"Effect of Surface Modifications of Cellulose Nanomaterials in Cementitious Materials" 

Akshat Verma, MSE PhD Candidate 

Advisor: Professor Jeffrey Youngblood

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ABSTRACT

Concrete is the world’s second most exploited resource. It is composed of coarse and small aggregates (rocks), which are bonded together with the aid of a binder called cement. Cement is a chemical mixture composed of silicate, aluminates, and oxides. Cement is extremely heterogeneous compositionally as every cement factory will have a mix of raw materials accessed locally, affecting the cement properties. Cellulose nanomaterials (CNMs), when added to cement, have resulted in improvements in cement properties, which include improved hydration, improved strength, and lower permeability. Additionally, CNMs, sourced from renewable materials, can also assist in lowering the global warming potential of cement by sequestering carbon for a long duration. CNMs, though, are beneficial for cementitious materials and can be made more compatible with cement by modifying their surface chemistry. CNMs include cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs), which differ in their aspect ratios, with CNFs having a higher aspect ratio. Both the CNCs and CNFs have alcohol groups on their surfaces through which surface modifications like the grafting of silica, alumina, or polyelectrolytes are carried out. There is a plethora of research in this regard available in the literature. Surface modified CNMs can significantly improve the properties of cementitious materials compared to pristine CNMs in cement, and there is not much available literature in this regard.