Effect of coconut fibers addition to early age unfired soil lime bricks strength

Low rise buildings and rural houses in Indonesia are often constructed with non-standard bricks. In some provinces, like West Java, fired clay and unfired soil lime bricks co-exist as non standard bricks. These bricks are traditionally produced in home run plants with little adherance to appropriate mix designs. These unfired soil lime bricks enter the market within 2 weeks of production, which inflicts potential loss to the buyers due to their low performance quality. The paper discusses strength improvements of these early age unfired bricks by adding natural fibers. Untreated coconut fibers with three different lengths (1 cm, 2.5 cm and 4 cm) were prepared for bricks reinforcements. The effects of 2%, 4% and 6% fiber addition to the strength of bricks were investigated. The bricks reinforced with 4% fiber content resulted in better strengths compared to those reinforced with other percentage of fibers. The effect of fiber length uniformity to the brick's strength was also evaluated. A 4% non-uniform fiber addition, which constitutes 1/3 part each of 1 cm, 2.5 cm and 4 cm average fiber length, was investigated. The results show that unfired bricks added with uniform fiber resulted in better performances compared to those added with nonuniform fibers. Higher compressive and bending strengths, compared to those strengths of unfired plain soil lime bricks and traditional soil lime bricks, could be achieved through fiber addition.