Abstract : This paper studies the flexural, brittle and impact properties of high-performance concrete with different content of polypropylene fiber. It comprehensively discusses the flexural strength, brittleness, impact resistance and impact of the fiber-doped high performance concrete, and discusses and analyzes the high Performance The mechanism of the brittleness of the cement-based fiber composite material is reduced and the impact resistance is improved. Tests have proved that the fiber-doped high-performance concrete can significantly reduce the brittleness of the concrete and improve the flexural strength and impact resistance of the concrete. High Visibility Coverall,Orange Working Coverall,Work Jumpsuit,High Visibility Safety Workwear Xinxiang Worldbest Patron Saint Co., Ltd , https://www.xxhyhsworkwear.com
I. Introduction High-performance concrete must not only have good strength properties, but also have excellent durability and suitable work performance to meet the current and future construction needs of large-scale concrete projects. After a lot of experimental research, we applied silicon. Ash and fly ash are used to formulate high-performance concrete. The concrete not only has high strength, but also has good workability, and the freeze-thaw resistance, penetration resistance, and erosion resistance of hardened concrete are excellent. However, large brittleness and poor impact resistance are important factors affecting the practical application of high performance concrete. It has been considered that self-shrinkage cracking, wet-swelling cracking and brittleness are important issues for high-performance concrete that need to be solved. This article will use polypropylene fibers to improve the brittleness and impact resistance of high-performance concrete.
Second, the experimental method
1, raw materials
1. 1 Cement: Adopted Sanken Bureau Ono-City Cement Co., Ltd. 525# Portland Cement
1. 2 Doping all materials: Tested using silica fume supplied by Chemical Union Additives Factory, water reducing agent using SN-II superplasticizer produced by Wusi Factory
1. 3 Aggregate: The coarse aggregate adopts 5-8mm quartz gravel, and the fine aggregate uses standard quartz sand.
1. 4 Polypropylene fiber: A new type of modified polypropylene fiber is used. Its physical properties are listed in Table 1.
Table 1 Physical Properties of Modified Polymerized Fibers Water Absorption No Specific Gravity 0.91
Fiber length (mm) 12-19
Melting point (°C) 160-170
Boiling Point (°C) 590
Conductivity Low thermal conductivity Low acid and alkali High compressive strength (Mpa) 560-770
Tensile strength (Mpa) 350
2. Test method Compression resistance and compressive strength test GB177-85 cement mortar strength test method. The amount of water used is the standard consistency water consumption, and its standard consistency and setting time are all according to GB134-77 cement standard consistency water consumption.
Wear-resisting specimen size 15cm×15cm×7cm. The wear test was conducted using a GLM-200 steel wheel concrete wear tester. The test method was conducted according to GB/T12988-91 "Test Method for Insulation Resistance of Inorganic Floor Materials". The wear resistance is expressed in terms of the resistance length L, in mm, and in each group of 5 abrasion tests, the average of ten tests is taken.
The impact resistance dimensions are 15cm×15cm×5cm and 5 test pieces in each group. The 8kg heavy steel ball is free to fall from a height of 25cm. When the crack width of the test piece is more than 3mm, the number of impacts is recorded. The average of the middle 3 data is taken as the test result.
Third, the results and discussion
1. The effect of polypropylene fiber on the brittleness of high-performance concrete The strength and durability of high-performance concrete are mainly affected by the water-cement ratio and the mineral polymer. When the water-cement ratio (w/c) is certain, the amount of mineral admixture will have a direct impact. A variety of physical and mechanical properties into high performance concrete. Resistant polypropylene fiber can improve the mechanical properties of high performance concrete. Table 2 shows the effect of high-performance concrete instead of fiber content (0, 0.1%, 0.15%) on the strength of concrete. Table 2 High-performance cement-based polypropylene fiber composites Strength Specimens Silica fusant Content (%) Fiber content (Kg ) Compressive Strength Flexural Strength R3 R28 R3 R28
1 0 0 36.9 63.4 5.31 8.53
2 5 0 43.0 73.9 5.45 9.05
3 10 0 47.5 82.4 6.06 9.82
4 0 0.1 29.3 60.8 5.36 8.59
5 5 0.1 29.9 61.3 5.33 8.72
6 10 0.1 32.4 66.9 5.45 9.25
7 0 0.15 38.4 68.5 6.08 9.35
8 5 0.15 39.9 77.7 6.28 11.02
9 10 0.15 47.4 82.3 7.55 12.52
The experimental results show that when the water-cement ratio (W/C) is certain, the mechanical properties of concrete increase with the increase of the amount of concrete. At the same time, the durability of the concrete is also greatly improved. However, the variation of silica fume dosage has different effects on the compressive and flexural strength of concrete. From the data in the table, it can be seen that when the compressive strength of silica fume is increased by more than 30% from 0 to 10%, and the flexural strength is only increased by about 15%, the brittleness of the high-performance mixture is significantly improved.
The test results show that blending polypropylene fibers can improve the brittleness of high performance concrete. When the polypropylene fiber content is from (0-15%), the compressive strength of the high performance concrete hardly changes, but the flexural strength increases by more than 27%. The number of brittleness of concrete dropped from 8.39 to 6.5%. The result is that high-performance concrete significantly reduces the brittleness of concrete under the premise of ensuring the compressive strength and durability performance.
2. Impact of polypropylene fiber mesh on the impact resistance of high-performance concrete The impact of polypropylene fiber on the impact resistance of high-performance concrete is significant. According to the experimental data, the addition of fibers in high-performance concrete can significantly improve the impact resistance of concrete. The impact resistance of high-performance concrete increases significantly with the increase of fiber content, and the impact resistance of concrete is directly proportional to the fiber content. In addition, the impact resistance of high-performance fiber concrete is one of the main technical approaches for the preparation of high-performance cement-based composites with concrete substrates.
3. Mechanism of Polypropylene Fibers on the Folding and Impact Improvement of High Performance Concrete. In summary, the inclusion of polypropylene fiber in high performance concrete can significantly increase the flexural strength of concrete.