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Acceptance by the construction industry of recycled concrete as a sustainable alternative material is contingent upon a reliable assessment of its permeability to corrosive agents. This study analyses the transport mechanisms associated with chloride (Cl−), oxygen (O2) and carbon dioxide (CO2) ions in concrete with cement made with 10% or 25% ground recycled concrete (GRC) separately or in combination with 50% mixed recycled aggregate (MRA). The findings show that, irrespective of aggregate type, concrete with GRC exhibited lower resistance to ingress than conventional concrete due to its greater porosity. Nonetheless, O2 permeability was consistently below 4.5 × 10−17 m2 and CO2 penetration, under 4 mm/year0.5, indicative of concrete with high quality. Resistance to CO2 and Cl− penetration in the materials with 10% GRC was similar to the values observed in conventional concrete. On the other hand, the incorporation of 25% GRC increased the penetration of CO2 and Cl- by 106% and 38%, respectively. Further to those findings in normal carbonation environments, reinforcement passivity would be guaranteed in such recycled materials over a 100 year service life.
Blas Cantero; Miguel Bravo; Jorge de Brito; Isabel Sáez del Bosque; César Medina. Assessment of the Permeability to Aggressive Agents of Concrete with Recycled Cement and Mixed Recycled Aggregate. Applied Sciences 2021, 11, 3856 .
AMA StyleBlas Cantero, Miguel Bravo, Jorge de Brito, Isabel Sáez del Bosque, César Medina. Assessment of the Permeability to Aggressive Agents of Concrete with Recycled Cement and Mixed Recycled Aggregate. Applied Sciences. 2021; 11 (9):3856.
Chicago/Turabian StyleBlas Cantero; Miguel Bravo; Jorge de Brito; Isabel Sáez del Bosque; César Medina. 2021. "Assessment of the Permeability to Aggressive Agents of Concrete with Recycled Cement and Mixed Recycled Aggregate." Applied Sciences 11, no. 9: 3856.
This research evaluates the fracture behavior of concrete with reactive magnesium oxide (MgO). Replacing cement with MgO is an attractive option for the concrete industry, mainly due to sustainability benefits and reduction of shrinkage. Four different MgO’s from Australia, Canada, and Spain were used in the concrete mixes, as a partial substitute of cement, at 5%, 10%, and 20% (by weight). The fracture toughness (KI) intensity factor and the stress–strain softening parameters of the wedge split test were evaluated after 28 days. The experimental results showed that the replacement of cement with MgO reduced the fracture energy between 13% and 53%. Moreover, the fracture energy was found to be correlated with both compressive strength and modulus of elasticity. A well-defined relationship between these properties is important for an adequate prediction of the non-linear behavior of reinforced concrete structures made with partial replacement of cement with MgO.
J. Forero; M. Bravo; J. Pacheco; J. de Brito; L. Evangelista. Fracture Behaviour of Concrete with Reactive Magnesium Oxide as Alternative Binder. Applied Sciences 2021, 11, 2891 .
AMA StyleJ. Forero, M. Bravo, J. Pacheco, J. de Brito, L. Evangelista. Fracture Behaviour of Concrete with Reactive Magnesium Oxide as Alternative Binder. Applied Sciences. 2021; 11 (7):2891.
Chicago/Turabian StyleJ. Forero; M. Bravo; J. Pacheco; J. de Brito; L. Evangelista. 2021. "Fracture Behaviour of Concrete with Reactive Magnesium Oxide as Alternative Binder." Applied Sciences 11, no. 7: 2891.
