Books by Luiz Pereira de Oliveira
Papers by Luiz Pereira de Oliveira
O artigo apresenta os resultados de um estudo experimental elaborado para o desenvolvimento de um... more O artigo apresenta os resultados de um estudo experimental elaborado para o desenvolvimento de uma metodologia de dosagem de concreto auto-adensável reforçado com fibras de aço (CAARFA) para ser utilizado no preenchimento de vazados de alvenarias estruturais. O método proposto é simples e baseia-se na determinação da granulometria óptima dos materiais finos através da observação do teor de argamassa no concreto fresco. Foram utilizados dois comprimentos de fibras, 30mm e 60mm, adicionadas ao concreto em volumes de 0,5%, 1,0% e 1,5%. Os resultados obtidos confirmam a viabilidade do uso de uma metodologia simples para a obtenção de misturas de concreto com fibras cujas propriedades reológicas caracterizam como auto-adensáveis. A presença de fibras de aço no concreto auto-adensável pode ser pensada como um aumento da fracção de agregados graúdos sendo portanto necessário um aumento da fracção fina para volumes de fibras crescentes. As resistências à compressão e a equivalente à flexão permitem determinar a mistura óptima para uma classe de resistência do concreto desejada. Abstract This paper deals with the mix design and properties of self-compacting steel fiber reinforced concrete (SCFRC) used to filling the voids of the structural masonry. The SCFRC is designed by application of different fibers volumes (0 %, 0,5%, 1,0% and 1,5%.) of two fibers lengths, 30mm and 60mm. The optimum mixture fine grading is determined observing the mortar ratio in the fresh concrete. It turned out that self-compacting behavior could be obtained at high steel contents. It has also been shown the viability of a simple mix design method to attain the self-compacting ability of the reinforced steel fibers mixtures. The compressive and equivalent flexural strengths as parameters to find the optimal mixture for the desired concrete strength class were studied.
Construction and Building Materials, 2012
Applied Rheology, Sep 20, 2012
Construction and Building Materials, 2013
Construction and Building Materials, 2012
Construction and Building Materials, 2011
This paper describes a series of anomalies occurred on a bridge slab due to inappropriate concret... more This paper describes a series of anomalies occurred on a bridge slab due to inappropriate concrete placing conditions. Although it was the first Portuguese large scale experience with self-compacting concrete and great care was taken to study its correct composition, several anomalies occurred during concrete placing. The anomalies that took place arise due to inappropriate concrete placing conditions, namely due to severe rainfall while concrete was placed. This might greatly influence its self-compacting behaviour, as explained here. The inspection of the bridge slab took place two weeks after concrete being placed. The inspection works are described. It consisted on the verification of concrete strength class and of reinforcement correct position. The testing techniques adopted are explained in detail. The inspection results revealed that the slab compressive strength was below expected values, and concrete was segregated. It was also found that many steel reinforcement bars were moved to be at an incorrect position. From the case study, several conclusions can be taken, particularly regarding the importance of appropriate meteorological conditions when self-compacting concrete is placed. Streszczenie W referacie opisano szereg anomalii, jakie wystąpiły w płycie pomostowej na skutek niewłaściwych warunków betonowania. Opisany przypadek dotyczy pierwszego w Portugalii doświadczenia z zastosowaniem betonu samozagęszczalnego na dużą skalę. Pomimo dołożenia wielu starań przy projektowaniu składu betonu w trakcie betonowania wystąpiło szereg anomalii. Powstały one na skutek niewłaściwych warunków betonowania a mianowicie intensywnego deszczu, który wystąpił w czasie układania betonu. To mogło w sposób istotny wpłynąć na właściwości samozagęszczania jak to wyjaśniono w referacie. Inspekcja płyty pomostowej nastąpiła dwa tygodnie po zakończeniu betonowania. Opisano przebieg prac inspekcyjnych. Obejmowały one sprawdzenie wytrzymałości betonu oraz właściwego położenia zbrojenia. Opisano w szczegółach zastosowane do tego techniki. W wyniku inspekcji stwierdzono, że wytrzymałość płyty pomostowej na ściskanie była poniżej przewidywanej wartości a beton uległ segregacji. Stwierdzono także, że szereg prętów zbrojenia znalazło się w niewłaściwym położeniu. Na podstawie opisanego przypadku można wyciągnąć szereg wniosków, w szczególności dotyczących znaczenia właściwych warunków pogodowych w trakcie układania betonu samozagęszczalnego.
