ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
Displaying 1 - 3 of 3
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- All Subjects: Building materials
- All Subjects: Three-dimensional printing
- Creators: Mobasher, Barzin
Description
Manufacture of building materials requires significant energy, and as demand for these materials continues to increase, the energy requirement will as well. Offsetting this energy use will require increased focus on sustainable building materials. Further, the energy used in building, particularly in heating and air conditioning, accounts for 40 percent of a buildings energy use. Increasing the efficiency of building materials will reduce energy usage over the life time of the building. Current methods for maintaining the interior environment can be highly inefficient depending on the building materials selected. Materials such as concrete have low thermal efficiency and have a low heat capacity meaning it provides little insulation. Use of phase change materials (PCM) provides the opportunity to increase environmental efficiency of buildings by using the inherent latent heat storage as well as the increased heat capacity. Incorporating PCM into concrete via lightweight aggregates (LWA) by direct addition is seen as a viable option for increasing the thermal storage capabilities of concrete, thereby increasing building energy efficiency. As PCM change phase from solid to liquid, heat is absorbed from the surroundings, decreasing the demand on the air conditioning systems on a hot day or vice versa on a cold day. Further these materials provide an additional insulating capacity above the value of plain concrete. When the temperature drops outside the PCM turns back into a solid and releases the energy stored from the day. PCM is a hydrophobic material and causes reductions in compressive strength when incorporated directly into concrete, as shown in previous studies. A proposed method for mitigating this detrimental effect, while still incorporating PCM into concrete is to encapsulate the PCM in aggregate. This technique would, in theory, allow for the use of phase change materials directly in concrete, increasing the thermal efficiency of buildings, while negating the negative effect on compressive strength of the material.
ContributorsSharma, Breeann (Author) / Neithalath, Narayanan (Thesis advisor) / Mobasher, Barzin (Committee member) / Rajan, Subramaniam D. (Committee member) / Arizona State University (Publisher)
Created2013
Description
Buildings consume a large portion of the world's energy, but with the integration of phase change materials (PCMs) in building elements this energy cost can be greatly reduced. The addition of PCMs into building elements, however, becomes a challenge to model and analyze how the material actually affects the energy flow and temperatures in the system. This research work presents a comprehensive computer program used to model and analyze PCM embedded wall systems. The use of the finite element method (FEM) provides the tool to analyze the energy flow of these systems. Finite element analysis (FEA) can model the transient analysis of a typical climate cycle along with nonlinear problems, which the addition of PCM causes. The use of phase change materials is also a costly material expense. The initial expense of using PCMs can be compensated by the reduction in energy costs it can provide. Optimization is the tool used to determine the optimal point between adding PCM into a wall and the amount of energy savings that layer will provide. The integration of these two tools into a computer program allows for models to be efficiently created, analyzed and optimized. The program was then used to understand the benefits between two different wall models, a wall with a single layer of PCM or a wall with two different PCM layers. The effect of the PCMs on the inside wall temperature along with the energy flow across the wall are computed. The numerical results show that a multi-layer PCM wall was more energy efficient and cost effective than the single PCM layer wall. A structural analysis was then performed on the optimized designs using ABAQUS v. 6.10 to ensure the structural integrity of the wall was not affected by adding PCM layer(s).
ContributorsStockwell, Amie (Author) / Rajan, Subramaniam D. (Thesis advisor) / Neithalath, Narayanan (Thesis advisor) / Mobasher, Barzin (Committee member) / Arizona State University (Publisher)
Created2013
Description
This dissertation aims at developing novel materials and processing routes using alkali activated aluminosilicate binders for porous (lightweight) geopolymer matrices and 3D-printing concrete applications. The major research objectives are executed in different stages. Stage 1 includes developing synthesis routes, microstructural characterization, and performance characterization of a family of economical, multifunctional porous ceramics developed through geopolymerization of an abundant volcanic tuff (aluminosilicate mineral) as the primary source material. Metakaolin, silica fume, alumina powder, and pure silicon powder are also used as additional ingredients when necessary and activated by potassium-based alkaline agents. In Stage 2, a processing route was developed to synthesize lightweight geopolymer matrices from fly ash through carbonate-based activation. Sodium carbonate (Na2CO3) was used in this study to produce controlled pores through the release of CO2 during the low-temperature decomposition of Na2CO3. Stage 3 focuses on 3D printing of binders using geopolymeric binders along with several OPC-based 3D printable binders. In Stage 4, synthesis and characterization of 3D-printable foamed fly ash-based geopolymer matrices for thermal insulation is the focus. A surfactant-based foaming process, multi-step mixing that ensures foam jamming transition and thus a dry foam, and microstructural packing to ensure adequate skeletal density are implemented to develop foamed suspensions amenable to 3D-printing. The last stage of this research develops 3D-printable alkali-activated ground granulated blast furnace slag mixture. Slag is used as the source of aluminosilicate and shows excellent mechanical properties when activated by highly alkaline activator (NaOH + sodium silicate solution). However, alkali activated slag sets and hardens rapidly which is undesirable for 3D printing. Thus, a novel mixing procedure is developed to significantly extend the setting time of slag activated with an alkaline activator to suit 3D printing applications without the use of any retarding admixtures. This dissertation, thus advances the field of sustainable and 3D-printable matrices and opens up a new avenue for faster and economical construction using specialized materials.
ContributorsAlghamdi, Hussam Suhail G (Author) / Neithalath, Narayanan (Thesis advisor) / Rajan, Subramaniam D. (Committee member) / Mobasher, Barzin (Committee member) / Abbaszadegan, Morteza (Committee member) / Bhate, Dhruv (Committee member) / Arizona State University (Publisher)
Created2019