Micromechanical modelling based on the Discrete Element Method (DEM) has been widely used to investigate asphalt behaviour due to its ability to represent an irregular microstructure with variable-sized aggregates, bitumen and voids. The 3D rigid particle models with randomly distributed spherical particles and adopting elastic and/or simple viscoelastic models at the contacts are the standard approach, however, in recent years, a significant research effort is noted to incorporate real particle morphologies in the numerical models.In this study, a previously developed 3D DEM model of asphalt employing a generalised Kelvin contact model formulation for the viscoelastic contacts is further improved with realistic particle shapes representing the coarse aggregates. A digital library of aggregate shapes was created from the X-ray computed tomography (CT) scan of an asphalt specimen, using an adaptive image-processing method to separate the aggregates in the CT images and the Delaunay triangulation method to define the aggregate 3D surface model. Several virtual aggregates with different sizes were selected from the library to represent the coarse aggregate gradation of the modelled 3D DEM asphalt specimen. Each virtual aggregate is discretized with smaller spherical particles and its deformability is taken into account through the inner particle contacts. The numerical asphalt specimens with realistic particle shapes were submitted to uniaxial tension-compression cyclic tests to determine the stiffness properties, and the results were compared with those of the numerical specimens with all constituents represented by single spherical rigid particles. As shown, the proposed methodology greatly enhances the 3D DEM model's ability to simulate the asphalt behaviour.

LAYERS project proposes to explore, using geophysical methods, such as ground penetrating radar (GPR), in the thickness of the walls and in the soil depth around buildings of heritage interest, the layers in which the history of constructive and decorative elements, such as azulejos, may be resolved. In this paper, the results of some GPR sensitivity tests are presented. These tests were performed at Laboratório Nacional de Engenharia Civil (LNEC) campus and at Museu do Azulejo, on walls covered with azulejo, ceramic pieces, clay bricks and clay tiles, and on floors covered by stone slabs, to evaluate the ability of GPR to distinguish the different types of wall and floor coverings in historic buildings.

The presentation delves into Portugal's initiatives dedicated to enhancing the environmental performance of buildings. It specifically examines national strategies, building regulations, certification systems, incentive programs, and efforts to raise public awareness. Its scope are four vital resources: energy, water, materials, and waste. Ultimately, the conclusion is that over the past 10 years, sustainable building has evolved from an emerging trend into a widely recognized challenge that consistently permeates discussions within the construction industry, catalysing a shift in practices.

Railway tracks consist of various components and experience different support conditions along the longitudinal axis. The vertical stiffness of railway tracks varies significantly in space and time, and the resilient properties of the supporting layers are also affected by several factors. While many studies propose complex behaviour models for geomaterials to represent these variations, very little work has been done to account for the random variability of these properties over space and time. In this study, 133-m long 3D train-track numerical models were used to investigate different scenarios with stochastic spatial variability in the ballast layer. The used finite element method program

LAYERS research project* proposes to explore, using geophysical methods, such as ground penetrating radar (GPR) and electrical resistivity, in the thickness of the walls and in the soil depth around buildings of heritage interest, and the layers in which the history of constructive and decorative elements, such as azulejos, may be revealed. In this paper, the results of some GPR and electrical resistivity tomography profiles carried out at Museu do Azulejo are presented. Preliminary results point to the identification of tombstones thickness, pathway detection of water supply system between two cloisters, and the possible presence of an underground water tank.

Presentation of LNEC's activity in support of innovative products for construction

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Keeping an effective disinfectant residual concentration in reclaimed water is still a challenge due to its high levels of ammonia and organic matter when compared with those in drinking water. Particularly, in reclaimed water containing ammonia, chloramines formation is expected. This paper presents a novel mechanistic chlorine decay model, integrating the reaction schemes of monochloramine auto-decomposition with a kinetic mechanism accounting for reactive chlorine species decay in the presence of organic matter. A parallel second order mechanism, where monochloramine reacts both with fast and slow organic matter reactive fractions, was identified as the most suitable and a successful calibration of the model was achieved. Further studies are being conducted to promote the ease of use of the model by correlating the model parameters with quality parameters related to the organic matrix of the waters.

Comunicação apresentada no XVI Seminário Ibero-Americano sobre Sistemas de Abastecimento e Drenagem (SEREA 23), 11-13 de julho, Córdoba, Espanha.

As infraestruturas de abastecimento e saneamento da água são importantes consumidores de eletricidade, tendo sido feitos esforços nos últimos anos para aumentar a sua eficiência energética. Em tempo de chuva, os aumentos dos caudais de águas residuais afluentes às estações elevatórias (EE) e estações de tratamento de águas residuais (ETAR) pode levar a acréscimos significativos no consumo de energia. Esses aumentos de caudal ocorrem tanto nos sistemas unitários, como em sistemas separativos de águas residuais, devido às afluências indevidas. O controlo da afluência de caudais pluviais ou de infiltração da água do solo no sistema de águas residuais domésticas é um desafio difícil que tem merecido uma atenção crescente nos últimos anos.