Effect of fibre aspect ratio on mechanical properties of soil building blocks

•Most fibres will produce increasing block strength with increasing fibre length.•Some fibres have an optimal aspect ratio when used in soil blocks.•Natural fibres continue to hold blocks together after failure of the soil matrix.•The effect of fibre aspect ratio is similar in magnitude to effect of fibre content. Inclusion of fibres in soil blocks has been shown to enhance strength development. This study investigates the effect of aspect ratio of coconut, bagasse and oil palm fibres on the mechanical properties of soil blocks. Experiments were conducted on soil blocks with fibre aspect ratios (25–125) to determine the compressive and tensile strength of the blocks. Blocks with coconut and oil palm fibres showed increasing strength with increase aspect ratio, while bagasse fibres showed an initial increase followed by a decline at higher aspect ratio. The study concludes that generally longer aspect ratios produce better mechanical properties of soil blocks.