Banca de QUALIFICAÇÃO: DAYANNE GABRIELLA DA SILVA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : DAYANNE GABRIELLA DA SILVA
DATE: 17/06/2025
TIME: 14:00
LOCAL: Auditório do Laboratório de Cimentos da UFRN
TITLE:

Development of cementitious nanocomposites based on graphene nanoplates for applications in CCS wells.

KEY WORDS:

CCS wells; cementing; graphene nanoplatelets; durability.

PAGES: 74
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
SPECIALTY: Materiais Conjugados Não-Metálicos
SUMMARY:

Carbon capture and storage (CCS) is a strategic technology for mitigating the greenhouse effect. It enables the safe confinement of carbon dioxide (CO₂), one of the main gases responsible for global warming, in deep geological formations, thereby reducing its release into the atmosphere. To make this technology feasible, wells must be constructed to inject the captured CO₂ from industrial sources, ensuring safe storage and preventing its return to the surface. These wells are cemented to ensure structural integrity, prevent leakage, and promote the isolation of geological formations, keeping the CO₂ securely confined in a stable and permanent manner. However, continuous exposure to pressure and temperature cycles, coupled with the corrosive action of CO₂, accelerates the degradation of the cementitious materials, compromising the well's durability. In this context, incorporating graphene nanoplatelets (GNPs) into cement slurries for CCS well construction emerges as a promising alternative. This is attributed to the two-dimensional lamellar structure and high aspect ratio of GNPs, which provide exceptional mechanical strength, as well as excellent electrical and thermal conductivity and chemical stability. This research aims to investigate the effect of different GNP concentrations (0.03%, 0.06%, and 0.09% BWOC) on cement slurries, assessing their impact on mechanical strength, permeability, and chemical resistance. The developed cement formulations were subjected to carbonation tests in a supercritical CO₂ aqueous environment, with evaluations performed at 7, 14, and 28 days of exposure. To complement the analysis, thermogravimetric analysis (TG) and Scanning Electron Microscopy (SEM) were conducted to identify and quantify the hydration and carbonation compounds formed before and after chemical exposure. Additionally, these techniques allowed for the assessment of GNP dispersion in the cement matrix and its influence on the development of these products. The results demonstrated that GNP-containing cement pastes exhibited enhanced compressive strength and reduced permeability, particularly at early curing ages. Moreover, the addition of GNPs decelerated the carbonation process, with the 0.06% concentration showing the best performance. Microstructural analysis revealed well-dispersed GNPs within the cement matrix, along with carbonation products. Meanwhile, thermal analysis quantitatively highlighted the influence of GNP incorporation on the formation of hydration and carbonation compounds before and after CO₂ exposure. Therefore, the addition of GNPs to cement slurries represents a promising strategy for developing cementitious nanocomposites tailored for CCS well applications.

COMMITTEE MEMBERS:
Interno - 1298936 - ANTONIO EDUARDO MARTINELLI
Externa ao Programa - 2621720 - ANA CECILIA VIEIRA DA NOBREGA - UFRNExterno ao Programa - 1804366 - JÚLIO CÉZAR DE OLIVEIRA FREITAS - UFRN