This thesis work focuses mainly on the application of non-destructive testing (NDT) methods on wood-based panels (WBP) in order to estimate the bending properties. To prove the accuracy and applicability of these methods on WBP, their results are correlated with results from a standardized static bending test. The behavior in different climate conditions and the application on panels of larger sizes is also questioned to provide an indication about strong points and boundaries of NDT methods applied on WBP.The bending properties are of major importance, especially for materials suited to bear loads. Bending stiffness, represented by the modulus of elasticity (MOE), is an expression of the deflection rate of a material under load. The bending strength, represented by the modulus of rupture (MOR), is an expression of the maximum load withstood by a material before rupture.Before testing, the material is acclimatized in three climate conditions: dry (20°C, 35% RH), standard (20°C, 65% RH) and wet (20°C, 85% RH), to understand the bending properties variation and how the NDT methods are affected by the variation in moisture content.The materials used are seven types of WBP, in particular four types of particleboards (PB), one type of high-density fiberboard (HDF), one type of dual density PB (with high and low density areas along the production direction) and one type of light-weight panel (Board-on-stiles, a composite panel of HDF, PB and paper honeycomb).To test the bending properties the following NDT methods are considered: transversal resonance vibration and longitudinal resonance vibration with the use of the BING system and the time-of-flight with the use of Fakopp Ultrasonic Timer and Silvatest Trio. The resonance vibration methods, transversal and longitudinal, are based on the relation between resonance vibration properties and bending properties of a material. The relation with bending properties also exists for the stress wave velocity (SWV) through a material, calculated with the time-of-flight method. The dynamic MOE resulting from these tests is then correlated with the static MOE and MOR from the static bending test.The NDT methods resulted to be reliable on WBP, with generally high levels of correlation between dynamic MOE and static MOE and MoR. The highest correlation value for MoE is with the transversal resonance vibration while the highest for MOR is with the longitudinal resonance vibration. The results of the dynamic MOE for all the NDT methods are higher than the static MOE, as confirmed also in the literature; the average ratio between the dynamic and the static MOE is, for example, up to 1,6 for WBP in standard climate condition, tested with Fakopp U.T.. These results are extremely higher than values suggested by previous studies. Moreover, the ratio increases with increasing relative humidity of the climate condition. The results from the tests on larger sizes suggest a possible application in this field. The time-of-flight method is suitable for in-plane uniform materials, like the PB and HDF, while the transversal resonance methods give also a good representation of the properties of the dual density PB and the light-weight panel.

A model is presented to use normalized multi-linear tension and compression material characteristics of strain-hardening textile reinforced concrete and derive closed form expressions for predicting moment-curvature capacity. A set of design equations are derived and simplified for use in spreadsheet based applications. The model is applicable for both strain-softening and strainhardening materials. The predictability of the simplified model is checked by model calibration and development of design charts for moment capacity and stress developed throughout the cross section of a flexural member. Model is calibrated by predicting the results of Alkali Resistant Glass and Polyethylene fabrics. A case for the flexural design of Glass Fiber Reinforced Concrete (GFRC) specimen as a simply supported beam subjected to distributed load is used to demonstrate the design procedure.

