This Help Center article is a summary of the official Earthaus PHL Binder Compressive Strength Test Results document.
Testing Overview
Conducted by: Braun Intertec Corporation | Concrete Science, Chicago, IL
Date: February 6, 2025
Standard: ASTM C1707 (Pozzolanic Hydraulic Lime for Structural Purposes)
Method: Plaster samples made with Earthaus PHL Binder and sand were tested for compressive strength at different curing ages.
Results
28-Day Compressive Strength:
Material | Strength (psi) |
Earthaus PHL | 310 psi |
NHL 3.5 | 300 – 400 psi |
Cement Stucco | 1,500 – 3,000 psi |
6-Month Compressive Strength:
Material | Strength (psi) |
Earthaus PHL | 1,090 psi |
NHL 3.5 | 750 – 1,000 psi |
Cement Stucco | 3,000+ psi |
12-Month Compressive Strength:
Material | Strength (psi) |
Earthaus PHL | 1,220 psi |
NHL 3.5 | 750 – 1,100 psi |
Cement Stucco | 3,000+ psi |
Key Findings
Earthaus PHL Binder tested at 310 psi at 28 days, 1,090 psi at 6 months, and 1,220 psi at 12 months.
Gradual strength gain prevents premature cracking and accommodates structural movement.
Earthaus PHL achieves higher compressive strength than NHL 3.5 at 6 months.
Cement stucco gains strength rapidly, but its rigid nature makes it prone to cracking and moisture entrapment, making it unsuitable for natural wall systems.
Conclusion
Earthaus PHL develops steady, long-term strength gains, ensuring structural reliability.
It balances strength and flexibility, making it uniquely suited for natural building applications — providing structural reliability without the brittleness of cement or the variability of NHL.
Customer Support
For product questions, email support@earthausplaster.com.
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