EN
Polypropylene fiber is widely used to strengthen concrete, mortar and other building materials. Nevertheless, the advantages of this fiber like reduction of crack, impact resistance and enhanced durability can only be achieved when the fibers are well spread all over the mixture. Low dispersion results in fiber clumping, weak spots and poor performance. Hebei Runhuabang New Material Technology Co., Ltd. is a company that deals with crushing, processing and distribution of non-metallic minerals such as polypropylene fiber. Through complete exploitation of local geographical and resource advantage, we assist our customers to learn how to test and check the quality of dispersion in large-scale mixing processes.
Why Dispersion Quality Determines Fiber Performance
The very essence of polypropylene fiber addition to concrete or mortar is to develop a three-dimensional reinforcement structure of the material. Well dispersed fibers are considered to be millions of small reinforcements which intercept micro-cracks before they can develop into large failures. Fibers that are not dispersed well are in the form of balls or clumps called bird nests. Not only do these clumps fail to provide reinforcement, but they also create defects that can initiate cracking. Thus, the testing dispersion quality is not a luxury but a crucial aspect of quality control. Hebei Runhuabang New Material Technology Co., Ltd. manufactures polypropylene fibers with surface treatments and length to diameter ratios that are controlled to ensure that the fibers are easily dispersed in place, but even the finest fibers still need to be mixed and checked.
Visual Inspection Methods for Fresh Mixtures
Visual inspection of the fresh mixture is the easiest and quickest method of testing fiber dispersion. A sample of concrete or mortar must be taken immediately after mixing and spread out on a flat surface, or washed gently over a screen. Fine polypropylene fiber is presented in the form of separate filaments which are uniformly dispersed in the sample and no clumps or bundles can be seen. An inspector can search in places where fibers tend to concentrate or where there are no fibers. When large volumes of production are involved, the sample must be taken in various positions within a batch e.g. on top of the mixer discharge, middle, and bottom. Hebei Runhuabang New Material Technology Co., Ltd. advises customers to establish a regular visual check plan with definite pass or fail guidelines in place. The operators must be trained to identify the normal dispersion and clumping problems.
The Wash Test for Quantitative Assessment
To further control the quality, the wash test can give a numerical value of fiber dispersion. A new concrete or mortar sample in this technique is softly washed by using a row of sieves to eliminate the cement paste and fine aggregates. The polypropylene fibers left are then harvested and analyzed. An evenly distributed batch will produce single fibers that are evenly distributed on the surface of the sieve. The dispersed batch will have a separate clump of fibers or balls. Clumps can be counted in terms of their number and size to be used in statistical process control. Hebei Runhuabang New Material Technology Co., Ltd. collaborates with the customers to draw acceptable limits of clump size and frequency depending on the application that they need. The test can be conducted within a quality control laboratory within a period of less than thirty minutes, and thus is practical to do on a routine basis.
Adjusting Mixing Procedures to Improve Dispersion
Where dispersion tests indicate issues, it is often possible to fix the problem by modifying mixing processes, but not the fiber. Polypropylene fiber needs enough energy and time to be mixed in order to disperse and come out in single strands. Fiber can clump during an early or late addition to the mixing cycle. One of the best practices is often to incorporate polypropylene fiber, once all the dry ingredients are mixed, but before the bulk of the mixing water is added. The fiber must be incorporated step by step and not put in one lump. The length of mixing time after adding the fiber is normally one to two minutes. Hebei Runhuabang New Material Technology Co., Ltd. offers technical services to assist customers in maximizing the mixing sequences of various types of mixers such as pan mixers, drum mixers and twin-shaft mixers.
Avoiding Common Causes of Poor Dispersion
Poor fiber dispersion may be caused by a number of factors despite the good quality of polypropylene fiber. Slow mixing rate does not produce sufficient shear force to separate fiber bundles. Above two percent volume rates of fiber dosage are considered high and risky to produce clumping irrespective of mixing quality. Any kind of excess moisture on the fiber wrapping, or the storage conditions, may result in fibers sticking together prior to their entry into the mixer. Hebei Runhuabang New Material Technology Co., Ltd. informs customers of these pitfalls and offers polypropylene fiber in a package which prevents moisture ingress. Our strong quality control measures will assure us that the fiber that exits our facility has been dry and has flowed freely.
Conclusion
To ensure uniform performance of reinforcement, testing the quality of dispersion of polypropylene fiber in large scale mixing is crucial. The visual inspection and the wash test are convenient ways of checking that there are no harmful clumps of fibers and that they are spread evenly. The change in mixing processes can be an excellent solution when problems arise, rather than switching fiber suppliers. Hebei Runhuabang New Material Technology Co., Ltd. integrates modern technologies of production with an advanced multi-layer system of management to provide polypropylene fiber with dispersion properties. We open our doors to both local and foreign traders, and invite them to negotiate collaboration and grow together.