Speaker
Description
Biochar, a carbon-rich solid produced through the pyrolysis of biomass feedstocks, has demonstrated potential as a sustainable concrete additive. In addition to its sustainability benefits, biochar presents physical benefits in concrete as an inert filler material with a porous structure, high specific surface area (SSA), and surface functional groups: the result has demonstrated improvements to performance and durability. However, the relationships between biochar microstructure, water adsorption, superplasticizer interactions, and the impact of biochar incorporation on the rheology and flowability of cementitious systems remain poorly understood. Super-plasticizers such as poly carboxylate ether (PCE), used as additives, can reduce suspension viscosity. Relaxation and diffusion NMR are used to characterize water and PCE dynamics within biochar dispersions of 7 μm and 14μm particle sizes at varying concentrations. We examine the relative populations of free, surface, and pore-confined water through diffusion coefficient analysis. Proton NMR measurements will also investigate whether the PCE signal in biochar-water-PCE dispersions can reliably be resolved. Time-dependent changes in signal intensity, if observable, will provide insight into distribution changes of PCE between free and biochar-associated states. Further, the macroscopic properties of biochar-cement dispersion are being investigated using a combination of a rotational rheometer and mini-cone slump tests. A comparison of relative slump over at least three weeks and proton NMR measurements will be used to track any reduction in free PCE concentrations. A relationship between concrete flowability and relative biochar and PCE concentrations is expected to emerge.
| Keyword-1 | Biochar |
|---|---|
| Keyword-2 | NMR |
| Keyword-3 | Rheology |