MATURE FINE TAILINGS (MFTs): A STUDY OF COMPRESSIVE STRENGTH AND RHEOLOGICAL PROPERTIES OF ATHABASCA OIL SANDS PETROLEUM MINING WASTE APPLIED IN CONCRETE MIXTURES

This study investigates the compressive properties of concrete incorporating Mature Fine Tailings (MFTs) waste stream from a tar sands mining operation. The objectives of this study are to investigate material properties of the MFT material itself, as well as establish general feasibility of the utilization of MFT material in concrete mixtures through empirical data and visual observations. Investigations undertaken in this study consist of moisture content, materials finer than No. 200 sieve, Atterburg Limits as well as visual observations performed on MFT material as obtained. Control concrete mixtures as well as MFT replacement mixture designs (% by wt. of water) were guided by properties of the MFT material that were experimentally established. The experimental design consists of compression testing of 4”-diameter concrete cylinders of a control mixture, 30% MFT, 50% MFT and 70% MFT replacement mixtures with air-entrainer additive, as well as a control mixture and 30% MFT replacement mixture with no air-entrainer. A total of 6 mixtures (2 control mixtures, 4 replacement mixtures) moist-cured in lime water after 24 hours initial curing were tested for ultimate compressive strength at 7 days and 28 days in accordance to ASTM C39. The test results of fresh concrete material show that the addition of air-entrainer to the control mixture increases slump from 4” to 5.5”. However, the use of MFT material in concrete mixtures significantly decreases slump as compared to controls. All MFT replacement mixtures (30%, 50%, and 70%) with air-entrainer present slumps of 1”. 30% MFT with no air-entrainer presents a slump of 1.5”. It was found that 7-day ultimate compressive stress was not a good predictor of 28-day ultimate compressive stress. 28-day results indicate that the use of MFT material in concrete with air-entrainer decreases ultimate compressive stress for 30%, 50% and 70% MFT replacement amounts by 14.2%, 17.3% and 25.1% respectively.

Multimembership and Identity in Writing Centers and in Industry: Examining the Work of Reconciliation in the Michigan Tech Multiliteracies Center and at Kimberly-Clark Corporation

Writing center scholarship and practice have approached how issues of identity influence communication but have not fully considered ways of making identity a key feature of writing center research or practice. This dissertation suggests a new way to view identity -- through an experience of "multimembership" or the consideration that each identity is constructed based on the numerous community memberships that make up that identity. Etienne Wenger (1998) proposes that a fully formed identity is ultimately impossible, but it is through the work of reconciling memberships that important individual and community transformations can occur. Since Wenger also argues that reconciliation "is the most significant challenge" for those moving into new communities of practice (or, "engage in a process of collective learning in a shared domain of human endeavor" (4)), yet this challenge often remains tacit, this dissertation examines and makes explicit how this important work is done at two different research sites - a university writing center (the Michigan Tech Multiliteracies Center) and at a multinational corporation (Kimberly-Clark Corporation). Drawing extensively on qualitative ethnographic methods including interview transcriptions, observations, and case studies, as well as work from scholars in writing center studies (Grimm, Denney, Severino), literacy studies (New London Group, Street, Gee), composition (Horner and Trimbur, Canagarajah, Lu), rhetoric (Crowley), and identity studies (Anzaldua, Pratt), I argue that, based on evidence from the two sites, writing centers need to educate tutors to not only take identity into consideration, but to also make individuals' reconciliation work more visible, as it will continue once students and tutors leave the university. Further, as my research at the Michigan Tech Multiliteracies Center and Kimberly-Clark will show, communities can (and should) change their practices in ways that account for reconciliation work as identity, communication, and learning are inextricably bound up with one another.