Stabilization of a Residual Soil Using Calcium and Magnesium Hydroxide Nanoparticles: A Quick Precipitation Method  
[PERSON]  
1 Civil Engineering Discipline, School of Engineering, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway 47500, Selangor, Malaysia; [PERSON]DDRESS] (L.L.Y. );  
[PERSON]L_ADDRESS] (S.V.A.D.N.J.P. ); [EMAIL_ADDRESS] (E.E. );  
[PERSON]ADDRESS] (S.C.P. )2 Institute of Energy Infrastructure (IEI), Universita Tenaga Nasional, Jalan Ikram-Uniten, Kajang 43000, Selangor, Malaysia; [PERSON]@uniten.edu.my3 Department of Civil Engineering, International University of Business Agriculture and Technology, Dhaka 1230, Bangladesh  
2  
S.V.A.D. [PERSON]  
1 Civil Engineering Discipline, School of Engineering, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway 47500, Selangor, Malaysia; [PERSON]DDRESS] (L.L.Y. );  
[EMAIL_ADDRESS] (S.V.A.D.N.J.P. ); [EMAIL_ADDRESS] (E.  
minerals [3]. The significant percentage of silt and clay present in the tropical residual soil deposits may cause the soils to experience poor engineering properties [4; 5]. Hence, soil stabilization is required to improve the engineering properties of such tropical residual soils prior to their application in various construction works. Calcium-based additives such as cement and lime stand as the most popular and commonly used soil stabilization materials due to their robustness and easy adaptability to various soil types [6]. Moreover, their availability in various parts of the globe is also an added advantage. The mechanism of soil stabilization using calcium-based additives is mainly attributed to the formation of cementing gels such as calcium aluminate hydrates (C-A-H) and calcium silicate hydrates (C-S-H) associated with the reactions between the calcium ions and clay minerals [7]. Previous studies have demonstrated that calcium-treated soils showed improved engineering properties such as increased shear strength and reduced hydraulic conductivity, shrinkage, and swelling limits [8]. However, the cost of production for cement and lime is relatively expensive, and the carbon dioxide emission during their production poses environmental concerns [9; 10]. Consequently, these concerns have motivated the exploration of environmentally friendly, cost-effective, and efficient materials that exhibit similar cementing properties as calcium-based additives. Nanotechnology refers to the utilization of nanoscale materials with dimensions smaller than 100 nm [11]. The nature-friendly nanomaterials, which are characterized by their fine particle size, high specific surface area, and high reactivity, can cause significant improvements to the engineering properties of poor soil [12]. In recent years, nanotechnology has been gaining momentum ever since the successful application of various nanomaterials in soil stabilization. [PERSON] and [PERSON] [13] reported that the addition of nano-silicon dioxide and recycled polyester fiber increased the elastic modulus, unconfined compressive strength (UCS), and shear strength of the soft clay. [PERSON] et al. [14] indicated that the inclusion of nanoparticles in kaolin clay led to an increase in the shrinkage limit and a reduction in the total volume of the treated clay. [PERSON] and [PERSON] [11] indicated that four types of nanomaterials such as nanoclay, nanocopper, nanoalumina, and nanosilica showed different effects on the engineering properties of collapsible soils. [PERSON] et al. [15] also investigated the effects of nanocarbons on the Afterberg limits, compaction characteristics, specific gravity, pH, and hydraulic conductivity of Malaysian residual soils. They concluded that the presence of nanocarbons in residual soil caused an increment in pH values and a reduction in their plasticity index, compaction characteristics, specific gravity, and hydraulic conductivity. [PERSON] et al. [16] reported a significant reduction in the swelling potential and improved workability of an expansive soil treated with nano magnesium oxide and nano alumina.