Papers by Author: Normando Perazzo Barbosa

Abstract: In the state of Paraíba, one of the activities of great economic importance is that of the kaolin processing industry. This type of processing generates large amounts of waste that are displayed randomly in the environment, which has attracted attention, because the environmental impact caused by it and the lack of established process of recycling. The University Federal o Paraíba has been developing several research to explore the potential for recycling of industrial waste from Paraíba, mainly waste of kaolin. This research have pointed to the feasibility of using waste as aggregate and pozzolan in the development of mortars use multiple. These wastes have different size fractions, depending on the stage of processing: a sandy (termed in this study of RGC) containing mainly quartz, mica and calcite; and other clay (termed in this study of RFC) is thinner, containing higher amounts of kaolinite. This study aims to evaluate the potential of alkaline activation from waste kaolin (RGC and RFC) by comparing the activation using sodium silicate and hidroxide of calcium. With the objective of studying the potential of waste as a material pozzolanic, it was processing through grinding at 80.000, 60.000, 40.000, 20.000 and 10.000 rotations and with the purpose of evaluating the reactivity of materials, these wastes were calcined at 750°C/2h. For the mechanical characterization was using an equipment universal testing of Shimadzu Servopulser, where it was observed that only RFC, when calcined, developed strength in both activations, and the activated with silicate sodium with higher strength. The RGC, both in the state in natura and calcined did not show satisfactory mechanical strength to the test under the conditions of synthesis used in this research. Thus, the waste RFC's studied in this work has the potential to be used as constituent materials for building blocks in terms of its mechanical properties.

Abstract: The University Federal of Paraíba has developed various researches to explore the potential for recycling of industrial waste of Paraíba. Among them, the potential of use in the waste generated by processing of kaolin, which is one of the activities of great economic importance to the State of Paraíba and municipalities producers, because it causes a great environmental impact due to lack of an established recycling process. The kaolin processing generates large amounts of waste, one of fractions, a sandy (called in this study of RGC) containing quartz, mica and calcite; and other clay (called in this study of RFC) containing higher amounts of kaolinite. This objective of study is the characterization physical, chemical and mineralogical of waste kaolin (RFC and RGC) in order to evaluate the potential use of these wastes in the alkaline activation using silicates sodium and potassium. The characterizations physics, chemistry and mineralogy were by XRF, XRD, Unit Mass, Specific Mass and Specific Area. With the objective of studying the potential of waste as a material pozzolanic, it was processing through grinding at 10.000, 20.000, 40.000, 60.000 and 80.000 rpm and with the purpose of evaluating the reactivity of materials, these wastes were calcined at 750°C/2h.The wastes RFC and RGC had different properties according to the processing. Thus, the waste RFChas the potential pozzolanic to use in alkaline activation.

Abstract: Sugar cane bagasse ash (SCBA) is a byproduct rich in silica, which it is present as of both crystalline and amorphous phases. This paper aims to evaluate the effect of grain size of residual SCBA particles on the solubility of silicate species in alkaline solutions that still needs examination. The influence of the amorphous character of the material was also investigated. Physical characterization was performed by the assessment of density and specific area of powder samples. Chemical and mineralogical characterizations were performed using different techniques including x-ray fluorescence, x-ray diffraction, infrared spectroscopy and scanning electron microscopy. The results indicate that the grinding process reduces the specific area of the particles of ash in a non linear fashion. The controlled burning of sugar cane bagasse increased the amorphous character of the ash. Nonetheless both factors affected the solubility of silicates, the degree of crystalinity appears to be the most important factor.

