Banca de QUALIFICAÇÃO: ITALO BATISTA DA SILVA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : ITALO BATISTA DA SILVA
DATA : 21/12/2017
HORA: 09:00
LOCAL: LABCIM- UFRN
TÍTULO:

Effect of the addition of polyurethane on the thermo-mechanical properties of Portland cement pastes subjected to high temperatures

PALAVRAS-CHAVES:

 Cementation; Flexible cement pastes; Thermomechanical properties; Simulation; Polyurethane (PU).

PÁGINAS: 100
GRANDE ÁREA: Engenharias
ÁREA: Engenharia Civil
RESUMO:

In order to adapt Portland cement to well at high temperature conditions and thermal gradients, the application of additives of polymeric nature can be a way to improve their thermomechanical behavior. The objective of this work is to evaluate the effect of the addition of different concentrations of polyurethane (PU) on the thermo-mechanical properties of cement pastes submitted to temperatures up to 300 ° C. Formulations added were prepared with 1, 2 and 3 gpc of polyurethane, respectively named PU1, PU2 and PU3. A standard paste (without PU) was also prepared. The slides were cured for 14 days (38 ° C thermal bath for 11 days plus 3 days in the curing chamber at 300 ° C) and 28 days (38 ° C thermal bath for 11 days plus 3 days in the 300 ° C). These conditions are characteristic of pastes subjected to high temperatures in steam injection operations. The mechanical properties of the cured pastes were analyzed by compressive strength using strain gauges, diametrical compression tensile strength, resonance frequency for the calculation of the Poisson's coefficient and ultrasonic test for the calculation of the modulus of elasticity. The thermal properties were investigated by the study of the behavior of the coefficient of linear thermal expansion (CTE) in argon atmosphere. The samples were also characterized by X - ray diffraction (XRD) and field emission scanning electron microscopy (SEM - FEG). The results of compressive strength showed a slight reduction of values with addition of polyurethane. After 14 days of curing, the compressive strength was 24.7 MPa, 22.3 MPa and 20.0 MPa, for the formulations PU1, PU2 and PU3 respectively. The tensile strength was 4.5 MPa, 4.0 MPa and 2.8 MPa, respectively. The standard slurry, without PU, had compressive strength of 28.4 MPa and tensile strength of 4.8 MPa. After 28 days, PU2 obtained higher compressive strength of 27.8 MPa and tensile strength of 4.82 MPa, while the standard sample had 29.88 MPa and 5.03 MPa. The PU2 sample also showed good elastic behavior after 28 days of curing, evidenced by the modulus of elasticity and the Poisson's coefficient, 16.5 GPa and 0.22 (reference paste obtained 17.6 GPa of elastic modulus and Poisson ratio of 0.20). After 28 days, the samples had high xonotlite peaks, which gives higher stability to the cement according to literature data. The dilatometry tests revealed that the CTEs of the PU-formulated formulations behaved differently from the standard non-linear pulp and were satisfactory for the cyclic injection of the well cement, presenting PU1 (11.15 x 10-6 ° C-1) with 14 days and in PU2 (10.15 x 10-6 ° C-1) with 28 days of curing dilatometric behavior approximated to the coating of oil wells that presents values in the literature around 12 x 10-6 ° C-1 and the rock formation near 10 x 10-6 ° C-1. Thus, the results show that the thermomechanical properties of PU formulations were satisfactory compared to the standard paste, mainly with 28 days of curing, presenting better stability in the crystallographic and morphological characterization, in the study of the compressive strength and tensile strength in the (elastic) and dilatometric behavior in the PU2 formulation, believing in the feasibility of applying cementitious materials additives with PU in the petroleum industry.

MEMBROS DA BANCA:
Presidente - 1298936 - ANTONIO EDUARDO MARTINELLI
Interno - 1804366 - JÚLIO CÉZAR DE OLIVEIRA FREITAS
Externo ao Programa - 1754344 - MARCOS ALLYSON FELIPE RODRIGUES