Características estructurales del hormigón con árido reciclado mixto reforzado con fibras

Abstract

Despite the advance that has led the incorporation of Annex 15 in the Spanish EHE-08, the use of recycled aggregate concrete (RAC) is minimum in structural applications. This regulation limits the percentage of substitution to 20 % of the coarse fraction. Moreover, only the recycled concrete aggregates (RCA) with ceramic particle content less than 5 % and water absorption less than 7 % are accepted. However, recent studies have shown that most of recycled aggregates produced in Spain exceeds these limitations, mainly due to the high content of ceramic material (mixed recycled aggregates), and absorption capacity water. This fact causes that only 15-20 % of construction and demolition waste (CDW) generated in Spain are treated and revalued as a construction material. This mark is below the goal (70 %) fixed in European regulations for year 2020. Currently, the recycled aggregates from CDW are considered as a waste material, only suitable in applications like filling-material in trenches or road subbase. The main objective of the Doctoral Thesis is demonstrate the feasibility of RAC made with a 100 % of mixed recycled aggregates (MRA) in structural applications. To reach this goal, an extensive experimental campaign (in concrete factory, in UPC ¿Luis Agulló¿ Lab and a field test) was carried out. This field test was part of the construction of an underground parking in C/Badajoz (Barcelona). Six diaphragm-walls were cast from as many doses of mixed RAC. In this experience, two properties were added to the concrete, self-compactability and fiber-reinforced. The aim of this decision was prevent the usual casting difficulties in these structural elements. Three months later, the elements were removed and fragmented in order to obtain specimens. Physical, mechanical and durability properties of the concretes were analyzed, and 18 full-scale flexural slab tests were carried out. Additionally, another experience was carried out in ESCOFET 1886, SA plant (Martorell), in order to verify the feasibility of this type of concrete in an industrial process. The results are satisfactory in both applications, opening new promising prospects for this type of concrete.