O artigo apresenta um estudo experimental no qual se exploram variáveis relacionadas a uma fibra ... more O artigo apresenta um estudo experimental no qual se exploram variáveis relacionadas a uma fibra acrílica desenvolvida para reforçar argamassas de construção. O objetivo foi identificar as variáveis mais influentes das fibras acrilicas através de modelos de representação do desempenho das argamassas. A partir das variáveis: comprimento
diâmetro e volume de fibras, misturas de argamassas reforçadas com fibras acrílicas definidas por um plano fatorial 23 foram ensaiadas no estado fresco e no estado
endurecido. Ensaios de consistência, de massa volúmica, de resistências mecânicas, módulo de elasticidade, de retração livre e de absorção de água por capilaridade compuseram o plano de ensaios. O volume e o comprimento das fibras tem influências significativas tanto na resistência à flexão como na resistência à compressão. O volume de fibras também diminui ligeiramente a massa volúmica da argamassa endurecida favorecendo a redução do módulo de elasticidade. O diâmetro das fibras contribuem para o aumento da retração e a diminuição do coeficiente de capilaridade.
The main objective of the experimetal work carried out was the evaluation of the influence of coa... more The main objective of the experimetal work carried out was the evaluation of the influence of coarse aggregates geological source, dimension and water content in the concrete permeability. Four different aggretates, obtained from different geological environments, were selected, like granite, basalt, calcareous and marble coarse aggregates. After their mechanical and physical characterization, three concrete mixtures were produced with constant volume proportions, workability, mixing and curing conditions using different sizes of each aggregate type. Concrete durability parameters, such as capillary water absorption and oxygen permeability, measured at 28 days, were found to be affected by coarse aggregate size and its water content rather than aggregate mineralogy, as presented and discussed.
This article presents the methodology used, in the Construction Laboratories, of Civil Engineerin... more This article presents the methodology used, in the Construction Laboratories, of Civil Engineering Department, of University of Beira Interior, for the determination of water absorption, oxygen and water permeability of concrete and aggregate. Aspects of samples preparation and of procedures of these tests are discussed, demonstrating that these two aspects can affect, significantly, the results obtained. It is also discussed here the significance of permeability determination when small differences in the variables of the tests occur, namely the applied pressure. Some examples of water absorption and of oxygen and water permeability obtained with different concrete types and different types of aggregates are presented. It is also presented a typical relationship between water absorption and oxygen permeability. Finally, it is concluded about the interest of the water absorption and permeability tests as parameters to evaluate concrete durability.
This paper describes a series of anomalies occurred on a concrete structure due to inappropriate ... more This paper describes a series of anomalies occurred on a concrete structure due to inappropriate concrete placing conditions, namely due to severe rainfall while concrete was placed. This has greatly influenced its self-compacting behaviour, as explained here. The case study clearly shows the importance of appropriate meteorological conditions needed when self-compacting concrete is placed. Furthermore, its influence is even more important when white cement and admixtures are used to produce self-compacting concrete.
This paper examines the possibility of using finely ground waste glass as partial natural sand re... more 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.
This paper examines the possibility of using finely ground waste glass of the three most common c... more This 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.
The permeability and ability for capillary absorption of concrete are usually served as criteria ... more The permeability and ability for capillary absorption of concrete are usually served as criteria for assessing the long-term performance (durability) of concrete. In order to know the long-term performance (durability) of concrete, the permeability or capillary absorption test is usually required. However, a long term preconditioning procedure prescribed in RILEM TC 116-PCD is unavoidable if one wants to carry out the permeability or capillary absorption tests. An attempt is made in this paper to address the possibility of simplifying the RILEM preconditioning procedure. The RILEM preconditioning method and a simplified preconditioning procedure were carried out on several sets of specimens which were cut from the same concrete slab. Thereafter, capillary absorption and gas permeability tests were carried out on these same specimens. Results of these two tests were compared between RILEM procedure and the simplified procedure and the results indicate that the two procedures provided similar results and as thus comparable to one another.
This paper describes a series of anomalies occurred on a concrete structure due to inappropriate ... more This paper describes a series of anomalies occurred on a concrete structure due to inappropriate concrete placing conditions, namely due to severe rainfall while concrete was placed. This has greatly influenced its self-compacting behaviour, as explained here. The case study clearly shows the importance of appropriate meteorological conditions needed when self-compacting concrete is placed. Furthermore, its influence is even more important when white cement and admixtures are used to produce self-compacting concrete.
