Clay-based mortars are susceptible to water intake and exhibit low mechanical strength, presenting challenges in their application within the construction sector. This research addresses these vulnerabilities by investigating the combination of alkali activators with waterproofing agents, specifically a nano-clay and an acrylic emulsion, to enhance the properties of clay mortars. Alkali-activated materials are known for their superior mechanical properties and sustainable potential, especially when derived from low-cost by-products. Recent studies have focused on alkali activation using clays and soils as precursors to improve their physical and mechanical properties while increasing durability. However, the high absorbency of these mortars remains a concern, as it can lead to matrix degradation. Therefore, to address these problems, this research studied the combination of a highly alkaline activator (potassium metasilicate) with hydrophobic agents, such as a nano-clay and an acrylic emulsion, using two different clayey soils. The results indicated that potassium metasilicate (PO) enhanced the mechanical properties and stability for both aluminosilicate systems, while nano-clay (PONC) significantly reduced the capillary absorption through time, especially in A2 systems. The addition of acrylic emulsion (POD) proved highly effective in both systems, significantly improving durability. By integrating these agents, the mortar systems were protected against water intake, while durable construction materials were formed.

Freezing and thawing (F/T) is an important occurrence in cold regions influencing soil geotechnical characteristics. Current study investigates effects of lime, Rice Husk Ash (RHA) and Nano-clay on unconfined compressive strength and F/T of loess under open and closed schemes. Loess was treated with 2, 4, 6 and 8% lime and RHA and 0.5, 1.0, 1.5 and 2% Nano-clay and compacted at optimum conditions. Samples were cured for 1, 7, 14 and 28 days at 35 degrees C before freezing at -23 degrees C and thawing at room temperature for 24 h intervals. Tests conducted on untreated and RHA and Nano-clay treated samples showed total loss of strength after one F/T cycle with noticeable weight and volume changes by samples subjected to open F/T. Exposing samples to closed F/T resulted in smaller changes in volume and strength. Samples treated independently with lime or concurrently with RHA and Nano-clay showed significant resistance to F/T particularly with curing time. Formations of chemical compounds bind particles, reduce void ratio resulting in a solid durable structure resisting freezing. Open F/T proved more detrimental than closed F/T scheme exhibiting moisture accessibility to be a dominant factor on F/T process.

The usage of locally available soil for construction purposes is a wise choice for enhancing its engineering properties. Depending on the size of the particles, the silty and clayey soils possess voids at the nano level. Generally, clay soil is affected by increased settlement, decreased stability and altered soil structure due to the increased plasticity index. Hence, it is necessary to enhance the soil properties using various additives. In recent days, nanomaterials have been increasingly utilized for improving soil stability and strength in various geotechnical engineering applications. This paper deals with the effect of nano-clay on the various geotechnical properties of three different silty and three different clayey soil samples. The influence of the wet-dry cycles on the unconfined compressive strength (UCS), coefficient of permeability (k) and settlement were discussed. Furthermore, the UCS and California bearing ratio (CBR) of the nano-clay-treated soil were predicted by using multiple regression analysis based on the index properties. Test results revealed that the optimum dosage of nano-clay was found to be 0.4%, 0.35%, 0.35%, 0.25%, 0.25% and 0.2% for three different silty soil samples and three different clayey soil samples, respectively. The UCS and CBR values were enhanced significantly irrespective of the nano-clay content and the soil type, due to the formation of CSH gels that effectively bonds the soil particles and facilitates the improvement of UCS and CBR and thus reduces the 'k' and settlement of soil samples. The predicted UCS and CBR values by regression analysis are in line with the experimental results in both treated and untreated conditions. As a result, this amorphous nano-clay is recommended for stabilizing weak soils irrespective of the type of soil.