The Application Study Of Y-Polypropylene Fiber In The Cementitious Composites

Cement mortar and concrete not only are most widely used modern building materials, but also are the largest amount of man-made materials currently. Ordinary cementitious materials have unique advantages, such as low cost, resistance to high pressure, durability, difficult to combustion, security, stability, et al. Such materials also have low tensile strength, elongation limit, and easy to produce plastic shrinkage cracks in the early casting. To overcome these shortcomings, composite is the main channel of improving high-performance of cementitious composites, and fiber reinforced is one of its core content.In order to reduce the contraction of cementitious materials in the process of condensation curing and to improve its toughness, adding Y-polypropylene fiber in cementitious materials in this paper is studied systematically. Y-polypropylene fiber has profiled section through a special spinning polypropylene production technology and surface treatment, and its Y-shaped cross-section can increase the specific surface area compared with the traditional circular section. When adding in cementitious composites, increased the contact area between fiber surface and the cementitious materials, this increases the bonding force of matrix to fiber.This paper focuses on the performance of Y-polypropylene fiber in cementitious composites. The main research includes: (1) Water-cement ratio influences the mechanical properties of polypropylene fiber-reinforced cement mortar; (2) Study on the influences of different mixing process of adding polypropylene fiber in the cementitious composites to determine the best mixing technology, and its mechanics; (3) Change the content of Y-polypropylene fiber in the cement mortar, and study concrete cracking performance, impact resistance; (4) Study on the performance of adding polypropylene fiber in silica fume concrete; (5) Study on polypropylene fiber evenly distributed and gradient distribution of cement mortar; (6) Using orthogonal test to determine the best amount of polymer emulsion and polymer polypropylene fiber mortar, as well as the best mixture of concrete; (7) Using scanning electron microscopy (SEM) and the spectrum analyzer (EDS) to study the micro-analysis of the modified mechanism of water-resistant properties and properties of contraction deformation of polypropylene fiber and polymer emulsion in cementitious composites; (8) Study the fiber-reinforced cement, concrete barrier from the crack of a preliminary in theory, put forward the consolidation of polypropylene fiber / polymers concrete mortar model.The results show that, Water-cement ratio influences the mechanical properties of polypropylene fiber-reinforced cementitious composites obviously, when the water-cement ratio was 0.44, the compression and flexural strength of polypropylene fiber-reinforced cementitious mortar are higher than that of other water-cement ratio mixtures. Pre-adding Y-polypropylene fiber can make fiber disperse better and enhance the concrete performance. Compared polypropylene fiber-concrete with the regular concrete, the slump loss decreased 16.92% to 31.82%. Through the experimental analysis, the content of polypropylene fiber in concrete should better be the quality of cement 0.2% to 0.6%, while the amount of fiber in the mortar should better be 0.4% to 1.2%. Adding polypropylene fiber can increase the impact resistance, cracking, and anti-contraction performance of cement mortar or concrete. The effect of the Y-polypropylene fiber in cement composite is analyzed, such as impact resistance, anti-cracking performance, water resistance and anti-contraction performance. The orthogonal test indicates the best ratio of the polypropylene fiber polymer mortar is: polymer emulsion accounts 4%, superplasticizer is 1.0%, polypropylene fiber is 1.0%, cement is 100%, sand is 250%, and water-cement ratio is 0.44. The addition of emulsion polymer can fill the pores, reduce porosity and improve the shortcomings of loose transitional zone crystal structure, which increased the density, the intensity and the durability of performance of concrete. The fiber-reinforced cement, concrete barrier from the crack of a preliminary is studied theoretically, and the consolidation of polypropylene fiber polymers concrete mortar model is put forward.The results show that,as polypropylene fiber has chemical stability, corrosion resistance, and the cement-based adhesive power, it can be added into cementitious mortar, concrete to improve the performance. And adding polypropylene fiber will be the effective way to improve cementitious mortar and concrete.