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LOW COST SURFACING APPROACHES IN ZIMBABWE

LOW COST SURFACING APPROACHES IN ZIMBABWE. CASE STUDY: Marondera - Musami Road Construction Project K. Mukura TRL Ltd. Introduction. Constructed in 1993-1994 period Before construction: 22 km was narrow mat 41 km was gravel road in poor condition After construction: 22 km is narrow mat

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LOW COST SURFACING APPROACHES IN ZIMBABWE

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  1. LOW COST SURFACING APPROACHES IN ZIMBABWE CASE STUDY: Marondera - Musami Road Construction Project K. Mukura TRL Ltd

  2. Introduction • Constructed in 1993-1994 period • Before construction: • 22 km was narrow mat • 41 km was gravel road in poor condition • After construction: • 22 km is narrow mat • 41 km is surfaced to a 7/8 standard • Low cost surfacing method was used

  3. Introduction To Mozambique Malawi • Location: Cross 63km 60km Marondera-Musami Road 73km HARARE CITY To Mozambique Beira Port Marondera Town MUTARE CITY

  4. Construction Standards • Alignment: • closely followed the existing gravel road • cuts and fills were designed by eye • curvature was designed by eye except in complicated situations • very sharp curves were acceptable to minimise costs • Super-elevation was difficult to set by eye

  5. Construction Standards • Pavement Design: • x-section: 7/8, 3% camber, 2m wide drains ( detour) • 150mm sub-grade and base 1 thickness • Compaction: • Ls 91% HCE for sub-grade • Ls 93% HCE for base 1 • Materials specification: • base 1: triaxial class 2.8, laterite & decomposed granite sometimes marginal • sub-grade: SG9

  6. Construction Standards • Pavement Design: • Surfacing: single seal • 10mm crushed stone @ 10x10-3m3/m2 • TP7 prime @ 0.9 litres/m2 • bitumen 150/200 @ 1.2 litres/m2

  7. Observations • Traffic: • traffic increased beyond design capacity of road • heavy to opted for the short cut bypassing Harare despite 22km of narrow mat • Pavement: • still sound to date in spite of marginal materials used. • re-sealing was done after 5 years and the carriageway looks good

  8. Conclusion • Most sealed rural roads in Zimbabwe have been over-designed • Low-cost surfacing technique is used widely now to upgrade rural roads • Drainage system should be good enough to prevent water seeping into pavement

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