Durability properties of engineered pulp fibre reinforced concretes made with and without supplementary cementitious materials

An experimental program designed to determine the compressive strength, permeability, and interfacial properties of reinforced concretes with two modified softwood and an unmodified hardwood Kraft pulp fibre. The modified fibres were engineered by extreme refinement followed by proprietary chemical modification. The modification was done to create numerous tiny fibrils on the surface of the fibres to facilitate increasing the bond between the fibres and the matrix. These fibres are called mechanically modified fibre and chemically treated fibre, and these are not yet commercially available. In addition, binary use of five supplementary cementitious materials (SCM) were also included in the production of the concretes. Test results showed an increase in the permeability characteristics for the reinforced concretes. However, two modified fibres performed better than the unmodified fibre in terms of compressive strength, chloride ion permeability and water sorptivity. Moreover, silica fume, metakaolin, and slag blends, significantly improved the strength and permeability characteristics of fibre reinforced concretes. Scanning electron microscopy for specimen with no SCM, showed that fibres de bonded from the matrix. Hence, this study found that SCM improved the adherence between the fibre and the matrix.