Optimizing the Use of Supplementary Cementitious Materials by Incorporating Small Dosages of Colloidal Nano-Silica

Restricted (Penn State Only)
Author:
Ayad, Achraf
Graduate Program:
Architectural Engineering
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
April 25, 2018
Committee Members:
  • Aly Marei Said, Dissertation Advisor
  • Aly Marei Said, Committee Chair
  • Somayeh Asadi, Committee Member
  • James Freihaut, Committee Member
  • Farshad Rajabipour, Outside Member
  • James Rosenberger, Outside Member
Keywords:
  • Colloidal nano-silica
  • concrete
  • mortar
  • MIP
  • TGA
  • Hydration
  • Concrete
  • Cement
  • EDS
  • SEM
  • NMR
  • Isothermal Calorimetry
  • alkali–silica reaction; aggregate; accelerated mortar bar; concrete; nano-silica; fly ash; thermogravimetric analysis
Abstract:
The use of nanomaterials in construction gained wide popularity in the last few decades due to their capacity to impart significant enhancements to the performance of materials. Numerous studies were published contributing to furthering the understanding of cement hydration and its mechanisms that are still not fully understood. Furthemore, incorporating nano-silica in concrete has shown significant improvement in its mechanical properties, durability and consequently its sustainability. However, further research is needed to improve the state-of-knowledge on the mechanisms through which nano-silica improves certain properties of concrete, especially in the presence of supplementary cementitious materials. The current study aims to investigate the mechanical properties of cement mortars incorporating both nano-silica and Class F fly ash at the macro-level and at the micro-level. It will also evaluate their influence on the kinetics of cement hydration and on the pozzolanic reaction in cement pastes. Finally, the durability of cementitious mortars will be evaluated by studying the effects of NS and Class F fly ash on the Alkali-Silica reaction.