Reação álcali-agregado: potencial reativo dos agregados miúdos provindos das jazidas dos municípios de Ferreira Gomes, Macapá e Porto Grande no Estado do Amapá

Abstract

The concrete is one of the most employed materials in engineering, its performance and durability can be altered by various deterioration processes, making it essential that materials used in its composition be analyzed and suitable for each type of construction. Among these processes, there is the alkali-aggregate reaction (AAR), which is defined as a chemical process that occurs between the alkaline components of cement and certain types of reactive aggregates, which can result in the emergence of expansive products that cause structural damage to concrete (Neville, 1997). The objective of this work is to analyze the reactive potential of fine aggregates, specifically the alkali-reactive potential of 8 sand samples from the main deposits in the municipalities of Ferreira Gomes, Macapá, and Porto Grande in the state of Amapá (AP). The motivation for this research arose due to the lack of data regarding the reactivity of fine aggregates in the state and as a preventive measure against the occurrence of alkali-silica reaction (ASR). For this evaluation, the first test used was the accelerated mortar bar method following NBR 15577 - 4 (ABNT, 2018). In addition to this, the chemical method following NBR 9774 (ABNT, 2008) was employed as an auxiliary, as well as scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS) attached, in order to observe the microstructure of the bars, verify the presence or absence of products that evidence the occurrence of AAR, and through semi-quantitative elemental chemical analysis, identify the substances present in the bars. The results indicated in the accelerated method that the collected samples do not have deleterious potential, as the bars did not reach 0.19% expansion; the highest percentage of expansion was 0.12% in the Translima Deposit (J7), this innocuous behavior was confirmed with the use of the chemical method. Regarding the use of SEM, the formation of the gel related to ASR was not observed. Finally, the mapping of reactive aggregates was carried out, and it was found that the aggregates are innocuous and can be used satisfactorily regarding ASR.