Jordan Journal of Civil Engineering

Paper Detail

Effect of Random Inclusion of Kenaf Fibres on Strength Behaviour of Poor Subgrade Soils

Volume 14, No. 1, 2020
Received: 2020/03/16, Accepted:


Ayush Mittal; Shalinee Shukla;


The present study demonstrates the effect of using natural kenaf fibres on the strength behaviour of weak subgrade soils. The two types of soils classified as silt of high compressibility (MH) and clay of intermediate compressibility (CI) are used in this study. Laboratory compaction, soaked California bearing ratio (CBR) and unconfined compressive strength (UCS) tests are conducted on soil samples reinforced with kenaf fibres at four different percentages (i.e., 0.0625%, 0.125%, 0.25% and 0.50%) by weight of soil. Maximum improvements of 150% in CBR and 84% in UCS are reported when silty soil is reinforced with kenaf fibres, whereas these increases are only 18% and 40%, respectively, in case of clayey soil. Smaller post peak strength loss and greater failure strain are observed for soil samples reinforced with various percentages of kenaf fibres with more pronounced effect in case of silty soil. The scanning electron microscope images indicate significant bonding between soil particles and fibres in case of silty soil, thus causing stress transfer from soil to reinforcing material, which leads to strength enhancement, whereas this is lacking in clayey soil. Multiple linear regression analysis is used to develop predictive models for soaked CBR and UCS in terms of compaction characteristics and fibre content.


California bearing ratio (CBR), Compaction, Kenaf fibre, Reinforcement, Strength, Subgrade