Utilização de agregados reciclados de concreto tratados pelo método de pré-imersão em soluções de ácido acético

Abstract

In order to improve the recycling concrete aggregate (RCD - acronym in Portuguese) quality, and to decrease the environmental impacts by the improper disposal of the waste material from the civil construction industry, this research explored the application of the pre-soaking treatment in acetic acid solutions. The aggregates were obtained by crushing old concrete in a jaw mil. This material was separated in seven groups, and each group received a different treatment. They were treated during times of 24 and 48 hours in concentrations of 1, 3 and 5% of acetic acid. Also, one group of them did not receive any kind of treatment. Further, these seven groups were tested to get the water absorption and their specific gravity. After the treatment, seven groups of concrete were produced changing the virgin coarse aggregate for recycled aggregate in a 100%. Under these circumstances was possible to evaluate the mechanical improvement of the treated aggregates when they are used in concrete production. During the concrete fabrication, the slump test was made to verify the concrete workability. At the 3rd, 7th and 28th days the groups were tested to get the compressive strength. The obtained values of strength did not show substantial variation between the groups. However, the sample that received 1% of acid treatment during 24 hours showed values 8% higher than the others samples. About the final cost of the concrete, when it is compared to the conventional concrete, it has a higher cost. However, if there is a reuse of the acid, then the cost can be lower than the conventional concrete. This way, the use can be made possible since the recycling process in civil construction has become necessary.