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- Mechanical and Durability Properties of Concrete with Ground Waste Glass SandPublication . Oliveira, Luiz António Pereira de; Gomes, João Castro; Santos, P.This paper examines the possibility of using finely ground waste glass as partial natural sand replacement in concrete. The reduction of waste glass particle size was accomplished in the laboratory by crushing and grinding the waste glass in a jar mill. The compressive strength at 7, 28 and 90 days, was determined for different ground waste glass sand percentage replacement in concrete. Absorption and permeability tests were also carried out. A test method was followed to verify the potential concrete expansion caused by the alkali silica reaction. The results showed a very significant compressive strength improvement with the increasing of percentage replacement of natural sand by ground waste glass. A higher compressive strength was obtained with a lower expansion verified by the bar tests. The same trend for durability properties were also observed in this study. The results obtained attested the high possibility of recycling and using of the ground waste glass collected in central region of Portugal as natural sand replacement in concrete mixtures.
- Effect of acrylic fibres geometry on physical, mechanical and durability properties of cement mortarsPublication . Oliveira, Luiz Antonio Pereira de; Gomes, João Castro; Nepomuceno, MiguelThis paper presents the results of an experimental investigation to verify the feasibility of using acrylic textile fibre to improve cement based mortars properties. The assessment of acrylic fibres influence on mortars properties was performed comparing the physical, mechanical and durability behaviour with mortars produced using glass and polypropylene fibres. The influence of the mixing procedures was also investigated. Effects of acrylic fibre aspect ratio (l/d) and volume fraction (Vf) on mortar bulk density, compressive strength, flexural strength, water absorption and plastic shrinkage were investigated. For this purpose, acrylic fibres having six different l/d ratios 93, 148, 222, 278, 444 and 833 were used and the volume percentage of fibres were added to mortar mixes was of 0.2%; 0.5% and 1.0%. The mortar plastic shrinkage was also studied on slabs casted with 0.5%, 0.2%, 0.1% and 0.05 % acrylic fibres volume. It was found that acrylic fibre reinforced mortars have physical, mechanical and durability related properties similar to the mortar reinforced with glass or polypropylene fibres. These results indicate that there is a potential technical feasibility of using this type of fibres in cementitious composites.
- Development and optimisation of phase change material-impregnated lightweight aggregates for geopolymer composites made from aluminosilicate rich mud and milled glass powderPublication . Kastiukas, Gediminas; Zhou, Xiangming; Gomes, João CastroMacro-encapsulated aggregates (ME-LWAs) consisting of expanded clay lightweight aggregates (LWAs) impregnated with a paraffin wax phase change material (PCM) was produced. To fully exploit the thermal energy retaining properties of PCM, it is fundamental to retain as much of the PCM as possible within the pores of the LWA. This paper investigates 3 different commercial materials to create a total of 14 different coating regimes to determine the most efficient coating method and material regarding its ability at retaining the PCM. The ME-LWAs are then further used as aggregates in geopolymer binders made from a combination of aluminosilicate rich mud and waste glass. Physical properties such as thermal conduc- tivity and mechanical strength are determined for the geopolymer binder with and without the addition of the ME-LWA. A polyester resin was determined to be the most suitable choice of coating material for the ME-LWA, producing a practically leak-proof coating. The ME-LWA was also determined to be chem- ically neutral, showed a 42% higher thermal conductivity than the LWA in their raw state and maintained a latent heat of 57.93 J/g before and after being used in the geopolymer binder. Carbon fibres and graphite spray were used to improve the thermal conductivity of the resin coating, however no significant increase was detected. Finally, the compressive strength and thermal conductivity results achieved are acceptable for applications in buildings for enhancement of their energy efficiency.
- Reabilitação de edifícios: metodologias de diagnóstico e intervençãoPublication . Lanzinha, João; Freitas, Vasco P. de; Gomes, João CastroA reabilitação de edifícios, no contexto europeu, continuará a crescer nos próximos anos, até se consolidar como um sector de grande importância no conjunto da construção. Para acompanhar esta realidade, é importante desenvolver uma nova metodologia de inspecção exigencial de modo a que todos os intervenientes no processo de reabilitação de edifícios, disponham de um instrumento de trabalho que permita rapidamente obter informações correctas e adequadas sobre o edifício objecto de intervenção.
- The influence of wastes materials on the rheology of rendering mortarsPublication . Oliveira, Luiz Antonio Pereira de; Gomes, João Castro; Nepomuceno, MiguelThe objective of this paper is to present the results of a research about the effect of mineral additions and some lightweight aggregates from wastes materials (crushed EPS and Cork) on the rheological properties of renderings mortars. Four series of mortar formulations were prepared. Each series was composed by four mortars mixes with different mineral additions: hydrated lime (L), glass powder (G), tungsten ash (A) and metakaolin (K). The proportions of the mortars expressed in terms of apparent volume of cement, mineral addition and sand was 1:1:5. Flowability of mortar was measured using a standard flow table test. The density and the water retention capacity of mortars were also determined. The mortar rheological parameters were evaluated with a specific rheometer for mortars. The results show that the mortar yield stress is strongly influenced by the water amount, binder fineness and mineral addition nature. The mortars plastic viscosity is also influenced by the nature of mineral addition and the partial replacement of sand by EPS aggregates introduce incongruent values, caused by the segregation, in the mortar yield stress, whereas, the Cork aggregates is responsible by the yield stress reduction.
