Novel multifunctional construction materials are needed to promote resilient infrastructure in the face of climate change and extreme weather. Nanostructured materials such as geopolymer reinforced with carbon-based nanomaterials are a promising way to reach that goal. In recent years, several studies have investigated the influence of nanomaterials on the physical properties of geopolymer composites such as compressive strength and fracture toughness. Yet, a fundamental understanding of the influence of nanomaterials on the nanoscale and micron-scale structure has been elusive so far. Our research objective is to understand how multiwalled carbon nanotubes (MWCNT) can help tailor the microstructure of geopolymers to yield architected multifunctional nanocomposites. We synthesized geopolymer nanocomposites reinforced with 50-nm thick multiwalled carbon nanotubes with mass fractions in the range of 0.1 wt%, 0.2 wt%, and 0.5 wt%. Our major finding is that MWCNTs act as hard templates that promote geopolymer formation via self-assembly. Geopolymer nanoparticle growth is observed along the walls of MWCNTs. A refinement in grain size is observed: increasing the fraction of MWCNTs by 0.5 wt% leads to a reduction in grain size by 54%. Similarly, increasing the mass fraction of MWCNTs leads to a densification of the geopolymer matrix as demonstrated by the Fourier transform infrared spectroscopy results and the statistical deconvolution analysis. Mercury intrusion porosimetry shows a nanoscale tailoring of the pore size distribution: a 26% decrease in porosity is observed as the fraction of MWCNTs is increased to 0.5 wt%. As a result of these nanoscale structural changes, a greater resistance to long-term deformation is observed for MWCNT-reinforced geopolymers, as the creep modulus increases both locally and macroscopically. At the macroscopic level, a 42% increase in the macroscopic logarithmic creep modulus is observed as the fraction of MWCNTs is increased to 0.5 wt%. These findings and the supporting methodology are important to understand how to manipulate matter below 100 nm. This research also paves the way for the design of resilient infrastructure materials with tailored microstructure and mechanical properties.
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Characteristics and microstructures of the GFRP waste powder/GGBS-based geopolymer paste and concrete
Abstract A novel method is developed for reusing the waste glass fiber-reinforced polymer (GFRP) powder as a precursor in geopolymer production. Several activation parameters that affect the workability and strength gain of GFRP powder-based geopolymers are investigated. The results of an experimental study reveal that the early strength of GFRP powder-based geopolymer pastes develops slowly at ambient temperature. The highest compressive strength of GFRP powder-based geopolymer pastes is 7.13 MPa at an age of 28 days. The ratio of compressive strength to flexural strength of GFRP powder-based-geopolymers is lower than that of fly ash and ground granulated blast furnace slag (GGBS)-based geopolymers, indicating that the incorporation of GFRP powder can improve the geopolymer brittleness. GGBS is incorporated into geopolymer blends to accelerate the early activity of GFRP powder. The binary geopolymer pastes exhibit shorter setting times and higher mechanical strength values than those of single GFRP powder geopolymer pastes. The GGBS geopolymer concrete mixture with 30 wt% GFRP powder displayed the highest compressive strength and flexural strength values and was less brittle. The developed binary GFRP powder/GGBS-based geopolymers reduce the disadvantages of single GFRP powder or GGBS geopolymers, and thus, offer high potential as a building construction material.
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- Award ID(s):
- 1916677
- NSF-PAR ID:
- 10355227
- Date Published:
- Journal Name:
- REVIEWS ON ADVANCED MATERIALS SCIENCE
- Volume:
- 61
- Issue:
- 1
- ISSN:
- 1605-8127
- Page Range / eLocation ID:
- 117 to 137
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1515/rams-2022-0005
