酸环境下石灰-偏高岭土改性遗址土的强度及色差分析

Strength and Color Difference Analysis of Lime-Metakaolin Modified Site Soil in Acidic Environment

采用X射线衍射、热重分析、扫描电镜观测、色差分析和强度性能测试等方法,研究了酸环境下石灰-偏高岭土(L-MK)及天然水硬性石灰(NHL)改性遗址土强度与色差的变化规律,并探讨了其微观机制.结果表明:随着酸环境下干湿循环次数的增加,L-MK改性遗址土强度先增后减,而NHL改性遗址土则单调递减,且经历20次干湿循环后L-MK改性遗址土强度为NHL改性遗址土强度的1.6倍以上;与原样遗址土相比,8%偏高岭土掺量下L-MK改性遗址土色差最小,且小于8%及10%NHL改性遗址土,L-MK与NHL改性遗址土强度变化规律的差异性与水化产物水化硅酸钙(CSH)的稳定性及CaSO_(4)·2H_(2)O等膨胀性物质的生成量有关,采用L-MK替代NHL应用于土遗址修复领域是可行的.

Influenced by different dry‑wet cycles combined with acidic environment,lime‑metakaolin(L‑MK)and natural hydraulic lime(NHL)modified site soils were tested for unconfined compressive strength and split tensile strength,and color difference analysis was carried out on the basis of color consistency.X‑ray diffraction(XRD),thermo gravity(TG)and scanning electron microscopy(SEM)tests were used to explain the strength degradation mechanism.The results show that the strength of L‑MK modified site soil increases first and then decreases with the increasing number of dry‑wet cycles in acidic environment,while the strength of NHL modified site soil decreases monotonically.After 20 dry‑wet cycles in acidic environment,the strength of L‑MK modified site soil is more than 1.6 times that of NHL modified site soil.Comparing the color parameters of the earthen site soil,the color difference of the L‑MK modified site soil(with MK content of 8%)is less than that of the NHL modified site soil.The variation of strength is depended on the stability of hydration product calcium silicate hydrate(CSH)and the amount of expansive material such as CaSO_(4)·2H2O produced.It is feasible to use L-MK instead of NHL in the field of site soil restoration.