Date of Award

Spring 2025

Document Type

Thesis

Publisher

Santa Clara : Santa Clara University, 2025

Department

Civil, Environmental and Sustainable Engineering

First Advisor

Vito Francioso

Abstract

This research explores the integration of graphene oxide (GO) derived from invasive sargassum seaweed into cementitious composites to enhance concrete performance while addressing critical environmental and sustainability challenges. With the dual goal of reducing the carbon footprint of cement and repurposing harmful sargassum blooms in Puerto Rico, the research investigates the viability of sargassum-derived GO (SGO) as a partial cement substitute in mortar mixes. The study is motivated by the urgent need to lower cement-related CO₂ emissions—currently contributing nearly 8% of global totals—and by the ecological and economic burdens caused by the accumulation of sargassum along coastlines. Graphene oxide, with its exceptional mechanical and microstructural properties, offers the potential to improve concrete’s strength, durability, and workability. This research adopts a lab-based methodology involving the controlled batching of mortar samples with varying concentrations of both industrial and sargassum-derived GO. Key experimental procedures include compressive strength testing using a universal testing machine, flow table tests for workability, thermogravimetric analysis (TGA) for thermal stability, and X-ray diffraction (XRD) to examine mineralogical changes. Findings indicate significant improvements in both early-age and long-term compressive strength of GO-enhanced mixes compared to controls. The optimal replacement dosage was identified as 0.05% GO by weight of cement, consistent with prior literature and confirmed through experimental results. While the conversion of sargassum to GO is not directly within the study’s scope, the project builds on established pyrolysis methods and emphasizes the environmental advantages of using rapidly renewable biomass. The thesis focuses on optimizing mix designs, understanding material behavior, and comparing the performance of SGO-enhanced concrete to that of conventional GO and control mixes. Ultimately, this research seeks to contribute to the development of greener construction materials while promoting a circular economy and offering potential socio-economic benefits to sargassum-affected communities.

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