This paper intends to analyze the performance of mortars with reactive MgO, as a sustainable alternative to cement. Six different MgOs from Australia, Canada, and Spain were used in the production of mortars as partial substitutes for cement, namely 5%, 10%, 15%, 20%, and 25% (by weight). MgOs with different levels of reactivity were used to analyze its influence on the performance of MgO mortars. In order to evaluate the mechanical performance of these mortars, compressive strength, flexural strength, dynamic modulus of elasticity, and ultrasonic pulse velocity tests were performed. Compressive strength tests showed that the use of 25% reactive MgO can cause a decrease of this property of between 28% and 49%. The use of reactive MgO affected the other mechanical properties less. This paper also intends to analyze the durability performance of mortars with reactive MgO. To that effect, water absorption by capillarity was assessed. In this research, the effect of using MgO on the shrinkage was also analyzed. It was found that shrinkage may decrease by more than a half in some cases.
Miguel Bravo; Javier Forero; José Nobre; Jorge de Brito; Luís Evangelista. Performance of Mortars with Commercially-Available Reactive Magnesium Oxide as Alternative Binder. Materials 2021, 14, 938 .
AMA StyleMiguel Bravo, Javier Forero, José Nobre, Jorge de Brito, Luís Evangelista. Performance of Mortars with Commercially-Available Reactive Magnesium Oxide as Alternative Binder. Materials. 2021; 14 (4):938.
Chicago/Turabian StyleMiguel Bravo; Javier Forero; José Nobre; Jorge de Brito; Luís Evangelista. 2021. "Performance of Mortars with Commercially-Available Reactive Magnesium Oxide as Alternative Binder." Materials 14, no. 4: 938.
This works intends to analyze, experimentally and numerically, the bond-slip behavior between steel and concrete made with recycled aggregates (RA) from construction and demolition waste (CDW) from several recycling plants in Portugal. Pull-out tests performed in concrete mixes with RA from CDW are described and the main results (bond strength, bond-slip curves and failure modes) are shown and discussed. Additionally, a comparison between experimental and analytical (using equations from the literature) results is made. Afterwards, finite element (FE) models using Abaqus are developed and compared with the experimental results. The interface behavior between steel and concrete follows that prescribed by the CEB-FIP Model Code and uses as input experimental results. After validation, the models show good results when extended to predict the bond-slip behavior of the remaining concrete mixes studied. It is generally concluded that, per each 10% of natural aggregates replaced with RA from CDW, the bond strength decreases in circa 3% (numerically) to 5% (experimentally). CEB-FIP Model Code equations are shown to be able to predict bond strength and, when used in FE models, to lead to accurate simulation of the bond-slip response of steel and concrete with RA from CDW: the average ratio between numerical and experimental bond strengths is 0.95. In the scope of the FE models developed, a simple equation to be used along with those prescribed by CEB-FIP, which accounts for fraction and ratio of aggregates replaced, is put forward, as a first approach, showing good results.
Miguel Bravo; António P. C. Duarte; Jorge De Brito; Luís Evangelista. Tests and Simulation of the Bond-Slip between Steel and Concrete with Recycled Aggregates from CDW. Buildings 2021, 11, 40 .
AMA StyleMiguel Bravo, António P. C. Duarte, Jorge De Brito, Luís Evangelista. Tests and Simulation of the Bond-Slip between Steel and Concrete with Recycled Aggregates from CDW. Buildings. 2021; 11 (2):40.
Chicago/Turabian StyleMiguel Bravo; António P. C. Duarte; Jorge De Brito; Luís Evangelista. 2021. "Tests and Simulation of the Bond-Slip between Steel and Concrete with Recycled Aggregates from CDW." Buildings 11, no. 2: 40.
This paper presents a literature review concerning the characteristics of MgO (magnesium oxide or magnesia) and its application in cementitious materials. It starts with the characterization of MgO in terms of production processes, calcination temperatures, reactivity, and physical properties. Relationships between different MgO characteristics are established. Then, the influence of MgO incorporation on the properties of cementitious materials is investigated. The mechanical strength and durability behaviour of cement pastes, mortars and concrete mixes made with MgO are discussed. The studied properties of MgO–cement mixes include compressive strength, flexural strength, tensile strength, modulus of elasticity, water absorption, porosity, carbonation, chloride ion penetration, shrinkage, expansion, and hydration degree. In addition, microscopic analyses of MgO-cement mixes are also assessed. Summarizing the results of different studies, it is concluded that MgO incorporation in cementitious materials generally decreases the mechanical strength and shrinkage, and increases the porosity, expansion, carbonation and chloride ion migration. However, it should be emphasized that the properties of the specific MgO used (mainly the calcination temperature, the reactivity and the surface area) have a significant influence on the characteristics of the cementitious materials produced.
