Banca de QUALIFICAÇÃO: ANDRESSA GALVÃO DE ARAÚJO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : ANDRESSA GALVÃO DE ARAÚJO
DATE: 23/06/2023
TIME: 08:30
LOCAL: Auditório do Laboratório de Cimentos da UFRN
TITLE:

Synergistic effect of vermiculite-lignosulfonate mixtures on the thermomechanical properties of coating mortars

KEY WORDS:

Efficient building, light mortars, expanded vermiculite, plasticizer, thermal insulation.

PAGES: 75
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
SPECIALTY: Materiais Conjugados Não-Metálicos
SUMMARY:

The search for building materials that promote energy efficiency in buildings has drastically increased, as in addition to contributing to the reduction of greenhouse gas emissions, they also increase thermal comfort and reduce energy consumption. The partial replacement of sand by porous aggregates, such as vermiculite, has great potential in improving the thermal insulation of constructions. However, porous aggregates also reduce the mechanical strength of mortars. To get around this difficulty, plasticizing additives, such as lignosulphonates, can be used together with porous aggregates, to reduce the mixing water, resulting in greater mechanical strength and durability of the mortars. Therefore, the objective of this study was to evaluate the synergistic effect of the combined addition of vermiculite and a plasticizer based on lignosulphonate in coating mortars. Mortars with a ratio of 3:1 in volume were prepared, replacing 0%, 25% and 50% of sand with expanded vermiculite and adding 0 and 2% of lignosulphonate. The resulting mortars were characterized in the fresh state by measuring the consistency index and fresh mass density. In the hardened state, apparent mass density, water absorption, void index, modulus of elasticity, compressive and flexural strength were evaluated. The thermal insulation of the mortars was evaluated by measuring the temperature gradient between opposite faces of mortar plates 26.5 x 20.0 by 1.5 cm thick. It was observed that as the vermiculite concentration increased, the density of mortars and their mechanical strength decreased. The addition of 2% plasticizer to the mortar containing 50% vermiculite reduced the amount of mixing water, improving the compressive strength by 15% and the flexural strength by 9%. The combined use of 50% vermiculite and 2% lignosulphonate resulted in an increase in the temperature gradient between opposite faces of the mortars from 6.7 °C (reference mortar) to 9.2 °C. This result confirms the synergistic effect of the vermiculite-lignosulphonate mixture in the formulation of mortars with improved thermal insulation effect.

COMMITTEE MEMBERS:
Presidente - 1298936 - ANTONIO EDUARDO MARTINELLI
Externo ao Programa - 1804366 - JÚLIO CÉZAR DE OLIVEIRA FREITAS - UFRNExterno à Instituição - KLEBER CAVALCANTI CABRAL - UFERSA