Normando Perazzo Barbosa

Behaviour of composite soil reinforced with natural fibres

Abstract Next to the food shortage, the housing shortage is one of the most crucial problems on earth. To improve this situation and make it possible to build more houses, particularly for low-income families, it is necessary to examine all locally available materials which can be used for construction. Bamboo, sisal and coconut fibres are materials which are available in abundance in Brazil and are not used in civil construction. To increase the amount of information concerning the physical and mechanical behaviour of these materials several research programmes were executed at Pontifical Universidade Catolica in Rio de Janeiro (PUC-Rio) and Universidade Federal da Paraiba (UFPb) under the general supervision of the first author. In this paper new results are presented concerning the application of sisal and coconut fibres in conjunction with three types of locally appropriate soil for the production of composite soil blocks reinforced with sisal and coconut fibres.

Iron Distribution in Geopolymer with Ferromagnetic Rich Precursor

Geompolymers and their engineering applications have attracted significant attention of the scientific community. This is due to properties such as good thermal stability and high resistance to aggressive environments. Most studies on this subject are based on traditional precursor materials such as calcined kaolinite clay (metakaolinite) and fly ash. The iron content is significant, reaching around 10% in metakaolinite, for instance. The role of iron in geopolymers still lacks systematic investigation. This can be attributed to the limitations presenting nuclear magnetic resonance (NMR) spectroscopy, which is a widely used technique to study geopolymers structure. Ferromagnetic elements such as iron, which is often present in some precursors, affect the magnetic response of the material, compromising the proper analysis of its structure by NMR results. Iron content in some industrial residues may be several times higher as it is often found in metakaolinite. This work presents x-ray diffraction, infrared and Mössbauer spectroscopy studies on the distribution of iron species in iron oxide/hydroxide-rich precursor, which was used to synthesized geopolymers.

Potencialidades de um caulim calcinado como material de substituição parcial do cimento portland em argamassas

The use of burnt clays, in the metakaolin form, as pozzolanic material for mortars and concretes has received a remarkable attention in the last years. This paper aimed to evaluate the mechanical property of mortars, in which a calcined kaolin originating from the State of Paraiba, was used as partial cement replacement material. Two finess of the kaolin were used: ABNT 200 (0.074 mm) and 325 (0.044 mm) and burnt at temperatures of 700, 800 and 900 oC for a period of 2 h. Both materials were characterized by chemical analysis, differential thermal analysis, X-ray diffraction, specific area tests. The pozolanic activity index was obtanied using lime and cement Portland. The amounts of replacement were 10, 20, 30 and 40%, besides the reference mortar. The binder: sand ratio was 1:1.5 and the water/binder ratio was constant and equal to 0.4. The effect of partial substitution of cement in mortar was evaluated through compressive strength at 7, 28 and 90 days. Mortars with kaolin presented superior strength comparing to reference mortar, up to the level of 30% of substitution.

Adhesion of Geopolymer Bonded Joints Considering Surface Treatments

In this study the adhesion properties of a geopolymer-based adhesive on metallic substrates are investigated, considering different surface conditions. Mechanical treatments (grit-blasting and sand-blasting) and chemical treatments (nitro-phosphoric acid and silanization) were performed on steel and aluminium plates. Single lap joint specimens were tested in order to access the influence of these pretreatments on the shear bond strength. The surfaces were scanned and the average surface roughness parameters were used in order to assess their effect on bond strength. The results indicated that the effect of individual surface roughness parameters alone is not statistically significant when correlated with bond strength. In general, chemical treatments were usually less effective than mechanical treatments alone for both steel and aluminium joints with geopolymers as adhesives.

Resistência à compressão do solo-cimento com substituição parcial do cimento Portland por resíduo cerâmico moído

Neste trabalho, apresenta-se o estudo experimental da resistencia a compressao do solo-cimento, com substituicao parcial do cimento Portland por residuo cerâmico moido. Para tanto, foram ensaiados 81 especimenes cilindricos desse material a compressao, em que parte do cimento foi substituida por material cerâmico moido. Realizou-se uma programacao fatorial, na qual tres variaveis foram selecionadas para estudo: o teor de material ligante (cimento + residuo cerâmico), a umidade do solo e o teor de residuo cerâmico adicionado. E apresentado um estudo estatistico atraves de analise de variância da massa especifica do material e da resistencia a compressao. Tal estudo permitiu concluir-se que substituicoes de 25 e 57% do teor de cimento por material cerâmico podem produzir blocos de solo-cimento com resistencias superiores a 2 MPa, com teor de material ligante de 6 e 8%, respectivamente.

Determinação da tensão de aderência do bambu-concreto

This paper presents and discusses a study about the bamboo-concrete bond stress. Based on a statistical design of experiment, the investigation was divided in two steps: the first one, where the effects of the concrete compressive strength and the dimensions of the bamboo-splint cross-section were investigated; and the second, where the effect of artificial pins studding in the bamboo splints were evaluated. In both steps, ten replicates for each factor combination were done, resulting in 159 push-out tests. Bond stress versus relative displacement curves were presented and discussed. In addition, the design bond stresses of bamboo-concrete were calculated and their values were compared with those specified by International Building Codes for smooth steel and concrete. In the first step, it was observed that only the concrete compressive strength influences the bamboo-concrete bond stress and that, this stress is only 20% inferior to the smooth steel-concrete bond stress. In the second step, it was verified that bamboo and steel pins increased the transfer stress capacity between the concrete and bamboo.

