Papers by maria rita ribeiro
Fibre-Reinforced Polymer Reinforcement for Concrete Structures, 2003
Restoration of Buildings and Monuments, 2013
In the present study, fire reaction and mechanical behaviour improvements of an epoxy polymer mor... more In the present study, fire reaction and mechanical behaviour improvements of an epoxy polymer mortar (PM) formulation, induced by binder modification with alumina particles at micro and nano-size levels, were analysed and quantified. For this purpose, several series of PM specimens, modified with different types of microparticles, nanoparticles and nanodispersion of aluminium oxide were manufactured and tested for fire reaction, flexural and compressive load carrying capacities. Obtained results were compared with those obtained for plain epoxy polymer mortars. Fire reaction properties, such as time to ignition, heat release rate, smoke extinction area, carbon monoxide and carbon dioxide yield rates were assessed by means of cone calorimeter test. Test results revealed that the addition of alumina particles to binder matrix of polymer mortars, even in small amounts (3.9 % in weight of total mass), are effective in improving flexural and compressive behaviours of resultant polymer mortars, especially in the case of alumina nanoparticles. However larger amounts of aluminium oxide nanoparticles will be required to attain effective levels of fire retardancy.
Materials Today: Proceedings, 2015
This study is aimed at developing a new type of unsaturated polyester based composite material wi... more This study is aimed at developing a new type of unsaturated polyester based composite material with enhanced fire retardancy through polymer matrix modification with nano/micro oxide particles, such as silicon dioxide, carboncoated silicon dioxide and aluminium oxide, in combination with common flame retardants systems. For this purpose, the design of experiments based on Taguchi methodology and analyses of variance were applied. Samples with different material and processing parameters resultant from L9 Taguchi orthogonal array were produced, and their fire and mechanical properties were assessed and quantified by vertical flammability tests (UL-94), flexural and Charpy impact tests. The effect of the sonication time of mixtures on final properties was also assessed. It was found that both material and processing parameters have different effects on the various analysed properties. The results revealed that addition of hybrid flame retardant systems introduced reasonable improvements in at least one fire reaction property; however, filler addition also led to decreases in some mechanical properties, most likely due to poor matrix-filler adhesion. Future studies are anticipated in order to improve mix design formulations towards further fire retardancy enhancement without significantly compromising mechanical properties.
Polymer concrete is a material where a thermoset resin binds together natural or artificial aggre... more Polymer concrete is a material where a thermoset resin binds together natural or artificial aggregates. This material combines high compressive strength with very high corrosion resistance. However its general mechanical behaviour is brittle. In this work, cork granules and wood shavings are added to the formulation in order to improve the ductility and reduce weight, taking advantage of its low stiffness and low density, respectively. In addition, these organic materials also exhibit large compressive strains, which may lead to a more energy absorbing concrete material. Flexural and compressive tests were performed and load vs. displacement curves were plotted up to failure. Both the influence of organic aggregate weight fraction and organic aggregate type were considered in the mechanical behaviour. The results anticipate a very interesting expectation in terms of lighter modified polymer concretes with a less brittle behaviour.
Key Engineering Materials
Journal of Physics: Conference Series, 2015
Polymer binder modification with inorganic nanomaterials (NM) could be a potential and efficient ... more Polymer binder modification with inorganic nanomaterials (NM) could be a potential and efficient solution to control matrix flammability of polymer concrete (PC) materials without sacrificing other important properties. Occupational exposures can occur all along the life cycle of a NM and "nanoproducts" from research through scale-up, product development, manufacturing, and end of life. The main objective of the present study is to analyse and compare different qualitative risk assessment methods during the production of polymer mortars (PM) with NM. The laboratory scale production process was divided in 3 main phases (pre-production, production and post-production), which allow testing the assessment methods in different situations. The risk assessment involved in the manufacturing process of PM was made by using the qualitative analyses based on: French Agency for Food, Environmental and Occupational Health & Safety method (ANSES); Control Banding Nanotool (CB Nanotool); Ecole Polytechnique Fédérale de Lausanne method (EPFL); Guidance working safely with nanomaterials and nanoproducts (GWSNN); Istituto Superiore per la Prevenzione e la Sicurezza del Lavoro, Italy method (ISPESL); Precautionary Matrix for Synthetic Nanomaterials (PMSN); and Stoffenmanager Nano. It was verified that the different methods applied also produce different final results. In phases 1 and 3 the risk assessment tends to be classified as medium-high risk, while for phase 2 the more common result is medium level. It is necessary to improve the use of qualitative methods by defining narrow criteria for the methods selection for each assessed situation, bearing in mind that the uncertainties are also a relevant factor when dealing with the risk related to nanotechnologies field.
