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Recent Submissions
Stabilisation of Laterite Soils With Cement and Metakaolin
(2024-04-11) Paul Kakooza
The research carried out was aimed at improving the properties of the laterite soils while using cement and metakaolin in the subbase soil layer. The research was guided by three specific objectives which included determining the engineering properties of the neat soils, determining the properties of the metakaolin and determining the engineering properties of the cement-metakaolin stabilized laterite soil. The case study of the research was Jambula road located in Entebbe municipality and the metakaolin was got from Buwambo. Furthermore, the study discussed about the sampling and preparation of the materials used. Different laboratory tests were carried out at Sterling laboratory while following the specific objectives stated in reference with the required standards of British Standards, General Specification MOW and others. Different tests of CBR, MDD, PI and UCS were carried out on the stabilized cement-metakaolin laterite soil and at optimum cement and metakaolin content of 3% and 4%, the mix had an MDD value of 2.071gm/cm³, CBR value of 57%, Pi value of 13.1% and USC value 1.41Mpa which all lied in the required range for a subbase soil layer in accordance with Ministry of works and Transport. Hence making cement and metakaolin good chemical stabilizers for the laterite soils. For this research, some conclusions were drawn and as well recommendations for further research were given.
Stabilisation of Laterite Soils With Cement and Metakaolin
(2024-04-08) Joel Agaba
The purpose of this research was to stabilize laterite soils using cement and metakaolin. The need for this research is driven from the problems experienced during cement stabilization particularly autogenous shrinkage that is associated with cement hydration. Metakaolin which is pozzolanic in nature has in previous research demonstrated the capacity to minimize this shrinkage by increasing the voids formed during hydration of cement. Metakaolin has also been found to improve the strength properties of concrete. Therefore, this research aimed at increasing the strength of laterite soil stabilized with cement and metakaolin. To achieve this, cement and metakaolin were mixed together with cement kept at a constant 3%, which is the optimum for this purpose according previous research and metakaolin increased from 0% to 8% in intervals of 2% in order to determine the suitable mix design for stabilization of the laterite soils. A design mix of 3% cement and 4% metakaolin was selected as the optimum since this soil gave the highest values for the strength properties of the laterite soil after stabilization that is 57% for CBR and 1.41MPa for UCS. The shrinkage characteristics of the soil that is PI, CBR swell and linear shrinkage were all found to be within the allowable range according to the MoWT general specifications for road and bridge works 2005.
Assessing the Use of River Sand and Sawdust Ash in the Stabilization of Weak Subgrade Soils
(2024-04-11) Justine Shilla Nambooze
Expansive soils usually have a high compressibility they also have a tendency to shrink upon drying and swelling when wet, and high-water absorption. These expansive soils make it impossible to build civil engineering projects without adequate stability due to a number of issues they cause. In places where these soils exist, before construction of any structure, various techniques are frequently used to enhance their engineering qualities. Traditionally, common additives for stabilizing soil have included cement and lime.
But in Uganda, where there is a lot of waste from the agricultural sector, and the increasing prices of these additives, there is need to use the locally available materials to stabilize these weak soils. Thus, the purpose of this study was to determine whether river sand and sawdust ash (SDA) were suitable for stabilizing expansive soils.
Through carrying out experiments, the percentages of river sand and saw dust ash were varied in the following ranges; 0% river sand and 0% saw dust ash and 100% soil, 0% river sand and 12% saw dust ash, 15% river sand and 9% saw dust ash, 30% river sand and 6% saw dust ash, 45% river sand and 3% saw dust ash, 60% river sand and 0% saw dust ash with varying percentages of soil which were varied by mass. The tests were carried out which include classification tests, durability tests and strength tests. The results showed that the neat soil was a highly plastic clay soil which was poor to be used for road construction and therefore required stabilization. On addition of river sand and saw dust ash in the above proportions showed a notable decrease in the plasticity index from 30.4% for the neat soil to 5.2% at 45% river sand and 3% saw dust ash. However, at 60% river sand and 0% saw dust ash the soil matrix was non-plastic. The maximum dry density was also seen to increase until it reached its highest of 1.898 g/cm3 and a reduction in optimum moisture content to 8.1%. The results reveal the potential for the use of the combination of river sand and saw dust ash to stabilize the weak subgrade soils. The research also adds to the existing body of knowledge in that it addresses the problem of poor soils and also environmental waste concerns brought about by the agricultural sector.
Investigating the use of River Sand in Stabilising Expansive Soils
Case Study: Moroto-Nadunget Pavement Section
(2024-04-08) Ambrose Mwine
The research carried out was aimed at improving the properties of expansive soils while using river sand for use in the subgrade soil layer. The research was guided by three specific objectives which included determining the engineering properties of the neat soils, determining the engineering properties of river sand and lastly determining the engineering properties of the river sand stabilized mix. The case study of the research was Moroto-Nadunget road section located in Moroto District and the river sand was bought along the banks of river Kangole from the locals. Furthermore, the study discussed about the sampling and preparation of the materials used. Different laboratory tests were carried out at Sterling labaratory while following the specific objectives stated in reference with the required standards of British Standards, General Specification MOW and others. Lastly different tests of CBR, MDD, PI were carried out on the stabilized river sand mix and at optimum river sand content of 20%, the mix had an MDD value of 1.889gm/cm3, CBR value of 33.8%, PI value of 16.1% which all lied in the required range for a subgrade soil layer. Hence making river sand a good mechanical stabilizer for expansive soils. For this research, some conclusions were drawn and as well recommendations for further research were given.
A Comparative Study Between the Conventional Method and the Use of Powdered Activated Carbon in Iron Reduction from Groundwater
(2024) Andrew Mbabaali
This report was specifically looking at the comparison between the conventional treatment method (aeration followed by settling and filtration) and the use of Powdered Activated Carbon (PAC) in an adsorbent filter in total iron reduction from groundwater sources. The PAC was prepared from sawdust. The water sample was collected from iron contaminated ground water source (borehole with hand pump). Both treatment methods indicated above (conventional and adsorption) were applied to check the total iron reduction from the ground water source and the results were compared in order to determine which method could be more effective in total iron reduction. Total iron levels were tested both before and after the treatment and the results showed that the conventional method was able to reduce the total iron concentration by 95.22% (from 41.44mg/L to 1.98mg/L) while on the other hand, PAC layer thicknesses of 2.5cm, 5cm, and 7.5cm were able to reduce the total iron concentration by 99.08%, 99.20%, and 99.40% respectively between 41.44mg/L and 0.38mg/L, 41.44mg/L and 0.33mg/L and 41.44mg/L and 0.25mg/L respectively . However, the reduced iron levels
to (1.98mg/L and 0.33mg/L for conventional and PAC respectively) were still above the permissible limits compared to the Uganda National Standards for treated potable water which is 0.3mg/L. But since 0.33mg/L total iron is also within the permissible limit of the Uganda National Standards for untreated potable water (1mg/L), it was considered to be safe at household level.