纤维掺量对水泥改良风积沙强度及孔径分布的影响

Influence of fiber content on unconfined compressive strength and pore size distribution of cemented aeolian sand reinforced with fiber

为了研究纤维掺量对水泥改良风积沙无侧限抗压强度和孔径分布的影响,进行聚丙烯纤维水泥改良风积沙的无侧限抗压强度试验和核磁共振试验。纤维掺量为0,6‰,8‰和10‰,水泥掺量为4%和5%,试样标准养护龄期为7 d。试验结果表明,纤维水泥改良风积沙的T2谱曲线存在3个峰值,最可几孔径和孔隙率随着纤维掺量的增大而减小,纤维掺量大于8‰,结果则相反。适量纤维加筋水泥改良风积沙,可以减小水泥改良风积沙内部孔隙,小孔和中孔增多,大孔减少。未掺纤维的水泥改良风积沙的应力-应变曲线呈应变软化型,而纤维水泥改良风积沙的应力-应变曲线随着纤维掺量的增大逐渐趋向于应变硬化型。纤维水泥改良风积沙的应力-应变曲线大致分为孔隙压实、弹性变形、弹塑性变形和应力衰减等4个阶段。随着纤维掺量增大,应力-应变曲线整体右移,延性增强,无侧限抗压强度、峰值应变和能量吸收能力随着纤维掺量的增大而增大,超过最优纤维掺量8‰,规律则相反。水泥掺量4%,纤维掺量8‰的水泥改良风积沙的无侧限抗压强度、峰值应变、能量吸收能力分别为水泥改良风积沙的1.31倍、2.04倍和1.37倍。纤维水泥改良风积沙的孔隙率与无侧限抗压强度呈幂函数关系。研究成果可为纤维水泥改良风积沙填料的应用提供参考。

In this study,a series of unconfined compressive strength(UCS)tests and nuclear magnetic resonance(NMR)tests were performed on cemented aeolian sand reinforced with fiber(CASRF)in order to determine the effect of fiber content on UCS and the pore size distribution of CASRF.The fiber contents were 0,6‰,8‰,and 10‰by weight of the dry aeolian sand,and the cement contents were 4%and 5%by weight of the dry aeolian sand.The samples were cured for 7 days under standard curing conditions.The results show that there are three peaks in the T2 spectrum curve of CASRF.The most probable pore size and porosity decrease with increasing fiber content.However,the rule is opposite when the fiber content exceeds 8‰.The internal pores of CASRF are reduced by the inclusion of fiber,while the number of small and medium pores are increased,and the number of large pores is decreased.The stress-strain curve of cemented aeolian sand shows an obvious strain-softening type,whereas the stress-strain curves of CASRF gradually tend to strain-hardening type with increasing fiber content.The stress-strain curve of CASRF could be roughly divided into four stages:pore compaction,elastic deformation,elastic-plastic deformation,and stress attenuation.The curves shift to the right as a whole with an increase of fiber content,and the ductility increase.The UCS,peak strain and energy absorption capacity of CASRF increased with fiber content until exceeding the optimal fiber content,and then decreased.The UCS,peak strain and energy absorption capacity of cemented aeolian sand with 4%cement and 8‰fiber content are 1.31 times,2.04 times and 1.37 times greater than that of cemented aeolian sand without fiber,respectively.The UCS of CASRF decreases with porosity,which is a power function relationship.The research results can provide a reference for the application of CASRF filler.