Experimental study on dual capillary barrier using recycled asphalt pavement materials

Abstract

The performance of a capillary barrier cover as a cover system is affected by the ability of the capillary barrier to store water. To increase the water storage of a capillary barrier cover, the dual capillary barrier (DCB) concept is proposed. The objective of this paper is to investigate the water storage of the proposed DCB as compared to the storage of a traditional single capillary barrier (SCB). The investigation is conducted using two one-dimensional infiltration column tests under different rainfall conditions. The results show that a DCB stores more water as compared to SCB. The results show that the fine-grained layers of a DCB have higher volumetric water contents during drainage as compared to that of the fine-grained layer of an SCB. The higher volumetric water content is caused by the fact that the thickness of the layers in a DCB corresponds to a pore-water pressure head range where the material has the highest volumetric water content. In addition, a slower drainage rate is resulted from additional layering in a DCB. Résumé :La performance d'une couverture à effets de barrière capillaire en tant que système de recouvrement est affectée par la capacité de la barrière capillaire à stocker l'eau. Afin d'augmenter le stockage d'eau dans une couverture à effets de barrière capillaire, le concept de double barrière capillaire (DCEBC) est proposé. L'objectif de cet article est d'étudier le stockage de l'eau dans la DCEBC proposée en comparaison avec le stockage d'une simple barrière capillaire (CEBC) traditionnelle. Les investigations sont réalisées à l'aide de deux essais en colonne d'infiltration unidimensionelle soumis à différentes conditions de précipitations. Les résultats démontrent que la DCEBC stocke plus d'eau comparativement à la CEBC. Les résultats montrent que les couches fines de la DCEBC ont des teneurs en eau volumiques plus élevées durant le drainage par rapport à la couche fine de la CEBC. La teneur en eau volumique plus élevée est causée par le fait que l'épaisseur des couches dans la DCEBC correspond à l'étendue des pressions interstitielles où le matériel a la teneur en eau volumique la plus élevée. De plus, un taux de drainage plus faible est obtenu avec l'ajout d'une couche dans la DCEBC. [Traduit par la Rédaction] Mots-clés : stockage d'eau, double barrière capillaire, colonne d'infiltration, teneur en eau volumique, asphalte recycle.

Combinations of soil materials for granular capillary barriers for minimizing rainfall infiltration and gas emission

“…The working mechanisms of capillary barriers have been described by Khire et al 35 (1999), Shackelford and Benson (2006), Harnas et al (2014) and others. A capillary cover 36 utilizes the contrast in hydraulic properties between a finer grained soil layer and a coarser 37 grained layer under unsaturated conditions to limit the rainfall penetration into the waste.…”

“…A simple cover with 31 capillary barrier effects (CCBE) is a two-layer system consisting of a fine texture soil layer 32 overlying a coarse texture soil layer (e.g. Harnas et al 2014;Rahardjo et al 2013;Yan et al 33 2017). 34…”

“…The rainwater water is stored temporarily in the fine texture soil 42 layer and removed by evapotranspiration and lateral drainage afterwards. The capillary 43 barrier is considered effective when the combined amount of evapotranspiration, lateral 44 diversion, and water storage capacity is significantly higher than the amount of rainfall 45 infiltration (Harnas et al 2014). During a rain event, the suction at the interface between the 46 fine texture soil and its underlying coarse soil layer will decrease to a value that permits water 47 to enter and form a continuous network.…”

Moisture Migration and Control of New Embankment for Reconstruction and Expansion Project in Southern China

“…e rainwater is stored temporarily in the fine-texture soil and discharged after evapotranspiration and lateral drainage. e capillary barrier is considered effective when the combined amount of evapotranspiration, lateral diversion, and water storage capacity is significantly higher than the amount of rainfall infiltration [30]. Infiltration tests on soil columns of finer layers over coarser layers were conducted to investigate the capillary barrier [31,32].…”

Anisotropy in hydraulic properties of unsaturated soils

“…A rainfall-induced slope failure preventive measure termed the Capillary Barrier System (CBS) has attracted significant interests over the past decade (Tami et al, 2004;Krisdani et al, 2006;Rahardjo et al, 2012b;Harnas et al, 2014). CBS is an environmentally-friendly and sustainable slope cover system which has advantages such as reducing surface runoff (the root cause of flash flooding) and the possibility of using recycled materials (recycled asphalt or concrete) with vegetation on top of the CBS.…”