Banca de QUALIFICAÇÃO: NATHAN BEZERRA DE LIMA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : NATHAN BEZERRA DE LIMA
DATE: 22/06/2022
LOCAL: Programa de Pós-Graduação em Ciência de Materiais
TITLE:

Investigation of new structural, morphological, chemical and mechanical aspects of the interface between ZnO coated steel and cementitious materials

KEY WORDS:

zinc oxide, thermal treatment, cement-based materials, structural properties, morphology, mechanical properties.

PAGES: 65
BIG AREA: Outra
AREA: Multidisciplinar
SUMMARY:

Reinforced concrete is a very popular building material, and it is widely employed for large and medium-sized constructions due to the advantage in mechanical performance, low cost, and execution. By considering the perspective of Materials Science, reinforced concrete can be defined as a hybrid material that contains a composite coating (concrete) and a high-performance metal alloy (steel). A relevant and current challenge is the protection of steel structures, for example, from the application of coatings, in which the main goal of the present work was to investigate structural, morphological, chemical and mechanical aspects of the interface between the coated steel and cementitious materials. In this sense, zinc oxide coatings were applied to steel bars with a thickness of Ø 6.3 mm - CA 50 by two strategies: 1) via electrolysis and 2) via thermal treatment. Qualitative results revealed that the second strategy was more efficient, since apparently a larger area of the steel was coated. Subsequently, prismatic and cylindrical specimens of two types of cementitious materials were prepared. After the curing time of 28 days, tests of compressive and flexural strengths were performed. The corresponding mean values of the compressive strength tests were, respectively, 5.79 MPa and 6.49 MPa. The corresponding flexural strengths were 1.86 MPa and 2.66 MPa, respectively. Further, incident ultrasonic wave propagation tests were also carried out, in which the velocity values of 2195.6 m/s were obtained for the cementitious material of the type 1 and 2813.04 m/s for the type 2. These results revealed that the material of the type 2 presented higher quality compared to the type 1. On the other hand, structural properties were analyzed by XRD, and the results revealed that for type 1 cementitious materials, 5 phases were verified for cementitious material of the type 1 and only 2 phases were found for the material of the type 2. Finally, SEM/EDS analyzes were performed for the precursor materials and for the cement-based materials. The results revealed that the cementitious material of the type 2 presented a more adequate chemical composition compared to the type 1 material. In conclusion, the type 1 cementitious material proved to be more suitable for the insertion of steel bars with steel coating in the second phase of this work, in which the interface region between zinc oxide coated steel and cementitious material will be investigated.

BANKING MEMBERS:
Externo à Instituição - ELIANA CRISTINA BARRETO MONTEIRO - UPE
Externo à Instituição - FELIPE MENDES DA CRUZ - UPE
Externo ao Programa - 2154866 - TIAGO FELIPE DE ABREU SANTOS