Materials Science Forum, 2008
In the present study, fire reaction improvement of an epoxy polymer mortar (PM) formulation, indu... more In the present study, fire reaction improvement of an epoxy polymer mortar (PM) formulation, induced by polymer modification with three different flame retardant (FR) systems, was analyzed and quantified. For this purpose, several epoxy PM formulations, modified with different contents and/or types of phosphate, metal hydroxide and brominated based FR systems, were manufactured and tested for both, fire reaction and flexural strength. The results were compared with those of plain epoxy PMs. Fire reaction of PM formulations was assessed by means of the Oxygen Consumption Calorimeter test, also known as Cone Calorimeter test. This test allows the determination of the main parameters that assess fire reaction behaviour of combustible materials: heat release rate, smoke extinction area, carbon dioxide and monoxide release rates, and ignitability. Test results revealed that all FR systems, in particular the phosphate based one, are effective in improving fire reaction performance of epox...
Key Engineering Materials, 2014
Unsaturated polyester based composites materials present several improved properties over convent... more Unsaturated polyester based composites materials present several improved properties over conventional materials. However, these composites show great sensitivity to high temperatures and poor fire behaviour. In the present study, an effort is undertaken to develop new unsaturated polyester composites with improved fire reaction behaviour by matrix modification with hybrid flame retardant systems based on nanooxides and phosphinates. For this purpose, a series of composite formulations containing different contents and types of both metal oxide nano/micro particles and organic phosphinates were manufactured, with basis on the Taguchi L9 orthogonal array, and tested for fire reaction and mechanical properties. The data treatment was carried out through analyses of variance. Fire reaction properties were analysed and quantified by the vertical flammability test (UL-94), and the mechanical properties were studied by flexural, Shore D, and Charpy impact tests. The results were compared ...
Mechanics of Composite Materials, 2009
mer mor tars, ep oxy and poly es ter ma tri ces, weath er abil ity, nat u ral and ar ti fi cial w... more mer mor tars, ep oxy and poly es ter ma tri ces, weath er abil ity, nat u ral and ar ti fi cial weath er ing tests The weath er ing re sis tance of two dif fer ent poly mer mor tar (PM) for mu la tions to strong cor ro sive en vi ron ments is an a lyzed and as sessed by means of both nat u ral and ar ti fi cial weath er ing tests. In an ex per i men tal pro gram, spec imens of both for mu la tions were ex posed to the nat u ral en vi ron ment dur ing one year at a mar i time site in the mid dle of Por tu gal. In an other ex per i men tal pro gram, by means of a so lar box and salt fog cham ber de vices, the ef fects of ar ti fi cial weath er ing were con sid ered. The flex ural strength re tained af ter ex po sure to the en vi ron ments was the key pa ram e ter for as sess ing the weath er abil ity of the PM for mu la tions. Ac cel er a tion fac tors, based on a one-year time scale, were de ter mined and em ployed to pre dict the flex ural strength of the ma te ri als un der a long-term out door expo sure at a nat u ral mar i time site. 515 0191-5665/09/4505-0515 © 2009 Springer Sci ence+Busi ness Me dia, Inc. *Com pos ite Ma te ri als Unit, In sti tute of Me chan i cal En gi neer ing and In dus trial Man age ment (INEGI), Rua do Barroco 174, 4465-591 Leca do Balio, Por tu gal.
Materials Science Forum, 2010
The aim of this work is to assess the feasibility of using polymer mortars reinforced with untrea... more The aim of this work is to assess the feasibility of using polymer mortars reinforced with untreated natural fibres instead of artificial ones, for applications requiring highly alkali resistant materials, such as tanks and drainage systems for wastewater treatment plants. For this purpose, several formulations of polyester polymer mortars reinforced with different contents of jute and piassava natural fibres were investigated. Flexural and compressive behaviour, before and after exposure to a strong alkaline solution was analysed and quantified. Test results highlighted the high potential of these materials as basis construction material for precast applications requiring specific resistance under alkaline environments.
