Banca de DEFESA: JORGE LUIS OLIVEIRA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : JORGE LUIS OLIVEIRA SILVA
DATE: 28/03/2023
TIME: 08:00
LOCAL: LCCV
TITLE:

STRUCTURAL PERFORMANCE OF CONCRETES PRODUCED WITH CONCRETE RECYCLED AGGREGATES

KEY WORDS:

Concrete Recycled aggregate. Structural concrete. Composition.

PAGES: 93
BIG AREA: Engenharias
AREA: Engenharia Civil
SUMMARY:

Currently, more sustainable alternatives have been sought within the civil construction sector, as a way of reducing harmful interference to the environment. Among these alternatives, the use of recycled concrete aggregates stands out for the production of mortars and concrete, with or without a structural function. However, the use of these aggregates is a subject that still needs to be studied, in the sense of seeking alternatives that aim to understand the porosity present in recycled aggregates, considered as the main obstacle to its use for structural purposes. Thus, the main objective of this study is to evaluate the contribution of recycled concrete aggregate (ARC) dosages on the properties of structural concrete in fresh and hardened states. Concretes with different dosages were produced, using the method proposed by ABCP, varying the percentage of replacement of natural aggregate by recycled in 25%, 50%, 75% and 100%, as well as varying the size of the ARCO (fine and coarse). Fresh state performance was evaluated using the slump test. The evaluation of properties in the hardened state was carried out using the compressive strength test, modulus of elasticity and physical indices of concrete, such as water absorption, voids index and actual specific mass. From the results of the consistency test, voids index, and absorption, all mixtures showed high values. With regard to the compressive strength results at 28 days, the mixes produced with 100% ARCO replacing only the fine aggregate, showed a result of 21.21 MPa; for the mixtures replacing only the coarse recycled aggregate, up to 75% replacement, satisfactory results were found in terms of compressive strength, with a value of 20.98 MPa being obtained for the referred percentage. For replacements of both (fine and coarse), the replacement limit was between 50% and 75%, with values of 25.60 MPa and 19.74 MPa, respectively. In this way, the interference of the size of the aggregate in the properties of concrete is evident, both in the fresh state and in the hardened state. This can be justified by the granulometry of the aggregate, which interferes with the filling of voids in the concrete, favoring greater compaction and locking of the particles; in addition to the effect of the porosity of the recycled aggregate, which is more evident in the coarse aggregate, due to the particle size. This higher porosity of the coarse recycled aggregate also influenced the results of modulus of elasticity, since this property determines the stiffness of the aggregate which, in turn, controls the ability of the aggregate to restrict matrix deformation. Complementarily, the results demonstrated the potential use of ARCO, with the possibility of replacing the natural aggregate in large part, as opposed to the current standard, which limits the percentage of replacement to up to 20% in applications for structural purposes (resistance class of C20), without bringing a clear indication if this replacement refers to fine aggregate, coarse aggregate or both.

BANKING MEMBERS:
Presidente - 1582140 - KAROLINE ALVES DE MELO MORAES
Interno(a) - 2120767 - PAULO CESAR CORREIA GOMES
Externo(a) ao Programa - 3182546 - CASSIA VANESSA ALBUQUERQUE DE MELO