Banca de DEFESA: GIOVANNI CHAGAS BERGAMASCHINE
Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.STUDENT : GIOVANNI CHAGAS BERGAMASCHINE
DATE: 16/02/2022
TIME: 08:00
LOCAL: Banca on-line
TITLE:
Fabrication and characterization of metakaolin-based geopolymer matrix composite with expanded vermiculite incorporation as dispersed phaseKEY WORDS:
Geopolymers. Composite. Metakaolin. Vermiculite
PAGES: 77
BIG AREA: Ciências Exatas e da Terra
AREA: Física
SUMMARY:
The study of alternative cementitious materials has been growing over the years. This is because the construction industry has shown itself to be an aggravating sector in terms of the environmental impacts generated, mainly due to the production of Portland cement. Another inconvenience related to this material is the continuous incorporation of dead load in the structures due to its density (~2300 kg/m³). However, materials called geopolymers are economically viable as a possible alternative to using Portland cement in certain applications. Geopolymers are produced by activating materials rich in alumina and silica in an amorphous state with alkaline solutions. The properties of these materials can be manipulated from the chemical and mineralogical composition of the raw material, the molar constitution of the alkaline solution, curing time and temperature. Among the precursor materials used in the manufacture of geopolymers, metakaolin stands out for its reactive potential in addition to its high availability in nature. This research investigated the production of a lightweight geopolymer composite, based on metakaolin, through the incorporation of a clay mineral called expanded vermiculite (EV). The effects of volumetric percentage factors (15%, 30% and 45%) of EV in two different particle sizes (medium and fine) were evaluated. The composites were cured at 60°C for 24 hours, and remained at laboratory temperature for 28 days. The composites obtained were subjected to mechanical strength and electron microscopy tests. Physical properties such as: water absorption, apparent porosity, bulk and volumetric density were evaluated. The behavior of the composite material when exposed to high temperatures (600°C) was also evaluated, since the aggregate used is considered a good thermal insulator and has good thermal stability. The volumetric percentage was the dominant factor that affected all the investigated response variables, whereas the particle size had a significant role only for porosity and water absorption. The compressive strength of the composite significantly reduced from 52.1 MPa (0% VE) to 19.2 MPa when incorporating 45% of fine EV. The bulk density was reduced by approximately 22% with maximum aggregate incorporation (1.71g/cm³) while the pure geopolymer matrix presented a density of 2.1g/cm³. It is observed that the dispersed phase contributed to reduce the embrittlement of the composite at high temperatures, it is believed that this occurrence is related to the reduction of internal thermal stresses.
BANKING MEMBERS:
Presidente - 1507262 - KURT STRECKER
Externa à Instituição - SIMONE PEREIRA TAGUCHI BORGES - UFRRJ
Interno - 1691537 - TULIO HALLAK PANZERA