Determination of Particles and Minerals Content in Soft Clay Soil of the Mekong Delta Coastal Provinces, Southern Vietnam for Inorganic Adhesives Stabilization

Abstract

The paper aims at investigating the content of particles and minerals of soft clay soil in the Mekong Delta coastal provinces, southern Vietnam, as well as improving soil stability using inorganic adhesives, i.e.lime and cement-based stabilization. To study the composition of soft clay soil, a series of different laboratory methods were carried out and revealed various characteristics related to mineral composition, pH value, soluble salt content, and grain particle composition of soft clay soils. The results demonstrated five soil subtypes, namely high – saline soil (S2), low-saline soil (S1), acid sulfate soil (A), acid sulfate - saline soil (S-A), soil without salt andacid sulfate content (S0- A0). The soft clay soil (C) included 5 subtypes, which were C-S2, C-S1, C-A, C-AS, and C-S0-A0, whereas the soft sandy clay soil (SC) included three subtypes, namely SC-S2, SC- S1, and SC-S0-A0. Analysis of the above results showed that the high - saline soil, acid sulfate soil, and acid sulfate - saline soil are not suitable for lime and cement stabilization. This observation was illustrated by the initial experiment of cement – soil mixture properties.

Characterization of physical, chemical and microstructure properties in the soft clay soil of the paddy field area

“…We observed an abundance of kaolinite in the soil matrix. This result was consistent with another study by Nu et al (2020) that found a higher amount of kaolinite, and illite in soft clay soil. This clay mineral would affect the swelling, plasticity, and compression properties of the soil.…”

“…The soft clay soil was distinguished by a silty clay texture (Table 1) with the percentage of clay content was around 44-48%. This result was consistent with a study by Nu et al (2020) who obtained total clay content in the soft clay samples of the Mekong Delta Region of Vietnam was ranged from 44 to 50%. In general, the parent material could contribute to a significant impact on the soil particle composition.…”

“…The value of cation exchange capacity was associated with organic matter content in the soil. The cation exchange capacity value in our study was notable lower than other soft clay soil in a study by Nu et al (2020), they found the value varied from 21.84 cmolc kg -1 , and 25.86 cmolc kg -1 . This difference might be due to the specific mineralogical content in each site.…”

“…Therefore, we assumed the paddy cultivation practice in the study area was less applied organic component into the paddy soil. Nu et al (2020) was also found almost similar organic matter content in their study site that was ranged from 2.15 to 3.85%. Low organic matter in the soil could make soil structures become more susceptible to the dispersion process when it was soaked with water (Jensen et al, 2019).…”

“…The pH value of soft clay soil was at acidic class (<3.8), this value was still below an optimum level for paddy cultivation (pH 6.5) (Table 3). If we compared with another study, we found the pH value was significantly lower than soft clay soil in Southern Vietnam with values ranging from 4.7 to 6.8 (Nu et al, 2020). The different value of soil pH could be caused by there was acid sulfate soil in the study area.…”