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Q. What is the difference between synthetic microfibers and macrofibers? A. Synthetic fibers for concrete reinforcement can be broadly classified into microfibers and macrofibers, each with distinct characteristics and applications. Synthetic microfibers are primarily used to control cracks caused by plastic shrinkage. These fine fibers have diameters typically ranging from 0.0004 to 0.012 in. (0.01 to 0.3 mm) and lengths between 1/8 to 2 in. (3 to 50 mm). Their contribution to the mechanical properties of hardened concrete is minimal. Microfibers are available in two forms: monofilament and fibrillated. Monofilament microfibers are typically added at dosages of 0.5 to 1.5 lb/yd³ (0.3 to 0.9 kg/m³) or 0.03 to 0.1 percent by volume, depending on the fiber type and performance needs. Fibrillated microfibers require a minimum dosage of 1.5 lb/yd³ (0.9 kg/m³) or 0.1 percent by volume. In contrast, synthetic macrofibers, with diameters greater than or equal to 0.012 in. (0.3 mm), are designed to improve the mechanical properties of hardened concrete, especially post-crack behavior. These larger fibers typically have diameters between 0.012 to 0.04 in. (0.3 to 1.0 mm) and lengths of 1/2 to 2.5 in. (12 to 65 mm). They come in various geometries, such as stick, rope, or tape filaments, and can be embossed for improved bonding. Their bond with concrete is primarily achieved through friction, although chemical bonding has also been observed. The dosage of synthetic macrofibers varies by application and performance requirements, typically ranging from 3.0 to 10 lb/yd³ (1.8 to 6.0 kg/m³). While both types of synthetic fibers reinforce concrete, they differ significantly in their dimensions, applications, and impacts on the material's properties. References: ACI 544.1R, ACI 544.2R Topics in Concrete: Concrete Fundamentals, Fiber Reinforced Concrete, Shrinkage of Concrete
Q. What is the difference between synthetic microfibers and macrofibers?
A. Synthetic fibers for concrete reinforcement can be broadly classified into microfibers and macrofibers, each with distinct characteristics and applications.
Synthetic microfibers are primarily used to control cracks caused by plastic shrinkage. These fine fibers have diameters typically ranging from 0.0004 to 0.012 in. (0.01 to 0.3 mm) and lengths between 1/8 to 2 in. (3 to 50 mm). Their contribution to the mechanical properties of hardened concrete is minimal. Microfibers are available in two forms: monofilament and fibrillated. Monofilament microfibers are typically added at dosages of 0.5 to 1.5 lb/yd³ (0.3 to 0.9 kg/m³) or 0.03 to 0.1 percent by volume, depending on the fiber type and performance needs. Fibrillated microfibers require a minimum dosage of 1.5 lb/yd³ (0.9 kg/m³) or 0.1 percent by volume.
In contrast, synthetic macrofibers, with diameters greater than or equal to 0.012 in. (0.3 mm), are designed to improve the mechanical properties of hardened concrete, especially post-crack behavior. These larger fibers typically have diameters between 0.012 to 0.04 in. (0.3 to 1.0 mm) and lengths of 1/2 to 2.5 in. (12 to 65 mm). They come in various geometries, such as stick, rope, or tape filaments, and can be embossed for improved bonding. Their bond with concrete is primarily achieved through friction, although chemical bonding has also been observed. The dosage of synthetic macrofibers varies by application and performance requirements, typically ranging from 3.0 to 10 lb/yd³ (1.8 to 6.0 kg/m³).
While both types of synthetic fibers reinforce concrete, they differ significantly in their dimensions, applications, and impacts on the material's properties.
References: ACI 544.1R, ACI 544.2R
Topics in Concrete: Concrete Fundamentals, Fiber Reinforced Concrete, Shrinkage of Concrete