Abstract: Repair mortar and methods of preparing repair mortar are provided. The repair mortar comprise a cement binder, fine aggregate and cellulose fibrils. In some embodiments, the cellulose fibrils are dispersed uniformly throughout the repair mortar. In some embodiments, the cellulose fibrils comprise nanofibrillated cellulose and/or microfibrillated cellulose. In some embodiments, the cellulose fibrils comprise an aspect ratio of between about 20 to about 500. The methods comprise mixing a cement binder, fine aggregate with water/chemical admixture to provide a cementitious material of good consistency, mixing cellulose fibrils with water to provide a cellulose fibril slurry, and mixing the cellulose fibril slurry with the workable cementitious material. In some embodiments, the cellulose fibrils are dispersed uniformly throughout the workable cementitious material.

Abstract: Cellulosic materials modified with a surface modifier to promote compatibility with a hydrophobic material and methods for producing surface-modified cellulosic materials are provided. The methods include providing a slurry of a cellulosic material and adding a surface modifier to the slurry. The surface modifier may be added to the slurry in a soluble form and precipitated by adjusting the pH. The surface-modified cellulosic material may be solvent-dried and/or dried using conventional drying methods to enhance hydrophobicity. To solvent-dry the surface-modified cellulosic material, a solvent is added to an aqueous slurry of the surface-modified cellulosic material to form an azeotrope. The azeotrope has a boiling point that is less than the boiling point of the solvent. The slurry is distilled to remove the azeotrope from the surface-modified cellulose material. The solvent is removed from the surface-modified cellulose material.