Based on expert analysis, waterproof polypropylene applications should generally use 425 cement over 325. The higher strength and durability of 425 cement (28-day compressive strength ≥ 7,000 psi) make it better suited for demanding environments, while 325 cement (5,000 psi) is adequate only for low-stress scenarios.

The choice hinges on performance requirements. 425 cement offers superior resistance to chemical degradation and water absorption, critical for long-term waterproofing integrity. Studies by the American Concrete Institute (ACI) indicate that 425 cement-based composites exhibit 20–30% lower water渗透 rates compared to 325水泥. Polypropylene’s non-polar nature requires a compatible matrix; 425 cement’s higher bond strength with polymers, as per ASTM C150 standards, ensures better adhesion and load distribution. For instance, a 2021 study in Materials Science and Engineering found 425 cement reduced delamination in polypropylene-reinforced concrete by 40% under cyclic loading. While 325 cement is cost-effective, its lower performance limits its use to non-critical applications. Industry guidelines from the Portland Cement Association (PCA) recommend 425 for structural waterproofing systems involving polymers. Thus, 425 cement is the optimal choice unless budget constraints or minimal stress justify 325.