{"421241":{"#nid":"421241","#data":{"type":"event","title":"PhD Defense by Nathan Mayercsik","body":[{"value":"\u003Cp align=\u0022center\u0022\u003E\u003Cstrong\u003ESchool of Civil and Environmental Engineering\u003C\/strong\u003E\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003E\u003Cstrong\u003EPh.D. Thesis Defense Announcement\u003C\/strong\u003E\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003ECharacterization of Multiscale Porosity in Cement-based Materials: \u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003EEffects of Flaw Morphology on Material Response Across Size and Time Scales\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003E\u003Cstrong\u003Eby:\u003C\/strong\u003E\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003ENathan Mayercsik\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003E\u003Cstrong\u003EAdvisor:\u0026nbsp; \u003C\/strong\u003E\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003EDr. Kimberly Kurtis (CEE)\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003E\u003Cstrong\u003ECommittee Members:\u0026nbsp; \u003C\/strong\u003E\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003EDr. Chloe Arson (CEE), Dr. Arun M. Gokhale (MSE), Dr. Laurence Jacobs (CEE), Dr. Lori L. Graham-Brady (Johns Hopkins University)\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003E\u0026nbsp;\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003E\u003Cstrong\u003EDate \u0026amp; Time:\u003C\/strong\u003E Monday, July 13, 2015 at 2:00pm\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003E\u003Cstrong\u003ELocation:\u003C\/strong\u003E\u0026nbsp; 122 Sustainable Education Building (SEB)\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003E\u003Cbr \/\u003E\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003EABSTRACT\u003Cbr \/\u003E\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003E\u003C\/p\u003E\u003Cp align=\u0022JUSTIFY\u0022\u003EIt is perhaps paradoxical that many material properties arise from the \u003Cem\u003Eabsence\u003C\/em\u003E of material rather than the presence of it. For example, the strength, stiffness, and toughness of a concrete are related to its pore structure. Furthermore, the volume, size distribution, and interconnectivity of porosity is important for understanding permeability, diffusivity, and capillary action occurring in concrete, which are necessary for predicting service lives in aggressive environments. This research advances the state-of-the-art of multiscale characterization of cement-based materials, and uses this characterization information to model the material behavior under competing durability concerns. In the first part of this research, a novel method is proposed to characterize the entrained air void system. In the second and third parts of this research, microstructural characterization is used in tandem with mechanical models to investigate the behavior of cementitious materials when exposed to rapid rates of loading and to cyclic freezing and thawing.\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003E\u003C\/p\u003E\u003Cp align=\u0022JUSTIFY\u0022\u003EFirst, a novel analytical technique is presented which reconstructs the 3D entrained air void distribution in hardened concrete using 2D image analysis. This method proposes a new spacing factor, which is believed to be more sensitive to microstructural changes than the current spacing factor commonly utilized in practiced, and specified in ASTM C457, as a measure of concrete\u0027s ability to resist to damage under cyclic freeze\/thaw loading. This has the potential to improve economy by improving the quality of petrographic assessment and reducing the need for more expensive and time-consuming freeze\/thaw tests, while also promoting the durability of concrete.\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003E\u003C\/p\u003E\u003Cp align=\u0022JUSTIFY\u0022\u003ESecond, qualitative measurements of the sizes, shapes, and spatial arrangements of flaws which are through to drive failure at strain rates above 100\/s were obtained in order to model mortar subjected to high strain-rate loading (i.e., extremes in load rate). A micromechanics model was used to study the ways in which flaw geometry and flaw interaction govern damage. A key finding suggests that dynamic strength may be multimodal, with larger flaws shifting the dynamic strength upwards into the highest strength failure mode.\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003E\u003C\/p\u003E\u003Cp align=\u0022JUSTIFY\u0022\u003EThird, a robust theoretical approach, based upon poroelasticity, is presented to further validate the utility of the novel spacing factor proposed this research. The model is truly multiscale, using in its formulation pore size data ranging from the nanoscale to the micro-scale, entrained air data from the micro-scale to the millimeter scale, and infers a representative volume element on the centimeter scale. The results provide an underlying physical basis for the performance of the novel spacing factor. Furthermore, the framework could be used as a forensic tool, or as a tool to optimize the entrained air void system against freeze\/thaw damage.\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003E\u003Cbr \/\u003E\u003C\/p\u003E\u003Cp align=\u0022center\u0022\u003E\u003Cbr \/\u003E\u003C\/p\u003E\u003Cp\u003E \u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":"","field_summary_sentence":[{"value":"Characterization of Multiscale Porosity in Cement-based Materials: Effects of Flaw Morphology on Material Response Across Size and Time Scales"}],"uid":"27707","created_gmt":"2015-07-06 09:05:12","changed_gmt":"2016-10-08 02:12:22","author":"Tatianna Richardson","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2015-07-13T15:00:00-04:00","event_time_end":"2015-07-13T17:00:00-04:00","event_time_end_last":"2015-07-13T17:00:00-04:00","gmt_time_start":"2015-07-13 19:00:00","gmt_time_end":"2015-07-13 21:00:00","gmt_time_end_last":"2015-07-13 21:00:00","rrule":null,"timezone":"America\/New_York"},"extras":[],"groups":[{"id":"221981","name":"Graduate Studies"}],"categories":[],"keywords":[{"id":"100811","name":"Phd Defense"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[{"id":"1788","name":"Other\/Miscellaneous"}],"invited_audience":[{"id":"78771","name":"Public"}],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[],"email":[],"slides":[],"orientation":[],"userdata":""}}}