Sustainability and reduction of environmental impacts have continued to increase in importance in the concrete marketplace. Portland-limestone cement (PLC) has been shown to reduce total energy consumed and CO2 produced during the cement manufacturing process. This material may also have the ability to benefit concrete properties, such as compressive strength and time of set. Other concrete performance measures of potential interest evaluated in this study include durability and modulus of elasticity. In this dissertation PLC was evaluated for its ability to further increase concrete sustainability, while at the same time providing advantageous properties. This study’s focus was to show that PLC can improve concrete mixtures that are similar to commonly used ordinary portland cement (OPC) mixtures. PLC was also evaluated for its ability to increase the amount of total cement replacement (further increasing sustainability). Additionally PLC properties and concrete mixture combinations were evaluated in an attempt to clarify which PLC properties are crucial in performance benefits. Approximately 2000 concrete specimens were tested along with approximately 1000 cement paste specimens. This dissertation also includes an evaluation of PLC being used in a large scale construction and renovation project on a college football stadium. The scope of the dissertation included 12 cements from four manufacturing facilities that represent a large portion of the cement industry in the southeast US. Supplementary cementitious materials (SCMs), Class C fly ash, Class F fly ash, and slag cement, were also evaluated in single and dual SCM concrete mixtures at replacement rates up to 70%. Replacement rates of this magnitude are not being used in common practice but may become preferred in some conditions with PLC. Results indicated that PLC outperformed OPC in areas tested, in almost all cases at up to 50% replacement with single and dual SCMs. PLC also showed considerable advantages at 60% replacement but was often outperformed by OPC at 70% replacement. Aggregate type played a large role at 70% replacement. Elastic modulus, durability, and variability were all similar with PLC and OPC. Combinations of certain SCMs were more advantageous than others, and optimal SCM combinations changed depending on cement source.
| Identifer | oai:union.ndltd.org:MSSTATE/oai:scholarsjunction.msstate.edu:td-4496 |
| Date | 11 December 2015 |
| Creators | Shannon, Jameson Davis |
| Publisher | Scholars Junction |
| Source Sets | Mississippi State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations |
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