PVA fibers are a new, high performance fiber for concrete and mortar from Kuraray. Like steel, these PVA fibers have high tensile strength and a greater modulus of elasticity than regular concrete. Unlike steel, PVA fibers develop a molecular and chemical bond with the cement during hydration and curing. This high bond strength makes PVA fibers very tough to pull out during bending or tension. Studies published by University of Michigan researchers demonstrate PVA engineered cementitious composites (PVA-ECC) with tensile strain capacity of 5%, approximately 500 times that of normal concrete or fiber-reinforced concrete (FRC).
This application uses 1.4% fibers by weight of the mix. (2% by volume) But even at much lower dosages, PVA fibers are effective in controlling:
• plastic shrinkage cracking
• drying shrinkage cracking
• autogenous cracking
• fatigue cracking
• spalling
They can be used together with steel reinforcement, where PVA's micro-crack control helps to prevent water penetration and improves toughness and stiffness. Or they can be used alone as a truly structural fiber, one whose modulus of elasticity is greater than that of regular concrete and two times stiffer than polypropylene fibers.
|
|
Strain-hardening and micro-cracking give PVA-ECC amazing ductility |
