 % WD = 7.33 MPa; 15 % WD = 5.66 MPa), consistent with the lower stiffness and higher water affinity of organic fines. Critically, the incorporation of finely graded ID at low dosages substantially mitigated these losses: for example, 5 % WD combined with 2 % ID attained 19.70 MPa and with 3 % ID attained 23.30 MPa (the latter exceeding the control mean), while the 7 % WD + 10 % ID special mix achieved 25.49 MPa at 28 days. Splitting tensile results paralleled compressive trends, evidencing restoration of tensile capacity (control = 2.24 MPa; 5 % WD = 1.23 MPa; 5 % WD + 3 % ID = 2.39 MPa; 7 % WD + 10 % ID = 2.40 MPa). Fracture observations indicate that increasing WD content promotes more tortuous, bridged failure modes with greater post-peak energy dissipation, whereas ID refines crack propagation and produces more consolidated fracture surfaces. A preliminary materials cost appraisal—assuming waste feedstocks available at minimal acquisition cost shows modest unit savings (approximately 0.9 % at 5 % WD up to ≈2.6 % at 15 % WD per m3). Taken together, the results identify a defensible operational window—low WD substitution (≈5–7 %) combined with low-to-moderate ID dosing (≈1–3 %) that secures substantial waste incorporation while preserving or recovering mechanical properties; the 7 % WD + 10 % ID formulation appears particularly promising. Prior to field implementation, however, further replication, production-scale trials, and systematic quality-control procedures are recommended to ensure reproducibility and long-term performance.