Effects of Curing Method and Glass Transition Temperature on the Unconfined Compressive Strength of Acrylic Liquid Polymer–Stabilized Kaolinite

Polymers have been widely known as nontraditional soil stabilizers capable of replacing common soil additives to reach superior soil stabilization outcomes. While numerous studies represent the efficiency of polymers as one of the soil additives, there is still ambiguity about the optimum condition of curing, soil-polymer interaction, and effect of each property of the polymer on the final mixture. In this study, to investigate the effect of sample preparation on the strength of the clay, five different curing methods were examined to assess the unconfined compressive strength (UCS) of the stabilized clay with acrylic polymers. Since the glass transition temperature ($T_g$) is one of the most important characteristics of polymers that influences various mechanical properties of the polymer such as elastic modulus, in this study, it is considered by choosing two similar acrylic polymers with different glass transition temperatures. Two acrylic polymers with $T_g$ above and below the ambient temperature (i.e., $-13°\mathrm{C}$ and $+33°\mathrm{C}$) were used as soil stabilizers. Different curing variables including polymer concentration (0%–10%), curing time (immediately to 1 week), and curing temperature (ambient to 100°C) may control the clay-polymer composite behavior and were analyzed in this work. For Method I, samples were prepared, compacted, and tested immediately. For methods II and III, samples were oven-dried at 100°C for 1 day, air-dried at room temperature for 7 days, respectively, and subjected to UCS testing. Method IV consisted of curing the remolded samples in a double vinyl bag for 1 day before the UCS test. For Method V, the treated soil mix was oven-dried and then remoistened (using the original liquid: i.e., water or polymer solution) to reach the target moisture content followed by a UCS test. Samples cured at 100°C in the oven showed a significant increase in the UCS due to a complete moisture loss. There was no considerable difference between the samples cured in a vinyl bag and noncured samples. The results also showed that the polymer with a higher $T_g$ is more effective for soil improvement given all other conditions are kept unchanged.