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The Photochemical Evolution Of Polycyclic Aromatic Hydrocarbons And Nontronite Clay On Early Earth And Mars, Nina Kopacz, Maria Angela Corazzi, Giovanni Poggiali, Ayla Von Essen, Vincent Kofman, Teresa Fornaro, Hugo Van Ingen, Eloi Camprubi, Helen E. King, John Brucato, Inge Loes Ten Kate

Biology Faculty Publications and Presentations

The photochemical evolution of polycyclic aromatic hydrocarbons (PAHs), an abundant form of meteoritic organic carbon, is of great interest to early Earth and Mars origin-of-life studies and current organic molecule detection efforts on Mars. Fe-rich clay environments were abundant on early Earth and Mars, and may have played a role in prebiotic chemistry, catalyzing the breakdown of PAHs and freeing up carbon for subsequent chemical complexification. Current Mars is abundant in clay-rich environments, which are most promising for harboring organic molecules and have comprised the main studied features by the Curiosity rover in search of them. In this work we …

Studying The Relationship Between Indigenous Microbial Communities, Urease Activity, And Calcite Precipitation In Artificial Mixes Of Clay And Sand, Somaye Asghari, Bhaskar C. S. Chittoori, Malcolm Burbank, Nick Hudyma

Civil Engineering Faculty Publications and Presentations

Microbial-induced calcium carbonate precipitation (MICP) is evolving as a new method of improving the mechanical properties of soil. This environmentally friendly technique is a bio-geo-chemical process where microbes play a key role in increasing soil strength through precipitating calcium carbonate. Past studies at Boise State University have indicated that MICP via bio-stimulation could be a viable alternative for expansive clayey soil treatments. However, these studies raised a new question about the relationship between soil composition, urease activity, and calcite precipitation. To answer this question, batch studies were conducted using autoclaved-sterilized sand mixed with different percentages of non-sterile natural clay and …

Evaluating The Applicability Of Biostimulated Calcium Carbonate Precipitation To Stabilize Clayey Soils, Md Touhidul Islam, Bhaskar C.S. Chittoori, Malcolm Burbank

Civil Engineering Faculty Publications and Presentations

Clayey soils with medium to high plasticity are prevalent in several parts of the world, causing billions of dollars in damage annually to various civil infrastructures. Several ground-improvement techniques can be employed to counteract this issue. However, these methods are impractical in certain situations and unsustainable in others due to their economic and environmental impacts. Microbial-induced calcite precipitation (MICP) could provide a more sustainable alternative. Researchers have successfully used MICP to alter specific geotechnical properties of sands and silts. This research investigates the applicability of MICP via biostimulation to treat clayey soils with low to high plasticity. The goal is …

Estimation Of The Compression Behaviour Of Reconstituted Clays, Martin D. Liu, Ziling Zhuang, Suksun Horpibulsuk

Faculty of Engineering and Information Sciences - Papers: Part A

The void index is a relative quantity measuring the position of the current void ratio of a clay against the void ratios of the clay at two specific vertical effective stresses (i.e., σ v ′ = 100 kPa and σ v ′ =1000 kPa). Based on this concept, a simple systematic tool is proposed for estimating the compression behaviour of reconstituted clays over a wide range of stresses and water contents. Following the practice of geotechnical engineering computation, the compression behaviour of clays is idealised as linear segments in the Iv ~ lnp′ (or the void index and the mean …

Variations In Strength Of Lime-Treated Soft Clays, Martin D. Liu, Buddhima Indraratna, Suksun Horpibulsuk, Jirayut Suebsuk

Faculty of Engineering - Papers (Archive)

Strength is often the most significant parameter in measuring the effect of soil improvement in geotechnical engineering practice. In this paper, a primary study is made of the variation in unconfined compressive strength of lime-treated soft clays under various practical conditions. There are three major factors that affect the strength development: lime content, curing time, and curing temperature. The variations in strength with the three factors are analysed and quantified by proposed empirical equations. These equations are verified against experimental data independently. Based on an analysis of the above simulations, a general strength equation is proposed, unifying the influence of …

Strength And Compressibility Of Lightweight Cemented Clays, Suksun Horpibulsuk, Apichat Suddeepong, Avirut Chinkulkijniwat, Martin D. Liu

Faculty of Engineering - Papers (Archive)

Lightweight cemented clays have wide applications in infrastructure rehabilitation and in construction of new facilities. The strength and compression characteristics of lightweight cemented clays with non- to high swelling potential are investigated and presented in this article. The workable state, the optimum water content to produce the lightweight cemented clay, is about 1.9 times the liquid limit. The void/cement ratio, V/C, which is defined as the ratio of the void volume of clay to the cement volume, is proved to be the prime parameter governing the strength and compression characteristics of lightweight cemented clays. The fabric (arrangement of clay particles, …

The Utility Of Nanocomposites In Fire Retardancy, Linjiang Wang, Xuejun He, Charles A. Wilkie

Chemistry Faculty Research and Publications

Nanocomposites have been shown to significantly reduce the peak heat release rate, as measured by cone calorimetry, for many polymers but they typically have no effect on the oxygen index or the UL-94 classification. In this review, we will cover what is known about the processes by which nanocomposite formation may bring this about. Montmorillonite will be the focus in this paper but attention will also be devoted to other materials, including carbon nanotubes and layered double hydroxides. A second section will be devoted to combinations of nanocomposite formation with conventional (and unconventional) fire retardants. The paper will conclude with …

A Study Of The Strength Of Lime Treated Soft Clays, Martin D. Liu, Stephen Pemberton, Buddhima Indraratna

Faculty of Engineering - Papers (Archive)