Nobre José; Hawreen Ahmed; Bravo Miguel; Evangelista Luís; De Brito Jorge. Magnesia (MgO) Production and Characterization, and Its Influence on the Performance of Cementitious Materials: A Review. Materials 2020, 13, 4752 .
AMA StyleNobre José, Hawreen Ahmed, Bravo Miguel, Evangelista Luís, De Brito Jorge. Magnesia (MgO) Production and Characterization, and Its Influence on the Performance of Cementitious Materials: A Review. Materials. 2020; 13 (21):4752.
Chicago/Turabian StyleNobre José; Hawreen Ahmed; Bravo Miguel; Evangelista Luís; De Brito Jorge. 2020. "Magnesia (MgO) Production and Characterization, and Its Influence on the Performance of Cementitious Materials: A Review." Materials 13, no. 21: 4752.
The 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.
Miguel Bravo; António P. C. Duarte; Jorge De Brito; Luis Evangelista; Diogo Pedro. On the Development of a Technical Specification for the Use of Fine Recycled Aggregates from Construction and Demolition Waste in Concrete Production. Materials 2020, 13, 4228 .
AMA StyleMiguel Bravo, António P. C. Duarte, Jorge De Brito, Luis Evangelista, Diogo Pedro. On the Development of a Technical Specification for the Use of Fine Recycled Aggregates from Construction and Demolition Waste in Concrete Production. Materials. 2020; 13 (19):4228.
Chicago/Turabian StyleMiguel Bravo; António P. C. Duarte; Jorge De Brito; Luis Evangelista; Diogo Pedro. 2020. "On the Development of a Technical Specification for the Use of Fine Recycled Aggregates from Construction and Demolition Waste in Concrete Production." Materials 13, no. 19: 4228.
This novel study was triggered by a lack in the international literature of the simultaneous use of ground recycled concrete (GRC) as a cement replacement and mixed recycled aggregate as part of the granular skeleton in recycled concrete. It explores the thermal behaviour of concrete mixes bearing 10 wt% or 25 wt% GRC as a cement replacement and 25 wt% or 50 wt% mixed recycled aggregate (MRA) sourced from construction and demolition waste (CDW). The experimental programme conducted assessed concrete’s dry density, open porosity, electrical and thermal conductivity and specific heat capacity. The findings showed that the use of 10% and 25% GRC, in conjunction with 50% MRA, reduced thermal conductivity by 7.9% to 11.8% and raised specific heat capacity by 6.0% to 9.1% relative to concrete with 100% natural aggregate (NA). A cross-property analysis revealed that improved thermal performance was linearly related to lower density and higher porosity. The results also support the conclusion that these new recycled aggregate concrete mixes are more energy-efficient construction materials than conventional concrete.
Blas Cantero; Miguel Bravo; Jorge De Brito; Isabel Fuencisla Sáez Del Bosque; César Medina. Thermal Performance of Concrete with Recycled Concrete Powder as Partial Cement Replacement and Recycled CDW Aggregate. Applied Sciences 2020, 10, 4540 .
AMA StyleBlas Cantero, Miguel Bravo, Jorge De Brito, Isabel Fuencisla Sáez Del Bosque, César Medina. Thermal Performance of Concrete with Recycled Concrete Powder as Partial Cement Replacement and Recycled CDW Aggregate. Applied Sciences. 2020; 10 (13):4540.
Chicago/Turabian StyleBlas Cantero; Miguel Bravo; Jorge De Brito; Isabel Fuencisla Sáez Del Bosque; César Medina. 2020. "Thermal Performance of Concrete with Recycled Concrete Powder as Partial Cement Replacement and Recycled CDW Aggregate." Applied Sciences 10, no. 13: 4540.
