Cold Sintered Calcium Carbonate Binders and Affinity Examination of 1D|2D Graphitic and Silica Nanoparticles in Civil Cementitious Materials
Open Access
- Author:
- Zahabi, Mehrzad
- Graduate Program:
- Architectural Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- December 05, 2019
- Committee Members:
- Aly Marei Said, Dissertation Advisor/Co-Advisor
Aly Marei Said, Committee Chair/Co-Chair
Ali M Memari, Committee Chair/Co-Chair
Mauricio Terrones, Outside Member
Farshad Rajabipour, Outside Member
Somayeh Asadi, Program Head/Chair
Ali M Memari, Dissertation Advisor/Co-Advisor - Keywords:
- Cold Sintering
Precast Construction Material Alternative
Precipitate and Ground Calcium Carbonate
Graphitic Nanoparticles
Graphene Oxide
Carbon Nanotube
Strain Sensing
Porosity
Carbonation
Alkali-Silica Reaction - Abstract:
- An alternative to ordinary portland cement concrete through “cold sintering” of calcium carbonate was explored. This has a potential in utilization of limestone, a primary source for ordinary portland cement synthesis and largely composed of calcium carbonate to reduce/bypass cement production in precast applications. Sintering of ground and precipitate calcite grains subjected to temperatures from 150 to 200 C and axial compressive stress of various degrees was evaluated. A higher temperature less than calcium carbonate decomposition temperature enhances the sintering. Post treatment of cold sintered samples by cold isostatic press followed by heat treatment at 550 C was studied. Sintered zinc oxide as partial or full replacement of binders supplemented with ultra-conductive single-walled carbon nanotube was studied and the thermoelectric power factors were compared. In a separate study, effects of few 1D and 2D nanoparticles were evaluated. They have at least one dimension less than one micron that provide high surface areas (ultra-low densities) and anisotropy. If dispersed well, they furnish more deposit sites for constituents of matrices in which they are utilized. In civil infrastructure materials, these matrices can be ordinary cement hydration products and its alternatives such as alkali-activated materials. Durability and mechanical properties, electrical and thermal conductivities, thermoelectric materials, energy harvesting, strain-sensing/self-sensing, fire retardance, and radiation shielding are applications in which nanomaterials' volumetric (physical) and chemical transformations have been explored. In this report, a holistic investigation of 1D|2D graphitic nanoparticles' (graphene oxide, carbon nanotube and carbon nano-fiber) influence in ordinary portland cement and geopolymer was carried out. Durability properties such as carbonation, porosity, alkali-silica reaction, and pozzolanic reactivity were studied. Nano-silica and natural pozzolans, possessing high pozzolanic reactivity were utilized in some of the studies for comparison purposes. Electrical and thermal conductance and strain-sensing properties were evaluated. It is shown that graphitic nanomaterials are predominantly chemically inert within the cement matrix, consistent mostly with the literature, and therefore, pursuit of their mechanical property improvements and chemical alternation of the cement matrix are discouraged when compared to reinforcements with sizes in the micron range and above and supplementary cementing materials. They, however, excel in terms of such physical contributions as durability, porosity refinement, carbonation prohibition, strain-sensing and thermoelectric materials development.