In this paper, a comprehensive study of the strength of lime treated soft clays is made. There are three major factors that affect the strength of the soils; they are the lime content, curing time, and curing temperature. The variations of soil strengths with the three factors are analysed and quantified via proposed empirical equations. These equations are verified against experimental data. Finally, a general strength criterion, unifying the influence of all the three factors into a single equation, is proposed. The capacity of the general equation is also demonstrated. It is seen that the proposed strength equations can provide …

Behavior Of Cemented Soft Clays In Undrained Situations, Suksun Horpibulsuk, Jirayut Suebsuk, Martin D. Liu

Faculty of Engineering - Papers (Archive)

In this paper, a constitutive model for cemented clay is introduced. This model is designated as "Modified Structured Cam Clay (MSCC) model". In the model, the influence of cementation structure is incorporated into effective stress concept, yield function, hardening rule and plastic potential function to describe the mechanical behavior of cemented clay during strain-hardening and softening. The methodology of modeling the shear behavior of structured clay is simple, which is the same way as that of the other models of the Cam Clay family. The capability of the MSCC model is verified by comparing the simulated undrained shear response of …

Polystyrene Nanocomposites Based On An Oligomerically-Modified Clay Containing Maleic Anhydride, Xiaoxia Zheng, David D. Jiang, Charles A. Wilkie

Chemistry Faculty Research and Publications

An oligomerically-modified clay containing maleic anhydride was used to prepare polystyrene-clay nanocomposites by melt blending and the effect of this modified clay on the thermal stability and fire performance was studied. These nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, thermogravimetric analysis and cone calorimetry. The results show a mixed immiscible/intercalated/delaminated morphology. The maleic anhydride modified clay improved the compatibility between the clay and the polystyrene.

Beta Testing Implementation Of The Purdue Time Domain Reflectometry (Tdr) Method For Soil Water Content And Density Measurement, Vincent P. Drnevich, Xiong Yu, Janet Elaine Lovell

JTRP Technical Reports

The Purdue TDR method is a new technology for simultaneously measuring soil water content and dry density insitu. An ASTM standard for using TDR to measure soil water content and dry density based on Purdue TDR method was approved during the time span of this project and is designated ASTM D6780. The primary objective of this study was to take the Purdue TDR Method to the point where it is widely field tested by users on a broad spectrum of soils around the country. This goal was achieved by involving researchers at other universities and practitioners in federal and state …

Review Of Stabilization Of Clays And Expansive Soils In Pavements And Lightly Loaded Structures - History, Practice, And Future, Thomas M. Petry, Dallas N. Little

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Expansive clay soils-those that change significantly in volume with changes in water content-are the cause of distortions to structures that cost taxpayers several billion dollars annually in the United States. Much has been learned about their behavior over the past 60 years, and relatively successful methods have been developed to modify and stabilize them. This paper reviews some of the key advances developed over the past 60 years in improving our understanding of the nature and methods of modifying and stabilizing expansive clay soils. The state of the practice in stabilization is presented, and practical and research needs to help …

Fire Retardant Halogen-Antimony-Clay Synergism In Polypropylene Layered Silicate Nanocomposites, Marco Zanetti, Giovanni Camino, Domenico Canavese, Alexander B. Morgan, Frank K. Lamelas, Charles A. Wilkie

Chemistry Faculty Research and Publications

Nanocomposites of polypropylene-graft-maleic anhydride with organically modified clays have been prepared and characterized by X-ray diffraction and transmission electron microscopy. Their combustion behavior has been evaluated using oxygen consumption cone calorimetry. Synergy is observed between the nanocomposite formed and conventional vapor phase fire retardants, such as the combination of decabromodiphenyloxide and antimony oxide. The presence of bromine and antimony does not affect the heat release rate curves of the virgin polymer.

Real-Time Determination Of Soil Type, Water Content, And Density Using Electromagnetics, Vincent P. Drnevich, Chih-Ping Lin, Quanghee Yi, Janet Elaine Lovell

JTRP Technical Reports

The primary objective of this study was to explore the potential use of electromagnetic characteristics of soils using the Time Domain Reflectometry (TDR) technique to identify physical properties of soils. Three fundamental studies in this exploration are the frequencydependent electromagnetic properties of soils, the wave propagation in a TDR system, and the inverse analyses of TDR waveforms. The three-phase model for soils was extended to a four-phase model so as to account for the interface effect and hence the soil fineness. The physical parameters of the four-phase model are related to the frequency-dependent dielectric permitivity of the soil through a …

Analysis Of Time-Deflection Consolidation Data, E. Gregory Mcnulty

Kentucky Transportation Center Research Report

A computerized statistical curve-fitting algorithm has been developed for determining the time-dependent properties of conventional (load-incremental) consolidation test data. Analytical models of the graphical methods developed by Taylor and Casagrande and of the Naylor-Doran method of successive approximations determtne values for the coefficients of consolidation, permeability, and the values of deflection corresponding to the begimltng and endtng of primary consolidation. The coefficients of volume change and secondary compression are also calculated. A modified statistical definition is used to select the linear portions of the data curves and is applicable to other data-fitting problems. After the Naylor-Doran method has been used, …

The Effect Of Thermal Treatment On The Engineering Properties Of Clays, George R. Laughlin

Kentucky Transportation Center Research Report

Of the cohesive soils the property of plasticity is usually of the most concern to the engineer. The clay minerals rather than the clay size material present in a soil determine the degree and magnitude of plastic properties. In turn, the plasticity of the clay minerals varies according to their mineralogy and particle size. Of the various types of clay minerals present in a soil, only kaolinite, illite and montmorillonite occur in sufficient abundance to be of general engineering significance.

Much prior work has been performed to alter these plastic properties of clay soils. This has been accomplished in some …