Banca de DEFESA: VINICIUS ALMEIDA COELHO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : VINICIUS ALMEIDA COELHO
DATA : 18/01/2021
HORA: 08:00
LOCAL: online
TÍTULO:

DEVELOPMENT OF ALKALI-ACTIVATED MORTAR BASED ON DENDÊ BOILER ASH AND WOOD BURNING ACTIVATED WITH SODIUM SILICATE SOLUTION

PALAVRAS-CHAVES:

 Alkali-Activation; Mortar; Industrial Ashes; Wastes

PÁGINAS: 82
GRANDE ÁREA: Engenharias
ÁREA: Engenharia Civil
RESUMO:

Cement-based products are the most widely used building materials in the world and  their growing demand and high volume of use have raised discussions about negative  environmental impacts and stimulated the search for alternative materials. In this  scenario, alkali-activated binders presents interesting characteristics such as the rapid  development of high mechanical strength and high chemical stability, being possible  to reuse wastes in its formulation, which contributes to the reuse of resources and  reduction of various environmental impacts. The present research aimed to develop  an alkali-activated mortar based on the mix of palm oil fuel ash and wood ash, residues  with high world production, activated with an alternative solution of sodium silicate. The  precursor materials were processed through grinding and sieving, and their physical chemical characteristics were evaluated by laser diffraction, x-ray diffraction and  fluorescence and thermogravimetry. Six binders were formulated, varying the ash ratio  to achieve CaO/SiO2 molar ratios between 0.3 and 1.0 and SiO2/Al2O3 between 8 and  17, fixing the Na2O/SiO2 ratio of the activating solution to 1.40. Two of the developed  binders used metakaolin as a complementary source of Al2O3. After evaluating the  mechanical properties of the binders, three mortars were developed with 25% and 50%  variation in the volumetric aggregate content, observing the influence of this parameter  in the development of flexural and compressive strength, water absorption, voids index, specific mass and accelerated efflorescence development. It was concluded  that the ashes used are suitable for alkali-activation, which is a potentially beneficial  use from both environmental and economic point of view, since such residues have  little or no added value and high production volume worldwide, being its alkali 

activation a positive way for reuse in the construction industry. Relevant data were also  obtained on the theoretical formulation, production process and mechanical  characteristics of the alkali-activation of the ash, with the production of binders with full  development of resistance within 2 days. It was observed that the high organic matter  content of the residues (greater than 30%) hindered the development of mechanical  strength of the mixtures, even so, adjustments in the dosage parameters allowed to  achieve average flexural strength of 3.54 MPa and compressive strength of 10.5 MPa  at 14 days with 25% aggregate by volume, values higher than the requirements of NBR  13281 (2005) for use as laying and covering mortar. In addition, the developed mortars  showed low susceptibility to the development of efflorescence, the increase in the  aggregate content from 25% to 50% reduced the affected area by 50% and did not  change the absorption rate

MEMBROS DA BANCA:
Externo(a) à Instituição - CLÁUDIO HENRIQUE DE ALMEIDA FEITOSA PEREIRA
Presidente - 1522482 - FRANCISCO GABRIEL SANTOS SILVA
Externo(a) ao Programa - 2362069 - RAILDO ALVES FIUZA JUNIOR