The objective of this experimental study was to examine the possibility of reusing ceramic materi... more The objective of this experimental study was to examine the possibility of reusing ceramic materials waste from container glass, bricks and tiles of red-clay ceramic industry in Portugal as partial cement replacement in mortar and concrete. The different types of waste were finely ground to specific sizes
(0–45 lm, 45–75 lm and 75–150 lm) and its pozzolanic activity was determined. The reduction of glass and ceramic waste particle size was accomplished in the laboratory by crushing and grinding using a ball jar mill. After gridding, the fine waste materials were characterized by the determination of density,
Blaine fineness and particle morphology using scanning electrical microscope. The compressive strength activity index, at 7, 28 and 90 days, was determined in mortars produced with each finely grounded waste ceramics and different percentages of partial cement replacement. Standard ASTM accelerated
mortar bar tests and a modified test carried on in 40 ! 40 ! 160 mm size mortar specimens were performed to investigate the potential expansion caused by the alkali–silica reaction of finely grounded waste glass as partially cement replacement.
The results obtained confirm the pozzolanic activity of the grounded waste, collected in the central region of Portugal, making feasible their incorporation as cement mortars and concrete components.
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Books by Luiz Pereira de Oliveira
Papers by Luiz Pereira de Oliveira
diâmetro e volume de fibras, misturas de argamassas reforçadas com fibras acrílicas definidas por um plano fatorial 23 foram ensaiadas no estado fresco e no estado
endurecido. Ensaios de consistência, de massa volúmica, de resistências mecânicas, módulo de elasticidade, de retração livre e de absorção de água por capilaridade compuseram o plano de ensaios. O volume e o comprimento das fibras tem influências significativas tanto na resistência à flexão como na resistência à compressão. O volume de fibras também diminui ligeiramente a massa volúmica da argamassa endurecida favorecendo a redução do módulo de elasticidade. O diâmetro das fibras contribuem para o aumento da retração e a diminuição do coeficiente de capilaridade.
The results obtained confirm the pozzolanic activity of the ground waste glass of different colour collected in central region of Portugal.
(0–45 lm, 45–75 lm and 75–150 lm) and its pozzolanic activity was determined. The reduction of glass and ceramic waste particle size was accomplished in the laboratory by crushing and grinding using a ball jar mill. After gridding, the fine waste materials were characterized by the determination of density,
Blaine fineness and particle morphology using scanning electrical microscope. The compressive strength activity index, at 7, 28 and 90 days, was determined in mortars produced with each finely grounded waste ceramics and different percentages of partial cement replacement. Standard ASTM accelerated
mortar bar tests and a modified test carried on in 40 ! 40 ! 160 mm size mortar specimens were performed to investigate the potential expansion caused by the alkali–silica reaction of finely grounded waste glass as partially cement replacement.
The results obtained confirm the pozzolanic activity of the grounded waste, collected in the central region of Portugal, making feasible their incorporation as cement mortars and concrete components.
diâmetro e volume de fibras, misturas de argamassas reforçadas com fibras acrílicas definidas por um plano fatorial 23 foram ensaiadas no estado fresco e no estado
endurecido. Ensaios de consistência, de massa volúmica, de resistências mecânicas, módulo de elasticidade, de retração livre e de absorção de água por capilaridade compuseram o plano de ensaios. O volume e o comprimento das fibras tem influências significativas tanto na resistência à flexão como na resistência à compressão. O volume de fibras também diminui ligeiramente a massa volúmica da argamassa endurecida favorecendo a redução do módulo de elasticidade. O diâmetro das fibras contribuem para o aumento da retração e a diminuição do coeficiente de capilaridade.
The results obtained confirm the pozzolanic activity of the ground waste glass of different colour collected in central region of Portugal.
(0–45 lm, 45–75 lm and 75–150 lm) and its pozzolanic activity was determined. The reduction of glass and ceramic waste particle size was accomplished in the laboratory by crushing and grinding using a ball jar mill. After gridding, the fine waste materials were characterized by the determination of density,
Blaine fineness and particle morphology using scanning electrical microscope. The compressive strength activity index, at 7, 28 and 90 days, was determined in mortars produced with each finely grounded waste ceramics and different percentages of partial cement replacement. Standard ASTM accelerated
mortar bar tests and a modified test carried on in 40 ! 40 ! 160 mm size mortar specimens were performed to investigate the potential expansion caused by the alkali–silica reaction of finely grounded waste glass as partially cement replacement.
The results obtained confirm the pozzolanic activity of the grounded waste, collected in the central region of Portugal, making feasible their incorporation as cement mortars and concrete components.