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“Smart Mortars: Tiny Particles, Big Strength and Less CO2”
Monday, May 4, 2026
Researchers have developed a high‑strength, low‑carbon mortar by blending two ultra‑fine powders—nano‑silica (NS) and nano‑alumina (NA)—with polypropylene fiber (PPF). The base matrix consists of fly ash and slag, both industrial by‑products.
Experimental Design
- Central Composite Design: 17 recipes tested, varying NS, NA, and PPF percentages.
- Objective: Identify the optimal mix for compressive and bending strength while minimizing environmental impact.
Key Findings
| Property | Best Result | Composition |
|---|---|---|
| Compressive Strength | 82 MPa | 2 % NA |
| Bending Strength | 12 MPa | 1 % NS + 0.5 % PPF |
| Acid Resistance (Sulfate) | >20 % strength retained | 2 % NS + 2 % NA |
| CO₂ Emission | 607 kg CO₂/m³ | 26 % lower than conventional cement |
- Statistical Accuracy: Model fit values > 0.97 for both crushing and bending tests.
- Nano‑Particle Effects:
- NA contributes more to overall strength than NS.
- Combined use tightens the micro‑structure via C‑(A)‑S‑H and N‑A‑S‑H gels.
- Fiber Role: PPF mitigates micro‑cracking, enhancing durability in harsh environments.
Microstructural Insights
- Early hardening accelerated by nano‑particles packing micro‑pores.
- Smoother interior reduces crack initiation sites.
Implications
The study demonstrates that alkali‑activated mortars can rival or surpass ordinary cement in toughness while offering significant environmental benefits. These mixes are viable for real‑world construction, delivering both durability and reduced carbon footprint.
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