Banca de DEFESA: NATHAN BEZERRA DE LIMA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : NATHAN BEZERRA DE LIMA
DATE: 08/12/2023
TIME: 09:00
LOCAL: Programa de Pós-Graduação em Ciência de Materiais
TITLE:

Adhesion performance for plaster mortars applied to solid concrete block substrates

KEY WORDS:

mortars; ultrasonic waves; thermography.

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

In the present work, characteristics of the adhesion capacity of plaster mortars applied to buildings were evaluated by combining ultrasonic wave propagation testing, infrared thermography (IRT), flexural traction and adhesion tensile strength. The investigation was carried out for mortars with metakaolin incorporated by addition and partial replacement of Portland cement in proportions of 5%, 10% and 15%. Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Energy Dispersive Spectroscopy (EDS) and stereoscopy analyzes were also carried out. They were used to investigate the morphological characteristics of the mortar surface. A simple theoretical model was made based on the strength of hydrogen bonds and the stoichiometric ratio SiO2/(Ca(OH)2 is used to advance a chemical approach to the adhesion capacity of plaster mortars. The results revealed that the model was useful for predicting aspects of the adhesion capacity of plaster mortars with the substrate. Furthermore, the XRD and SEM results showed the presence of important phases in the microstructures of the mortars, such as Portlandite and CSH, the adhesion resistance tests agreed with what was predicted by the model simple theoretical, where: average values similar to the reference were obtained, and the mortars prepared with the addition of metakaolin, which are superior to the corresponding adhesion strengths of the mortars prepared with cement replaced by metakaolin. The stereograms of the rupture interfaces revealed a non-homogeneous adhesion when the mortar is applied directly to the concrete substrate and homogeneous adhesion when the mortar is applied to the slab/concrete block substrate. Considering the tensile strength behavior in flexion, only the plaster mortar with 10% metakaolin incorporated presents better mechanical performance than the reference mortar. Furthermore, the propagation speed of the incident ultrasonic waves was useful in calculating the Young's modulus, which is associated with the adhesion capacity of plaster mortars. Furthermore, IRT results revealed significant water absorption by the substrate when a layer of roughcast was applied before the metakaolin plaster mortar. When plaster mortars are applied directly to the concrete substrate, there is a lower capacity to transfer water to the solid surface. The stereoscopy results showed heterogeneity in the interface area between the mortar applied directly to the concrete surface and homogeneity in the interface between the mortar and the surface of the plaster/concrete block. In conclusion, the characteristics of the ability of metakaolin plaster mortars to transfer water molecules to solid substrates.

COMMITTEE MEMBERS:
Presidente - 2457389 - EDUARDO PADRON HERNANDEZ
Externa à Instituição - ELIANA CRISTINA BARRETO MONTEIRO - UPE
Externo ao Programa - 1810494 - KLEBER GONCALVES BEZERRA ALVES - nullExterno à Instituição - LEONARDO BARBOSA TORRES DOS SANTOS - INPE
Externa ao Programa - ***.468.484-** - LILIAN KÁSSIA CAVALCANTE DA SILVA DE ASSIS - UFPE