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Use of agricultural waste fibres as enhancement of soil blocks for low-cost housing in Ghana

Student thesis: Doctoral Thesis

The work presented in this thesis investigates the properties and internal mechanism of novel soil blocks made with three different agricultural waste fibres in two different soil types. Experiments were conducted and the main variables include: three fibres (bagasse, coconut and oil palm), three soil samples (Brown, Red and Horsea Island), five fibre content (0, 0.25, 0.5, 0.75 and 1 wt.%) and five fibre aspect ratios (25, 50, 75, 100 and 125). Tests conducted include density, compressive, tensile, erosion, wearing, SEM, CT scan, optical microscope analysis and pull-out.

Initial tests on small cylindrical specimens produced to determine the effect of compaction rate for producing soil blocks on the strength properties found that, although the low rate of compaction achieved slightly better performance characteristics, there was not a statistically significant difference between the soil blocks produced with low and high compaction rates.

Investigation on the effect of aspect ratio of the fibres on the mechanical properties of soil blocks revealed that, in general, an increase in fibre aspect ratio has a positive effect (20-25% improvement) on the strength of enhanced soil blocks. Fibre lengths of 50, 80 and 38 mm for coconut, bagasse and oil palm fibres, respectively, produced maximum strength, only bagasse showed an optimum. Another investigation on the properties of soil blocks reinforced with different fibre contents found that, the inclusion of fibres, enhanced the properties of soil blocks (16-57% strength and 20-70% durability improvement), with optimum performance generally at 0.5wt.% fibre content. Furthermore, the high clayey soil performed better in all the properties of the fibre reinforced soil blocks than the low clay soil.

The study on the internal mechanism of fibre-soil matrix interaction established that fibres in the soil matrix are randomly distributed with gaps between the fibres and matrix due to fibre shrinkage. It also found that natural fibres in soil matrix can either be pulled out or break under load. In addition, fibres in the soil matrix undergo changes in size when wet and at its natural moisture content state. In general, the work concludes that the fibre reinforced soil blocks are suitable for use as a building material especially for less economically developed (LED) countries, particularly Ghana, because of the abundance and low-cost of the selected fibres.
Original languageEnglish
Awarding Institution
Award dateMar 2016


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