Capillary Characteristics and Applicability of Coal Bottom Ash as an Anti-Capillary Material for Coastal Constructions

Abstract

Utilization of Coal bottom ash (CBA) as well as finding the solutions to prevent saline intrusion, meeting the needs of coastal infrastructure development have been considered by the authors of the article for a long time. In this study, the authors focused on analyzing capillary characteristics in order to find a suitable group of CBA particles, which can be applied in the design of foundations with the high ability in restricting or preventing the effects of salt in saline groundwater. The obtained results show that (1) The capillary height is inversely proportional to the particle size: the larger the particle, the smaller the capillary height and vice versa. The CBA group with a diameter of 2.0 - 5.0 mm has an average capillary height around 3.33 cm; a group of particles size of 1.0 - 2.0 mm is 7.16 cm; a group of particles size of 0.5 – 1.0 mm is 23.36 cm. Meanwhile, the group of particles size of 0.1 - 0.5 mm is 31.26 cm. (2) The capillary height is inversely proportional to the salt concentration in the capillary solution: the maximum capillary height exhibits with the lowest capillary solution salinity ~ 0.0 g/L, whereas it reaches minimum value when salinity approximate 33.0 g/L. Thus, CBA with the same particle size of gravel (diameter from 2.0 to 5.0 mm) is able to block capillary flow. This study forms the basis for the design solutions of anti-saline foundation, especially in the context of climate change and sea-level rise.