NHL 3.5 mortars with scrap tire rubber

The use of wastes and industrial by-products as building materials is an important issue in order to decrease costs with waste management and the embodied energy of building products. Scrap tire rubber has been studied as aggregate for cementitious materials. Natural hydraulic limes are natural binders with particular characteristics of both air and hydraulic binders. Their specifications became stricter with the last version of EN 459-1:2010. In this study scrap tire rubber was used as additional aggregate of mortars, based on NHL3.5 and natural sand. Different particle size fractions and proportions of scrap tire rubber were used: a mix obtained almost directly from industry (only after sieving for preparation of particle sizes similar to mortar aggregate) and separated fine, medium and coarse fractions; 0%, 18%, 36% and 54% weight of binder, corresponding to 2.5%, 5% and 7.5% weight of sand. The influence of the rubbers´ additions on the mortars´ fresh state, mechanical and physical performance is presented, namely by flow table consistency, water retention, fresh bulk density, dynamic elasticity modulus, flexural and compressive strength, open porosity and bulk density, capillary absorption, drying and thermal conductivity. The use of the rubber mix coming from the waste tire industry seems advantageous and may open possibilities for use as raw material by the mortars industry.

Evaluation of mechanical soft-abrasive blasting and chemical cleaning methods on alkyd-paint graffiti made on carbonate stones

In the context of this dissertation several studies were developed resulting in submission and publication “Evaluation of mechanical soft-abrasive blasting and chemical cleaning methods on alkyd-paint graffiti made on calcareous stones” to Journal of Cultural Heritage. (http://dx.doi.org/10.101 /j.culher.2014.10.004)

Utilização de colas naturais para placas de derivados de madeira – uma síntese

Resumo: Nos últimos anos tem-se verificado um interesse crescente pela área das colas naturais, em particular na produção de placas de derivados de madeira para utilização no interior das construções. Estas colas parecem ser uma boa alternativa às colas sintéticas, derivadas do petróleo, pois, ao contribuírem para uma melhor qualidade do ar interior associada a uma menor incorporação de energia no produto final, apresentam vantagens interessantes em termos ambientais e de saúde. Nesse sentido fez-se uma revisão da bibliografia sobre a utilização laboratorial e mesmo semi-industrial de colas naturais em placas de derivados de madeira. São apresentados e discutidos alguns exemplos de materiais que estas colas aglutinam, bem como as suas características finais com vista a futuros desenvolvimentos experimentais de placas fabricadas a partir de resíduos agrícolas comuns. Abstract: An increased interest for bio-based adhesives for wood-based panels for building purposes has been arising. This type of adhesives could be a good alternative for petroleum based synthetic adhesives as bio-based adhesives can contribute for healthier indoor environments and, simultaneously, present lower embodied energy. For the previous reasons a bibliographic review was conducted, on the use of bio-based adhesives for the production of wood-based building panels. Some examples of the adhesives, the type of applications and the characterization of the resulting products are presented and compared, bearing in mind contributing for a future increase of research in this area.

Natural hydraulic lime (nhl3.5) mortars with scrap tire rubber

The use of wastes and industrial by-products as building materials is an important issue in order to decrease costs with waste management and the embodied energy of building products. In this study scrap tire rubber was used as additional aggregate of mortars based on natural hydraulic lime NHL 3.5 and natural sand. Different particle size fractions and proportions of scrap tire rubber were used: a mix obtained directly from industry and separated fine, medium and coarse fractions; 0 %, 18 %, 36 % and 54 % of the weight of binder, corresponding to 2.5 %, 5 % and 7.5 % of the weight of sand. As mortars based on NHL specifications became stricter with the current version of EN 459–1:2015, the influence of the rubber’s additions on the mortars’ fresh state, mechanical and physical performance is presented in this work: flow table consistency, water retention, dynamic elasticity modulus, flexural and compressive strength, open porosity and bulk density, capillary absorption, drying and thermal conductivity are studied. The use of the rubber mix coming from the waste tire industry seems advantageous and may open possibilities for use as raw material by the mortars industry.

Development of sandwich panels of customized functionalities for the rehabilitation of the built patrimony

Considering that the future of the construction sector in most European countries will mainly lie in the renovation of the existing building stock, in the next coming years thousands of energy inefficient buildings will need renovation to force EU member states to reach the EU 2020 targets and implement the Energy Performance of Buildings Directive (EPBD). Seeing the actual crisis in the construction sector as an opportunity, this work aims to develop a concept for prefabricated customizable sandwich panels for the multifunctional renovation of buildings, focusing also on technological innovation. More than a conventional solution, this proposal aims to combine sustainable and recycled building materials, available technologies and systems with advanced design and manufacturing tools within an integrated and mass-customizable approach of advanced building renovation prefabricated solutions. The adoption of these new proposed solutions would improve the living standards of the inhabitants of our cities, reducing energy inefficiency and other existing construction/renovation problems, while enabling some advanced features like the incorporation of technical modules that could even monitor the building performance during its full lifetime and the living conditions of its occupants.

Analysis and strengthening of carpentry joints

Joints play a major role in the structural behaviour of old timber frames [1]. Current standards mainly focus on modern dowel-type joints and usually provide little guidance (with the exception of German and Swiss NAs) to designers regarding traditional joints. With few exceptions, see e.g. [2], [3], [4], most of the research undertaken today is mainly focused on the reinforcement of dowel-type connections. When considering old carpentry joints, it is neither realistic nor useful to try to describe the behaviour of each and every type of joint. The discussion here is not an extra attempt to classify or compare joint configurations [5], [6], [7]. Despite the existence of some classification rules which define different types of carpentry joints, their applicability becomes difficult. This is due to the differences in the way joints are fashioned depending, on the geographical location and their age. In view of this, it is mandatory to check the relevance of the calculations as a first step. This first step, to, is mandatory. A limited number of carpentry joints, along with some calculation rules and possible strengthening techniques are presented here.

