Felipe Hideyoshi Icimoto

Restoration of Structural Timber Elements Using Epoxy Resin: Analysis of Mechanical Properties

Brazil cultural heritage is composed by numerous constructions that describe the various historical periods lived by country. Constructions arent in good conservation status, showing systematically some deterioration level of their structural elements, among them those of wood. Restoration process aims to preserve the identity of original cultural heritage. It is essential maintain structural characteristics related to mechanical loads response which are closely dependent on wood properties avoiding possible structural shocks. Wood deterioration can be characterized by fungi decay or termite attack. Depending on level and position of the deteriorated area in structural set, local interventions are enough to maintain structural integrity. Polymeric resins are material options that can be used when removed these deteriorated regions, requiring compatibility with wood to maintain structural elements properties. This paper aims use of a technical for restoring structural timber from historic buildings, based on removal of decayed regions and filling them with epoxy resin. To analyze restoration effectiveness, properties in static bending, according to Brazilian standard, were determined. Samples were produced containing one and three restorations along the specimens (105 cm in length and nominal square cross section of 4.5 cm side), on the same side. Samples of Pinus taeda with gaps generated in the specimens with dimensions of 1.10 cm in depth and 8 cm in length were tested, with restorations placed in central region. For grafting of these gaps bicomponent epoxy resin was employed, prepared by mixing components in 1:1.5 proportions. Resin was injected into splices and its cure occurred in a seven days period, using methodology restoration to simulate a situation in which these structural elements have been used. Samples were requested in static bending to obtaining the product of inertia, analyzing the amendment under the aspect of tractioned and as well under compressed edge. It is observed the viability of restoration using filling epoxy resin in timber samples, considering the mechanical performance and practicality of the methodology for local keeping.

Influence of Proportion Polyol/Pre-Polymer Castor-Oil Resin Components in Static Bending Properties of Particleboards Produced with Pinus sp.

The aim of this research is to evaluate the influence of castor-oil based polyurethane resin formulation (particularly proportion pre-polymer/polyol) in static bending properties of particleboards produced with Pinus sp. wood specie. Results related to modulus of rupture (MOR) and modulus of elasticity were determined. Four proportions polyol/pre-polymer were evaluated: 0.75:1; 1:1; 1:1.25; 1:1.5. Results showed improvement in MOR and MOE with increase of pre-polymer component. Proportion 1:1.25 (poliol: pre-polymer) was considered the most interesting once employs the least amount of the petroleum-derived component.

Nondestructive Evaluation of Timber Columns of a Capela Bridge in the State of São Paulo, Brazil

After years of exposure in environmental conditions, the wood is subject to decay by chemical, mechanical, physical and biological agents. Consequently its physical and mechanical properties can be reduced, affecting their use. Timber used in bridge sustention columns is subject to intense decay process, mainly in outcrop area (area in contact to the ground), the most critical situation, because of the best combination of humidity e oxygen, factors that provide wood decay organisms. Decay process can be minimized with preventive maintenance, as wood impregnation with preservatives, before installation of the timber. After wood is installed, a periodical maintenance is necessary to conserve and prolong its life time. Thus, the aim of this study is to evaluate degradation occurred in timber columns used in Capela Bridge sustention, built with mixed system of wood and concrete, after 10-years-old of use. Located in Piracicaba - SP, Brazil, the bridge was made with Corymbia citriodora CCA-treated. The columns strength and degradation conditions were evaluated in 2 points with isntrumented driller. Point A was approximately 1,5 m of the ground and point B was in outcrop area. Instrumented driller results showed that all the columns, in both points, presented good strength and had no degradation level.

Environmental Life Cycle Assessment of industrial pine roundwood production in Brazilian forests

