Warm mix asphalt (WMA) has been used worldwide for many years, primarily in Europe. The National Asphalt Pavement Association first brought WMA to the United States in 2002. By using warm mix technology, the temperature of an asphalt mixture during production, transportation, and compaction decreases dramatically. Several concerns about WMA arise due to the reduced mixing temperature. One of the primary concerns in asphalt pavement is the moisture damage. The lower mixing temperature may not be high enough to vaporize all the moisture absorbed in the aggregate, and part of the moisture may be entrapped in the pavements during compaction. This thesis presents a laboratory study to evaluate the moisture susceptibility of warm mix asphalt (WMA) produced through plant foaming procedure. Two types of mixtures were evaluated. A base mixture meeting the state of Tennessee “BM-2” mix criteria was evaluated at 0, 30, 40, and 50 percent fractionated recycled asphalt pavement (RAP), and a surface mixture meeting the state of Tennessee “411-D” mix criteria was evaluated at 15, 20, 30, 40 percent fractionated RAP. WMA mixture specimens were obtained and compacted at the asphalt plant. The WMA specimens were compared to hot-mix asphalt (HMA) specimens through a set of laboratory mixture performance tests. In addition to traditional AASHTO T283 freeze and thaw (F-T) tensile strength ratio (TSR), Superpave indirect tensile test (IDT) with F-T and MIST conditioning, and Asphalt Pavement Analyzer (APA) Hamburg wheel tracking tests were utilized to evaluate asphalt mixtures. Moisture tests indicated that with the higher inclusions of RAP, specimens exhibited lower rut depths and higher tensile strength retention. Tensile strength ratio tests indicated that HMA specimens had higher tensile strength retention when freeze thaw conditioned. Dynamic modulus conditioned specimens indicated that simple performance tests can show the difference between conditioned and unconditioned specimens. HMA specimens showed lower susceptibility to moisture compared to WMA specimens for both BM-2 and 411-D mixtures. The higher percentages of RAP in WMA and HMA in both BM-2 and 411-D mixtures showed a reduction to moisture susceptibility.

<p>Run-around energy recovery systems are one of the several ways for transferring energy between two air streams. Compared with other air-to-air energy recovery systems, run-around systems are very reliable and flexible, especially in retro-fit applications. Previous research in this area has mainly dealt with sensible run-around heat recovery system. However, an ideal air-to-air energy recovery device should be able to recover moisture as well as sensible heat. It is the objective of this research project to simulate a run-around system that exchanges both moisture and sensible heat, and to do a performance analysis to find the design characteristics of such a system.</p><p>The first step in the study was to develop a numerical model for a run-around system with two sensible heat exchangers and validate the model using data from the published literature. Following this, a mathematical/numerical model of a heat and moisture exchanger and the run-around heat and moisture recovery system was developed using only basic physical and chemical principles, component properties and operating conditions. With this model, the position dependent temperature and moisture content properties of both a single exchanger and a run-around system were simulated for steady state operating conditions. This simulation enables the study of the performance of the exchanger and the run-around system. In the investigation, the method was employed to characterize the performance of a single exchanger and a run-around system and two new independent parameters, the number of mass transfer units and mass flow rate ratio, were introduced.</p><p>The results show that, for the sensible run-around heat recovery system with a specified NTU, the maximum effectiveness occurs approximately at a heat capacity ratio, but for the run-around system with both heat and moisture exchange, the maximum effectiveness occurs approximately at heat capacity ratio for ARI summer and winter test conditions and the maximum effectiveness varies with . The analysis of the run-around system with both heat and moisture exchange with and as independent parameters shows that the maximum effectiveness occurs approximately when . As well, the value of maximum effectiveness was found to be different when different coupling salt solutions were used.

<p>Run-around energy recovery systems are one of the several ways for transferring energy between two air streams. Compared with other air-to-air energy recovery systems, run-around systems are very reliable and flexible, especially in retro-fit applications. Previous research in this area has mainly dealt with sensible run-around heat recovery system. However, an ideal air-to-air energy recovery device should be able to recover moisture as well as sensible heat. It is the objective of this research project to simulate a run-around system that exchanges both moisture and sensible heat, and to do a performance analysis to find the design characteristics of such a system.</p><p>The first step in the study was to develop a numerical model for a run-around system with two sensible heat exchangers and validate the model using data from the published literature. Following this, a mathematical/numerical model of a heat and moisture exchanger and the run-around heat and moisture recovery system was developed using only basic physical and chemical principles, component properties and operating conditions. With this model, the position dependent temperature and moisture content properties of both a single exchanger and a run-around system were simulated for steady state operating conditions. This simulation enables the study of the performance of the exchanger and the run-around system. In the investigation, the method was employed to characterize the performance of a single exchanger and a run-around system and two new independent parameters, the number of mass transfer units and mass flow rate ratio, were introduced.</p><p>The results show that, for the sensible run-around heat recovery system with a specified NTU, the maximum effectiveness occurs approximately at a heat capacity ratio, but for the run-around system with both heat and moisture exchange, the maximum effectiveness occurs approximately at heat capacity ratio for ARI summer and winter test conditions and the maximum effectiveness varies with . The analysis of the run-around system with both heat and moisture exchange with and as independent parameters shows that the maximum effectiveness occurs approximately when . As well, the value of maximum effectiveness was found to be different when different coupling salt solutions were used.

