Browsing by Author "Pedro, Diogo"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
- Influence of the crushing process of recycled aggregates on concrete propertiesPublication . Pedro, Diogo; De Brito, Jorge; Evangelista, LuisThis work intends to evaluate the (mechanical and durability) performance of concrete made with coarse recycled concrete aggregates (CRCA) obtained using two crushing processes: primary crushing (PC) and primary plus secondary crushing (PSC). This analysis intends to select the most efficient production process of recycled aggregates (RA). The RA used here resulted from precast products (P), with strength classes of 20 MPa, 45 MPa and 65 MPa, and from laboratory-made concrete (L) with the same compressive strengths. The evaluation of concrete was made with the following tests: compressive strength; splitting tensile strength; modulus of elasticity; carbona-tion resistance; chloride penetration resistance; capillary water absorption; and water absorption by immersion. These findings contribute to a solid and innovative basis that allows the precasting industry to use without restrictions the waste it generates. © (2015) Trans Tech Publications, Switzerland.
- On the development of a technical specification for the use of fine recycled aggregates from construction and demolition waste in concrete productionPublication . Bravo, Miguel; Duarte, António P. C.; De Brito, Jorge; Evangelista, Luís; Pedro, DiogoThe possibility of using recycled aggregates from construction and demolition waste (CDW) in concrete is rather widely agreed upon when it comes to the use of coarse recycled aggregates. However, this is not the case when fine recycled aggregates (FRA) are considered, as it is deemed that these seriously impair the behaviour of concrete. Hence, this work presents a technical specification proposal for the use of FRA from CDW in concrete, to attempt to fill this gap in legislation. The specification is based on a wide collection of experimental results, from which it is shown that for low incorporation ratios (up to 25%), the properties of concrete with FRA from CDW are comparable to those of a reference concrete. The intended international scope of the specification is ensured by the fact that FRA from CDW are typified by composition (percentage of concrete, masonry, glass, etc.) rather than by geographical origin or construction type. It is shown that, after typifying the FRA and assuming, as per design, the acceptable percentage losses (relative to a reference concrete) of mechanical, durability-related and long-term physical properties, if the maximum incorporation ratios proposed of each type of FRA are used, the variation of properties remains within the limits established.
- Performance of concrete made with aggregates recycled from precasting industry waste: influence of the crushing processPublication . Pedro, Diogo; De Brito, Jorge; Evangelista, LuisThe aim of this paper is to evaluate the influence of the crushing process used to obtain recycled concrete aggregates on the performance of concrete made with those aggregates. Two crushing methods were considered: primary crushing, using a jaw crusher, and primary plus secondary crushing (PSC), using a jaw crusher followed by a hammer mill. Besides natural aggregates (NA), these two processes were also used to crush three types of concrete made in laboratory (L20, L45 e L65) and three more others from the precast industry (P20, P45 e P65). The coarse natural aggregates were totally replaced by coarse recycled concrete aggregates. The recycled aggregates concrete mixes were compared with reference concrete mixes made using only NA, and the following properties related to the mechanical and durability performance were tested: compressive strength; splitting tensile strength; modulus of elasticity; carbonation resistance; chloride penetration resistance; water absorption by capillarity; water absorption by immersion; and shrinkage. The results show that the PSC process leads to better performances, especially in the durability properties.