A capillary barrier is a two-layer cover system having distinct hydraulic properties to minimize water infiltration into the underlying soil by utilizing unsaturated soil mechanics principles. In this study, a capillary barrier system was designed as a cover system for a residual soil slope to maintain stability of the slope by minimizing infiltration during heavy rainfalls in the tropics. The capillary barrier system (CBS) was constructed using fine sand as the fine-grained layer and recycled crushed concrete aggregates as the coarse-grained layer. The coarse-grained layer is commonly constructed using gravels or granite chips. However, due to scarcity of aggregates and in consideration of environmental sustainability, recycled crushed concrete aggregates were used as the coarse-grained layer in this project. The suitability of recycled crushed concrete aggregates as a material within the coarse-grained layer of a CBS is subject to the hydraulic property requirement. For comparison, another CBS was constructed using fine sand as the fine-grained layer and a geosynthetic (Secudrain) as the coarse-grained layer. The performance of each constructed CBS on the residual soil slope was monitored using tensiometers installed at different depths -from 0.6 to 1.8 m below the slope surface -and a rainfall gauge mounted on the slope. An adjacent original slope without the CBS was also instrumented using tensiometers and piezometers to investigate the performance and effectiveness of the CBS in reducing rainwater infiltration and maintaining negative pore-water pressures in the slope. Real-time monitoring systems were developed to examine pore-water pressure, rainfall, and groundwater level in the slopes over a 1 year period. Characteristics of pore-water pressure distributions in the residual soil slope under a CBS with recycled crushed concrete aggregates and in the original slope during typical rainfalls are highlighted and compared. The measurement results show that the CBS was effective in minimizing rainwater infiltration and therefore, maintaining stability of the slope.Résumé : Une barrière capillaire est un système fait de deux couches ayant des propriétés hydrauliques distinctes, servant à minimiser l'infiltration d'eau dans le sol sous-jacent à l'aide des principes mécaniques des sols non saturés. Dans cette étude, un système de barrière capillaire a été conçu comme système de recouvrement pour une pente d'un sol résiduel visant à minimiser l'infiltration durant les fortes pluies des régions tropicales, et ce, afin de maintenir la stabilité de la pente. Le système de barrière capillaire (SBC) a été construit avec du sable fin comme couche de matériau fin et des agrégats de béton concassé recyclé comme couche de matériau grossier. La couche grossière est couramment construite avec des morceaux de granite ou du gravier. Cependant, en raison de la rareté des agrégats et pour des considérations environnementales, des agrégats de béton concassé recyclés ont été utilisés dans ce projet comme couche grossière. L'applica...