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Projeto de investigação
Civil Engineering Research and Innovation for Sustainability
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A sustainable production of natural hydraulic lime mortars through bio-amendment
Publication . García-González, Julia; Faria, Paulina; Pereira, Alice S.; Lemos, Paulo C.; Juan-Valdés, Andrés; CERIS - Polo NOVA; DEC - Departamento de Engenharia Civil; UCIBIO - Applied Molecular Biosciences Unit; DQ - Departamento de Química; LAQV@REQUIMTE; Elsevier
This article examined the effect of a bioproduct suspension obtained from fermentation of biodiesel's crude glycerol when used to formulate natural hydraulic lime mortars, as a fluid replacing the mixing water. The bioproduct was used either sonicated or non-sonicated and two volumes of mixing fluid were tested. The aim was to assess the advantages and drawbacks that could be achieved with a waste-based bioproduct, instead of petrochemical-based additions. The investigation revealed a positive effect on workability, producing mortars with a lower mixing fluid content, improving the mechanical performance. Finally, the bioproducts reduced the mortar water absorption by gravity and capillary.
Finite-Element Limit Analysis Formulation using Bishop's Strength Criterion for Anisotropic Undrained Soils
Publication . Vicente Da Silva, M.; Antão, A. N.; DEC - Departamento de Engenharia Civil; CERIS - Polo NOVA; ASCE - American Society of Civil Engineers
This paper presents a novel finite-element limit analysis formulation employing Bishop's strength criterion - an anisotropic model designed specifically for soils loaded under undrained conditions. The proposed approach employs a three-field mixed finite-element model, previously devised by the authors using the alternating direction method of multipliers (ADMM) framework. In this work, the inherent splitting operator approach associated with ADMM is exploited to seamlessly incorporate the anisotropic criterion. Importantly, the introduction of this new strength criterion does not compromise the formulation's ability to produce strict lower and upper bounds for the collapse loads of mechanical systems. The paper includes several numerical examples, covering two-dimensional (plane strain conditions) and three-dimensional scenarios, to demonstrate the effectiveness of the computational tool in accurately calculating collapse load limits for problems involving undrained anisotropic soils. In addition, these examples highlight the impact of anisotropy on the bearing capacity and stability of geotechnical structures.
Water Resistance of Compressed Earth Blocks Stabilised with Thermoactivated Recycled Cement
Publication . Cruz, Ricardo; Bogas, José Alexandre; Balboa, Andrea; Faria, Paulina; CERIS - Polo NOVA; DEC - Departamento de Engenharia Civil; Molecular Diversity Preservation International (MDPI)
Low water resistance is the main shortcoming of unfired earth materials, requiring chemical stabilisation for some durable applications. Ordinary Portland cement (PC) is an efficient stabiliser, but it goes against the ecological and sustainable nature of earth construction. This study explores the use of low-carbon thermoactivated recycled cement (RC) obtained from old cement waste as a new eco-efficient alternative to PC in the stabilisation of compressed earth blocks (CEBs). The objective is to improve the durability of the CEB masonry even when applied in direct contact with water, without compromising its eco-efficiency. The water resistance of the CEBs with 0% (unstabilised) and 5% and 10% (wt. of earth) stabiliser and partial to total replacement of PC with RC (0, 20, 50, 100% wt.) was evaluated in terms of compressive strength under different moisture contents, immersion and capillary water absorption, low-pressure water absorption, water permeability and water erosion. Low absorption and high resistance to water erosion were achieved in stabilised CEBs, regardless of the type of cement used. The incorporation of RC increased the total porosity and water absorption of the CEBs compared to PC, but significantly improved the water resistance of the unstabilised blocks. The eco-friendlier RC proved to be a promising alternative to PC stabilisation.
Toward a Novel Energy-Dissipation Metamaterial with Tensegrity Architecture
Publication . A. Santos, Filipe; CERIS - Polo NOVA; DEC - Departamento de Engenharia Civil; John Wiley & Sons, Ltd.
The interest in novel energy-dissipation devices that offer advanced functionalities for optimal performance in state-of-the-art engineering applications is growing. In this regard, a highly tunable and innovative dissipator is developed. This dissipator features movement amplification capabilities resulting from the radial replication of a unit-cell with tensegrity architecture. The kinematic response of the dissipator is analyzed for several layouts, by varying the number of unit-cells within the device, their internal geometry, and identifying the corresponding locking configurations. A fully operational 3D-printed prototype is presented, demonstrating its excellent performance in terms of damping capabilities and feasibility. The experimental results are used to validate a numerical model of the flower unit. This model demonstrates the importance of pre-strain on the overall stiffness and dissipative features of the proposed system. By utilizing these numerical models, it is shown that the proposed device can be used as a building block for more complex assemblies such as periodic metamaterials with tensegrity architecture.
The use of bio-oil from biodiesel production for enhancing the bitumen healing
Publication . Cabette, Marina; Micaelo, Rui; Pais, Jorge; CERIS - Polo NOVA; DEC - Departamento de Engenharia Civil; Elsevier
Road pavements are exposed to traffic and temperature effects that produce distress, mainly cracking that leads to pavement failure, after which rehabilitation actions are necessary to extend pavement life. Bio-rejuvenators have been used to recover the bitumen properties lost due to fatigue of the asphalt mixtures and ageing due to temperature variations and oxidation. Thus, this paper investigates the healing of bitumen modified with bio-oil derived from biodiesel production. One base bitumen in three different ageing stages (unaged, short and long-term ageing) was used for adding up to 3% of bio-oil to the bitumen. In addition to consistency and rheological tests to characterise the modified bitumen, fatigue resistance tests with and without rest periods were performed to assess the healing through three indexes, relating the complex shear modulus, the number of cycles to failure and the amount of damage, after a rest period. It was verified that the healing follows an exponential law with the rest period, but the number of cycles in each loading period decreases compared to the previous period. For a 15-minute rest period, the healing was limited to 26.9%, but the bio-oil contributed significantly to that restoration.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
6817 - DCRRNI ID
Número da atribuição
UIDB/04625/2020