The Role of Electrochemistry and Mineralogy in the Geotechnical Behavior of Salinized Soils

Abstract

The Atterberg limits are essential information and the first step in soil classification for geotechnical purposes. Established laboratoryprocedures use distilled water in the plasticity and liquid limits determination. However, saline solutions frequently interact with soilsin the construction environment through fluid percolation processes. This work aims to understand the variation of the geotechnicalbehavior of two standard materials with different mineralogical compositions (kaolinitic and smectitic) when affected by NaCl ionicsolutions in different concentrations. The purpose is to simulate different soils in environments with the presence of saline solutions.This paper reports an experimental program in which a kaolinite-rich and a smectite-rich material received NaCl solutions in threedifferent concentrations (0.6 %, 3.5 %, and 15.0 %) and had their Atterberg limits determined under these conditions. Additionally,non-contaminated samples of both materials have had their limits measured using distilled water. Physical characterization testsincluded hygroscopic moisture, grain size distribution, grain density, plastic limit (PL), and liquid limit (LL). These data allowed thedetermination of the Skempton activity index (AI), plasticity index (PI), consistency index (CI), classification of soils in the UnifiedSoil Classification System (USCS), and in the Highway Research Board (HRB) with the group index (GI). Mineralogy was determinedby X-ray diffraction and physical chemistry by measuring pH in H2O and KCl, determining the ΔpH, the point of zero-charge (PZC),and the surface electrical potential (Ψo). The results show that the pH values rise with increasing salinity, while ΔpH, PZC, Ψo, LL,AI, PI, GI decrease with increasing salinity. The PL decreases with the increase in salinity for smectite and increases for kaolinite. TheUSCS and HRB demonstrate that the materials start to behave as fewer plastic materials with increased salinity. It is concluded that thevariations in the physicochemical parameters of the environment control and modify the geotechnical behavior of the fine-grained soils.

Adsorption of Heavy Metals on Bentonitic Soil for Use in Landfill Liners

“…However, the Skempton’s activity index (AI) was 0.87, outside the range of 1–7 typical of smectites. Polivanov et al [55] affirmed that indexes that correlate cation exchange capacity (CEC) and specific surface area (SSA) to clay fraction are more helpful to distinguish mineralogic differences in fine-grained soils than AI. According to Melo and Alleoni [56], these values are within the range of CEC values commonly found in Brazilian soils.…”

Gambaran Sifat Fisik Dan Mekanik Tanah Di Kecamatan Kauman Kabupaten Tulungagung

“…Nilai indeks plastisitas menunjukkan nilai keplastisitasan suatu tanah. Nilai batas cair,batas plastis,dan indeks plastisitas digunakan sebagai salah satu parameter untuk mengidentifikasi jenis tanah (Polivanov et al, 2021), sehingga dapat diketahui sifat fisis dan karakteristik tanah sebelum dibangun sebuah konstruksi. Pengujian analisa ayakan dilakukan untuk mengetahui distribusi ukuran partikel tanah pada ukuran-ukuran diameter ayakan tertentu (Ding et al, 2023).…”