41 documents found, page 1 of 5
Thermal performance of concrete with reactive magnesium oxide as an alternative...
Forero Valencia, Javier Andres; Bravo, Miguel; Pacheco, João; Brito, Jorge de; Evangelista, LuisThis study evaluates the thermal conductivity of concrete produced with reactive magnesium oxide (MgO) as a partial replacement for cement. MgO is a viable option for the concrete industry, mainly due to its benefits in sustainability and reducing CO2 emissions compared to cement emissions. Four different MgO's produced in Australia, Canada, and Spain were used in concrete mixes as a partial replacement of ceme...
Mechanical performance and autogenous and drying shrinkage of MgO-based recycle...
Revilla-Cuesta, V.; Evangelista, Luis; Brito, Jorge de; Skaf, Marta; Ortega-López, VanesaThe high strength and durability of high-performance concrete (HPC) may be significantly reduced by shrinkage cracking. The use of reactive magnesium oxide (MgO) can reduce shrinkage of cement-based materials due to its expansive properties. This study intends to analyse the validity of MgO as shrinkage-reducing agent in recycled aggregate HPC. To do so, ten HPC mixes with 0%, 25%, and 100% of both early-age (7...
Improvement of the quality of recycled concrete aggregate subjected to chemical...
Forero, Javier A.; De Brito, Jorge; Evangelista, Luis; Pereira, CláudioThe main factor that alters the quality of recycled concrete aggregate (RCA) is the paste adhered to the natural aggregate (NA). Since it causes weakening of the interfacial transition zone (ITZ) between the aggregate and the cementitious paste, it becomes a determining factor for the mechanical behavior of concrete. It turns out that it is critical to enhance this interface by improving the surface of the aggr...
Eurocode shear design of coarse recycled aggregate concrete: reliability analys...
Pacheco, João; Brito, Jorge de; Chastre, Carlos; Evangelista, LuisThis paper contributes to the definition of design clauses for coarse recycled aggregate concrete. One of the main reasons for scepticism towards recycled aggregate concrete is the perceived notion that the heterogeneity of recycled aggregates may increase the uncertainty of the behaviour of concrete. Therefore, the paper uses structural reliability concepts to propose partial factors for recycled aggregate con...
Bond of recycled coarse aggregate concrete: model uncertainty and reliability-b...
Pacheco, João; Brito, Jorge de; Chastre, Carlos; Evangelista, LuisThis paper concerns the design of lap splice lengths for ribbed steel reinforcement bars embedded in concrete produced with coarse recycled concrete aggregates. Recycled aggregates are weaker and typically lead to concrete with lower tensile strength. Both aspects change the model uncertainty of bond strength formulae and a major topic of the paper is the influence of recycled aggregates on the model uncertaint...
Fracture behaviour of concrete with reactive magnesium oxide as alternative binder
Forero, J. A.; Bravo, M.; Pacheco, João; De Brito, Jorge; Evangelista, LuisThis 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 toughne...
Durability and shrinkage performance of concrete made with coarse multi-recycle...
Silva, Stefano; Evangelista, Luis; De Brito, JorgeSince construction is one of the most environmental impacting activities in existence, it is important to study and develop solutions to make its processes more efficient. Thus, multiple-recycling of concrete presents itself as a possible alternative for the reutilization of construction and demolition waste (CDW) over a large period of time. This paper presents the results and conclusions obtained from an exte...
Performance of mortars with commercially-available reactive magnesium oxide as ...
Bravo, Miguel; Forero, Javier A.; Nobre, José; De Brito, Jorge; Evangelista, LuisThis 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 e...
Effect of the maturity of recycled aggregates on the mechanical properties and ...
Revilla-Cuesta, V.; Evangelista, Luis; Brito, Jorge de; Ortega-López, Vanesa; Manso, Juan M.The high cement content of high-performance concrete (HPC) results in improved strength, but also in large shrinkage. The substitution of natural aggregates (NA) with recycled aggregates (RA) notably affects these properties in conventional concrete. This study intends to analyse the effect of the content of RA and their maturity (time elapsed between casting and crushing of the parent concrete from which RA ar...
Magnesia (MgO) production and characterization, and its influence on the perfor...
Nobre, José; Hawreen, Ahmed; Bravo, Miguel; Evangelista, Luis; De Brito, JorgeThis 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 pr...