Study On The Properties Of Basalt And Polypropylene Mixed Fiber Concrete

The disadvantages of low tensile strength,poor toughness,and poor durability of concrete severely limit its application in the engineering field.Compounding is an effective method to improve and improve the properties of materials.After the fibers are incorporated into the concrete matrix,the two constitute a whole synergy,which can make the concrete show more excellent performance.At the same time,compared with single-fiber-doped concrete,different fibers in hybrid fiber reinforced concrete can exert their respective advantages and can better improve the performance of concrete.Basalt fiber is an emerging material in the field of concrete reinforcement,and its regularity in the influence on the performance of concrete is studied in order to better improve the performance of concrete.This study selected two types of fiber: basalt fiber 12 mm,polypropylene fiber6 mm,12mm,18mm;four different fiber volume volume: 0.05%,0.1%,0.15%,0.2%.Under the condition of keeping the concrete mix ratio unchanged,the effect of single-doped fibers and hybrid fibers on the work performance,mechanical properties and impermeability of concrete was studied with the change of fiber content;and the effect of both on concrete performance was studied.A comparative analysis was conducted and the effect of different polypropylene fiber lengths on the mixing effect was investigated.The mechanism of fiber-reinforced concrete was discussed through microscopic tests and mechanical theory analysis.The pore structure of concrete was analyzed by using a nuclear magnetic resonance pore analyzer.The mechanism of the influence of fiber on the impermeability of concrete was discussed.The results show:(1)Single mixed basalt fiber and various series of mixed fibers have reduced the slump of concrete.Under the same volume fiber content,the influence of each series of hybrid fibers on the slump of concrete is less than that of single mixed basalt fiber.When the fiber is mixed with concrete,the water retention and cohesion of concrete are increased,and the bleeding rate is reduced.Early fiber on concrete compressive strength,splitting tensile strength enhancement effect is higher than that of the late,single admixture mixed mixed mode of concrete compressive strength and splitting tensile strength with the increase of fiber content increased after decreased first;6mm,12 mm long polypropylene fiber and basalt fiber mixed effect optimal.Fiber can greatly enhance the flexural strength of concrete.Under single and mixed mode,thecompressive strength of concrete increases with the increase of fiber content,and then decreases.Compared with the single doped basalt fiber,the mixed fiber presents a positive hybrid effect,and the toughness of concrete has been greatly improved.(2)After the fiber was mixed into the concrete,it was distributed in a three-dimensional chaotic manner,which had a good effect on the initial defects of the concrete.When the concrete is damaged by bending,the high elastic modulus basalt fiber bears the bridging effect of the matrix cracking,and the low elastic modulus polypropylene fiber can refine the micro cracks in the concrete and reduce the stress concentration at the crack tip,making it Internal stress is more even.Through the coordination and complementing each other,the performance of the concrete is enhanced.(3)The effect of fiber on the impermeability of concrete was analyzed macroscopically and microscopically by using the method of water seepage height and pore analyzer,and the mechanism of impermeability of fiber reinforced concrete was discussed.The results show that when the fiber content increases from 0.05% to 0.1%,the single-doped basalt fiber can enhance the impermeability of the concrete,and the impermeability of the hybrid fiber to the concrete is better than that of the single-doped basalt fiber.In the range of 0.05% to 0.2% fiber content,among the hybrid fibers,the BF12PP6 fiber reinforced concrete had the best impermeability.When the fiber content increased from 0.15% to 0.2%,the fibers of each group decreased the impermeability of the concrete.After the appropriate amount of fiber is incorporated into the concrete,the pore structure inside the concrete can be optimized so that the impermeability is improved.When the fiber content is too much,the result is reversed.