复合盐侵蚀作用下纳米氮化硼对PVA纤维混凝土力学及抗冻性能的影响OA

The effects of nano-boron nitride(BN)on the compressive strength,tensile strength,and frost resistance of PVA fiber concrete under combined salt attack were studied using compressive,splitting tensile,and freeze-thaw tests after simulated combined salt attack.Scanning electron microscopy(SEM)was used to analyze the modification mechanism of BN on PVA fiber concrete.The results show that incorporating BN enhances the mechanical and frost resistance properties of PVA fiber concrete under combined salt attack.After 120 d of salt erosion,the maximum reductions in compressive and splitting tensile strength of specimens without BN are 13.7%and 14.1%respectively;with BN,the reductions are 8.1%and 7.3%respectively.After 150 freeze-thaw cycles,specimens with BN show a decreased mass loss rate(as low as 2.3%)and a reduced decline rate in relative dynamic elastic modulus,indicating enhanced salt-freeze resistance.BN's bridging,pull-out,pinning,and nucleation effects fill pores,promote hydration,densify the matrix,and restrict microcrack initiation and propagation,thereby improving the mechanical and frost resistance properties of PVA fiber concrete.