Desenvolvimento de concreto geopolimérico leve: viabilidade de aplicação no setor da construção civil

Abstract

Portland cement is the main component of conventional concrete, considered the second most consuming material in the world, but its manufacture accentuates the greenhouse effect. Studies show that the production of geopolymer concrete is a sustainable alternative and has comparable physical mechanical characteristics. In this sense, this thesis developed and characterized lightweight geopolymeric concrete obtained from lightweight aggregates, such as vermiculite, perlite, diatomite and zeolite, in different granulometries, with the aim of investigating their influence on the physical properties -mechanics and verify the feasibility of application in the civil construction sector. Geopolymers were synthesized from metakaolin and activator solution (NaOH and Na2SiO3). The precursor and activator solution were initially characterized and a reference sample was prepared for comparison (without addition of aggregates). After different curing periods, the samples were characterized by XRD, FRX, FTIR, water absorption, apparent and total porosity, apparent density, evolution of mechanical resistance to compression and flexion in 3 points, Young modulus in cold in 1, 7 , 14 and 28 days and fire resistance. The accelerated aging test by UV exposure and immersion/drying and the evolution of the Young modulus in cold were performed. Additionally, the matrix/aggregate interface was analyzed by scanning and confocal electron microscopy, before and after accelerated aging. The results indicated that the addition of 5% by weight of aggregate resulted in lightweight concrete. Geopolymers composed of diatomaceous earth and zeolite exhibited the highest compressive strength values, 36 MPa and 31.5 MPa, respectively, after 1 day of curing. Compared to a commercial product, geopolymeric concretes showed superior flexural strength and no evidence of flame propagation, demonstrating their viability for the civil construction sector.