Recycled steel fibre reinforced concrete failing in bending and in shear

Recent research is showing that the addition of Recycled Steel Fibres (RSF) from wasted tyres can decrease significantly the brittle behaviour of cement based materials, by improving its toughness and post-cracking resistance. In this sense, Recycled Steel Fibre Reinforced Concrete (RSFRC) seems to have the potential to constitute a sustainable material for structural and non-structural applications. To assess this potential, experimental and numerical research was performed on the use of RSFRC in elements failing in bending and in beams failing in shear. The values of the fracture mode I parameters of the developed RSFRC were determined by performing inverse analysis with test results obtained in three point notched beam bending tests. To assess the possibility of using RSF as shear reinforcement in Reinforced Concrete (RC) beams, three point bending tests were executed with three series of RSFRC beams flexurally reinforced with a relatively high reinforcement ratio of longitudinal steel bars in order to assure shear failure for all the tested beams. By performing material nonlinear simulations with a computer program based on the finite element method (FEM), the applicability of the fracture mode I crack constitutive law derived from the inverse analysis is assessed for the prediction of the behaviour of these beams. The performance of the formulation proposed by RILEM TC 162 TDF and CEB-FIP 2010 for the prediction of the shear resistance of fibre reinforced concrete elements was also evaluated.

Seismic behaviour of portuguese rammed earth buildings

Rammed earth is one of the oldest building materials in the world and is present in the Portugal with a particular focus in the South of the country. The mechanical properties and the structural behaviour of rammed earth constructions have been the subject of study of many researchers in the recent years. This study is part of a broader research on vernacular seismic culture in Portugal. Numerical analyses were carried out on a rammed earth masonry construction representative of the vernacular heritage of Alentejo region. Variations in the geometry, constructive characteristics and material properties were implemented and the main conclusions of the non-linear static and modal analysis are presented. Analysing the damage framework allowed interpreting the weaknesses of this type of constructions and consider the most appropriate reinforcement methodologies.

Application of near surface mounted (NSM) strengthening technique to traditional timber frame walls

Timber frame buildings are well known as an efficient seismic resistant structure popular all over the world not only due to their seismic performance, but also to their low cost and the strength they offer. These constructions still exist today and it is important to be able to preserve them, so a better knowledge on their behaviour is sought. Furthermore, historic technologies could be used even in modern constructions to build seismic resistant buildings using more natural materials with lesser costs. A great rehabilitation effort is being carried out on this type of buildings, as their neglect has led to decay or their change in use and alterations to the structure has led to the need to retrofit such buildings; only recently studies on their behaviour have become available and only a few of them address the issue of possible strengthening techniques for this kind of walls. In this scope, an innovative retrofitting technique (near surface mounted steel flat bars) is proposed and validated on traditional timber frame walls based on an extensive experimental program. The results of the static cyclic tests on distinct wall typologies retrofitted with the NSM technique are herein presented and discussed in detail. The main features on deformation, lateral stiffness, lateral resistance and seismic performance indexes are analysed

Assessment of the properties to characterize the interface between clay brick substrate and strengthening mortar

The behaviour of masonry elements under in-plane and out-of-plane loads can be improved through the application of strengthening systems based on reinforcing overlays. After strengthening, the transition region between the original substrate and the strengthening layer is especially stressed, and premature failure of the strengthened masonry is reached if insufficient interfacial capacity is assured. Therefore, the assessment of the mechanical behaviour of the interface is critical to the development of the masonry strengthening system based on the application of strengthening overlays. In this research a method for the characterization of the interface behaviour between two different materials, a polypropylene fibre reinforced mortar (PFRM) and a ceramic brick used for masonry construction is presented. Direct shear tests were carried out in couplet specimens. Due to the orthotropic nature of the bricks surface, the shear load was applied along three different directions in order to perform an overall estimation of the interface behaviour. The peak and residual shear stresses, as well as the failure modes, were obtained at different levels of the normal stress. Based on these experimental results constitutive laws were assessed for the simulation of the interface mechanical behaviour based on the Mohr and Mohr-Coulomb failure criteria.

Using polymers to improve the rutting resistance of asphalt concrete

This study assesses rutting on two types of modified asphalt mixtures containing: (i) amorphous polyolefin polymer and (ii) a particular polymer obtained by combining LDPE (low density polyethylene) and EVA (ethyl-vinyl-acetate). Rutting tests were performed by a wheel tracking device. Stiffness and fatigue tests were carried out to confirm the performance of the asphalt mixtures. The testing showed that polymer modification in this study improved rut resistance without compromising the stiffness and fatigue behavior. The rutting results were fit in the NCHRP 1-37A model and the in situ rutting performance of asphalt mixtures can be predicted.

Materiais compósitos com incorporação de cânhamo industrial

Projeto de Investigação integrado de mestrado Internacional em Sustentabilidade do Ambiente Construído

Development of sandwich panels of customized functionalities for the rehabilitation of the built patrimony

Dissertação de International Master in Sustainable Built Environment

Estudo de revestimentos ativos para o isolamento térmico de edifícios

Dissertação de mestrado em Sustentabilidade do Ambiente Construído

Indicadores chave de sustentabilidade para edifícios residenciais em estrutura metálica

Dissertação de mestrado integrado em Engenharia Civil