Title:
The Effect of Nano-Additives on the Hydration Behavior and Durability of Concrete Containing Fly Ash
Author(s):
Olek
Publication:
Web Session
Volume:
Issue:
Appears on pages(s):
Keywords:
DOI:
Date:
10/23/2022
Abstract:
Incorporation of fly ash in cementitious systems containing ordinary portland cement (OPCs) increases their long-term strength and durability. However, inclusion of fly ash also reduces the heat of hydration of such systems and their hydration rate. Thus, its use slows the development of strength at early ages. The reduced rate of hydration, and the associated lower early-age strength, can increase the risk of durability problems such as early surface deterioration (scaling) if young concrete is exposed to challenging environmental conditions. The purpose of this research was to assess the influence of nano-additives (including titanium dioxide nanoparticles/nano-TiO2 and nano-silica) on the hydration process and the durability of fly ash concrete. The experiments were performed on cementitious composites containing class C fly ash (24% by weight of cement) and various levels of nano-additives. The isothermal calorimetry (IC), thermogravimetric analysis (TGA), and Vicat setting time tests were carried out to investigate the effect of nano-additives on the hydration process of fly ash pastes. The influence of nano-additives on the permeability of concrete containing fly ash was determined by water absorption test using different methods of sample conditioning. Furthermore, the scaling test was performed to evaluate the influence of the nano-additives on the scaling resistance of concrete containing fly ash. Preliminary results indicated that the addition of nano-additives can accelerate hydration process, reduce water permeability, and improve scaling resistance of concrete containing fly ash.