Influence of green’s coconut fibers in the unsaturated behavior of compacted clayey soil

Abstract

Abstract. The green coconut’s shell is considered to be waste while it represents most of its volume and weight. The objective of this research was to analyze the influence of the addition of 1% (by weight) of green coconut’s (Cocos nucifera) fibers in the unsaturated behavior of compacted mixtures of clayey soil, with fibers randomly distributed in the soil matrix. Both the pure soil and the mixture were submitted to filter paper tests according to Chandler and Gutierrez (1986) and Marinho (1994), in order to obtain their characteristic curves and verify their differences, using the relation suction-humidity proposed by Chandler, Crilly and Montgomery-Smith (1992) and van Genuchten’s (1980) adjustment method, which was also used to estimate the unsaturated hydraulic conductivity and relative permeability to air and water as functions of the degree of saturation. The results revealed that the addition of fibers provided greater water percolation in the drying path, and greater air flow during wetting. This behavior is a reflection of the greater retention capacity provided by the fibers, which promotes a more gradual change in the degree of saturation, in relation to the ‘pure soil’, which is a very interesting characteristic for applications subject to large variations in humidity.