Browsing by Author "Jjuuko, S."

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    Effect of Wood Ash as a Partial Replacement of Lime in the Stabilisation of Laterite Soil for Pavement Layers
    (Cape Town, 2019) Odongo, D.; Otyama, L.J.; Jjuuko, S.; Kalumba, D.
    This research considered the use of wood ash (WA) as a partial replacement of lime in stabilisation of laterite soil for pavement layers. The study investigated the physical properties and chemical composition of wood ash and laterite soil sample. The results showed that WA is a good pozzolan with combined SiO2, Al2O3 and Fe2O3 of 56.34% exceeding the minimum requirement of 50%. Laterite soil was categorised as Clayey Gravel with Sand, A-2-7(1), using the AASHTO classification system. The Initial Consumption of Lime of the soil sample, from the pH tests, was determined as 4%. The 4% lime content was gradually substituted with appropriate amounts of WA in proportions of 0%, 10%, 20%, 30%, 40% and 50% from which the geotechnical properties of the soil-lime-WA mixtures were investigated. The index and strength parameters of the laterite soil improved substantially. The results support the idea of making use of on-site materials and thus lowering construction costs. At the same time, the rapid fill-up rate of landfills would be solved.
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    Prediction of Compaction Density of Lateritic Soil Base Pavement Layers from Dynamic Cone Penetration Values in Uganda
    (arcsmge, 2015) Jjuuko, S.; Kalumba, D.; Mutaasa, H.K.; Lukanda, J.
    The study focused on obtaining a correlation between sand replacement method density values and dynamic cone penetration (DCP) rate values (mm/blow) for base pavement layers of lateritic soils in Uganda. A maximum depth of 500 mm of gravel of lateritic soil on existing roads, in Rubaga division in Kampala (Uganda), was penetrated using the DCP to obtain the rate of penetration (mm/blow). They were also investigated for their index properties and field density values using sieve analysis, Atterberg limits and sand cone replacement methods. The gravel was generally classified as reddish-brown clayey sand with an AASHTO class of A-2-6. The correlation obtained between dry density values from the sand-cone replacement method and DCP rates showed an inverse relationship with R2 coefficient of 0.5999 indicating a moderate correlation between the two variables. The correlation was validated with data from other lateritic base layers of roads in Wakiso district, Uganda
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    A Review of Application and Benefits of Thin Spray- On Liners for Underground Rock Support in South African Mines
    (Spier Conference Centre, Stellenbosch, Western Cape, 2014) Jjuuko, S.; Kalumba, D.
    Thin Spray-on Liners (TSLs), an emerging alternative surface support system for underground rock support with performance characteristics in-between those of shotcrete and wire mesh, are receiving increasing attention from the South African mining industry. Previous rock support trials conducted at South African mines and laboratory sites to determine the reinforcement potential of TSLs, and to assess their effectiveness relative to existing traditional support techniques showed positive results. The purpose of this article is to review the reinforcement potential of TSLs surface support system critically in light of the traditional mining technologies. Both laboratory simulations of loose rock deformations and in-situ observation of falls of loose rock fragments, constrained solely by TSL layer strength and rock adhesion were reviewed. An overview of the technology and observed and measured support capabilities is provided and thereafter assessment of rock reinforcement potential done plus the benefits of the technology in the South African mining industry.
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    The use of locally available sand in stabilization of Ugandan clayey soils: Case study of clayey soil from Busega area
    (Umaru., 2011) Jjuuko, S.; Kalumba, D.; Bagampadde, U.
    Clayey soils need to be stabilized to improve their engineering properties and make them suitable for pavements and foundation engineering. Stabilization of pavements and foundation engineering soils in Uganda has traditionally relied on treatment with lime and cement and most designers (engineers) are hesitant to specify nontraditional stabilizers, like sand, without evidence of material effectiveness. This study aimed to use sand to improve the engineering properties of a typical Ugandan clayey soil. Sand was specifically selected because of its abundance locally. A series of laboratory experiments were implemented for specimens whose sand contents ranged between 20 - 80%. The results confirmed that sand blending diminishes shrinkage behavior of clayey soils. Additionally, plasticity index and shrinking potential decreases from 30.5% to non-plastic and from 9.3% to 1.8% respectively depending on the sand concentration in the composite. The MDD and OMC increased from 1867 to 2357 kg/m3 and decreased from 16.5 to 8.5%, respectively, at sand blends of 20-100% while the unconfined compressive strength decreased from 787 to 95kPa at sand blends of 20-60%. The soil internal friction angle concerning shear strength parameters was enhanced from 26.6 to 42.1o and soil cohesion decreased as well from 62 to 2kN/m2 at sand blends of 20-80%. At sand blends 20- 80%, consolidation settlement was lowered from 2.00 to 1.52