Browsing by Author "Lingwanda, Mwajuma Ibrahim"

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    Can Pumice Support Structural Foundations?
    (Mbeya University of Science and Technology, 2023-06-10) Lingwanda, Mwajuma Ibrahim
    The current practice with regard to pumice soils is to remove them when encountered during excavation for the foundations of multi storey buildings. Consequently, foundations become unusually deep where pumice deposits are located near ground level and extend to a significant depth. The decision to avoid pumice as a foundation supporting soil is logical, although not supported by literature. The question of whether pumice can support structural foundations was triggered by observation of the current practice with regard to this unique geological material. The question was approached through a literature review that aimed to find out what is known so far about pumice, point out what should be known, and suggest what to do with regard to pumice as a foundational supporting material. It was revealed that pumice is abundant in many parts of the world and has peculiar characteristics in comparison to most geotechnical materials. Many studies are concerned with pumice as a building material applied in concrete manufacturing and block making, but not as a foundation supporting strata. Pumice materials are characterised by high porosity, low specific gravity, low strength, and high crushability. A limited number of studies have indicated that pumicious materials require special treatment in laboratory testing, insitu testing, and the interpretation of results. Insitu and laboratory tests on pumice materials were conducted in this study for the purpose of enriching the discussion. Further research is recommended in areas of characterisation, insitu testing, correlations between test results, and improvement of pumice materials for consideration as foundation-bearing strata.
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    Determination of Dynamic Cone Penetration Index (DCPI) of Borrow Pit Materials for Construction of Low Volume Roads in Dodoma Tanzania.
    (MJRD, 2024-12-05) Lwanda, Vincent; Chengula, Duwa Hamisi; Lingwanda, Mwajuma Ibrahim
    The study for determination of dynamic cone penetration index (DCPI) of borrow pit materials for construction of low-volume roads was conducted in the Dodoma region in Tanzania. Samples for tests were collected from five borrow pits, which are Nkulabi, Zuzu, Mahomanyika, Dinda, and Ntyuka. Results of plasticity indices were 14%, 11%, 10%, 16%, and 13% for Nkulabi, Zuzu, Mahomanyika, Dinda, and Ntyuka borrow pits, respectively. Results of grading coefficients and shrinkage products were 33.7 and 148.1 units for Nkulabi, 19.9 and 295.9 units for Zuzu, 32.3 and 56.0 units for Mahomanyika, 25.4 and 391.3 units for Dinda, and 32.8 and 111.2 units for Zuzu borrow pits, respectively. Results of dynamic cone penetration indices were 5.8 mm/blow, 5.2 mm/blow, 4.7 mm/blow, 6.0 mm/blow, and 4.5 mm/blow for Nkulabi, Zuzu, Mahomanyika, Dinda, and Ntyuka borrow pits, respectively. Specifications require DCPI values for the tested material not to exceed 5.69 mm/blow in order to be suitable for use as gravel-wearing course material. Therefore, these results indicate that materials from Zuzu, Mahomanyika, and Ntyuka borrow pits have satisfied the requirement and hence qualify to be used as gravel-wearing course material. However, materials from Dinda and Nkulabi borrow pits have DCPI values above the limiting value of 5.69 mm/blow, and therefore they did not meet strength requirements as gravel-wearing course material. Based on grading coefficient, shrinkage product, and strength parameters, which are used for the selection of suitable materials, only Zuzu borrow pit materials qualified for the construction of the gravel wearing course. Therefore, engineering properties of materials from Dinda, Mahomanyika, Nkulabi, and Ntyuka need to be improved through the blending process.