Compósitos à base de cimento reforçado com polpa celulósica de bambu. Parte II: Uso de resíduos cerâmicos na matriz

This paper is the second part of a series of two articles concerning the experimental results of newly developed composite with cementations matrix reinforced with bamboo pulp. In this part the results of the investigations concerning the partial substitution of Portland cement by grinded residues from a brick factory are presented. The cement was partially replaced in percentages of 20, 30 and 40% by weight. These composites were reinforced with only refined bamboo pulp. The same procedures described in Part I were adopted and used in the experimental program. Considering the results of the mechanical properties it is verified that 20% of cement replacement presented the best results.

Resistência mecânica de compósitos cimentícios leves utilizando resíduos industriais e fibras de sisal 1

R ESU M O A valorizacao de materiais alternativos incorporados com residuos como opcao ao convencional deve possibilitar a geracao de um produto com qualidade, estetica, produtividade e com potencial de reduzir impactos da poluicao ambiental. Este trabalho foi realizado com o objetivo de desenvolver elementos construtivos para forro e divisorias, a partir de matrizes cimenticias com incorporacao de residuos industriais (residuo cerâmico, etil vinil acetato - EVA) e fibras de sisal. Desenvolveram-se tecnicas de moldagem em matrizes cimenticias autoadensaveis e se avaliou a resistencia mecânica dos novos compositos. Uma placa com residuos de EVA foi produzida e, atraves de trabalhos de reologia, encontrouse a pasta matriz de revestimento desta placa, com teor adequado de adicoes pozolânicas e aditivo superplastificante. Avaliaram-se as resistencias mecânicas das placas, da pasta matriz de revestimento encontrada, com e sem adicao de fibras, e do novo composito formado pela uniao desses dois elementos. Utilizou-se a tecnica de alinhamento de fibras com o intuito de incrementar resistencia ao novo composito leve. A adicao da matriz com fibras alinhadas melhorou a resistencia a flexao do novo composito. Palavras-chave: elementos construtivos, flexao, reologia, fibras de sisal e residuos industriais Mechanical resistence of lightweight cement composites utilizing industrial residues and fibers of sisal A B ST R A C T The appreciation of alternative materials incorporated in waste as an option to conventional material should enable to generate a product with quality, aesthetics, productivity and reduce the potential impacts of environmental pollution. This study aims to develop constructive elements for ceilings and walls from cementitious matrix incorporating industrial waste (ceramic waste, ethyl vinyl acetate - EVA) and sisal fibers. Moulding techniques to produce self-compacting cementitious matrices were developed and the strength of the new composites were evaluated. A plate with EVA waste was produced and through rheology studies, a matrix plaster for coating of plate surface was found, with appropriate content of pozzolanic and superplasticizer additions. The mechanical resistance of the plates, the pulp coating matrix, with and without added fiber and the new composite formed by the union of these two elements was assessed. The technique of fiber alignment with the aim of increasing resistance of the new lightweight composite was used. The addition of the matrix with aligned fibers improved the flexural strength of the new composite.

Swine deep bedding ashes as a mineral additive for cement based mortar

The sustainability of intensive swine production demands alternative destinations for the generated residues. Ashes from swine rice husk-based deep bedding were tested as a mineral addition for cement mortars. The ashes were obtained at 400 to 600oC, ground and sieved through a 325 mesh sieve (# 0.045 mm). The characterization of the ashes included the determination of the index of pozzolanic activity with lime. The ashes were also tested as partial substitutes of Portland cement. The mortars were prepared using a cement:sand proportion of 1:1.5, and with water/cement ratio of 0.4. Three percentages of mass substitution of the cement were tested: 10, 20 and 30%. Mortar performances were assessed at 7 and 28 days determining their compressive strength. The chosen condition for calcinations at the laboratory scale was related to the maximum temperature of 600oC since the resulting ashes contained vitreous materials and presented satisfactory values for the pozzolanic index under analysis. The pozzolanic activity indicated promising results for ashes produced at 600oC as a replacement of up to 30% in cement masses.

Compósitos à base de cimento reforçados com polpa celulósica de bambu. Parte I: Determinação do teor de reforço ótimo

This work presents the experimental results of a study which intended to develop a composite with cementations matrix reinforced with bamboo pulp. Two types of pulps were used: refined and unrefined pulps. The fibre content varied between 0 and 16% cement (weight basis). After the preparation of fresh composite mix the experimental specimens were prepared applying a specially developed process based on Hastshek method using suction then moulding and pressing. The compression, tension and the flexural behavior and their constitutive relations were established using 5 cm diameter by 10 cm high cylindrical specimens and three point bending tests at respectively. The energy absorbing capacity of the new composites was also established. Physical properties such as water absorption, apparent porosity, dry and humid density were also obtained. The results showed a better performance of composites with refined fibres when compared to those with unrefined ones. It was observed that the optimum fibre content was approximately 8% of refined fibre which improved the mechanical properties of the composites.