Concrete with recycled aggregate is a fragile material under tensile stresses. However, like conventional concrete, it is possible that its contribution is relevant in the design of reinforced concrete elements under tension or bending, even after cracking. The objective of this work is to evaluate the application of the analytical models used to predict the effect of tension stiffening on recycled reinforced concrete. Tests of reinforced concrete under tensile were performed using conventional concrete and concrete containing 25% and 50% replacement of the natural aggregate with recycled aggregate. From the experimental results of reinforced concrete, the contribution of the concrete was isolated and a parametric study was carried out to identify which analytical model in the literature may be more appropriate. The models proposed by Carreira and Chu (1986), Vecchio and Collins (1986) and Hsu and Mo (2010) were evaluated. A numerical analysis, based on the finite element method, was implemented to model the mechanical behavior of the reinforced concrete under tensile using the analytical models already adjusted to concrete with recycled aggregate. The stress distribution in steel and concrete and the cracking mode were evaluated numerically. The results indicate that the parameters used in the analytical models for conventional concrete cannot predict the behavior of concrete with recycled aggregate and need to be modified to obtain a more accurate answer.

Obtenção de quartzo citrino a partir de tratamentos térmicos de ametistas procedentes do distrito de Brejinho (BA) Citrine quartz obtained from thermal treatments of amethysts from the district of Brejinho (BA)

The present study seeks to develop a simple methodology capable of relating the propagation of acoustic waves with the compressive strength of ceramic sealing bricks. For this purpose, were captured acoustic signals generated by the impact of a steel sphere on the surface of ceramic bricks from three different origins. With the acoustic signal as a function of frequency, was possible to identify the main amplitude peak, which increases with the increase in compressive strength. Other characteristics of the acoustic signal, such as for instance a greater number of amplitude peaks presented below 5 mHz, could be also related to the compressive strength of the bricks indicating a possibility of fast and non-destructive testing.For the compression testing, it is recommended use a press that is in accordance with the descriptions in Annex C of [5], in addition to taking care with the receipt, preparation and packaging of the bricks that will be used Carvalho Júnior et al.