Study on mechanical properties and mechanism of new basalt fiber reinforced concrete

In bridge and tunnel engineering, concrete cracking is one of the common diseases, the current commonly used means is to add fiber to concrete to enhance the cracking resistance of concrete, basalt fiber as a new type of inorganic environmental protection green high-performance fiber material, is widely used in machinery and aviation fields, but should be expensive in concrete applications less, therefore, A new type of basalt fiber has been developed by Shixin, Guizhou. In order to verify the influence of the new fiber on concrete, the experimental study is carried out in this paper. This study explored the feasibility of promoting the properties of concrete by incorporating new basalt fiber (NBF). The effects of NBF content and length on the workability and mechanical performance of the concrete were examined. The morphology of NBFRC (new basalt fiber reinforced concrete) with different fiber content and length was observed using Scanning Electron Microscopy (SEM). Results indicate that with the increase in NBF content and length, the slump and expansion degree of NBFRC decreased gradually. When the NBF content was fixed, the mechanical properties of NBFRC first increased and then decreased with the length of the fibers. Conversely, when the fiber length was fixed, the mechanical properties of NBFRC showed a similar trend with varying NBF content. The optimal mechanical performance was achieved when the NBF content was 2 kg/m³ and the fiber length was 24 mm, resulting in improvements in compressive strength, splitting tensile strength, flexural strength, axial compressive strength, and elastic modulus by 12.6 %, 16.1 %, 6.3 %, 10.3 %, and 13.7 %, respectively, compared to the control concrete. SEM analysis revealed that incorporating NBF created a bridging effect within the concrete, improving pore structure, reducing the number of microcracks, and inhibiting the propagation of microcracks, thereby enhancing the compactness of the concrete.