Resilient Behavior of Sodium Alginate–Treated Cohesive Soils for Pavement Applications

Evaluation of Dynamic Properties of Sodium-Alginate-Reinforced Soil Using A Resonant-Column Test

“…This is because the SA was not uniformly distributed throughout the specimen, as will be discussed in more detail in Section 3.3 . Im et al (2017) [ 2 ] found a similar trend in the initial test of gellan-gum-treated specimens, and Arab et al (2019) showed that the value of the resilient modulus of SA-treated specimens decreased for SA concentrations above 2% [ 28 ]. This adverse effect appears to be due to a lack of the cations required for SA to form a cemented gel [ 28 ].…”

“…Alginate is used in the food, medical, and textile industries, and has gelling, viscous, and stabilizing properties with its ability to retain water [ 27 ]. When soil and sodium alginate are mixed, the permeability decreases and the resilient modulus increases [ 28 ]. Since the properties of this polymer have not been measured, exactly how much the effect of reinforcing the dynamic properties of the ground according to the polymer content appear cannot be known.…”

Improved Shear Strength Performance of Compacted Rubberized Clays Treated with Sodium Alginate Biopolymer

“…In the presence of water, the divalent cations present in the vicinity of the negatively charged clay surfaces, including calcium (Ca 2+ ) and magnesium (Mg 2+ ), tend to substitute the lower-valance sodium cations (Na + ) of the SA molecules, with Ca 2+ initiating the substitution process and first replacing Na + , owing to its larger ionic radius compared to that of Mg 2+ [ 54 , 57 , 58 , 75 ]. Since these divalent cations would still remain electrostatically attracted to the negatively charged clay surfaces, the so-called “cation exchange/substitution” process described above allows the SA molecules to be attracted (and hence adsorbed) to the negatively charged clay surfaces—in other words, the exchanged divalent cations function as so-called “attraction bridges” between the clay particles and SA molecules [ 42 , 44 , 54 ]. The formation and propagation (over time) of these strong cationic bridges between adjacent clay surfaces—which bring and hold the clay particles together—induce flocculation of the clay particles, thus increasing the soil’s overall shear resistance (and hence its UCS capacity).…”

“…Assuming that the number of attraction sites—that is, the number of clay particles (or the soil clay content) and/or the amount of exchangeable divalent cations (i.e., Ca 2+ and Mg 2+ )—available for the SA molecules was not exhausted with the employed SA dosages, higher SA dosages (greater than 15 g/L) may produce further improvements in the UCS. Nevertheless, beyond a certain SA (or polymer) dosage for which the available attraction sites are exhausted (or saturated), the clay particle flocculation process is expected to cease—beyond this critical dosage, the excess SA (or polymer) molecules will likely function as a lubricant rather than a flocculant, hence potentially reducing the mobilized UCS [ 39 , 41 , 54 ]. In view of the UCS results presented in this study, the maximum flocculation capacity (for the SA agent) may not have been achieved.…”

“…SA has been successfully employed within a variety of industries, including, most importantly, its widespread application as a thickener, a gelling agent and an emulsifier in the food industry [ 49 , 50 , 51 ]. In the geotechnical context, reported applications for SA have been limited to natural soils and include increasing soil compaction efficiency, enhancing soil shear strength/stiffness and soil seepage/erosion control [ 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 ]. Though promising, the results reported by these studies, particularly in the context of clay soil stabilization, are still limited (and somewhat inconsistent) to warrant SA as an ad hoc soil stabilization solution.…”