Title: Nanoengineered C-S-H and C-A-S-H Using Biomimetic Molecules for Enhanced Functionality

Author(s): Warda Ashraf

Publication: Web Session

Volume: ws_S22_WardaAshraf.pdf

Issue:

Appears on pages(s):

Keywords:

DOI:

Date: 3/28/2022

Abstract:
This work presents a novel way of modifying the intrinsic characteristics and functionality of C-S-H and C-A-S-H using polydopamine and L-Aspartic acid biomimetic molecules. For this work, C-S-H and C-A-S-H with Ca/Si ratios in the range of 1.0 to 2.0 were synthesized with and without the addition of biomimetic molecules (10% by weight). The characteristics and functionality of the synthesized C-S-H and C-A-S-H were evaluated using varieties of tools and techniques, including Fourier Transform Infrared Spectroscopy (FTIR), nanomechanical tests, transmission electron microscope (TEM), and 29Si Nuclear Magnetic Resonance (NMR). These experimental evaluations showed that the selected modification increased the density and elastic modulus of C-S-H/ C-A-S-H by nearly three times. Additionally, the modified C-S-H showed a lesser extent of degradation caused by atmospheric carbonation. It was further observed that due to the presence of biomimetic molecules, the modified C-S-H/ C-A-S-H converts to a hybrid phase containing in-situ deposition of amorphous CaCO3 once these are exposed to atmospheric CO2. The formation of such nano-hybrid phases eventually leads to further densification of the C-S-H when exposed to atmospheric CO2. Accordingly, this work shows that the selected biomimetic molecules can be used as an admixture in cement and concrete mixture to form C-S-H with superior properties and create in-situ sealing layers to improve durability performances by capitalizing the atmospheric CO2.