This work analyzes the technical and economic viability of using coarse recycled aggregates from crushed concrete in shotcrete, as a primary lining support in tunnels. Four incorporation ratios of coarse natural aggregate (CNA) with coarse recycled concrete aggregates from concrete (CRCA) were studied: 0%, 20%, 50% and 100%. The mechanical properties of the dry-mix shotcrete were obtained in an independent experimental campaign. Initially, the technical viability of CRCA shotcrete was validated for deep rock tunnels, based on the convergence-confinement method. Two cases were studied to determine the equivalent thickness for each combination of replacement ratio using CRCA shotcrete: (i) similar stiffness and (ii) similar yield stress. Subsequently, an economic assessment was performed. The stiffness criterion increased the thickness below 10% in both the 20% and 50% replacement ratios, which shows their technical viability with very marginal cost increase (
Gonçalo Duarte; Rui Carrilho Carrilho Gomes; Jorge De De Brito; Miguel Bravo; José Nobre. Economic and Technical Viability of Using Shotcrete with Coarse Recycled Concrete Aggregates in Deep Tunnels. Applied Sciences 2020, 10, 2697 .
AMA StyleGonçalo Duarte, Rui Carrilho Carrilho Gomes, Jorge De De Brito, Miguel Bravo, José Nobre. Economic and Technical Viability of Using Shotcrete with Coarse Recycled Concrete Aggregates in Deep Tunnels. Applied Sciences. 2020; 10 (8):2697.
Chicago/Turabian StyleGonçalo Duarte; Rui Carrilho Carrilho Gomes; Jorge De De Brito; Miguel Bravo; José Nobre. 2020. "Economic and Technical Viability of Using Shotcrete with Coarse Recycled Concrete Aggregates in Deep Tunnels." Applied Sciences 10, no. 8: 2697.
The purpose of this research is to study the effect of replacing natural coarse aggregates with coarse recycled concrete aggregates on shotcrete's durability performance. The dry-mix process was used and four mixes with 0%, 20%, 50% and 100% replacement ratios were analysed. The incorporation of recycled aggregates demanded an increase of the w/c ratio to maintain the workability in all the mixes, and resulted in reductions of the rebound effect, which is a very positive consequence since it is one of the biggest disadvantages of the dry-mix process. To characterize the durability of shotcrete, the following tests were conducted: water absorption by immersion, water absorption by capillarity, carbonation resistance, chloride ion penetration resistance and shrinkage. In all of them, a performance loss occurred. Nevertheless, all the losses were low, which means that, if considered in the design of the shotcrete, this type of aggregates can be used.
José Nobre; Miguel Bravo; Jorge de Brito; Gonçalo Duarte. Durability performance of dry-mix shotcrete produced with coarse recycled concrete aggregates. Journal of Building Engineering 2019, 29, 101135 .
AMA StyleJosé Nobre, Miguel Bravo, Jorge de Brito, Gonçalo Duarte. Durability performance of dry-mix shotcrete produced with coarse recycled concrete aggregates. Journal of Building Engineering. 2019; 29 ():101135.
Chicago/Turabian StyleJosé Nobre; Miguel Bravo; Jorge de Brito; Gonçalo Duarte. 2019. "Durability performance of dry-mix shotcrete produced with coarse recycled concrete aggregates." Journal of Building Engineering 29, no. : 101135.
This research intends to analyse the mechanical performance of shotcrete with coarse recycled concrete aggregates (CRCA). Four replacement ratios of coarse natural aggregate with CRCA were studied: 0%, 20%, 50% and 100%. A dry mix-process was used in the production of shotcrete. A considerable reduction of the rebound effect with the incorporation of recycled aggregates was observed. In terms of hardened properties, a reduction was observed in compressive strength, splitting tensile strength, modulus of elasticity and ultrasound pulse velocity. The adhered mortar in CRCA is the reason for their greater deformability and lower strength, which were reflected in a decline of the properties of shotcrete. However, the abrasion resistance increased with the incorporation of recycled aggregates, which can be explained by its roughness and higher porosity, allowing better bond with the new cement paste. The adhesion strength in the various compositions was not affected by the incorporation of these aggregates.
