纳米高岭土对隧道道床橡胶混凝土性能的影响研究

Influence of Nano⁃Kaolin on Performance of Rubber Concrete Used in Tunnel Ballast

本试验将纳米高岭土(NK)掺入橡胶水泥砂浆,研究NK对橡胶水泥砂浆力学性能的影响。橡胶等体积替代10%,20%和30%河砂制备橡胶水泥砂浆;在30%替代率橡胶水泥砂浆中,NK等质量替代3%,7%,11%水泥制备NK改良橡胶水泥砂浆。测试硬化砂浆的静态抗压强度和抗折强度;利用ϕ50分离式霍普金森压杆(SHPB)试验装置测试砂浆在不同平均应变率等级下的动态抗压强度、动态峰值应变和动态极限韧性等性能,研究NK改性后橡胶砂浆的力学性能。采用SEM观察代表性试件并从微观角度进行分析。结果表明:橡胶会显著降低水泥砂浆的力学性能,橡胶水泥砂浆力学性能均随NK掺量的增加而增加。橡胶水泥砂浆使用11%掺量NK改良后,28d抗压强度和抗折强度分别提高93%和43%;高应变率下峰值应力从19.39MPa提升至47.34MPa。动态增长因子、极限韧性也有所提高,峰值应变随NK掺量的增加略微减小。

In this experiment,nano-kaolin(NK)was incorporated into rubber cement mortar to study the effect of NK on the mechanical properties of rubber cement mortar.River sand was replaced by equal volumes of rubber(10%,20%,and 30%)to prepare rubber cement mortar.In the 30%replacement rate rubber cement mortar,NK is used to replace the 3%,7%,and 11%cement to prepare the NK modified rubber cement mortar.The static compressive strength and flexural strength of hardened mortar were tested.The dynamic compressive strength,dynamic peak strain,and dynamic ultimate toughness of mortar under different average strain rate grades were tested by aϕ50 split Hopkinson pressure bar(SHPB)test device,and the mechanical properties of NK modified rubber mortar were studied.The representative specimens were observed by SEM and analyzed from a microscopic point of view.The results show that rubber can significantly reduce the mechanical properties of cement mortar,and the mechanical properties of rubber cement mortar increase with an increase in NK content.The 28d compressive strength and flexural strength of rubber cement mortar were increased by 93%and 43%,respectively,after using 11%NK.The peak stress at high strain rate increases from 19.39MPa to 47.34MPa.The dynamic growth factor and ultimate toughness are also improved,and the peak strain decreases slightly with the increase in NK content.