João Pacheco

c5Lab - Sustainable Construction Materials Association · Use of recycled materials

The bias factor of the Eurocode 2 [CEN (European Committee for Standardization) (2008). Eurocode 2: Design of Concrete Structures-Part 1-1: General Rules and Rules for Buildings] and ACI 318 [ACI (American Concrete Institute) (2014). Building Code Requirements for Structural Concrete and Commentary] flexural resistance models of reinforced concrete...

The model uncertainty of the shear resistance equations of three design codes {the current Eurocode 2 (2004), Model Code (2010), and the final draft of the Eurocode 2 (2020)} was investigated for coarse natural and recycled aggregate concrete beams. Databases of beams with and without shear reinforcement were made with clearly defined criteria. The...

This two-part paper presents a study about the structural safety of pultruded fibre-reinforced polymer (FRP) profiles with respect to global buckling phenomena, which often govern their ultimate limit states design: flexural buckling, flexural-torsional buckling and lateral-torsional buckling. The first part [1] presented the resistance models for...

This 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...

Research argues in favor of using recycled aggregates in structural concrete. However, lack of specific clauses in standards for recycled aggregate concrete design hinders the use of recycled aggregate concrete by the industry. Recycled aggregate concrete‐specific design clauses are hindered because conventional research must be complemented with e...

SUMÁRIO Este artigo desenvolve composições de betão com agregados reciclados para utilização por uma central de betão pronto. São utilizadas as composições de betão e matérias-primas da central e os agregados reciclados são utilizados tal como fornecidos pelo operador de gestão de resíduos. As opções tomadas durante o estudo foram decididas em conj...

This 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 S...

This paper presents a modified Mazars damage model, based on a strain formulation, for the physically nonlinear analysis of concrete structures. The main objective is to propose a modified damage model, in which both tension and compression damage evolution laws are regularized using a classical fracture energy methodology. The original loading fun...

This paper concerns the recovery of construction and demolition waste as coarse recycled aggregates for concrete. Coarse recycled aggregates may be used as a partial or total replacement of natural aggregates, contributing to the circular economy and minimizing landfill disposals as well as the consumption of natural mineral resources. However, con...

The incorporation of recycled aggregates in concrete not only reduces the extraction of natural resources, but also decreases landfill disposal of construction and demolition waste. Hence, environmental impacts and costs are reduced, promoting the use of recycled aggregates and circular economy. However, the impacts of transport depend on the dista...

This 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 reliabilit...

To facilitate the assessment of concrete mix design and of its mechanical behaviour, numerical modelling techniques at meso-scale are currently being popularized as a valuable tool in materials and structural engineering. Generally, the structure of concrete at the mesoscale model is recognized as a three-phase heterogeneous material consisting of...

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...

Recycled aggregate concrete is a solution used to minimize the environmental impact of the concrete industry. Notwithstanding research worldwide validating structural applications of recycled aggregate concrete, specific design guidelines are lacking and are needed to address reservations of construction agents. Design guidelines should be based on...

This two-part paper proposes a resistance format and partial factors for the global buckling of FRP profiles based on reliability analysis and partial factor calibration. Most current recommendations for the design of structural members made with FRP materials are not grounded on reliability concepts and this poses questions concerning safety and e...

The search for more sustainable construction materials, capable of complying with quality standards and current innovation policies, aimed at saving natural resources and reducing global pollution, is one of the greatest present societal challenges. In this study, an innovative recycled aggregate concrete (RAC) is designed and produced based on the...

An analysis on the effect of the incorporation of coarse recycled concrete aggregates on the bond strength between concrete and embedded steel reinforcement is presented. The model's uncertainty of the Level I provision of the anchorage length of fib Bulletin 72 on ribbed steel/recycled aggregate concrete bond is quantified. Afterwards, reliability...

An investigation on the scatter of code-type constitutive models that relate compressive strength (fc) with tensile strength (fct) and Young’s modulus (Ec) of standard concrete specimens is presented. The influence of the mix design on the accuracy of the fc vs. fct and fc vs. Ecrelationships is discussed, with emphasis on the lithological type and...

This paper evaluates and compares the statistics of compressive strength data from three Portuguese ready-mixed concrete plants. A hierarchical model showed that different groups of concrete strength records are not statistically equivalent, even if they were produced in the same plant and using the same concrete composition. This finding is relate...

This paper investigates the effect of recycled coarse aggregate incorporation on the relationship between 150 mm cubic and Փ 150 mm cylindrical compressive strength (the reference strength of standards) by comparing data from recycled and natural aggregate concrete compositions in which both cubes and cylinders were tested. A conversion factor from...

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 polycar...

Sustainability is a pressing concern of the 21st century. Social development in most countries is raising awareness of the needs of future generations and legislation to protect the present and future quality of life. These needs are compelling various sectors, including construction, to find sustainable solutions. This paper investigates the feasi...

A study regarding the structural behavior of four three-dimensional, full-scale, recycled-aggregate concrete frame structures was carried out. This paper describes the final tests, which consisted of destructive horizontal tests, with incremental monotonic loading, in accordance with a pushover analysis. The test structures had a varying content of...

The incorporation of recycled aggregates produced from concrete waste is an option that could reduce the consumption of natural resources and landfill disposal, with significant environmental gains. Several investigations have been conducted to study the viability of this use of concrete waste, with a focus on the material, mechanical and durabilit...

Este artigo apresenta os resultados de uma campanha experimental desenvolvida com o intuito de avaliar o efeito da incorporação no betão de agregados provenientes da reciclagem de elementos de betão produzidos pela indústria da pré-fabricação. Pretendeu-se, em particular, estudar a utilização da fracção grossa destes agregados reciclados em diferen...

Aiming at characterizing the behaviour of concrete structures made with coarse aggregates recycled from crushing concrete elements from the precast industry, extensive testing was performed in four full-scale recycled concrete structures, made with various recycled aggregate ratios. This paper concerns the in situ concrete characterization tests ca...

This paper presents the results of an experimental campaign developed with the aim of evaluating the effect of the incorporation in concrete of recycled aggregates from crushed elements produced by the precasting concrete industry. The specific purpose was to study the use of the coarse fraction of these aggregates. This was done by studying variou...

In an effort to study the behaviour of concrete structures made with coarse aggregates recycled from crushing concrete elements from the precast industry, extensive testing was performed in four full-scale recycled concrete structures, made with various recycled aggregate ratios. This dissertation describes the design and modelling of the test stru...

Este artigo apresenta os resultados de uma campanha experimental desenvolvida com o intuito de avaliar o efeito da incorporação no betão de agregados provenientes da reciclagem de elementos de betão produzidos pela indústria da pré-fabricação. Pretendeu-se, em particular, estudar a utilização da fracção grossa destes agregados reciclados em diferen...