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CORRELATION BETWEEN AASHTO IDAHO IT-144 & T-84 METHODS FOR IDAHO FINE AGGREGATES
No full textThe design of a Hot Mixed Asphalt (HMA) pavement mix requires information about the Bulk Specific Gravity (Gsb) and Absorption characteristics of the fine aggregates. This data is often determined using the standard AASHTO T-84 test for fine aggregates, which usually takes 2-3 days to complete. As the test is strongly dependent on the expertise of the operator, it has encountered ongoing criticism due to the subjective nature of the test. To overcome some of the operator-dependent errors associated with the AASHTO T-84 procedures, a new method, known as the CoreLok method was developed. This method is quick, reliable, portable, and provides consistent, repeatable results for fine aggregates. The Idaho Transportation Department (ITD) has its own standard procedure for the CoreLok test, IT-144 (2008), which is based on the original ASTM standard D7370. As the CoreLok test may be completed on an aggregate sample within 30 minutes, it has become a popular replacement for the AASHTO T-84 test. This study was conducted to develop models which could correlate the IT-144 test results with AASHTO T-84 test results. For this purpose, 22 typical aggregate samples collected from the popular quarry sites in five ITD districts used by the ITD were tested using AASHTO T-84 and Idaho IT-144 test methods. A Round-Robin experiment was carried out involving ITD (Boise), ALLWEST and STRATA to confirm that the results were comparable between the participants. A total of 68 T-84 tests and 65 IT-144 tests were run at UI for the data analysis. Regression models were developed to predict the AASHTO T-84 values using the IT-144 values which were validated using the ALLWEST values. Simple regression analysis and multiple regression analysis were performed to develop linear and non-linear prediction models. AASHTO T-84 results were used as the dependent variable and IT-144 test results, and other variables like particle sizes, Specific Surface Area (SSA) and Fineness Modulus (FM) of the aggregates, Coefficient of Curvature (Cc), and Coefficient of Uniformity (Cu) were used as the predictor variables. A simple linear regression model with R2 = 90.53 percent and a multiple regression model with R2 = 85.77 percent was recommended for Gsb,Dry and Absorption prediction respectively. Data validation was better for simple linear regression for Gsb,Dry and multiple regression for Absorption. It is recommended that the Idaho IT-144 test method be adopted as it is faster, easier, repeatable, and produces results which are close to the AASHTO T-84 method. Keywords: Correlation, AASHTO T-84, IT-144, Specific Gravity, Absorption, Fine Aggregatesmasters, M.S., Civil Engineering -- University of Idaho - College of Graduate Studies, 2018-0
Subsurface Phosphorus Transport through a no-till Field in the Semiarid Palouse Region
No full textHeavy application of fertilizers containing nitrogen and phosphorus to soils causes surface water quality degradation because the nutrients flow out of the agronomic systems and enter water bodies in large quantities, causing algal blooms and eutrophication. Extensive studies focusing on phosphorus as a surface water pollutant from agronomic systems have been conducted in the many regions of the United States, however, there has been a lack of studies completed in the semiarid Palouse region of eastern Washington and western Idaho. The goal of this research was to better understand how no-till farm management has temporally altered soil P availability for off-site transport through an artificially drained catchment at the Cook Agronomy Farm in Pullman, WA. Preferential flow pathways were also characterized in extracted cores. Dissolved reactive P (DRP) concentrations in subsurface drainage from an artificial drain exceeded TMDL threshold concentrations during numerous seasonal high flow events over the two-year study time frame. Soil analyses of samples collected in 1998, 2008, and 2015 show a highly variable distribution of water-extractable P across the sub-catchment area, and translocation of P species deeper into the soil profile since implementing no-till practices. We hypothesized that a greater network of macropores from lack of soil disturbance allow for preferential flow of water rich in dissolved nutrients deeper into the subsurface and to the artificial drain system. Simulated flow experiments on soil cores from the study site showed large-scale macropore development, extreme variability in soil conductivity, and high P adsorption potential for the soils, suggesting a disconnect between P movement through macropore soil and subsurface drainage water rich in DRP at the artificial drain line outlet.masters, M.S., Water Resources -- University of Idaho - College of Graduate Studies, 2018-0
Investigation of Fatigue and Creep-Fatigue Crack Growth in Alloy 709 at Elevated Temperatures
No full textThe service life of Generation IV nuclear reactors is seeking to increase to 60+ years. With increased service life, the likelihood of creep-fatigue failures of structural components increases. Understanding creep-fatigue crack growth behavior is essential for structural applications within nuclear reactors and the power generation industry. Most service conditions involve a combination of creep and fatigue loading. Testing materials in the laboratory is critical to understanding the mechanics of creep-fatigue damage. To date, considerable work in the area of creep-fatigue characterization has taken place on various stainless steel power plant materials. A recently developed austenitic stainless steel Fe-25Ni-20Cr (Alloy 709), in consideration for various high temperature reactor applications, has yet to be properly and sufficiently characterized. Characterization of the creep-fatigue and fatigue properties of Alloy 709 in this study utilized the standard compact tension specimen geometry. The temperature conditions investigated included 550, 600 and 700℃. Proper exemplification of material characterization and consistency of processing techniques was the primary focus of this research. Testing included three separate batches of material that were provided by the project sponsor. To investigate the effect of prolonged exposure to elevated temperatures, the third batch of material consisted of three aging schedules: as-received, aged 1 and aged 2. Testing conditions under fatigue loading included loading ratios, R, of 0.1, 0.3, 0.5 and 0.7. R-ratio effects on crack growth rate were characterized in terms of da/dN versus ΔK. For investigation of creep-fatigue crack growth, hold times of 60 and 600s were tested. Fracture surface and crack plane characteristics were investigated with the aid of scanning electron microscopy, electron backscatter diffraction and optical imaging. The primary conclusion from this study indicates minimal sensitivity to loading conditions. Under creep-fatigue loading, creep crack growth was minimal at lower hold times. At a hold time of 600s, there was a noticeable increase in crack growth rate. Fracture surface and crack profile imaging indicated transgranular primary and secondary crack propagation. Crack topography and secondary cracking noticeably increased as hold time increased. Material in both aged 1 and aged 2 conditions showed little influence on crack growth rates under any tested loading condition of fatigue crack growth or creep-fatigue crack growth.masters, M.Engr., Mechanical Engineering -- University of Idaho - College of Graduate Studies, 2018-1