Gonçalo Duarte; Miguel Bravo; Jorge de Brito; José Nobre. Mechanical performance of shotcrete produced with recycled coarse aggregates from concrete. Construction and Building Materials 2019, 210, 696 -708.
AMA StyleGonçalo Duarte, Miguel Bravo, Jorge de Brito, José Nobre. Mechanical performance of shotcrete produced with recycled coarse aggregates from concrete. Construction and Building Materials. 2019; 210 ():696-708.
Chicago/Turabian StyleGonçalo Duarte; Miguel Bravo; Jorge de Brito; José Nobre. 2019. "Mechanical performance of shotcrete produced with recycled coarse aggregates from concrete." Construction and Building Materials 210, no. : 696-708.
The need to reduce the world’s ecological footprint has encouraged the construction sector to look for more innovative solutions to reuse its waste production. Since concrete waste is one of the biggest waste streams in the sector and in the world, reusing it would largely contribute to solve this problem. Various strategies have been followed and this kind of waste has been mostly used in road pavements activities. However, it has been proved that it is possible to use this waste for current concrete structural elements. This investigation proved that it is also possible to produce high-performance concrete made of both fine and coarse recycled concrete aggregates. It was even possible to produce a type of high-performance concrete made with total replacement of natural aggregates. However, present legislation, in the world in general and in Portugal in particular, does not allow this level of replacement ratio, particularly for fine recycled aggregates. In fact, most of the legislation around the world do not allow to use fine recycled aggregates in high-performance concrete. In this work, a simple specification proposal is presented to incorporate both fine and coarse aggregates to produce high-performance concrete. It was the result of a wide experimental campaign constituted of 3,049 laboratory tests. This specification defines the types of cement mix and the maximum replacement ratios that should be respected to produce five classes of high-performance concrete.
D. Pedro; J. De Brito; Luis Evangelista; M. Bravo. Technical Specification Proposal for Use of High-Performance Recycled Concrete Aggregates in High-Performance Concrete Production. Journal of Materials in Civil Engineering 2018, 30, 04018324 .
AMA StyleD. Pedro, J. De Brito, Luis Evangelista, M. Bravo. Technical Specification Proposal for Use of High-Performance Recycled Concrete Aggregates in High-Performance Concrete Production. Journal of Materials in Civil Engineering. 2018; 30 (12):04018324.
Chicago/Turabian StyleD. Pedro; J. De Brito; Luis Evangelista; M. Bravo. 2018. "Technical Specification Proposal for Use of High-Performance Recycled Concrete Aggregates in High-Performance Concrete Production." Journal of Materials in Civil Engineering 30, no. 12: 04018324.
The shrinkage and durability properties of a total of 34 concrete mixes with recycled aggregates produced from different untreated construction and demolition waste (CDW) were tested. The effect of a polycarboxylic superplasticizer on the enhancement of these properties is presented, discussed, and compared with the findings of studies on concrete whose recycled aggregates are sourced from concrete. All properties were significantly affected by recycled aggregate incorporation and this effect was strongly dependent on the properties of the recycled aggregates of each specific source. The superplasticizer was less efficient in mixes with CDW than when the recycled aggregates were produced from concrete, the most common source of recycled aggregates in experimental works, despite untreated CDW being more practical and desirable from an industrial and environmental perspective.
Miguel Bravo; J. de Brito; Luis Evangelista; J. Pacheco. Durability and shrinkage of concrete with CDW as recycled aggregates: Benefits from superplasticizer’s incorporation and influence of CDW composition. Construction and Building Materials 2018, 168, 818 -830.