En el Perú, las vías de comunicación más utilizadas son las terrestres, entre las cuales, las más importantes son las carreteras, estas presentan deficiencias debido a distintos factores relacionados con errores en el diseño, proceso constructivo y mantenimiento. En la actualidad, la ciudad de Lima, que posee casi un tercio de la población del Perú, presenta un alto volumen de tráfico vehicular, que afecta especialmente a las vías de Lima Sur donde la exposición a los sulfatos es alta y la capacidad portante del suelo es reducida. Considerando esto, en Lima sur se necesitan construcciones apropiadas de pavimentos de concreto con la tecnología adecuada, y con materiales óptimos, que puedan proveer un servicio de calidad con poco mantenimiento. Además, se deben tomar en cuenta procesos industriales que eleven el estándar de calidad y que optimicen el costo de inversión con la mejora de rendimientos. Por todo, ello se plantea el uso de pavimentos CRCP con cementos puzolánicas en su diseño. En esta investigación se realizó el diseño de ocho mezclas de concreto con cementos puzolánicos Tipo HS e IPM, dentro de las cuales se escogió una de ellas para ser aplicada como alternativa de solución para mejorar la durabilidad de los pavimentos rígidos en las carreteras del sur de Lima. Dicho diseño asegura una resistencia a la compresión superior a 310 kg/cm2, un módulo de rotura mayor a 35 kg/cm2, una relación agua/cemento menor a 0.45 y un slump de 2 ½” en obra, el cual es ideal para su uso con pavimentadora de encofrados deslizantes. Para validar estas características del concreto se realizaron ensayos en estado fresco y endurecido en laboratorio. Además, se realizó un análisis costo – beneficio comparando pavimentos flexibles, JPCP y CRCP utilizando la mezcla optima. / In Peru, the most important routes are terrestrial, among which, the most common are roadways, these present many deficiencies due to different factors related to errors in design, construction process and maintenance. Nowadays, in Lima, which has almost a third of the population of Peru, presents a large traffic volume, and this significantly affects the roads, especially in the South, where the pavement is highly exposed to sulfates and the natural subgrades have a relatively low bearing capacity. Considering this, in the south region of Lima appropriate constructions of concrete pavements are necessary, using the correct technology and with optimal materials, so they can provide a quality service with low maintenance. On the other hand, industrial processes should be applied to improve the quality and optimize the investment with efficiency. For all of this, the use of CRCP with pozzolanic cements is proposed. This research carried out the design of eight concrete mixtures with pozzolanic cements type HS and IPM, within which one of them was chosen to be applied as an alternative to improve the durability of rigid pavements in this zone. This design ensures a compressive strength of 310 kg / cm2, a rupture modulus of 35 kg / cm2, a water/cement ratio of less than 0.45 and a slump of 2½” in the workplace, which is ideal for a constructive process with a slip formed paving machine. To validate these main characteristics of the concrete, experiments took place in the laboratory for the concrete in fresh and hardened state. In addition, a cost – benefit analysis comparing different types of pavement (flexible, JPCP y CRCP) was made using the optimal mixture obtained in this research. / Tesis

Soil-cement is an integral part of pavement design, especially in areas that are aggregate deprived, such as Mississippi. Current designs are reliant on the relationship of unconfined compressive strength (UCS) to other mechanical properties. The other properties discussed in this dissertation are Modulus of Elasticity (E), Indirect Tensile Strength (St), and Modulus of Rupture (MOR). This dissertation includes a comprehensive review of past design methods and mechanical property relationships. While some mechanical property relationships were shown to be well understood (i.e. St to UCS), others were not as accurate, especially for the later life mechanical properties (i.e. MOR to UCS and E to UCS). This dissertation investigates the Plastic Mold (PM) Compaction (PM) Device and its ability to measure mechanical property relationships (UCS, E, St) for soil-cement as well as different materials, such as lime stabilized subgrade and Cold in Place Recycling (CIR) stabilized with cement. These mechanical property relationships were compared to soil-cement beam specimens, which are capable of being tested for the four previously mentioned mechanical properties from an individual specimen. Finally to have a better understanding of the later life mechanical properties and their relationships, PM and beam specimens were exposed to elevated temperatures to forecast out how these properties interrelate over time. These mechanical property values and relationship were then compared to Mississippi field cores ranging from 10 to 54 years old. These protocols, beam and elevated curing, were able to replicate what was seen for pavement cores that were extracted after decades of service. Over 1300 specimens were testing showing how these mechanical properties interacted from early ages and throughout a pavement’s life.

No description available.

In or around 2010, a nationwide reevaluation of the allowable properties for southern pine dimension lumber was initiated. This led to a 2013 reduction in the design values of visually graded southern pine dimension lumber and a resulting decrease in its commercial and utility value. This change compelled researchers and industry professionals to ponder what could be done to shore up the value of solid-sawn southern pine products going forward and potentially increase design values if appropriate. In pursuit of this question, this dissertation looks closely at three areas: 1) the possibility this reduction in mechanical performance is not merely limited to southern pine structural lumber but can also be observed in other solid-sawn softwood products and species, 2) flaws that might exist in commonly utilized statistical models for estimating allowable properties in lumber, and 3) the feasibility of using existing technologies to begin to compensate for the economic and/or utility losses attributed to the recent reduction in design values. This work is comprised of an introduction, a conclusion, and three independent content chapters utilizing a variety of statistical techniques to investigate whether strength and stiffness reduction might also be occurring in southern pine (and Douglasir) utility crossarms, evaluate the propriety of using a Weibull distribution model for estimating allowable properties in dimension lumber, and gauge the suitability of nondestructive testing methods for potentially identifying high-value premium grades in solid-sawn softwood products.