废纸纤维对砂浆早期收缩及孔结构的影响

Effects of Waste Paper Fibers on Early-Age Shrinkage and Pore Structure of Mortar

将废纸纤维掺入砂浆,研究了废纸纤维对砂浆力学性能、早期收缩性能及孔结构的影响.绝干废纸纤维掺量分别为水泥质量的1%和2%,以湿混方式与水泥混合成型为砂浆样品,并分别采取标准环境和密封环境进行养护.结果表明:在砂浆水灰比(质量比)0.30,且密封养护环境下,掺入废纸纤维并不能改善砂浆韧性,反而增大了砂浆的累计孔体积,导致其自收缩率增大;当水灰比升至0.40时,掺入废纸纤维可显著改善砂浆韧性,且当废纸纤维掺量为水泥质量的1%时,砂浆的折压比σF/σC最高,累计孔体积最小,抗收缩能力增强;与密封养护环境对比,标准养护环境下掺入废纸纤维未降低砂浆的早期收缩性能,但减小了砂浆的后期膨胀,并随着纤维掺量的增加,砂浆膨胀约束效果趋好.

Waste paper fibers（WPFs）were incorporated into mortar to study the effect of the WPFs on mechanical property,the early-age shrinkage and pore structure of the mortar.The use level of dry WPFs was fixed at 1% and 2% by mass of cement.In addition,the WPFs were mixed with cement using wet mixing and cured with sealed curing and standard curing.Results show that the WPFs do not improve the toughness of mortar with a sealed curing in a water-cement ratio of 0.3,the cumulative pore volume and self-shrinkage are increased instead.However,the WPFs can significantly improve the toughness of mortar in a water-cement ratio of 0.4,and when the use level of WPFs is 1% by mass of cement,the ratio of flexural strength to compressive strength（σF/σC）is highest,cumulative pore volume is lowest and the anti-shrinkage of mortar is enhanced.Moreover,compared with sealed curing,the WPFs do not improve the early-age shrinkage of mortar with a standard curing,but reduce the long-term volume expansion,and the restraint becomes better with the increase of the use level of WPFs.