Banca de DEFESA: ANA LUCIA SANTANA FREITAS CONCEIÇÃO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : ANA LUCIA SANTANA FREITAS CONCEIÇÃO
DATE: 11/08/2023
TIME: 09:00
LOCAL: Ambiente virtual
TITLE:

Recycling of asbestos-cement waste (ACW): the use of heat-treated ACW as fiber-cement binders

KEY WORDS:

Fiber-cement, asbestos-cement waste, heat treatment, alternative binder, KCV statistical design.

PAGES: 90
BIG AREA: Engenharias
AREA: Engenharia Civil
SUBÁREA: Construção Civil
SPECIALTY: Materiais e Componentes de Construção
SUMMARY:

Portland cement is one of the primary components of the fibercements, but its production process leads to significant environmental impacts. These impacts range from the extraction of limestone to the substantial CO2 emissions from the clinker production. The present study addresses this issue by developing fibercements with a heat-treated asbestos-cement waste matrix (ACWT). Additionally, a statistical KCV project was conducted to assess the technical feasibility of utilizing ACWT as the primary binder in the fibercements. The raw materials were thoroughly characterized in their physical, chemical, mineralogical, and mechanical properties. This characterization enabled the determination of the proposed dosage parameters for applying the KCV model. Initially, thirty-one formulations were produced, incorporating simultaneous variations in the mixing ingredients and the process factors (conformation pressure). These formulations were then subjected to physical and mechanical evaluations, including density (D), porosity (η), limit of proportionality (LOP), modulus of rupture (MOR), elastic modulus (MOE), and specific energy (EE). Six optimized formulations were selected to assess the silica fume efficacy on the composites' performance. X-ray diffractogram results of the ACWT indicated successful elimination of chrysotile from the waste. ACWT and silica fume contributed to the composites’ matrix densification. However, formulations with higher percentages of sisal fibers had the opposite effect. Porosity evaluations demonstrated that both matrix constituents and fibers significantly influenced this property. Notably, the addition of polypropylene fibers reduced the pores interconnectivity. The mechanical strength results confirmed that thermal curing enhanced mechanical strength development in matrices. Increasing the process factor resulted in reduced porosity and increased mechanical strength of the fibercements. Moreover, the appropriate addition of sisal and polypropylene fibers to the ACWT matrix enhanced the mechanical strength of fibercement after the first crack stress. The optimized formulations revealed that active silica played a vital role in refining the pores and improving the fiber-matrix transition zone in fibercement produced using the ACWT matrix. Furthermore, fibercement produced with the ACWT matrix and hybrid reinforcement demonstrated comparable physical and mechanical performance to fibercement produced with a Portland cement matrix.

COMMITTEE MEMBERS:
Presidente - 2137887 - CLEBER MARCOS RIBEIRO DIAS
Externa à Instituição - LEILA APARECIDA DE CASTRO MOTTA
Interno - 2315713 - MARCELO STROZI CILLA
Externo à Instituição - SERGIO FRANCISCO DOS SANTOS