Browsing by Author "Chengula, Duwa Hamisi"

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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.
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    Stakeholders’ Awareness and Perceptions on the Use of Force Account Method in Public Building Construction Projects in Tanzania.
    (DASJR, 2025-09-29) Magania, Faraji M.; Tekka, Ramadhani Said; Chengula, Duwa Hamisi
    The Force Account Method (FAM) is increasingly utilized as a procurement approach for public building construction projects in Tanzania, primarily due to its potential for cost savings, flexibility, and enhanced accountability. This study investigates stakeholders’ awareness of FAM selection criteria and their perceptions of its practical benefits. A descriptive survey design was employed, collecting data from 128 participants representing implementing agencies, contractors, consultants, and regulatory bodies through structured questionnaires. The results indicate high awareness of key selection criteria, especially the necessity for sufficient technical staff and the importance of minimizing disruption to ongoing operations. Stakeholders identified limited funding and uncertainty in disbursements as significant justifications for FAM, though opinions varied regarding remoteness and the clarity of work quantity definitions. Most participants agreed that FAM improves cost efficiency, adaptability to unforeseen changes, and public confidence in transparency. Nevertheless, concerns were raised about project completion timelines and the consistency of quality outcomes, with regulatory bodies and implementing agencies expressing differing perspectives. These findings underscore FAM’s advantages in affordability and governance, while also revealing deficiencies in project efficiency and technical oversight. The study concludes that FAM substantially contributes to value for money in Tanzania’s public construction sector. However, enhancements in institutional capacity, standardized guidelines, and monitoring mechanisms are necessary to address persistent challenges related to quality and timeliness. The findings offer actionable insights for policymakers, regulatory authorities, and practitioner aiming to improve the effectiveness of FAM in achieving sustainable infrastructure development.