Abstract:
Manufacturing Fired Clay Bricks (FCB) contributes to pollution and leads to loss of fertile soil. To save valuable natural resources, reduce pollution and increase energy efficiency, environment friendly Compressed Stabilized Earth Block (CSEB) can serve as a suitable alternative solution to FCB. This study aims at investigating the effect of flyash and cement as stabilizers on the strength characteristics of CSEB and its cost effectiveness.
Five soil samples were collected from different locations of Narsinghdi, Bhola and Barishal districts. Suitable soil for the production of CSEBs was selected from these collected samples. This investigation has been carried out with different combinations of soil-fly ash-cement mixes with varying level of compaction, cement percentage and water content. Fly ash content of 5%, 10%, 15%, 20% were used along with 5%, 7% and 10% cement content. Meanwhile water content was varied using 10%, 15%, 20% and 25% by weight of each sample. The soil mixtures were poured into steel moulds and compacted to produce cubic samples measuring 5cm × 5cm × 5cm.
The effect of the stabilizers on the compressive strength and water absorption capacity of the prepared CSEBs were observed and determined after 7, 14 and 28 days of curing. The maximum compressive strength of CSEB was obtained as 2.63 MPa consisting of 80% soil, 10% fly ash, 10% cement by weight and 20% of mixing water content by total weight of mixture. To understand microstructural behavior of these blocks, Scanning Electron Microscopy (SEM) tests were performed, it was found that size of voids decreases with an increase in fly ash content. The combined effect of flyash and cement contributed to good bonding and increased compactness which has been well interpreted in the images received. A comparative cost study was carried out between fly ash stabilized CSEBs and conventional fire burnt bricks, it has been found that fly ash block of equivalent brick size costs much less than FCBs available in Bangladesh. Meanwhile using the combination that attributed the highest strength of these CSEBs, unfired bricks measuring 25 cm × 12 cm × 7 cm (approximately) were made using the specifications of Bangladesh Standards and Testing Institution (BSTI), these bricks when experimented exhibited similar results of compressive strength like the flyash-cement stabilized blocks which makes both these suitable as construction materials in non-load bearing walls upon fulfilling specific building code requirements.
