The Effect of Modification with Nano-Alumina, Nano-Silica, and Polypropylene Fiber on the Frost Resistance of Concrete

This study presents a systematic evaluation of frost resistance in concrete modified with nano-alumina (NA, 1 wt%), nano-silica (NS, 2 wt%), and polypropylene fiber (PP, 0.2 wt%) through accelerated freeze–thaw testing. The investigation employed a comparative experimental approach, subjecting specimens with optimal mechanical dosages to 300 freeze–thaw cycles. The degradation was quantitatively assessed by monitoring the evolution of mass loss, dynamic elastic modulus, and compressive strength. Results reveal that PP-modified concrete demonstrates optimal performance, retaining 70% of its dynamic elastic modulus (vs. 68% for NA and 64% for control, and failing at 58% for NS after 200 cycles) and exhibiting only 9.3% compressive strength loss (vs. 13.9% for NA and 27.3% for control, and 43.6% for NS). These findings establish PP as the most effective modifier, offering both superior frost resistance (300+ cycle durability) and practical advantages (simpler processing, lower cost). The results provide a scientific basis for designing high-performance concrete in cold regions, with particular relevance to infrastructure requiring long-term durability under cyclic freezing conditions.