Silica fume is well known for its exceptional pozzolanic reactivity, which greatly enhances the strength and durability of cementitious materials. The Pozzolanic Activity Index (PAI) is a key indicator that measures how effectively silica fume reacts with calcium hydroxide to form additional calcium silicate hydrate (C–S–H) — the compound responsible for concrete strength.
What Is Pozzolanic Activity Index?
The Pozzolanic Activity Index represents the ratio of compressive strength of mortar containing silica fume to that of a control mortar made with cement only. It is expressed as a percentage and tested according to ASTM C311 and ASTM C1240 standards.
A higher index means better reactivity and stronger cementitious performance.
HSA Silica Fume Performance
Henan Superior Abrasives (HSA) provides high-purity, amorphous silica fume with excellent pozzolanic activity. Laboratory tests confirm that HSA silica fume exceeds international standards:
Test Method: ASTM C311 / ASTM C1240
Cement Replacement Level: 10% by weight
Curing Conditions: Standard curing at 20 ± 2 °C
| Test Age | Pozzolanic Activity Index (%) | ASTM C1240 Requirement |
|---|---|---|
| 7 days | 120 | ≥ 105 |
| 28 days | 110 | ≥ 105 |
These results demonstrate that HSA silica fume delivers outstanding early strength (7-day PAI of 120%) and maintains long-term performance (28-day PAI of 110%).
Benefits in Concrete and Mortars
- Faster early strength gain
- Reduced permeability and chloride ingress
- Improved long-term durability and chemical resistance
- Denser microstructure through additional C–S–H formation
By meeting and exceeding ASTM standards, HSA silica fume ensures reliable quality for high-performance concrete, repair mortars, self-compacting concrete, and high-strength applications.
About Henan Superior Abrasives (HSA)
Henan Superior Abrasives is a trusted silica fume manufacturer and supplier with years of experience in supplying high-quality materials to the global construction and refractory industries. Our silica fume grades (both densified and undensified) provide consistent performance and excellent reactivity, ensuring superior results in every project.
Contact US to learn more about our silica fume products and technical specifications.
- WhatsApp us at : +86-18638638803
- Email us at: sales@superior-abrasives.com