AMA StyleMiguel Bravo, J. de Brito, Luis Evangelista, J. Pacheco. Durability and shrinkage of concrete with CDW as recycled aggregates: Benefits from superplasticizer’s incorporation and influence of CDW composition. Construction and Building Materials. 2018; 168 ():818-830.
Chicago/Turabian StyleMiguel Bravo; J. de Brito; Luis Evangelista; J. Pacheco. 2018. "Durability and shrinkage of concrete with CDW as recycled aggregates: Benefits from superplasticizer’s incorporation and influence of CDW composition." Construction and Building Materials 168, no. : 818-830.
This research analyses the shrinkage and creep performance of concrete with recycled aggregates from various Portuguese construction and demolition waste recycling plants, studying the influence of the properties and composition of each recycled aggregate source on the characteristics of concrete produced with them. Recycled aggregates from four plants were used in the concrete mixes produced in this research, of which two were coarse recycled aggregates and two were fine recycled aggregates. During this experimental campaign, the behaviour of the mixes with recycled aggregates was evaluated by three fresh-state concrete tests (slump using the Abrams cone, density, and air content) and two hardened-state concrete tests (shrinkage and creep). It was found that the incorporation of recycled aggregates caused a qualitative drop in the concrete's properties. The properties of the concrete mixes were significantly dependent on the source (and composition) of the recycled aggregates.
Miguel Bravo; Jorge De Brito; Jorge Pontes; Luis Evangelista. Shrinkage and creep performance of concrete with recycled aggregates from CDW plants. Magazine of Concrete Research 2017, 69, 974 -995.
AMA StyleMiguel Bravo, Jorge De Brito, Jorge Pontes, Luis Evangelista. Shrinkage and creep performance of concrete with recycled aggregates from CDW plants. Magazine of Concrete Research. 2017; 69 (19):974-995.
Chicago/Turabian StyleMiguel Bravo; Jorge De Brito; Jorge Pontes; Luis Evangelista. 2017. "Shrinkage and creep performance of concrete with recycled aggregates from CDW plants." Magazine of Concrete Research 69, no. 19: 974-995.
This investigation intends to analyse the thermal performance of concrete with recycled aggregates (RA) from construction and demolition waste (CDW) collected from several locations in Portugal. A total of 17 concrete mixes were analysed by means of thermal conductivity tests. Firstly, the composition and characteristics of the aggregates (natural and recycled) used in the production of the concrete mixes were analysed thoroughly, by means of several physical and chemical tests. Later, in order to evaluate the thermal behaviour of the mixes, several tests were performed and their results analysed, both on the fresh-state (slump with the Abrams cone test, density and air content) and the hardened state (compressive strength and thermal conductivity). The analysis of the thermal behaviour showed that the use of RA improves the thermal performance of the concrete mixes. The extent of this change was shown to be quite variable depending on the origin of the RA used.
Miguel Bravo; Jorge De Brito; Luis Evangelista. Thermal Performance of Concrete with Recycled Aggregates from CDW Plants. Applied Sciences 2017, 7, 740 .
AMA StyleMiguel Bravo, Jorge De Brito, Luis Evangelista. Thermal Performance of Concrete with Recycled Aggregates from CDW Plants. Applied Sciences. 2017; 7 (7):740.
Chicago/Turabian StyleMiguel Bravo; Jorge De Brito; Luis Evangelista. 2017. "Thermal Performance of Concrete with Recycled Aggregates from CDW Plants." Applied Sciences 7, no. 7: 740.
