Identification method of concrete crack-resistant polypropylene fiber

Polypropylene fiber is a bundled monofilament fiber made of high-quality polypropylene as raw material through a special process. It has excellent dispersibility in concrete and bond strength with cement body, and has obvious advantages such as anti-cracking, enhanced anti-seepage, anti-freeze and impact resistance

Polypropylene fiber is a bundled monofilament fiber made of high-quality polypropylene as raw material through a special process. It has excellent dispersibility in concrete and bond strength with cement body, and has obvious advantages such as anti-cracking, enhanced anti-seepage, anti-freeze and impact resistance. High-quality polypropylene fiber is made of high-quality fiber-grade virgin polypropylene raw material and special additives; while inferior fiber is often made of powder or recycled material and ordinary textile additives. Kundu Chemicals offer PP fiber length 3mm,6mm,9mm,12mm,15mm,18mm.

How to identify the quality of polypropylene fiber? The identification method of polypropylene fiber is as follows:

1. Water removal method: Some inferior polypropylene fibers contain moisture (it is difficult to feel it with human hands). The moisture content can be measured by drying or sun drying. Although the price of the fiber is low, it contains water. Assuming the moisture content is 5%, 1 kg of fiber containing moisture is actually only 95% of the fiber, and the fiber price will be 1.05 times the original price.

2. Comparative visual inspection method: high-quality fibers are of uniform length, uniform thickness, and light white color. The fibers with less or no doubling, sizing, coarseness, coiling, oily, clumping, and impurities are high-quality fibers; the opposite is true for inferior fibers.

3. Water bath comparison method: Take 500ml of water and put it into two cups, add 0.4g of fibers of the same specification respectively, stir for 10 seconds and observe. The high-quality fibers are evenly dispersed and suspended in the water; the inferior fibers cannot be evenly dispersed or are suspended in the water or underwater in clumps or clusters.

4. Odor identification method: high-quality fibers: environmentally friendly, light and non-irritating; inferior fibers: polluted, strong and irritating.

5. Sunlight exposure method: inferior polypropylene fibers, due to cost reduction, have not been treated with UV protection at all, and polypropylene fibers lose their strength after one or two years of sunlight exposure, so it is difficult for inferior polypropylene fibers to play their role in concrete for a long time. As long as the inspection is carried out on site (the filaments sent for inspection must be strictly identified to be consistent with the short filaments of polypropylene fibers on the site), after a long period of sun exposure and night dew, the tensile strength can be tested to distinguish.

6. Testing method: The polypropylene fibers produced from recycled materials have:

① Low tensile strength, generally <350Mpa;

② Large elongation, generally >60%;

③ Poor alkali resistance. Since both the mixed concrete and the hardened concrete are strongly alkaline (pH ≥ 12), the strength of the fiber will gradually decrease in this environment, so the role played in the concrete will be very small, and the mechanical properties of the concrete cannot be improved at all.

It can be inspected on site (the filaments sent for inspection must be strictly identified to be consistent with the short filaments of polypropylene fibers on the site), and then sent for inspection.