Abstract: Papers presented at ICPIC 2010, Madeira Island, Portugal, dealing with the use of polymers in cementitious materials, show the need to combine different admixtures to optimize the properties of cement. This work is a continuation of a paper presented at NOCMAT 2010, Cairo-Egypt, about the incorporation of several materials in Portland cement to increase mechanical properties and workability. The best performance admixtures were chosen and they were combined considering the superposition of effects. Cement pastes were prepared with chalcedony and sulfonate (to increase compressive strength) and sugar (to increase workability). Two percent of cement was replaced by the admixtures. The water/cement ratio was constant and equal to 0.44. Results show that the combination of 0.05% of sugar and 1.95% of sulfonate and 0.10% of sugar and 1.90% of chalcedony produced a paste with the greatest compressive strength and good workability. Compression strength was respectively 27.4 MPa and 36.6 MPa, which represent increases of 33.5% and 78.6%, respectively, relative to the reference paste without admixtures. While increasing the paste compression strength with sulfonate has been significant, the results of the paste with chalcedony were the more surprising because the water/cement ratio of pastes was kept constant. The chalcedony is a type of crystalline silica, which shows deformation in their structure. So because of crystalline structure of chalcedony, there should be, probably, no significant reactivity of it with the cement hydrates, just the fact that its structure be deformed can explain this reactivity. The most important conclusion concerns is that the combinations of admixtures can improve a lot the properties of Portland cement paste.

Abstract: There are more than one thousand of bamboo species around the world, but in some areas the most common is the Bambusa vulgaris. Comparing with other species used in construction, it is more susceptible to insect attack and its strength is slower. This work shows some studies made using culms of this bamboo with the aim to improve its durability and mechanical properties by impregnation of polymeric resins into their vases. Some information about Bambusa vulgaris microstructure is done. The percentage of vases, fibers and parenchyma was measured using an optical microscope. The absorption of this species in liquids with different viscosities was determined. Using an equipment to force the liquid into the vases, time of penetration of fluids with different viscosity was measured. Results show that the fluids penetrate most easily in the internal vases, where the diameter is greater than that close to external face of the culms and confirm that it is possible to fill the bamboo vases with viscous fluid as oil or polymeric resins. The attack of insect was eliminated when a impregnation with a resin made by 80 % de styrene + 20 % de metilmetacriyate was applied to Bambusa vulgaris culms.

Abstract: The world crosses an energetic, environmental and social crisis without precedents. Architecture and Engineering are also responsible because the more used industrialized construction materials, as Portland cement, concrete and steel, in their production process, demand a lot of energy, cause serious impacts to the environment and need big investments. One possibility to decrease this problem is the non compulsory employment of products based on Portland cement and steel, but also using local materials with which is possible to construct worthily. This work has as proposal the development of a structural gypsum element reinforced with bamboo that can be used as lintel and against-lintel in the constructions. Prisms samples (4cm x 4cm x 16cm) of gypsum matrix reinforced with bamboo rods were prepared and flexural tests were made. To improve bond between the two materials, treatments in the bamboo were tested. The tests showed that the most efficient material for this treatment was epoxy glue. Pre-fabricated structural peaces in real size were also tested through flexion tests in laboratory and applied in an prototype built in the University campus. The casting was made using vibratory table. Results show that vibrated bamboo reinforced gypsum is viable to be used in small structural beams and even replacing wood peaces in roofs.

Abstract: Bonded joints have been used in substitution of more traditional techniques as screws, rivets and mainly welding. However, the applications in which the work temperatures are relatively high remain as an obstacle to the use of more common polymeric adhesives. In this sense, the study of adhesive properties of thermally stable materials as the geopolymers becomes a need. This work deals with the adhesion of aluminium sandwich beams using geopolymeric adhesives. Metakaolin-based geopolymers were used as adhesives, activated with sodium and potassium silicates. Shear mode adhesion tests were accomplished and the results indicate the possibility for use of these new adhesives.

Abstract: The detachment of ceramic tiles from buildings is a problem that still persists in several modern constructions. Although there are several specific techniques for the prevention of tiles from detaching this issue still requires in-depth research in order to be fully solved. These detachments happen commonly in facades that are submitted to the incidence of solar rays on the surfaces. In this work, the adhesion of porcelanate-adhesive-substrate was investigated through direct detachment tests according to Brazilian standards. Two types of adhesives were used: a commercial adhesive, classified by Brazilian standard as being of high adhesion (ACIII-E) and a geopolymer, developed through alkaline activation of metakaolin with sodium silicate. The bonded systems were submitted to two temperature exposure regimes. In general, geopolymeric adhesives had better adhesion than the systems bonded with ACIII-E adhesive mortar, especially with temperature increase.

Abstract: 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.