Abstract Geopolymers, a class of alkali‐activated binders, are studied as sustainable alternatives to Ordinary Portland Cement due to their potential for CO2emission reduction. However, the critical relationship between early‐age reaction kinetics, the development of material properties, and evolving chemical structure remains insufficiently explored, primarily because of the complexity of the underlying chemical reactions and the wide variety of geopolymer chemistries. To address this, we investigate the mechanism of early‐age (<72 h) strength development of a model metakaolin geopolymer by measuring curing kinetics using isothermal calorimetry, material property development via rheology, and chemical coordination at distinct extents of reaction via29Si and27Al NMR. A novel approach of collecting solid‐state29Si and27Al NMR spectra at low temperature (−17°C) successfully quenches the geopolymer reaction, allowing for spectrum collection at a desired extent of reaction despite long29Si NMR spectrum collection times. Applying the Avrami kinetic model to deconvoluted calorimetry data enables independent analysis of dissolution and polycondensation/crosslinking reactions. From these data, the gel reaction product mass fraction is estimated, revealing an exponential relationship with the storage modulus in the activated metakaolin slurry. This study provides new insights into the interconnected dynamics of molecular chemistry, reaction kinetics, rheology, and strength development, offering a semi‐empirical framework for understanding property evolution in geopolymers more broadly.
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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
- 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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