Durability of concrete mixed with fine recycled aggregates

Resumo

In this paper, an analysis was conducted on the influence of the use of 20%, 50% and 100% contents of two types of fine recycled aggregates (from demolish concrete and from old masonry) on the following properties of concrete: water absorption by immersion, pore volume, carbonation and resistivity. This analysis was not restricted to compare mixtures from a table of results. All the analysis was based on concrete family behavior. The Mix Design Nomograms (MDN) was made for concrete families: one as reference and six others with different recycled contents to replace the natural fine aggregate. The MDN obtained for the properties studied permitted compare class 20MPa, 30MPa and 40MPa concretes. The results obtained indicate that the carbonation depth reached a minimum and the resistivity reached a maximum when 50% contents of fine recycled masonry aggregates were used. However, this tendency was not repeated for pore volume and water absorption. Thus, it should conclude that the durability like a carbonation and resistivity are physical-chemical phenomena that, in this case, were inversely related to water absorption and volume of pores.