This dissertation presents an investigation of engineering behavior of expansive soils. An analytical study was undertaken for the development and modification of a Windows-based two-dimensional finite element computer program FLODEF that performs a sequentially coupled flow-displacement analysis for the prediction of moisture diffusion and the induced volume change in soils supporting various elements of civil infrastructure. The capabilities of the model are illustrated through case studies of shear strength envelope forecast and parametric studies of transient flow-deformation prediction in highway project sites to evaluate the effectiveness of engineering treatment methods to control swell-shrink deformations beneath highway pavements. Numerical simulations have been performed to study the field moisture diffusivity using a conceptual model of moisture diffusion in a fractured soil mass. A rough correlation between field and the laboratory measurements of moisture diffusion coefficients has been presented for different crack depth patterns.

Soil moisture in the shallow subsurface is a primary hydrologic state governing land-atmosphere interaction at various scales. The primary objectives of this study are to model soil moisture in the root zone in a distributed manner and determine scaling properties of surface soil moisture using passive microwave remote sensing. The study was divided into two parts. For the first study, a root zone soil moisture assessment tool (SMAT) was developed in the ArcGIS platform by fully integrating a one-dimensional vadose zone hydrology model (HYDRUS-ET) with an ensemble Kalman filter (EnKF) data assimilation capability. The tool was tested with dataset from the Southern Great Plain 1997 (SGP97) hydrology remote sensing experiment. Results demonstrated that SMAT displayed a reasonable capability to generate soil moisture distribution at the desired resolution at various depths of the root zone in Little Washita watershed during the SGP97 hydrology remote sensing experiment. To improve the model performance, several outstanding issues need to be addressed in the future by: including "effective" hydraulic parameters across spatial scales; implementing subsurface soil properties data bases using direct and indirect methods; incorporating appropriate hydrologic processes across spatial scales; accounting uncertainties in forcing data; and preserving interactions for spatially correlated pixels. The second study focused on spatial scaling properties of the Polarimetric Scanning Radiometer (PSR)-based remotely sensed surface soil moisture fields in a region with high row crop agriculture. A wavelet based multi-resolution technique was used to decompose the soil moisture fields into larger-scale average soil moisture fields and fluctuations in horizontal, diagonal and vertical directions at various resolutions. The specific objective was to relate soil moisture variability at the scale of the PSR footprint (800 m X 800 m) to larger scale average soil moisture field variability. We also investigated the scaling characteristics of fluctuation fields among various resolutions. The spatial structure of soil moisture exhibited linearity in the log-log dependency of the variance versus scale-factor, up to a scale factor of -2.6 (6100 m X 6100 m) irrespective of wet and dry conditions, whereas dry fields reflect nonlinear (multi-scaling) behavior at larger scale-factors.

Thesis (M. Sc.)--York University, 1997. / Typescript. Includes bibliographical references (leaves 104-113). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ27369.

Land surface albedo is the ratio of reflected to incident solar radiation. It is a function of several surface parameters including soil color, moisture, roughness and vegetation cover. A better understanding of albedo and how it changes in relation to variations in these parameters is important in order to help improve our ability to model the effects of land surface modifications on climate. The objectives of this study were 1) To determine empirical relationships between smooth bare soil albedo and soil color, 2) To develop statistical relationships between albedo and ground-based thematic mapper (TM) measurements of spectral reflectances, 3) To determine how increased surface roughness caused by tillage reduces bare soil albedo and 4) To empirically relate albedo with TM data and other physical characteristics of mixed grass/shrubland sites at Walnut Gulch Watershed. Albedos, colors and spectral reflectances were measured by Eppley pyranometer, Chroma Meter CR-200 and a Spectron SE-590, respectively. Measurements were made on two field soils (Gila and Pima) at the Campus Agricultural Center (CAC), Tucson, AZ. Soil surface roughness was measured by a profile meter developed by the USDA/ARS. Additional measurements were made at the Maricopa Agricultural Center (MAC) for statistical model testing. Albedos of the 15 smooth, bare soils (plus silica sand) were determined by linear regression to be highly correlated (r²=0.93, p>0.01) with color values for both wet and dry soil conditions. Albedos of the same smooth bare soils were also highly correlated (r²≥0.86, p>0.01) with spectral reflectances. Testing of the linear regression equations relating albedo to soil color and spectral reflectances using the data from MAC showed a high correlation. A general nonlinear relationship given by y=8.3661n(x)+37.802 r²=0.71 was determined between percent reduction in albedo (y) and surface roughness index (x) for wet and dry Pima and Gila field soils. Measurements of albedo, color and spectral reflectance at the Walnut Gulch Watershed indicated that albedo values were highly correlated with percent rock & gravel, color value and reflectance data (TM bands 1-4).

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

Revised; Original Published: 2004 / 2 pp. / Small grains are planted for a variety of reasons, but their rotational benefit makes them a popular crop all over the world and influences the way they are planted. One of the major benefits of small grains as rotational crops is that they cover the soil and suppress weeds. Thus, small grains are most commonly solid seeded with a grain drill.

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