استخدام الألياف المصنعة لتسليح الخرسانة في الأجزاء غير المعرضة للأحمال الإنشائية

الملخص EN

Reinforcing concrete to keep it from cracking is nothing new--even the earliest civilizations used natural fibers to inhibit cracking in masonry structures.

Today, synthetic-fiber reinforcement is available to reinforce non-structural concrete applications with superior results.

Currently, the most widely-accepted form of reinforcement is welded-wire fabric (WWF), a mesh of steel wires, steel fibers, polymeric nets and polymeric fibers that are placed in concrete.

However, synthetic-fiber reinforcement avoids the increased labor costs and difficulty in placement.

Synthetic-fiber reinforcement prevents cracks in concrete, small-diameter synthetic fibers (nylon, glass, steel or polypropylene) are now being added to concrete to reduce shrinkage cracking by more than 80 % according to independent lab tests.

Reducing cracks improves concrete impermeability, increases its toughness and long-term weather ability, and can reduce callbacks in concrete slab floors, decks, driveways, and walks.

The placement, curing, or finish characteristics of the concrete are not affected by the addition of fibrous reinforcement.

Larger-diameter synthetic fibers (steel or polyolefin), added at higher content by volume (0.5 % to 1.5 % respectively), also enhance hardened flexural strength, but at increased cost.

Fibrous reinforcement is primarily used to reduce cracking in non-structural concrete applications.

However, steel fibers rust and can cause surface discoloration.

Adding fibers to the concrete during mixing can add to the cost of concrete, but avoids the labor cost and time to place reinforcing steel.

Fibrous concrete reinforcement reduces concrete cracking and permeability, and increases strength, impact resistance, and durability of concrete non-structural slabs.

This research studies the effect of using steel fibers and polypropylene fibers in reinforcing prisms (100 x 100 x 400) mm, and slabs (500 x 500 x 50) mm for testing drying shrinkage and drop ball impact loading, then compare results with plain concrete.

Test results indicated that the presence of synthetic fibers enhance significantly the shrinkage and impact resistance properties.