PP纤维掺比优化改良混凝土的抗冻融力学性能研究

Study on the freeze-thaw resistance mechanical properties of PP fiber mix optimized and improved concrete

为提高粉煤灰泡沫混凝土的抗冻性能,采用聚丙烯纤维(PP纤维)对粉煤灰泡沫混凝土(FAFC)进行改良,对比0、0.1%、0.2%、0.3%、0.4%PP纤维掺量下的抗冻性能。结果表明:相比未掺PP纤维试验组,掺入PP纤维后,FAFC在冻融循环下的质量损失率、强度损失率降低,超声波波速增大,PP纤维可以显著提升FAFC的抗冻性能,且随掺量的增加,改善效果越明显,但PP纤维掺量过大时,可能会造成纤维分散不均导致抗冻性能下降;冻融损伤与冻融循环次数之间呈良好的对数函数关系,PP纤维掺量m-冻融循环次数N-损伤因子D三者之间满足D=-0.185+197×ln N-0.0454m模型,通过该模型可以对任意PP掺量下FAFC在低周冻融循环下的损伤值进行较准确的预测。

In order to improve the frost resistance of fly ash foam concrete,polypropylene fiber(PP fiber)was used to improve the fly ash foam concrete(FAFC),and the frost resistance of the fly ash foam concrete(FAFC)was com⁃pared with that of 0%,0.1%,0.2%,0.3%,0.4%PP fiber.The results showed that compared with the experimental group without PP fiber,the mass loss rate and strength loss rate of FAFC under freeze-thaw cycles decreased after the addition of PP fiber,and the ultrasonic wave velocity increased.PP fiber could significantly improve the frost re⁃sistance of FAFC,and the improvement effect becomes more obvious with the increase of the content.However,when the content of PP fiber was too large,it might cause uneven fiber dispersion and decrease the frost resistance.There was a good logarithmic relationship between freeze-thaw damage and the number of freeze-thaw cycles.The relationship between PP fiber content m,freeze-thaw cycle number N,and damage factor D satisfied the D=-0.185+197×ln N-0.0454m model.This model could accurately predict the damage value of FAFC under low cycle freeze-thaw cycles with any PP content.