Most research on recycled aggregates concrete concern aggregates produced from concrete waste, rather than actual construction and demolition waste. Different investigations have assessed that sulfonated-based superplastizers are not as efficient in recycled aggregates concrete than on natural aggregates concrete, but no significant loss of polycarboxylic-based superplasticizer efficiency has been reported. This may not be valid when the aggregates are sourced from actual construction and demolition waste, due to the higher porosity, roughness, and weaker mechanical properties of aggregates produced from this source. This paper analyses the mechanical properties of superplasticized concrete with the incorporation of construction and demolition waste. Recycled aggregates produced from construction and demolition waste were taken directly from plants and used as aggregates without screening or treatment, emulating what would happen in a practical application by the concrete industry. The results of the tests and the superplasticizer’s efficiency are compared with results on natural aggregate concrete compositions and on analogue recycled concrete aggregate concrete compositions with and without superplasticizers. The composition of the different construction and demolition waste aggregates is considered during the analysis of results. Evidence was found that when recycled aggregates are sourced from construction and demolition waste, polycarboxylic-based superplasticizers perform satisfactorily but may not be as efficient as in natural aggregate concrete compositions.
M. Bravo; J. de Brito; L. Evangelista; J. Pacheco. Superplasticizer’s efficiency on the mechanical properties of recycled aggregates concrete: Influence of recycled aggregates composition and incorporation ratio. Construction and Building Materials 2017, 153, 129 -138.
AMA StyleM. Bravo, J. de Brito, L. Evangelista, J. Pacheco. Superplasticizer’s efficiency on the mechanical properties of recycled aggregates concrete: Influence of recycled aggregates composition and incorporation ratio. Construction and Building Materials. 2017; 153 ():129-138.
Chicago/Turabian StyleM. Bravo; J. de Brito; L. Evangelista; J. Pacheco. 2017. "Superplasticizer’s efficiency on the mechanical properties of recycled aggregates concrete: Influence of recycled aggregates composition and incorporation ratio." Construction and Building Materials 153, no. : 129-138.
This paper intends to analyze the microstructure of concrete with recycled aggregates (RA) from construction and demolition waste from various Portuguese recycling plants. To that effect, several scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses were performed. Various concrete mixes were evaluated in order to analyze the influence of the RA’s collection point and consequently of their composition on the mixes’ characteristics. Afterward all the mixes were subjected to the capillary water absorption test in order to quantitatively evaluate their porosity. Results from the SEM/EDS analysis were compared with those from capillary water absorption test. The SEM/EDS analysis showed that the bond capacity of aggregates to the new cement paste is greatly influenced by the RA’s nature. On the other hand, there was an increase in porosity with the incorporation of RA.
Miguel Bravo; António Santos Silva; Jorge De Brito; Luis Evangelista. Microstructure of Concrete with Aggregates from Construction and Demolition Waste Recycling Plants. Microscopy and Microanalysis 2015, 22, 149 -167.
AMA StyleMiguel Bravo, António Santos Silva, Jorge De Brito, Luis Evangelista. Microstructure of Concrete with Aggregates from Construction and Demolition Waste Recycling Plants. Microscopy and Microanalysis. 2015; 22 (1):149-167.
Chicago/Turabian StyleMiguel Bravo; António Santos Silva; Jorge De Brito; Luis Evangelista. 2015. "Microstructure of Concrete with Aggregates from Construction and Demolition Waste Recycling Plants." Microscopy and Microanalysis 22, no. 1: 149-167.
This research aims at analysing the mechanical performance of concrete with recycled aggregates (RA) from construction and demolition waste (CDW) from various locations in Portugal. First the characteristics of the various aggregates (natural and recycled) used in the production of concrete were thoroughly analysed. The composition of the RA was determined and several physical and chemical tests of the aggregates were performed. In order to evaluate the mechanical performance of concrete, compressive strength (in cubes and cylinders), splitting tensile strength, modulus of elasticity and abrasion resistance tests were performed. Concrete mixes with RA from CDW from several recycling plants were evaluated, in order to understand the influence that the RA's collection point, and consequently their composition, has on the characteristics of the mixes produced. The analysis of the mechanical performance allowed concluding that the use of RA worsens most of the properties tested, especially when fine RA are used. On the other hand, there was an increase in abrasion resistance when coarse RA were used. In global terms, the use of this type of aggregates, in limited contents, is viable from a mechanical viewpoint. (C) 2015 Elsevier Ltd. All rights reserved
Miguel Bravo; Jorge de Brito; Jorge Pontes; Luis Evangelista. Mechanical performance of concrete made with aggregates from construction and demolition waste recycling plants. Journal of Cleaner Production 2015, 99, 59 -74.
