Loading...
Research Project
Centre of Materials and Building Technologies
Funder
Authors
Publications
An Input in the Asian Wasp Nest (AWN) Study
Publication . Pinto, Jorge; Ginja, Mário; Nepomuceno, Miguel C. S.; Pereira, Sandra
The Asian Wasp Nest (AWN) is an impressive and robust natural construction built by an insect. The building process occurs during spring and summer. This type of nest is not reused. The scale size between the Asian wasp and the AWN is substantial. In Portugal, we can find AWN on trees, roofs, balconies, chimneys, and other possibilities. When the AWN is built on trees, the tree's branches work as support. The complexity of this natural construction in terms of shape motivated this research work. Therefore, an AWN sample was used in order to obtain some information concerning this technical aspect. In this context, X-ray tests were performed to give guidance about the internal structure of the AWN without damaging it. The obtained experimental results show the richness of this type of construction. Understating the AWN may guide new building processes, different structural shapes, alternative natural building materials, and passive building technics, among other constructive fields.
Overview of Energy Systems in Africa: A Comprehensive Review
Publication . Santos, Michael M.; Ferreira, Ana Vaz; Lanzinha, João
Africa has abundant solar resources but only 2% of its current capacity is generated from renewable sources. Photovoltaics (PV) offer sustainable, decentralized electricity access to meet development needs. This review synthesizes the recent literature on PV in Africa, with a focus on Mozambique. The 10 most cited studies highlight the optimization of technical components, such as storage and bifacial modules, and challenges in integrating large-scale PV. Case studies demonstrated Mozambique’s potential for PV applications in water heating, irrigation, and rural electrification. These benefits include reduced emissions and energy access. However, barriers, such as high costs, lack of infrastructure, and training, exist. While solar cookers are insufficient, thermal systems have unrealized potential. Mozambique’s urban and rural electrification rates are 57% and 13%, respectively, despite its energy resources. Targeted policies, financing, and community engagement are essential for promoting adoption. While PV can sustainably expand electricity access, coordinated efforts must address costs, infrastructure, maintenance, and social factors for successful implementation. Mozambique has immense solar potential, but strategic planning and support are critical to unlocking these benefits. This review provides insights into optimizing PV systems and policy frameworks for a clean and inclusive energy production future in Africa, to synthesize the 10 most cited studies on photovoltaic solar energy in Africa, and to deeply reflect upon the current energy needs in Mozambique, the benefits of employing PV and solar thermal systems, and the challenges of implementing such systems within the Mozambican context.
Experimental evaluation of the potential use of waste recycled concrete fine aggregates to produce self-compacting concrete
Publication . Pinto, Hugo; Nepomuceno, Miguel; Bernardo, Luís; Oliveira, Luiz Pereira de
The current concern with sustainability in the construction sector has led to the adoption of processes to minimise the impact on the environment. The use of recycled concrete aggregates in self-compacting concrete (SCC), as an alternative to natural aggregates, seems to be a solution with great potential. However, it is common knowledge that the use of recycled aggregates in the production of SCC instead of natural aggregates may causes changes in some of its properties, both in the fresh and hardened state, and that the magnitude of those changes will depend on the percentages of incorporation and the nature of recycled aggregates. When using the mix design methodology proposed by Nepomuceno et al, SCC is assumed to be consisted basically of two phases, namely, the liquid phase (mortar phase) and the solid phase (coarse aggregates), being the main SCC properties controlled by the mortar phase. In this perspective, this research work reports the results obtained when testing mortars with flow properties appropriate to produce SCC, when binary and ternary blends of powder materials were used and natural fine aggregates were partially replaced by recycled concrete fine aggregates. The experimental program carried out involved, in a first stage, the production and testing of 11 binary mortar mixtures suitable for the production of SCC, with replacement percentages of natural fine aggregate by recycled concrete fine aggregate varying from 0% (reference mixture) to 50%, in 5% increments. Subsequently, 6 ternary mortar mixtures were produced and tested for the same purpose, with replacement percentages of natural fine aggregate by recycled concrete fine aggregate varying from 0% (reference mixture) to 50%, in 10% increments. Binary mortars included Portland cement type I 42.5R and limestone powder, while ternary mortars included Portland cement type I 42.5R, limestone powder and fly ash. In both cases, the dosages of superplasticizer and mixing water were determined experimentally to obtain the required fresh properties suitable to produce SCC. The results indicate that the 28 days age compressive strength and density of the mortars decrease with the increase in the percentage of incorporation of recycled concrete fine aggregates, regardless of whether they are mortars with binary or ternary blends of powders. In binary mixtures, the mixing water dosage increases with the percentage of incorporation of recycled aggregates, while in ternary mixtures the opposite occurs, at least up to a percentage of 40% of incorporation of recycled aggregates. The superplasticizer dosages, necessary to obtain the appropriate flow properties, were always higher in the ternary mixtures compared to the binary mixtures, even comparing only the reference mixtures. It can be concluded that mortars with the incorporation of recycled concrete fine aggregates constitute a viable material with potential for use in the construction industry, provided that the necessary adjustments to its performance are considered, thus contributing to the sustainability of construction.
