Study on the durability and failure mechanism of concrete modified with nanoparticles and polypropylene fiber under freeze-thaw cycles and sulfate attack
Jingge Ren, Yuanming Lai
Abstract
Nano-SiO2, nano-TiO2 and polypropylene fiber were added to concrete to investigate the durability and failure mechanism of the concrete under freeze-thaw cycles and sulfate attack. Compressive strength, mass change, microstructure and pore characteristics were measured to evaluate the durability of the samples. The results indicated that polypropylene fiber can best improve the durability of concrete by 67% due to its bridging effect. Nanoparticles can only improve the durability of concrete within 120 cycles and cannot enhance the long-term frost resistance. A “frost-salt heaving-corrosion” composite failure theory was proposed to explain the failure mechanism of concrete under the frost and sulfate attack. The theory indicated that water freezing bring more damages than sodium sulfate do and pore characteristic is the most important factor affecting durability.