Engineering Commons^™

Bond And Fatigue Characteristics Of High-Strength Cement-Based Composites, Somboon Chimaphant

Dissertations

The results of a series of tests on a variety of high strength cementitious composites yield a model from which an empirical equation of general normalized pull-out stress vs. pull-out displacement relationship is developed. A new variable named the "Brittleness Index" is defined and used in the proposed equation. Additionally, the concept of maximum strain is used to predict the fatigue life of high strength concrete.

Three sizes of deformed bars and two types of steel fibers with four different volume fractions were used to observe bond-slip and pull-out characteristics of high strength concrete. The results indicate that the maximum …

Anaerobic Biodegradation Of Trichloroethylene With The Addition Of Sugar Using Activated Carbon-Fluidized Beds, Suxan Huang

Dissertations

Anaerobic biodegradation of trichloroethylene (TCE) was carried out in a two-stage granular activated carbon fluidized bed bioreactor. The intermediate products were identified as: dichloroethylene (DCE), vinyl chloride (VC), 1,2-dichloroethane (DCA) and chloroethane (CA). Of the three geometric isomers of DCE, the trans-1,2 dichloroethylene (TDCE) was found to be the most predominant species, The production of DCA suggested a diverted reaction sequence from the conventional sequential reductive dechlorination pathway postulated in the past literature. CA was believed to be a product of VC and/or DCA. The co-substrate glucose was implicated for this reaction specificity. Based on our data and on other's …

Air Stripping Of Volatile Organic Contaminants Using Rotating Disc Contactor, Kai-Ping Hsueh

Dissertations

Previous studies have suggested that the transfer of VOCs to the atmosphere by air stripping may be a convenient and potentially cost-effective method to remove these compounds from the water. A Rotating Disk Contactor (RDC), similarly to other aeration devices, can provide intimate contact between the VOC-bearing water and air. It is believed that under carefully selected operating conditions, the RDC system are more competitive with packed tower than other aeration methods. The objectives of this study were to evaluate the feasibility of using the RDC to strip VOCs from the contaminated water and to develop a mathematical model to …

Permeability And Volume Change Characeristics Of Bentonite-Sand Mixes In A Contaminant Environment, Yuan-Hsun Wu

Dissertations

This research was conducted to study the characteristics of permeability and volume change of bentonite-sand mixes due to contaminants. The soil specimens consisted of clean sand, bentonite, and fly ash. Test liquids included seven diluted organic and inorganic chemicals and a landfill leachate.

Index tests included liquid limit, expansion, cracking, and sedimentation tests. Expansion tests proved to be the most useful for permeability evaluation in a contaminant environment.

The conventional consolidometer permeameter and flexible wall permeameter proved to be not completely satisfactory for testing soft bentonite mixes. A triple ring permeameter was developed to compensate for the limitations of these …