AMA StyleMiguel Bravo, Jorge de Brito, Jorge Pontes, Luis Evangelista. Mechanical performance of concrete made with aggregates from construction and demolition waste recycling plants. Journal of Cleaner Production. 2015; 99 ():59-74.
Chicago/Turabian StyleMiguel Bravo; Jorge de Brito; Jorge Pontes; Luis Evangelista. 2015. "Mechanical performance of concrete made with aggregates from construction and demolition waste recycling plants." Journal of Cleaner Production 99, no. : 59-74.
Miguel Bravo; Jorge De Brito; Jorge Pontes; Luis Evangelista. Durability performance of concrete with recycled aggregates from construction and demolition waste plants. Construction and Building Materials 2015, 77, 357 -369.
AMA StyleMiguel Bravo, Jorge De Brito, Jorge Pontes, Luis Evangelista. Durability performance of concrete with recycled aggregates from construction and demolition waste plants. Construction and Building Materials. 2015; 77 ():357-369.
Chicago/Turabian StyleMiguel Bravo; Jorge De Brito; Jorge Pontes; Luis Evangelista. 2015. "Durability performance of concrete with recycled aggregates from construction and demolition waste plants." Construction and Building Materials 77, no. : 357-369.
The objective of this research is the production of concrete with recycled aggregates (RA) from various CDW plants around Portugal. The influence of the RA collection location and consequently of their composition on the characteristics of the concrete produced was analysed. In the mixes produced in this research RA from five plants (Valnor, Vimajas, Ambilei, Europontal and Retria) were used: in three of them coarse and fine RA were analysed and in the remaining ones only coarse RA were used. The experimental campaign comprised two tests in fresh concrete (cone of Abrams slump and density) and eight in hardened concrete (compressive strength in cubes and cylinders, splitting tensile strength, modulus of elasticity, water absorption by immersion and capillarity, carbonation and chloride penetration resistance). It was found that the use of RA causes a quality decrease in concrete. However, there was a wide results scatter according to the plant where the RAs were collected, because of the variation in composition of the RA. It was also found that the use of fine RA causes a more significant performance loss of the concrete properties analysed than the use of coarse RA.
Miguel Bravo; Jorge De Brito; Jorge Pontes; Luis Evangelista. Performance of Concrete Made with Recycled Aggregates from Portuguese CDW Recycling Plants. Key Engineering Materials 2014, 634, 193 -205.
AMA StyleMiguel Bravo, Jorge De Brito, Jorge Pontes, Luis Evangelista. Performance of Concrete Made with Recycled Aggregates from Portuguese CDW Recycling Plants. Key Engineering Materials. 2014; 634 ():193-205.
Chicago/Turabian StyleMiguel Bravo; Jorge De Brito; Jorge Pontes; Luis Evangelista. 2014. "Performance of Concrete Made with Recycled Aggregates from Portuguese CDW Recycling Plants." Key Engineering Materials 634, no. : 193-205.
M. Gomes; Jorge De Brito; Miguel Bravo. Mechanical Performance of Structural Concrete with the Incorporation of Coarse Recycled Concrete and Ceramic Aggregates. Journal of Materials in Civil Engineering 2014, 26, 04014076 .
AMA StyleM. Gomes, Jorge De Brito, Miguel Bravo. Mechanical Performance of Structural Concrete with the Incorporation of Coarse Recycled Concrete and Ceramic Aggregates. Journal of Materials in Civil Engineering. 2014; 26 (10):04014076.
Chicago/Turabian StyleM. Gomes; Jorge De Brito; Miguel Bravo. 2014. "Mechanical Performance of Structural Concrete with the Incorporation of Coarse Recycled Concrete and Ceramic Aggregates." Journal of Materials in Civil Engineering 26, no. 10: 04014076.