The Re-Act 4 product family includes two distinct ground glass pozzolan grades — standard Re-Act 4 and Re-Act 4 SR — and the differences between them matter significantly for mix design, application selection, and project economics. If you’re evaluating ground glass pozzolan for the first time, or transitioning from slag or fly ash, understanding how these two products compare will help you select the right material for your specific requirements.
The Core Difference: Particle Size and Application Focus
Both Re-Act 4 and Re-Act 4 SR are manufactured from a controlled post-consumer waste glass stream at a production facility in Waterdown, Ontario. The fundamental difference lies in how finely each product is ground and what applications each is optimized to serve.
Re-Act 4 — Ultra-Fine Grade
- Ground to an ultra-fine micron level beyond the SR grade
- Designed for ultra-high-performance concrete (UHPC) and specialized applications
- Higher reactivity — performs as a more high-early-strength product
- Slightly higher performance per unit weight compared to Re-Act 4 SR
- Best suited for precast, architectural, and engineered applications requiring premium early strength
Standard Re-Act 4 is positioned for applications where early strength gain is critical and where material cost is secondary to performance — similar in some respects to metakaolin or silica fume applications, though Re-Act 4 does not claim to match the early reactivity of those materials.
Re-Act 4 SR — Slag Replacement Grade
- D50 particle size of approximately 6 microns
- Engineered as a direct replacement for slag in ready-mix operations
- Most economical product in the Re-Act 4 line
- Strength gain profile comparable to slag — familiar performance for ready-mix QC teams
- Recommended at 20–40% replacement by cementitious weight; optimal at 30–35%
- EPD: approximately 51.8 kg CO₂ per metric ton — among the best in the SCM industry
Re-Act 4 SR is designed for volume ready-mix production — batch plants, multi-plant operations, and projects where large quantities of material are required with consistent supply and competitive delivered pricing.
Performance Comparison Side by Side
Attribute | Re-Act 4 | Re-Act 4 SR |
Grind Level | Ultra-fine (sub-micron range) | ~6 micron D50 |
Primary Application | UHPC, specialty precast | Ready-mix, slag replacement |
Strength Profile | Higher early strength gain | Comparable to slag |
Typical Dosage | Lower % for equivalent performance | 20–40%, optimal 30–35% |
Economics | Premium grade | Most economical in line |
EPD CO₂ (kg/MT) | Favorable | ~51.8 kg CO₂/MT |
Supply Format | Supersacks / bulk | Supersacks / bag-to-bulk |
Best For | High-spec structural, UHPC | Data centers, infrastructure, volume ready-mix |
When to Choose Re-Act 4
Choose standard Re-Act 4 when your project requires maximum early strength gain, ultra-fine particle packing for dense microstructure, or when you’re producing UHPC, architectural precast, or any application where material quantity is low and performance per unit weight is the priority. It performs better per pound than Re-Act 4 SR, so less material is needed to achieve equivalent outcomes in the right applications.
When to Choose Re-Act 4 SR
Choose Re-Act 4 SR when you’re a ready-mix producer currently using slag and looking for a lower-carbon, more supply-stable alternative with a compatible strength gain profile. It’s the right choice for high-volume projects — data centers, bridge decks, municipal infrastructure — where consistent supply, competitive pricing, and a strong EPD are all required simultaneously.
Re-Act 4 SR also makes sense when your customers are beginning to specify GWP limits or require EPD documentation, as its carbon intensity of approximately 51.8 kg CO₂/MT is one of the lowest in the supplementary cementitious materials industry.
Supply Reliability for Both Products
A key advantage shared by both Re-Act 4 and Re-Act 4 SR is supply reliability. Because both products are manufactured from post-consumer waste glass — a controlled, consistently available feedstock — supply is not subject to the fluctuations that affect slag (dependent on steel production) or fly ash (dependent on coal plant operations). This reliability matters for projects with committed construction schedules.
Get Technical Data for Both Products
Tech Silica provides comparative testing sheets, Life 365 durability modeling, and full EPD documentation for both Re-Act 4 and Re-Act 4 SR. Samples are available for plant trial batches prior to bulk commitment.
Contact Tech Silica to discuss which product fits your project or request your technical data package at technicalco.com/ground-glass-pozzolan.