# Effects of Sand-Cement Columns on Primary Consolidation Settlement
###### Abstract  
The rapid increase in population and the corresponding increase in developments have necessitated the stabilization of areas with poor soil conditions. Due to consolidation settlement, the soft grounds available are deemed unsuitable for such structures. This paper presents the use of cement additives to build sand-cement columns in saturated clayey soils. The approach significantly reduces consolidation settlement and increases the bearing capacity, providing a viable solution to foundation problems. Consolidation tests were conducted on saturated clay specimens and sand-cement columns arranged in various patterns. A 5% cement content by the dry weight of the sand was used in building sand-cement columns. The results showed that the consolidation settlement rate was high due to the extra drainage formed by the widened pores in the sand-cement columns. The extra drainage caused more water to leave the specimen in a given time. However, after full contact between the loading platen and sand-cement columns, the rate of consolidation settlement decreased. At this stage, sand-cement participated in carrying the load. Additionally, the effect of vertical drainage on speeding up consolidation at higher stress levels was minimal, as the widened pores in the sand-cement columns began to close. capallation settlement; sand-cement columns; saturated clay 2025  
17 June 20257 July 202  
developed various techniques to address the challenges posed by weak or problematic soils, including vertical drains, preloading, geosynthetics, concrete piles, stone columns, and deep mixing columns [3]. Among these, the deep mixing method has gained significant attention for its effectiveness in mitigating sliding failures, controlling seepage, reducing shear deformation, and enhancing the dynamic performance of soft or contaminated soils, as [PERSON] and [PERSON] (2004) [5] explained. This method involves adding cement powder to soft ground to create soil-cement columns, which significantly improves the shear strength and compressibility of thick layers of weak soil, as noted by [PERSON] and [PERSON] (1979) [6]. Cement columns are particularly valuable for supporting the foundations of buildings and lightweight structures, with practical applications demonstrating their efficacy. For instance, [PERSON] (1996) [7] reported that cement columns 1 meter in diameter arranged in square or rectangular patterns successfully supported a five-story building in Japan. These advancements highlight the significance of ground improvement techniques in ensuring the stability and durability of structures constructed in challenging soil conditions. Chemical stabilization techniques have proven to be one of the most economical and effective methods for stabilizing subgrade material [8]. Clay soil can be treated with cement, fly ash, lime, and gypsum additives [9]. [PERSON] et al. (2006) [10] affirmed that chemical additives improved the consolidation index or rate of time of consolidation and [PERSON] (2003) [11] mentioned that using lime and fly ash to pavement subgrade settlement was more inexpensive than the traditional cut-and-fill method. For instance, adding 6% cement to soft mud improved pre-consolidation stress, reduced the secondary consolidation index, increased the coefficient of consolidation, and reduced post-construction settlement [12]. The soil-cement technique, widely recognized for its effectiveness in ground stabilization through deep soil mixing, has achieved global success by leveraging the binding properties of cement to create a cement-soil material. Application in saturated clayey soils benefits from the dual action of the sand core and cement binder [13; 14]. Sand provides drainage and densification, while cement introduces cohesion and long-term strength through pozzolanic reactions [15]. These composite columns further stiffen the soil matrix, creating preferential load paths through high-modulus inclusions and constraining lateral deformation in the surrounding clay [16]. [PERSON] et al.