Study On The Mechanical Properties Of Basalt Fiber-reinforced Concrete Under Dynamic And Static Loads

Concrete with high strength, high stiffness and better long-term durability is the most widely used engineering materials. However, the shortcoming of large shrinkage, low tensile strength, ultimate elongation and small impact resistance restricts the further applications as functional material. Practice show that concrete mixed with a certain amount of fiber materials can alleviate the above-mentioned drawbacks of concrete. In this thesis, the performance of various content fiber reinforced concrete were compared and analyzed, based on studies of the properties of basalt fiber reinforced concrete. The enhancement of fiber toughening effect on the concrete and the strain rate effect were analyzed by the quasi-static and dynamic compression test experiments, and the mechanism of fiber reinforced concrete were explored and the constitutive model of basalt fiber reinforced concrete were established .Through the quasi-static and dynamic compressive experiment, the following conclusions can be drawed:(1) The quasi-static experiments of basalt fiber reinforced concrete with different fiber contents were conducted. The results show that the influence of fiber content to the compressive strength of basalt fiber reinforced concrete is not obvious. The compressive strength of fiber reinforced concrete specimens with fiber content of 0.1% and 0.2% is close with that of plain concrete, even the strength will decreased when the content increase to 0.4%.(2) The quasi-static compressive strength experiments show that although the basalt fiber can not effectively increase the compressive strength of concrete, but it can change the failure modes. The plain concrete destruct conical and the damage is more serious, less integrity, The fiber reinforced concrete destroy along a main crack cracking, and also produce a number of sub-cracks. The fiber content is greater, the main crack is not more obvious when the concrete damage, and the sub-cracks is more.(3) The impact tests of basalt fiber reinforced concrete with different fiber content were conducted. The results showed that the fiber for improving the dynamic compressive strength of concrete is still limited.(4) The experimental curve of dynamic compressive tests showed that the basalt fiber reinforced concrete has obvious strain rate. That is the rate of increase with the strain, the dynamic strength improved significantly. We defined DIF as dynamic enhancement factor, and then the results showed that the fiber concrete at high strain rate DIF is bigger than plain concrete. And this explains that fiber reinforced concrete is more sensitive to strain rate.(5) Based on the experimental data, the improved ZWT constitutive model was fitted, this model is suited to basalt fiber reinforced concrete of three different fibers content, and the fitting results are in good agreement with the actual data.