Banca de DEFESA: RÍSIA AMARAL ARAÚJO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : RÍSIA AMARAL ARAÚJO
DATE: 27/05/2022
TIME: 09:00
LOCAL: Remota
TITLE:

EVALUATION OF CEMENT MIXTURES FOR 3D PRINTING WITH OPTIMIZED THERMAL PERFORMANCE

KEY WORDS:

3D printed concrete, light expanded clay aggregate, mix design, squeeze flow rheology, thermal comfort.

PAGES: 135
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
SPECIALTY: Materiais Conjugados Não-Metálicos
SUMMARY:

3D printing of concrete (3DCP) has gained increasing attention over the past few years. However, mixtures capable of optimizing the thermal comfort of printed structures still need to be studied. Thus, the objective of the present work is to evaluate the influence of the replacement of natural sand by light expanded clay aggregate (LECA) on the mechanical, physical and thermal properties of Portland cement-based mixtures for 3DCP. The mixtures were formulated using a 2² factorial design, having the replacement content (%sub) of sand by LECA and the aggregate to binder ratio (a/b) as independent factors. The replacement of natural sand by LECA was in volume% to account for the difference in density between them and to maintain the same volume of particles in the mixture. Squeeze-flow and flow-table tests were used to evaluate the rheological behavior of mixtures for 3DCP containing aggregates up to 1.2 mm in maximum diameter. The results showed that the replacement of sand by LECA increased the yield strength from 8 to 13 KPa and the viscosity of the mixture increased from 5x10⁵ to 3x10⁶ Pa.s, which resulted in improved constructability, while still showing workability equivalent to the reference mixture. The results showed that the total replacement of sand by LECA reduced the thermal conductivity from 1.19 to 0.68 W/m.K, and was accompanied by small variations in physical properties, such as water absorption and porosity. In addition, the replacement provided a decrease of ~ 16% in the modulus of elasticity without compromising important structural properties, such as mechanical strength, which was in the range of 60 ± 3 MPa. The thermal behavior of the mixtures was modeled and an equation dependent only on the substitution content factor (%sub) was found.

BANKING MEMBERS:
Presidente - 1298936 - ANTONIO EDUARDO MARTINELLI
Externa ao Programa - 2621720 - ANA CECILIA VIEIRA DA NOBREGA
Externo à Instituição - ROGERIO VALENTIM GELAMO - UFTM
Externo à Instituição - KLEBER CAVALCANTI CABRAL - UFERSA
Externo à Instituição - MARCOS ALYSSANDRO SOARES DOS ANJOS - IFRN