Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


akron1333037184.pdf (22.86 MB)

ETD Abstract Container

Abstract Header

Simulation of Interfaces in Construction Materials: Tricalcium Silicate, Gypsum, and Organic Modifiers

Mishra, Ratan K.
http://rave.ohiolink.edu/etdc/view?acc_num=akron1333037184

Abstract Details

2012, Doctor of Philosophy, University of Akron, Polymer Engineering.
Concrete is the most widely used building material in the world and it is impractical to think about its substitution with any other materials such as steel, wood and brick etc. Cement is the only component, which is responsible for binding in the concrete and also accountable for large share of human-made CO2 during cement production. To produce cement in a more environmental friendly way, we present the very first fundamental study on interfacial properties of tricalcium silicate. Tricalcium silicate is the major constituent (accounting for 50-70% of the mass of Portland cement) of cement clinker, which exists in the form of alite in cement as an impure form and also serves as a model for Portland cement due to similar reaction kinetics. Besides, we also consider studying the interfacial and adsorption properties on gypsum and plaster of Paris to enhance our knowledge on mechanism involved in chemical processes during gypsum wallboard production. Molecular dynamics simulations using models with validated structural and surface properties have been employed to gain insight into interfacial adsorption and reaction dynamics in conjunction with measurements. New models and simulation in all-atomic resolution aid in understanding molecular-level processes related to grinding of cement clinkers, adsorption of organic additives, and the action of dispersants on gypsum and plaster of Paris. Grinding of clinker is a crucial step in cement production which consumes a lot of energy and limits the overall throughput of a given plant. Our work can contribute to reduce this. We present and validate a force field model for tricalcium silicate (C3S) and alite (defective C3S) which yields structural and surface properties in quantitative agreement with experiment and is compatible with materials and biologically oriented force fields (PCFF, COMPASS, CVFF, AMBER and CHARMM) for the simulation of complex aqueous interfaces. The models are employed to analyze cleavage energies of C3S for a large set of possible cleavage planes which are in a narrow range of 1250 to 1450 mJ/m2 consistent with the approximate spherical shape of the particles and measurements of the surface energy of similar minerals. Present work also aims at understanding the effectiveness of grinding aids by computing molecular adsorption of organic molecules such as TIPA (Triisopropanol amine), TEA (Triethanol amine), glycerine and polycarboxylate ester (PCE) on the dry and hydroxylated C3S surfaces, which are believed to be more representative of reality due to humidity presence during the grinding. In addition, we have also validated the force field model for gypsum (CaSO4 •2H2O) and plaster of Paris (CaSO4•0.5H2O) by calculating surface and interfacial energies of crystallographic planes of both the compounds. In gypsum, the (010) surface yields a minimal cleavage energy of 297 ± 7 mJ/m2 due to cleavage across double layers of water molecules. Together with contributions from remaining surfaces (120), (–111) and (011), an average surface energy of 373 ± 20 mJ/m2 is computed in agreement with experimental data (370 ± 20 mJ/m2) and solid-water interface tension, 67 ± 3 mJ/m2 as a Wulff average (experiment 64 mJ/m2). The minimum cleavage energy and solid-water interface tension of plaster of Paris are 480 ± 40 mJ/m2 for (010) plane and –35 ± 3 mJ/m2 for (001) plane respectively. Cleavage energy is higher than gypsum due to the lower water content in (010) plane and the lower interface tension is due to hydration reaction with water.
Hendrik Heinz, Dr. (Advisor)
Thein Kyu, Dr. (Committee Member)
Mark Soucek, Dr. (Committee Member)
Gary Hamed, Dr. (Committee Member)
Zhenhai Xia, Dr. (Committee Member)
163 p.
Materials Science

Recommended Citations

Citations

  • Mishra, R. K. (2012). Simulation of Interfaces in Construction Materials: Tricalcium Silicate, Gypsum, and Organic Modifiers [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1333037184

    APA Style (7th edition)

  • Mishra, Ratan. Simulation of Interfaces in Construction Materials: Tricalcium Silicate, Gypsum, and Organic Modifiers. 2012. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1333037184.

    MLA Style (8th edition)

  • Mishra, Ratan. "Simulation of Interfaces in Construction Materials: Tricalcium Silicate, Gypsum, and Organic Modifiers." Doctoral dissertation, University of Akron, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1333037184

    Chicago Manual of Style (17th edition)

akron1333037184
1,051
© 2012, all rights reserved.
This open access ETD is published by University of Akron and OhioLINK.