Materials Science Forum, 2010
The aim of this investigation work is threefold: 1) To analyse and quantify freeze-thaw resistanc... more The aim of this investigation work is threefold: 1) To analyse and quantify freeze-thaw resistance of glass fibre reinforced epoxy polymer mortars, comparatively to both normal cement mortars and plain epoxy polymer mortars; 2) To determine glass fibre reinforcement effect on freeze-thaw behaviour; and 3) To evaluate the reliability of ASTM C666M-03 test methodology for the assessment of freeze-thaw resistance of polymer concrete materials. For this purpose several test specimens, normal cement mortars, plain and glass-fibre reinforced epoxy polymer mortars were submitted to freeze-thaw cycling between 36 up to 300 cycles, according to the above norm. Dynamic elasticity modulus, with basis on fundamental resonance frequency measurements, was calculated every 36 cycles, and the correspondent relative dynamic elasticity modulus was determined for each cycling period. In order to assess the reliability of this non-destructive test methodology, three specimens of each formulation were withdrawn at regular periods and tested in bending and compression. Relative mechanical strengths, as function of conditioning period, were compared with corresponding relative dynamic modulus of elasticity.
View the article online for updates and enhancements. Recent citations Study on thermal degradati... more View the article online for updates and enhancements. Recent citations Study on thermal degradation and combustion behavior of flame retardant unsaturated polyester resin modified with a reactive phosphorus containing monomer Ying Lin et al
Key Engineering Materials, 2002
In this paper it is reported a research undertaken in hybrid beams, where GFRP pultruded profiles... more In this paper it is reported a research undertaken in hybrid beams, where GFRP pultruded profiles are assembled, in an innovative way, with a layer of polymer concrete. The various beams were designed considering a pultrusion profile that will work in tension, and a polymer concrete filling that will work mainly in compression, in order to take benefit from the best mechanical properties of both materials. A model implemented in a finite element code was developed in order to predict the experimental results. Several beams, with four different hybrid designs, were tested in four-point bending and the flexural behaviour of such structures was studied. The results obtained show the synergetic effect of the joining of these two classes of materials.
Polymer Testing, 2003
The study was conducted in order to determine the coefficient of thermal expansion of two specifi... more The study was conducted in order to determine the coefficient of thermal expansion of two specific binder formulations of epoxy and unsaturated polyester polymer mortars. The variation of this parameter with temperature was also analysed. Polymer concrete and mortars have been observed to have lower coefficients of thermal expansion at lower temperatures than at higher temperatures. Plots of strains vs. temperature are often bilinear, indicating a sharp change in the coefficient of thermal expansion (International Congress on Polymers in Concrete, July 1995). To determine how this discontinuity varies for these two materials, specimens of both formulations were tested for several temperature ranges between Ϫ20 and 60°C. In addition, to determine the influence of fibre reinforcements on thermal expansion of polymer mortars, epoxy polymer mortars reinforced with both carbon and glass chopped fibres were also tested for thermal expansion. It was concluded that, for both formulations, the variation of thermal expansion with temperature follows a parabolic law rather than a bilinear law. The reinforcement of chopped glass fibres (1%) has no significant effect on thermal expansion of epoxy polymer mortar, while the inclusion of carbon fibres (2%) on the same mortar formulation has a reducing effect on thermal expansion of this composite material for temperatures above room temperature.
Macromolecular Chemistry and Physics, 2003
Macromolecular Chemistry and Physics, 2001
Page 1. Macromol. Chem. Phys. 2001, 202, 21952201 2195 Metallocene-Catalysed Copolymerisation of... more Page 1. Macromol. Chem. Phys. 2001, 202, 21952201 2195 Metallocene-Catalysed Copolymerisation of Ethylene with 10-Undecenoic Acid: The Effect of Experimental Conditions Jorge Moniz Santos,1 Maria Rosµrio Ribeiro ...
Journal of Polymer Engineering, 2003
An investigation on the influence of thermal effects on flexural strength of two different binder... more An investigation on the influence of thermal effects on flexural strength of two different binder formulations of polymer mortars was performed, by considering specimens of polyester and epoxy polymer mortars, and a wide range of temperatures. The strength degradation process occurring in the material, as a consequence of positive thermal fatigue cycles (+20°C / +100°C) and freezethaw cycles (-10°C / +10°C), was also quantified and analysed.
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Papers by maria rita ribeiro