Compressive and shear strength of cob wallettes reinforced with bamboo and steel mesh

Abstract

In the present study, a novel experimental programme is conducted to evaluate the compression and shear behaviour of cob wallettes reinforced with bamboo and steel mesh. Three major categories of wallettes were prepared comprising at least three samples for each type for both compression and shear tests. The first category comprises four types of samples: unstabilised, unreinforced cob wallettes (USURCWs), cement-stabilised cob wallettes (CSCWs), coir-fibre-reinforced cob wallettes (CFRCWs) and straw-fibre-reinforced cob wallettes (SFRCWs). In the second and third categories, similar sample types as included in the first category were reinforced with bamboo and steel mesh, respectively. Five per cent fibres and 10% cement (by dry mass of soil) was added to the respective dry soil mixes followed by addition of 33.7% water and thorough mixing. Test results showed that the addition of fibre, cement and bamboo or steel reinforcement prevents brittle failure. Fibre-reinforced samples showed improvement in compressive and shear load capacity by about 5 to 33% and 78 to 107%, respectively, with respect to the USURCWs. Both fibre and cement stabilisation enhance the deformable property of wallettes compared to unreinforced ones. Overall, steel reinforcement exhibited higher load capacity, strength and deformability as compared to bamboo-reinforced samples and samples without bamboo or steel reinforcement. Compressive and shear strength results obtained satisfy the design requirement prescribed in the 1998 New Zealand standard NZS 4297, with the exception of USURCWs and USURCWs reinforced with bamboo mesh.