Due to limited availability of construction site, many constructions are now carried out on site of poor ground condition, including on the soft soils. Vertical stone column technique has proven capable to increase the shear strength of soil and drain out water from the ground, decreasing the settlement of the structure. It is believed that the utilisation of coal ash as alternative material in constructing stone column can contribute to a more sustainable construction environment. This paper aims to investigate the improvement of bearing capacity of soft kaolin after installing with singular and group of encased bottom ash column using physical modelling. The white kaolin S-300 was used to represent the soft clay while bottom ash obtained from Tanjung Bin Power Plant, Johor was used in the construction of the stone column. The presence of bottom ash stone column has significantly increased the bearing capacity of kaolin clay. The increment of the bearing capacity in soft kaolin clay is higher when it is reinforced with group of bottom ash column and when the penetration ratio is larger. The penetration ratio showed more significant influences to the bearing capacity of soft kaolin clay as compared to the number of bottom ash column installed in soft kaolin clay.