Passive Solar Systems for the Promotion of Thermal Comfort in African Countries: A Review
Publication . Santos, Michael M.; Ferreira, Ana Vaz; Lanzinha, João
Globally, the residential sector consumes a significant amount of energy. Therefore, bioclimatic architectural systems which consider passive solutions should be studied, analyzed, and implemented to reduce energy consumption. This review aims to promote thermal comfort in African countries by using passive solar systems. It begins with the keyword thermal comfort and then reviews articles published over the last ten years that consider bioclimatic architecture and construction strategies in Africa, the main trends in scientific research in this field, and the possibilities for each climate zone in achieving the highest degree of climate comfort. Following an extensive review, certain bioclimatic architectural strategies adopted in specific countries can be applied in countries with similar climates and this can contribute to significant energy savings through effective functional solar and ventilation design strategies. Several countries have been identified as having the most significant publications on thermal regulations in buildings, and the associated regulations and projects are discussed. Several studies have also examined static and adaptive models of thermal comfort.
Microstructural properties of Asian hornet nest paper-like materials: Preliminary step towards biomimicry materials for civil engineering applications
Publication . Sedira, Naim; Pinto, Jorge; Gomes, Ana; Nepomuceno, Miguel; Pereira, Sandra
This paper presents a comprehensive examination of the microstructure and mineralogy of the paper-like material found in Asian hornet nests (referred to as AHN P-LM) and the nearby tree leaves, utilising scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD). The analysis conducted through SEM-EDS demonstrates that AHN P-LM is primarily composed of plant fragments, with slight traces of inorganic substances (such as CaOx). The thread-like morphologies observed in the SEM analysis, which are linked to the secretion of hornets, warrant attention due to their significance in understanding the microstructure of AHN P-LM. The presence of nitrogen (N) in the EDS analysis of AHN P-LM, in contrast to its absence in analysed leaves, strongly implies that the nitrogen originates from hornet saliva. Additionally, SEM-EDS analysis revealed the impact of chemical composition variations on colour differences within AHN P-LM. Furthermore, X-ray diffraction analysis on ash samples from AHN P-LM confirmed the presence of minerals such as quartz, lime, phlogopite, and microcline. These findings about mineral composition align closely with results obtained from SEM-EDS analyses, presenting various aspects related to understanding the structure and compositional makeup of AHN P-LM. Biomimicry principles can be applied to draw inspiration from the AHN P-LM for replication in the civil engineering field, facilitating innovative solutions. Understanding hornet behaviour and nest material composition is essential. Future outlook includes utilising these materials in wood construction, 3D printing for structural components, shelters, infrastructure repair, green building, and architectural innovation.
Organizational Units
Description
Keywords
Contributors
Funders
Funding agency
Fundação para a Ciência e a Tecnologia
Funding programme
6817 - DCRRNI ID
Funding Award Number
UIDB/04082/2020