Early Field Performance and Allometry of Three Inland Northwest Conifer Species, Influence of Root Growth Potential and Site Characteristics
No full textDouglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco), grand fir (Abies grandis), and western larch (Larix occidentalis) containerized seedlings were evaluated for aeroponic root growth potential (RGP) and planted on sites with variable soil environments. The sites differed in aspect and soil moisture environment; north-aspect (wet), north-aspect (dry) and south-aspect. Height and diameter growth, as well as survival, were evaluated over the first two seasons after planting. During the first growing season seedlings were destructively sampled to create specific allometric models and evaluate how seedling biomass accumulation and partitioning patterns were influenced by RGP and soil conditions, and how this relates to the growth and survival of planted seedlings. Douglas-fir and western larch seedlings have significantly lower growth and survival on a south-aspect site, than on north-aspect sites but seem more influenced by site aspect differences than site soil moisture differences. All species accumulated greater biomass on sites without soil moisture limitations. Grand fir seedlings did not exhibit differences in two-year field performance across sites, but did exhibit different patterns of biomass allocation on the south-aspect site favoring shoot growth on the south-aspect site. The increased presence of competing vegetation resulted decreased growth and survival of planted seedlings after two growing seasons. Douglas-fir seedlings two-year survival increased with RGP on the wet north-aspect but decreased with RGP on the dry north-aspect site; grand fir seedlings with high RGP had greater survival on either north-aspect site. However, grand fir seedlings with high RGP the south-aspect site and western larch seedlings on the dry north-aspect site had lower survival than other seedlings. All species responded variably to within site differences in soil moisture and temperature, but there was not consistent response, and it seems that differences in growth and survival are more related to between site differences. RGP was a successful predictor of survival for the more stress-tolerant species on north-aspects, but Douglas-fir displayed a negative relationship between survival and RGP on the dry north-aspect site. Results will help managers better understand how RGP results relate to field performance and provide a mechanistic understanding of periodic changes in seedling morphology and how they relate to early growth and survival on common planting sites in the region.masters, M.S., Natural Resources -- University of Idaho - College of Graduate Studies, 2018-1
An Analytical Spectroscopic Method for the Reliable Determination of Binding Constants and Fluorescent Rare Earth Element Detection
No full textMetal residues are found widely distributed in products and waste streams and recovery and detection of these materials is desirable. This thesis investigated the detection of rare earths in different matrices and determination of binding constants for characterizing N,N-diethylphenylarylazothioformamide (ATF) ligand. Low level fluorometric dectection of rare earths was investigated for Nd, Sm, and Eu in place of UV/Vis using the arsenazo-III ligand. Unfortunately, fluorometric detection was comparable to UV/Vis levels of detection and quantification. Metal-binding ligands, such as ATF, are a possible solution for purification of materials and recovery of valuable metals. However, binding of ATF to metals must be characterized to engineer it‘s affinity to metals. Ligand characterization showed cooperative binding between the redox active ATF ligand and Cu(I) salts. Characteristic UV/Vis and 1H NMR models were coupled for more reliable binding constant determination. In general, coupling two measurement methods increases the reliability of determined parameters.masters, M.S., Chemical and Materials Science Engineering -- University of Idaho - College of Graduate Studies, 2018-0
Model Guided Control of Radiant Slabs for Comfort and Efficiency
No full textRadiant slabs have the potential to deliver efficient heating and cooling to buildings while enhancing comfort. However, these systems do not operate on conventional time scales and there is often a delay between a thermostat’s signal and the system’s response. This research lays out a framework of how to overcome this problem by linking an energy model to weather forecasts to inform the controls. An overview of radiant systems and technologies demonstrates its inherent advantages for conditioning buildings. A method for connecting an energy model to control hardware for remote co-simulation is developed and tested. Results indicated operational savings of at least 12% could be achieved through the remote co-simulation approach. Once it was verified that an OpenStudio model could be used for virtual commissioning, the focus turned towards modeling of a radiant slab. Extensive data was collected at a design office in Boise Idaho with a radiant slab used for heating and cooling. An OpenStudio model was built and calibrated so that it could predict the heating and cooling required of the radiant slab in real time. A framework is set up for performing parametric simulations and incorporating weather forecasts into the energy model. The model was used to predict ideal control setpoints by using short simulations of four hours into the future. Model comparisons indicated that using the model to guide the control setpoints could save up to 13% of HVAC energy over one month and the office space was kept significantly more comfortable compared to the current control scheme.doctoral, Ph.D., Mechanical Engineering -- University of Idaho - College of Graduate Studies, 2018-0
