Banca de DEFESA: LUCAS RIBEIRO DE SOUSA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : LUCAS RIBEIRO DE SOUSA
DATA : 18/10/2019
HORA: 09:00
LOCAL: PROGRAMA DE PÓS-GRADUAÇÃO EM ENGENHARIA CIVIL
TÍTULO:

Evaluation of cement pastes containing catalytic cracking residue (Ecat) in exposure to saline mist and supercritical carbon dioxide.

PALAVRAS-CHAVES:

ECAT, FCC, supercritical carbon dioxide, cement slurries, salt-spray, metal stabilization

PÁGINAS: 279
GRANDE ÁREA: Engenharias
ÁREA: Engenharia Civil
RESUMO:

The Equilibrium Catalyst (Ecat) is a residue from Fluid Catalytic Cracking (FCC) units that has pozzolanic function that can contribute to mechanical properties and durability of cementitious materials. In this work, cement slurries containing Ecat were evaluated in aggressive environments. The slurries were prepared with G and Ecat cement (0, 10, 15, 20 and 30% mass/mass) evaluated mechanical properties before and after exposure to salt spray. CPV-ARI and Ecat cement slurries (0, 15, 30% mass/mass) were also prepared and evaluated for (i) axial compressive strength and flexural traction after 7, 14, 28 days of cure at room temperature. (28 ± 2 °C) and thermal (40 °C), as well as after 28 days of curing and exposure to salt spray for 72 h; (ii) mineralogical and morphological characterizations (XRD, DTA, TG / DTG and SEM) after 28 days in ambient, thermal, deterioration with saline mist and supercritical carbon dioxide (scCO₂= 20MPa/44,85 °C); (iii) Rockwell surface hardness before and after exposure to salt spray and scCO₂; (iv) leaching before and after attacks with ICP-OES or FRX analysis. In G cement slurries with up to 15% Ecat there was no loss of axial compressive strength, but decreases with 20-30% Ecat, maintaining the flexural tensile strength. The slurries with CPV-ARI and Ecat had higher contents lower Ca(OH)₂ contents, confirming the pozzolanicity of Ecat. In slurries with CPV-ARI, there was an increase in axial compressive strength with 15 and 30% Ecat, the flexural tensile strength has a slight loss in the paste with 30% Ecat. Thermal cure increases the gain of compressive strength and flexural tensile strength up to 14 days, between 14-28 days there is a tendency to lower rate of compressive strength gain and decreased flexural tensile strength, lower strength occurred in the paste 30% Ecat. G-cement slurries that were exposed to salt spray had a decrease in axial compressive strength, except with 30% Ecat, while flexural tensile strength decreased significantly in Ecat slurries. Exposure to saline mist in the CPV-ARI slurries caused a decrease in CSH, Af(t,m), CASH, CAH and mCA contents, more significantly in those containing Ecat. There was a significant loss in flexural and axial compression tensile strength, mainly in the 30% Ecat paste. In the carbonated CPV-ARI slurries, there was a decrease in C-S-H, Af(t), CASH, CAH and mCA levels, more significantly with Ecat, producing CaCO₃, with greater carbonation advance and increase in surface hardness. The slurries with CPV-ARI and Ecat did not leach metals contained in Ecat (V, Ni, Sb and Cu), there were in the slurries with and without Ecat small concentrations of Cr and Fe from the cement. Carbonation with scCO₂ decreased Fe leaching, increasing Cr concentration. Meanwhile, the salty spray deteriorated slurries tended to leach CaO, Cr₂O₃, and MgO.  

MEMBROS DA BANCA:
Externo à Instituição - GLADIS CAMARINI
Externo ao Programa - 130.974.825-04 - HELOYSA MARTINS CARVALHO ANDRADE - UFBA
Presidente - 2652701 - JARDEL PEREIRA GONCALVES
Externo ao Programa - 1475073 - VANESSA SILVEIRA SILVA