Laurenn Borges de Macedo

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.

Use of Coffee Plant Stem in the Production of Conventional Particleboards

When the productivity of a coffee plantation drops considerably, the crop must be renewed. In this case, the removed plants become residues to be discarded. This work aimed to verify the utilization of the coffee plant stem in the production of conventional particleboards. The basic density and chemical composition of the coffee stem was obtained. 3 particleboards were produced with urea-formaldehyde at 6% and paraffin at 1%. The target density of the panels was 0.600 g/cm3. The pressing cycle used was: pressure of 0.32 MPa, temperature of 160°C and time of 8 minutes. Apparent density (AD), water absorption (WA), thickness swelling (TS) after 2 and 24 hours immersion and thickness non-return rate (TNRR) were the physical properties obtained. Mechanical properties evaluated were parallel compression (CP), static bending (MOE and MOR) and internal bonding (IB). The average basic density, total extractive, lignin, mineral components and holocelluloses contents obtained were 0.581gcm-3, 11%, 28%, 2% and 59%, respectively. The average values of the physical and mechanical properties of the boards, followed by their standard deviation were: AD= 0.577 gcm-3 (0.018); CR = 1.03 (0.12); WA_2h = 55% (2.3); WA_24r = 76% (2.5); TS_2h = 32% (4.4); TS_24h = 59% (7.8); TNRR = 62 % (2.0); IB = 0.43 MPa (0.03); CP = 4.9 MPa (0.23); MOE = 1324.4 MPa (1.02); and MOR = 13.4 MPa (1.02). Coffee stem conventional particleboards presented poor physical resistance. On the other hand, they may be commercialized for general uses in dry-conditions.

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.

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.

Evaluation of Health Conditions of Wooden Structures of the Former Slave Quarters of Farm Santa Maria do Monjolinho, Located in the State of São Paulo, Brazil

Brazil still has a diversity of architectural structures that represent various historical periods experienced. However, much of this cultural heritage is not properly maintained and this work aims to contribute to the conservation of the wooden structure of a historic site in the state of São Paulo. Problems related to the health/physical normality of wood present in historical building structures are commonly found, therefore, assessment measures and maintenance should be performed to secure the structural integrity of these parts, so that these architectural references are not lost over time. The farm Santa do Maria Monjolinho, located in São Carlos, the central region of the state of São Paulo, Brazil, declared cultural heritage in 2007 by the department of state assets - CONDEPHAAT - stands out for the richness of its architectural set which was built in the nineteenth century, under the dominance of the coffee economy. Its facilities include the main house, yard coffee, granary and machine room, aqueduct and water wheel, chapel, mill, barn, settler houses and the building of the former slave quarters, fully preserved by the family Malta Campos. The old slave quarters, the object of our study, was built in the mid nineteenth century: today is the building that has the highest level of degradation. Originally consisted of two large environments, called wards, one female and the other male, with the function of house the farms slaves. After abolition, italian colonists adapted the building turning it into five houses with party walls of clay and wattle-and-daub. The roof, which consists in a wood structure and clay tiles, is bulging and has loads of broken tiles and the timber (rafters, beams and purlins) structurally compromised due to moisture attack and wood decay agents. The roof structure is supported by brickwork pillars and fresh mainstays, and some of them exhibit some level of degradation. To evaluate the health of these mainstays were used wood samples from other similar structures in the same property, built at the same era of the slave quarters. Tests of shear, compression parallel to the fibers and density that were developed made possible to make an analogy to the strength and condition of the wooden structures that support the roof of the slave quarters. The results as such tests show the reduction of the mechanical resistance of the pieces evaluated, leading to the need to reassess the conditions of service of the structures considered. Seeking an evaluation and diagnosis of health and structural conditions of the roof of the slave quarters, we intend to perform nondestructive tests on some parts of the wood of the structure itself. To do so, the following equipment could be used: Stress Wave Timer, Pylodin and Resistograph, offered by USP. Thus, using data obtained by the tests will be possible to determine the percentage of deterioration of structural components and the indication of restoration suitable for conservation of the structure, while cultural heritage of regional significance.