- Potential for reuse of tungsten mining waste-rock in technical-artistic value added productsPublication . Gomes, João Castro; Silva, Abílio P.; Peralbo Cano, Rafael; Durán Suárez, Jorge Alberto; Albuquerque, AntónioMining and quarrying activities in Europe generate approximately 55% of total industrial wastes, according to a recent Eurostat report. Most of these wastes are directly dumped on land or deposited in landfill sites. The first solution may lead to negative environmental impacts on land (removal of vegetation, deforestation, land slope changes and increased risk of erosion), water (pollutant transport through surface runoff, soil infiltration and contamination of water resources), may lead to the contamination of agricultural goods and may impose risks on human health. In Portugal, about 20% of industrial waste produced originates from mines and quarries, particularly from Panasqueira mining, one of the largest tungsten mines in the world. Currently, Panasqueira mining generates almost 100 tonnes of waste-rock, per day. Such waste-rock have accumulated over a number of years into very large heaps and it is desirable to seek new economic solutions that can contribute towards their reuse. In this context, this work discusses the potential for reuse of waste-rock piles of Panasqueira tungsten mine, which may be a case statement to be followed. The proposed solution described in this paper consists in developing innovative polymer-based composite materials, obtained from non-contaminated waste-rock tailings. Such materials must have suitable properties for technical-artistic value added applications, such as conservation, restoration and/or rehabilitation of historic monuments, sculptures, decorative and architectural intervention, or simply as materials for building revetments.
- Reciclagem de agregados das minas da Panasqueira como revestimento refratário da fundição de metaisPublication . Herrera, J. Montoya; Suarez, J.A. Durán; Silva, Abílio P.; Cano, R. Peralbo; Gomes, João CastroNas minas da Panasqueira (Covilhã, Portugal) acumulam-se montes de resíduos (agregados) provenientes da extração de tungsténio sem qualquer aplicação. Este trabalho pretende contribuir para implementar um novo uso para estes resíduos integrando-os como revestimento refratário no processo de moldação a verde da fundição de metais não ferrosos. Os resultados mostram o potencial do uso destes resíduos da fundição de metais não ferrosos.
- Optimization of pozzolanic reaction of ground waste glassPublication . Gomes, João Castro; Santos, P.; Oliveira, Luiz António Pereira deThis paper examines the possibility of using finely ground waste glass of the three most common coloured glass bottles used in Portugal as partial cement replacement in mortar and concrete. The pozzolanic activity of ground glass was optimised as function of different particle size. The reduction of waste glass particle size was accomplished in the laboratory by crushing and grinding the waste glass using a jar mill. The particle fineness, to obtain a required reactivity, was studied as function of grinding time. The compressive strength activity index, at 7, 28 and 90 days, was determined for different ground waste glass particle size and partial cement replacement percentage in mortar. Test method described in ASTM C 1260 was applied to verify the potential expansion caused by the alkali silica reaction. The results obtained confirm the pozzolanic activity of the ground waste glass of different colour collected in central region of Portugal.
- Smart Textiles for Strengthening of StructuresPublication . Górski, Marcin; Krzywoń, Rafał; Dawczyński, Szymon; Szojda, Leszek; Salvado, Rita; Lopes, Catarina; Araújo, Pedro; Velez, Fernando J.; Gomes, João CastroThis paper presents results of mechanical tests on a prototype of an innovative structural strengthening in form of self-monitoring fabric. Smart textile employs carbon fibers conductivity for measuring strains while monitoring changes of electric resistance under increasing load. A general solution was tested in a series of calibrating tests on strengthening of small size concrete slabs. Promising results of simple specimen, has encouraged the research team to perform the next tests using mastered carbon fibre reinforced fabric. Main tests were performed on natural scale RC beam. Smart textile proved its efficiency in both: strengthening and monitoring of strains during load increase. New strengthening proposal was given 10% increase of loading capacity and the readings of strain changes were similar to those obtained in classical methods. In order to calibrate the prototype and to define range limits of solution usability, textile sensor was tested in areas of large deformations (timber beam) and as well as very small strains (bridge bearing block). In both cases, the prototype demonstrated excellent performance in the range of importance for structural engineering. This paper also presents an example of use of the smart strengthening in situ, in a real life conditions.
- Lightweight Alkali-Activated Material from Mining and Glass Waste by Chemical and Physical FoamingPublication . Kastiukas, Gediminas; Zhou, Xiangming; Wan, Kai Tai; Gomes, João CastroA foamed alkali-activated material (FAAM) based on tungsten mining waste (TMW) and municipal waste glass (WG) is fabricated by using aluminum powder and organic surfactant foaming agents. The compressive strength and density of the FAAM are in- vestigated in terms of different parameters of production and formulation, including curing temperature as well as the dosage of Na2O, foaming agent, foam catalyzing agent, and stabilizing agent. FAAM made with aluminum powder consists of smaller open macropores and exhibits higher compressive strength compared with FAAMs with larger closed macropores obtained by organic surfactant counterparts. The final aluminum powder–based FAAM reaches a 7-day compressive strength in excess of 3 MPa and a density below 0.7 g=cm3. The implementation of an appropriate amount of foam stabilizer leads to a further 15% increase in compressive strength, 6% reduction in density, and a thermal conductivity below 0.1 W=mK. The FAAM explored in this study represents an ideal material for building envelope insulation.