When sourcing Concrete Fabric Canvas (GCCM), you must prioritize compressive strength and flexural strength. Ensure the product meets ASTM D8364 standards, which classify GCCMs based on their intended application (e.g., Type I, II, or III). Key metrics include a 28-day compressive strength of at least 40 MPa and a thickness range (typically 5mm, 8mm, or 13mm) that matches your project's load requirements. Additionally, verify the impermeability rating to ensure it provides an effective water barrier.