Banca de DEFESA: DAYANNE GABRIELLA DA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : DAYANNE GABRIELLA DA SILVA
DATE: 12/12/2025
TIME: 08:00
LOCAL: Auditório do Laboratório de Cimentos da UFRN
TITLE:

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

KEY WORDS:

CCS wells; cementing; graphene nanoplatelets; durability.

PAGES: 78
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 fundamental technology for reducing large-scale greenhouse gas emissions. This technique enables the safe confinement of carbon dioxide (CO₂), one of the main contributors to global warming, in deep geological formations, thereby limiting its release into the atmosphere. To implement this technology, it is essential to construct wells that allow the injection of CO₂ captured from industrial sources, ensuring secure storage and preventing its return to the surface. In this context, the cementitious material responsible for zonal isolation and well structural integrity must exhibit high chemical and mechanical resistance, as its degradation by CO₂ can compromise the long-term durability of the system. Thus, the incorporation of nanomaterials such as graphene nanoplatelets (GNPs) into cement pastes emerges as a promising approach, since their two-dimensional lamellar structure and high aspect ratio can enhance the mechanical strength, conductivity, and chemical stability of the cementitious system. Additionally, GNPs offer high scalability and lower cost compared with other graphene-based derivatives. This study aimed to evaluate the effect of different GNP concentrations (0.03%, 0.06%, and 0.09% BWOC) on the mechanical strength, permeability, and chemical resistance of cement pastes. The formulations were subjected to carbonation tests under supercritical CO₂ conditions in an aqueous medium, with evaluations performed after 7, 14, and 28 days of exposure. Complementary analyses, including X-ray Diffraction (XRD), Thermogravimetry (TG), and Scanning Electron Microscopy (SEM), were conducted to identify and quantify hydration and carbonation products formed before and after chemical attack, as well as to assess GNP dispersion within the cement matrix and its influence on product formation. The results showed that GNP-containing pastes exhibited increased compressive strength and reduced permeability, particularly at early curing ages. Carbonation was also slowed by the addition of GNPs, with the 0.06% concentration demonstrating the best performance. Microstructural analysis revealed well-dispersed GNPs in the cement matrix and the presence of carbonation products, while thermal and crystallographic analyses indicated the effect of GNP addition on the formation of compounds before and after CO₂ exposure. Therefore, the results indicate that GNPs present strong potential for the development of cementitious nanocomposites designed for CCS well construction.

COMMITTEE MEMBERS:
Presidente - 1298936 - ANTONIO EDUARDO MARTINELLI
Externo ao Programa - 1804366 - JÚLIO CÉZAR DE OLIVEIRA FREITAS - UFRNExterno à Instituição - GLAUCO SOARES BRAGA - IFRN