Mechanical Properties and Micromechanism of Calcium Sand–Cement Mortar Modified With Zirconium Dioxide and Basalt Fiber

In this paper, the modification effect of basalt fiber (BF) and nano‐zirconium dioxide on calcareous sand–cement mortar was studied according to the actual situation of the island construction project. Mechanical tests were carried out on specimens of calcareous sand–cement mortar doped with different dosages of BFs and nano‐zirconium dioxide, and the effects of BFs and nano‐zirconium dioxide on the compressive properties of calcareous sand–cement mortar were analyzed by using the unconfined compression test study and the modification mechanism was elaborated by using: (1) the stress–strain curves of calcium sand–cement mortar are all softened hump‐like convex curves, and the residual stresses tend to a stable constant value. (2) BF at 0.6 wt% was the optimum dosing and increased the compressive strength by 66%–94%, 55%–65%, and 44%–63%, respectively, compared to that of calcareous sand–cement mortar as the age of maintenance increased. The compressive strength of nano‐zirconium dioxide–cement was increased by 49.2%, 79.1%, 101.1%, and 95.4% at the dosage of 4%, 6%, 8%, and 10%, respectively, and the optimum dosage was 8% compared to that of calcareous sand–cement mortar. (3) BFs are interspersed in the cement mortar, forming a dense mesh structure, wrapping and binding the cement mortar, and playing the role of anchoring reinforcement under external load. Nano‐zirconium dioxide due to its filling and induced catalytic role in the formation of a certain plate‐like structure, so that it and the calcium sand–cement mortar between the overall more compact, improving the compactness of the specimen.