Abstract:
The need to address the shortage of housing in Kenya, led to the adaptation of the vibro technology used in sandcrete block making machine, for making stabilized-soil blocks. The adaptation envisaged to supplement the technologies used locally in producing stabilized-soil blocks which include the quasi-static and dynamic machines. The adaptation entailed determining the rotor shaft diameter, eccentric mass, the speed of the rotor, and selection of a close coiled helical compression spring and the static load where Non-stabilized sandy-clay-loarn soil containing sand/fine gravel 51.1%, and silt/clay 48.8% as sample ‘A’ was compacted and the density of the formed soil blocks determined before curing. In the trial, different eccentric masses were clamped to the shaft and run at varied speeds. The centrifugal force from the rotor induced vibrations which were confined to the mould by the springs. Static-weight was applied vertically onto the soil mixture simultaneously with the vibrations. A batch of three non- stabilized-soil blocks was produced in each production where the mean density of the batch was determined. A total of 24 batches were produced and Analysis of Variance (ANOVA) was done to determine the speed and eccentric mass or a combination of both that resulted in a batch with the highest density, keeping the compactor weight and spring constant. A t-Test indicated no significant difference between non-stabilized-soil block density from the proctor test and the vibro compaction technology. An optimum speed of 1850rpm and eccentric mass of 4750gms based on Fisher’s least significance difference was selected and applied to soil samples ‘A’, ‘B’ ( sand/fine gravel 60.8%, silt/clay 33.4% ) and ‘C’(sand/fine gravel 53%, silt/clay 46.6%) mixed with varying cement contents by weight of soil. Soil sample ‘C’ was mixed with 6%, 8% and 10% cement content by weight where the mean values for bulk density, wet compressive strength, dry compressive strength and water absorption were,l513 Kg/m3, 0.955 MN/m2, 1.4 MN/mg, and 16.7% respectively. It was observed that at 10% cement content, the bulk density was less by 5.4% from the minimum acceptable value of 1600 Kg/rn3, the water absorption was more by 1.7% from the minimum acceptable value of 15% and the ratio of mean dry compressive to wet compressive strengths was less than 2 which conformed to stabilized-soil block literature. Therefore, this study provides a baseline for further research in the adaptation of Vibro compaction technology for making soil blocks to supplement the Impact and Quasi static s oil block compaction methods.
