Performance and Durability of Cellulose Pulp-Reinforced Extruded Earth-based Composites

This study aimed to investigate the influence of two alternative cellulosic materials: bamboo organosolv pulp and recycled waste carton pulp, on the flexural strength, fracture toughness, drying shrinkage, and durability of extruded earth-based building materials by varying the reinforcement content at 5, 7.5, and 10 wt%. The results show the flexural strength and fracture toughness achieved by the inclusion of carton pulp were between the range of 2.87–3.20 MPa and 4.22–4.52 MPa.m0.5, respectively, while the introduction of bamboo pulp gave 2.04–2.20 MPa and 3.76–4.05 MPa.m0.5, respectively. Compared with the unreinforced material, composite reinforced with 5 wt% of recycled waste carton pulp significantly enhanced flexural strength (61%), specific energy (416%), and fracture toughness (57%), while increasing the drying shrinkage (81%) and water absorption (38%) and decreasing the bulk density (15%) of earth-based matrix. Although the addition of cellulose pulp in soil matrix increased the drying shrinkage due to the high absorption capacity of pulp fibre, it decreased the wearing percentage and the shrinkage cracking of the composite which contributed to an improvement in the durability of the earth-based material. The repeated drying shrinkage test led to an improvement in the dimension stability at 87%, 83%, 85%, and 82% for 0, 5, 7.5, and 10 wt% of recycled pulp composite, respectively. Cellulose fibre reacts as crack arrester during loading and shrinkage, improves the durability, and provides a lightweight earth wall material for insulation strategies.