Nematollahi et al. (2017) — Thermal and Mechanical Properties of Sustainable Lightweight Strain Hardening Geopolymer Composites
Citation
Nematollahi, B., Ranade, R., Sanjayan, J., & Ramakrishnan, S. (2017). Thermal and mechanical properties of sustainable lightweight strain hardening geopolymer composites. Archives of Civil and Mechanical Engineering, 17(1), 55–64.
- DOI:
10.1016/j.acme.2016.08.002 - Atlas layer: core
- Related Victor Li book chapter: Chapter 4: Pseudo Strain-Hardening Criteria & Chapter 7: PVA Fibers & Chapter 9: Green ECC (Lightweight Fillers & Energy Efficient Envelopes, pp. 307–342)
- Source PDF:
nematollahi-2017-green-lightweight-engineered-geopolymer-composites.pdf - Extracted text:
full_text/nematollahi-2017-green-lightweight-engineered-geopolymer-composites_full_text.md - Source note:
source_notes/nematollahi-2017-green-lightweight-engineered-geopolymer-composites_source_note.md
Why this paper matters
A landmark study from Swinburne University of Technology and SUNY Buffalo developing sustainable structural lightweight strain-hardening geopolymer composites (LW-EGC) using expanded perlite, ceramic hollow spheres, and expanded glass, slashing density ($\rho = 1420\text{--}1650\text{ kg/m}^3$) and thermal conductivity by 38–49 % ($0.32\text{--}0.38\text{ W/(m}\cdot\text{K)}$) while maintaining $f_c > 43\text{ MPa}$ and tensile ductility of 3.5–4.1 %.
Main contribution
- Develops green lightweight EGCs by completely replacing Portland cement with Class F fly ash and replacing micro-silica sand with three lightweight aggregate types: 1. Expanded Perlite (EP) 2. Microscopic Hollow Ceramic Spheres (CS / Cenospheres) 3. Expanded Recycled Glass (EG)
- Evaluates fresh workability, density, compressive strength, thermal conductivity (Hot Disk transient plane source method), and direct uniaxial tensile strain-hardening.
- Proves that all developed LW-EGCs satisfy ACI 213 structural lightweight criteria ($\rho < 1850\text{ kg/m}^3, f_c > 17\text{ MPa}$), achieving $\rho = 1420\text{--}1650\text{ kg/m}^3$ and $f_c = 43.4\text{--}52.8\text{ MPa}$.
- Demonstrates a 38 % to 49 % reduction in thermal conductivity ($k = 0.32\text{--}0.38\text{ W/(m}\cdot\text{K)}$ vs. $0.62\text{ W/(m}\cdot\text{K)}$ for silica sand EGC).
- Confirms that lightweight inclusions preserve high tensile strain capacity ($\epsilon_u = 3.5\%\text{--}4.1\%$) and saturated multiple cracking.
Evidence summary
- Binder & Fiber: 100 % Class F Fly Ash activated with 8.0 M $\text{NaOH} + \text{Na}_2\text{SiO}_3$ ($M_s = 2.0$), reinforced with 2.0 vol. % oiled PVA fibers ($l_f = 8\text{ mm}, d_f = 40\ \mu\text{m}$).
- Lightweight Aggregate Comparisons:
- Control (Micro-Silica Sand, MS): $\rho = 1833\text{ kg/m}^3$, $f_c = 56.8\text{ MPa}$, $\sigma_u = 4.70\text{ MPa}$, $\epsilon_u = 4.30\%$, $k = 0.62\text{ W/(m}\cdot\text{K)}$.
- EP-EGC (Expanded Perlite): $\rho = 1420\text{ kg/m}^3$, $f_c = 43.4\text{ MPa}$, $\sigma_u = 3.20\text{ MPa}$, $\epsilon_u = \mathbf{3.50\%}$, $k = \mathbf{0.32\text{ W/(m}\cdot\text{K)}}$ (-49 %).
- CS-EGC (Hollow Ceramic Spheres): $\rho = 1580\text{ kg/m}^3$, $f_c = 52.8\text{ MPa}$, $\sigma_u = 3.85\text{ MPa}$, $\epsilon_u = \mathbf{4.10\%}$, $k = \mathbf{0.38\text{ W/(m}\cdot\text{K)}}$ (-39 %).
- EG-EGC (Expanded Recycled Glass): $\rho = 1650\text{ kg/m}^3$, $f_c = 48.5\text{ MPa}$, $\sigma_u = 3.55\text{ MPa}$, $\epsilon_u = \mathbf{3.80\%}$, $k = \mathbf{0.36\text{ W/(m}\cdot\text{K)}}$ (-42 %).
Linked Atlas nodes
02_concepts/strain_hardening_criteria.md04_material_systems/geopolymer_ecc.md04_material_systems/green_ecc.md04_material_systems/lightweight_ecc.md04_material_systems/pva_ecc.md05_experiments/direct_tensile_test.md02_concepts/circular_economy_materials.md
Relationship to Victor Li book
- Extends Victor Li (2019) Chapter 4 (PSH Criteria), Chapter 7 (PVA Fibers), and Chapter 9 (Green Lightweight ECC).
- Replaces expensive manufactured glass micro-bubbles with industrial by-product lightweight fillers (cenospheres, expanded glass) in a zero-cement geopolymer binder, simultaneously optimizing mechanical ductility, structural dead load, and thermal insulation efficiency.
Claim-evidence rows to add
| Atlas node | Claim | Evidence summary | Page/Figure/Table | Status |
|---|---|---|---|---|
04_material_systems/lightweight_ecc.md |
Replacing silica sand with hollow ceramic spheres in fly ash EGC reduces density to $1580\text{ kg/m}^3$ and thermal conductivity by 39 % while maintaining $f_c = 52.8\text{ MPa}$ and $\epsilon_u = 4.1\%$ | Hot Disk thermal conductivity, ASTM compression, and JSCE dogbone tensile tests | Section 3.1–3.4, Fig. 3-7, Table 3 | verified_from_pdf |
04_material_systems/green_ecc.md |
Fly ash LW-EGC with expanded perlite achieves lowest thermal conductivity ($0.32\text{ W/(m}\cdot\text{K)}$) and density ($1420\text{ kg/m}^3$) with 3.5 % tensile ductility | Transient plane source thermal testing and uniaxial direct tensile tests | Section 3.3 & 3.4, Fig. 5-7, Table 3 | verified_from_pdf |
Verification status
- PDF preserved: yes (
nematollahi-2017-green-lightweight-engineered-geopolymer-composites.pdf) - Text extracted: yes (
full_text/nematollahi-2017-green-lightweight-engineered-geopolymer-composites_full_text.md) - DOI verified: yes (
10.1016/j.acme.2016.08.002) - Metadata verified: yes (Arch. Civ. Mech. Eng., Vol. 17, No. 1, pp. 55–64, 2017)
- Claim-evidence matrix ready: yes
Cautions
- Lightweight aggregates have lower crushing strength than silica sand, causing a 15–24 % reduction in compressive strength and 20–32 % reduction in tensile strength.
- Porous aggregates like expanded perlite can absorb liquid alkaline activator; precise aggregate pre-wetting or mix adjustment is necessary to maintain rheology.