Pine (Pinus oocarpa) wood has great economic importance in Brazil. Pine stands represent the second largest reforested area in the country due to their industrial interest. Combining the relevance of industrial pine stands in the country and corresponding environmental concerns, this current study aims to identify and quantify the environmental impacts derived from industrial pine roundwood production in Brazil. The environmental study was developed considering the Life Cycle Assessment (LCA) methodology according to ISO14040 framework. The study convers the life cycle of pine roundwood production from cradle-to-forest gate perspective and considers the current practices in the country. The production system was divided in five main stages: Soil preparation, seedlings plantation, forest management, forest harvesting and infrastructure establishment. The environmental profile was estimated considering characterization factors from the ReCiPe method, in terms of twelve impact categories. According to the results, forest harvesting stage was identified as the environmental hotspot being the main responsible of contributions to nine impact categories under assessment with contributing ratios ranging from 21% (e.g., freshwater eutrophication) to 76% (e.g., photochemical oxidants formation). The high amount of fossil fuel required by heavy machinery used in the activities involved in this stage is behind this result. Soil preparation stage reported also an outstanding contribution in categories such as freshwater eutrophication (37%) and toxicity related categories (≈35%). The rationale behind these contributions is associated with the use of chemical fertilizers, mostly superphosphate. The identification of the environmental hotspots in forest biomass production can assist the Brazilian forest practitioners to improve the environmental profile by means of the optimization of forest practices.

INFLUÊNCIA DA POSIÇÃO DOS INSTRUMENTOS DE MEDIDA NA DETERMINAÇÃO DO MÓDULO DE ELASTICIDADE DA MADEIRA NA COMPRESSÃO PARALELA ÀS FIBRAS (EC0)

The modulus of elasticity in compression parallel to the grain (Ec0) is a reference parameter to estimate the performance of the timber. Annex B of the Brazilian Code ABNT NBR 7190:1997 establishes, for determining the Ec0, to measure deformations at least on two opposite sides of the specimens. The aim of this study was to assess the influence of these test conditions in Ec0 values. This property was determined based on two opposite sides deformations of the specimens, and then, from the deformations obtained in complementary sides. Wood species were used to cover all strength classes assumed by this standard. Results showed a significant variation of Ec0 determined in mentioned tests, demonstrating that such a situation should be considered for future revision of the test methods for the determination of wood properties for structural application.

Influence of specimen orientation on determination of elesticity in static bending

Wood is a natural material and so many factors interfere in estimation of its physical and mechanical properties. Consequently variability in properties should be taken into account to rationalize its application. Longitudinal modulus of elasticity is one of the main mechanical properties of the material, and its value can be obtained via standardized tests. The aim of this study is to evaluate the influence of test conditions compatible with ABNT NBR 7190:1997 Code requirements to determine modulus of elasticity in static bending. For each of eight species, eight specimens were tested, all of them four times, with the sample oriented on each of its four faces related to load application. Data analysis was performed independently of species and their respective strength class, using hypothesis testing to evaluate influence of specimens’ orientations to determination. It was concluded that specimen orientation is significant in determining modulus of elasticity in static bending according to ABNT NBR 7190:1997. This aspect can lead to a future normative review by the National Committee responsible by redaction of this Code. To represent natural variability of wood in specimens’ volume by only one bending test, values of the modulus of elasticity should be lessened in 8%.

Emprego de resina epóxi em vigas danificadas de madeira de Pinus elliottii

A utilizacao da madeira em estruturas esta vinculada a condicoes que permitam sua utilizacao por muitos anos sem a perda de suas propriedades de resistencia e de rigidez. Entretanto, por se tratar de material natural, as estruturas em madeira projetadas podem estar sujeitas ao ataque de agentes biologicos, acao de intemperies, entre outros fatores, requerendo solucoes na forma de reparo ou reforco. O presente trabalho objetivou investigar a influencia do uso de resina epoxi como agente reparador em vigas danificadas de madeira de Pinus elliottii no calculo do produto de rigidez a flexao. Para tanto, foi realizado um planejamento experimental completo, tendo a posicao dos defeitos provocados (central ou laterais), o uso ou nao da resina nos defeitos, e a posicao desses defeitos (superior - compressao ou Inferior - tracao) como fatores. Os resultados da analise estatistica revelaram que o uso da resina epoxi nas regioes danificadas das vigas apresentaram valores do produto de rigidez na flexao significativamente superiores quando comparados com as vigas da condicao com defeito e sem a resina epoxi. Mesmo sendo significativo o uso da resina nas regioes danificadas, o produto de rigidez a flexao das vigas reparadas foi inferior ao produto de rigidez a flexao das vigas sem defeito (referencia), evidenciando a necessidade de outros estudos com outras resinas e outros materiais visando a recuperacao total da rigidez da peca de madeira danificada.