INVESTIGATION OF THE EFFECTS OF DIFFERENT NATURAL FIBERS ON THE STRENGTH OF COMPRESSED STABILIZED EARTH BLOCKS (CSEB)

Abstract

This study investigates the most effective combination of natural fibers (namely coconut coir,
abaca, and maguey) used as reinforcement for Compressed Stabilized Earth Blocks (CSEB). Portland cement
and 0.25% fibers by weight were used to stabilize and reinforce CSEB, respectively. The blocks were made
primarily with Manila soil and were formed using hand-pressed machine. CSEB without fibers were first
tested with varying cement contents of 6%, 8%, 10%, and 12% by weight. This was examined to determine
the practical cement content (PCC). Three strength tests namely dry compressive strength, wet compressive
strength, and flexural strength were conducted on CSEB at PCC with different fiber combinations of coir,
abaca, and maguey fibers to determine the mix producing maximum strength. The highest dry compressive
strength was obtained with 100% maguey fiber; the highest wet compressive strength was obtained with
100% abaca fiber; while the highest flexural strength was obtained with 17% coir fiber, 17% abaca fiber, and
67% maguey fiber. Using the Response Surface Methodology (RSM), the maximum strengths were predicted
as follows: 100% maguey for dry compressive strength, 100% abaca for wet compressive strength, and
38.4% abaca and 61.6% maguey for flexural strength. However, the optimal mix of CSEB for three the
strength tests consists of CSEB with 42.5% abaca and 57.5% maguey. The fibers were found to improve the
performance of the block such as the strength and post-crack behavior. Furthermore, the performances of a
wall made of fiber-reinforced and unreinforced CSEB were investigated. The test results showed a 33.79%
increase in load carrying capacity of the fiber-reinforced wall compared to unreinforced wall.