How to use PP fiber in concrete

The dosage range of polypropylene fiber is generally between 0.6kg and 1.8kg per cubic meter of concrete. The specific dosage can be adjusted according to factors such as project requirements, concrete strength grade, and use location. The recommended dosage is usually 0.9kg per cubic meter of concrete, but this is not absolute and the actual dosage may vary depending on specific circumstances.

 

The role of polypropylene fiber in concrete is multi-faceted, which can be summarized as follows:

 

1. Improve crack resistance: Polypropylene fiber can effectively control micro-cracks in concrete or mortar caused by plastic shrinkage, dry shrinkage, temperature changes and other factors, prevent and inhibit the formation and development of primary cracks in concrete, thereby greatly improving the crack resistance of concrete or mortar. anti-cracking properties.

2. Improve the anti-permeability performance: After adding polypropylene fiber, the number and width of cracks inside the concrete are significantly reduced, which plays the role of blocking the capillary cracks in the concrete and significantly improves the anti-permeability performance of the concrete. At the same time, the mobility of water, chloride ions and air in concrete is reduced, thereby delaying the corrosion of steel bars.

3. Improve impact resistance and wear resistance: The addition of polypropylene fiber allows the concrete to withstand tens of thousands or even millions of repeated stresses of static strength, while still maintaining good condition and enhancing the impact resistance of the concrete. and wear resistance, which is particularly beneficial for cement concrete structures (such as roads, sidewalks, etc.) that are often subject to impact fatigue.

4. Improve frost resistance: The addition of polypropylene fiber can significantly improve the freeze-thaw damage resistance of concrete, more than doubling the frost resistance rating of fiber-mixed cement concrete.

5. Improve toughness: Polypropylene fiber has been chemically and physically modified to make the surface rough and porous, which improves the binding force between the fiber and cement-based aggregate, thus increasing the toughness of concrete.

6. Improve fire resistance: At high temperatures, polypropylene fibers will form pores in the concrete, allowing moisture to be discharged along these pores, avoiding the vaporization of moisture, thus improving the fire resistance time and grade of concrete.

7. Improve the quality of concrete products: After special anti-static and anti-ultraviolet treatment, polypropylene fibers can be evenly dispersed in concrete and exert their effect for a long time, improving the overall quality of concrete products.

To sum up, polypropylene fibers play a multi-faceted role in concrete and can significantly improve the performance and durability of concrete. However, in practical applications, the dosage and usage of polypropylene fiber need to be reasonably selected and determined based on specific engineering requirements and conditions.

The dosage and use method of polypropylene fiber in concrete are usually determined based on specific engineering requirements and material properties.

 

1. Dosage range

 

The dosage range of polypropylene fiber is generally between 0.6kg and 1.8kg per cubic meter of concrete. The specific dosage can be adjusted according to factors such as project requirements, concrete strength grade, and use location. The recommended dosage is usually 0.9kg per cubic meter of concrete, but this is not absolute and the actual dosage may vary depending on specific circumstances.

 

2. How to use PP fiber in concrete

 

1. Measuring and feeding:

-According to the amount of concrete mixed each time, accurately measure the weight of polypropylene fiber that needs to be added each time according to the mix ratio requirements (or recommended dosage).

 

2. Feeding sequence:

- After the sand and gravel materials are ready, add the polypropylene fiber into the mixer. It is recommended to use a forced mixer so that the aggregates can be fed into the mixer along with the fibers.

- Fiber should be added after adding dry materials (sand, cement, etc.) and before adding water.

 

3. Stirring time:

- The mixing time should be slightly longer than that of concrete without fiber by 30-60 seconds to ensure that the fibers are evenly dispersed in the concrete.

- After mixing is completed, random samples should be taken to check whether the polypropylene fibers have been evenly dispersed into single filaments. If there are still bundles of fibers, the mixing time should be extended by 20-30 seconds.

 

4. Fiber length selection:

- Polypropylene fibers of different lengths are suitable for different uses. For example, 2-3 mm long fibers can be used in dry-mixed mortars, putties, and plasters to provide excellent crack resistance; 6-12 mm long fibers are usually used as plasters, surface layers, leveling layers, base concrete, or Insulation mortar, etc.; 19mm long fibers are usually used in various concretes.

 

5. Other notes:

- When carrying larger loads, composite geotextiles based on woven geotextiles and nonwoven fabrics can be considered.

- Polypropylene fiber can be used as a filling material in concrete, mortar, etc. to improve the impact resistance, waterproof and heat insulation properties of concrete.

 

Please note that the specific dosage and usage method should be determined based on the actual engineering conditions, material characteristics and design requirements. When working with polypropylene fibers, it is recommended to consult a professional engineer or technician for accurate guidance.