Suchergebnisse

This paper presents result of a laboratory investigation on soil samples from Abeokuta South Local Government, Southwestern Nigeria. Three comparative efforts namely standard Proctor (SP), West African Standard (WAS) and modified Proctor (MP), were employed. The results obtained showed that the compaction characteristics and unconfined compressive strength of the soil samples were found to increase with comparative effort. The unconfined compressive strength (UCS) values increased with compactive effort and decreased with increase in degree of saturation of the soil samples. All the samples did not meet the minimum specified requirements except for A1, A6 and A8. Upon stabilized with cement, samples A2 and A7 did not also meet the minimum CBR value of 180% as specified by the Nigerian General Specification for roads and bridgeworks (1997) or stabilized soil using standard Proctor compactive effort at 4% cement content. However, all the soil samples met the requirement using WAS compactive effort at 4% cement content. The samples met the conventional UCS values of (1500-3000 kN/m2) for base course of lightly trafficked roads while only sample A4 compacted at 10% cement content using WAS compactive effort met the minimum (3000- 6000 kN/m2) for base course of highly trafficked road. It is thus recommended that 4% cement should be used as an optimal content to stabilize the soils, if they are to be used as road construction materials.

Rapid stabilization of weak soils is one of the important and current topics in geotechnical researches such as military application and stabilization of landslides. Deep mixing is an improvement method applied in the form of creating mixed columns which involves in-situ mixing of soil and lime or Portland cement with special equipment. The aim of this study was to evaluate the feasibility of utilizing polymers as a binder for rapid stabilization of sandy soils with deep mixing method. For this purpose, a series of unconfined compression tests were conducted on three dierent sandy soils improved with polyester. In the experiments, polyester was used at three dierent ratios of 10%, 20% and 30% and samples cured for 3 hour, 1, 3, 7 and 28 days. The laboratory test results of 3 hours samples showed that soils mixed with adequate polyester could reach a similar strength range of 28 days cured soils improved with cement or lime which was reported in the literature. The unconfined compressive strength increased with the increasing polyester ratio, effective diameter, and relative density and curing period, whereas, the changes on unconfined compressive strength were insignificant with the increase of freeze-thaw cycles. The overall evaluation of results has revealed that polyester is a good promise and a potential candidate for rapid deep mixing applications.

The investigation carried out in this paper was to evaluate the effect of eggshell powder and sodium silicate as stabilizers to laterite soil used as fill material for the purpose of constructing light traffic pavement. The laterite soil used in this study was collected from Ikorodu North Local Government Area in Lagos State, Nigeria and treated with eggshell powder (ESP) and sodium silicate (SS) blend in stepped concentrations of 3% ESP + 2% SS, 6% ESP + 4% SS, 9% ESP + 6% SS, 12% ESP + 8% SS and 15% ESP + 10% SS by dry weight of the soil. Results from the tests carried out showed a general improvement on the engineering properties of the laterite treated with ESP and SS blend. Optimum California Bearing Ratio (CBR) tests results for un-soaked and soaked samples were recorded as 51% and 22% at 12% ESP + 8%SS content. Peak Unconfined Compressive Strength (UCS) values of 355 KN/m2and 570 KN/m2 were recorded at 7- and 28-days curing periods respectively at an optimum blend of 12% ESP + 8%SS content. From the results obtained in this research, an optimum blend of 12% ESP and 8% SS using the West African Standard (WAS) compactive effort can be used to stabilize laterite soil material for use as fill material for the construction of light traffic roads. An advantage of applying the ESP is the decrease in the deleterious environmental impact of eggshell waste.