The development of road infrastructure is a factor of growth and development in any country. As such, the maintenance of the road network and its extension are a central concern of the governments’ policy. However, this high degree of interest faces the scarcity of funding to be allocated to road maintenance and construction operations, the costs of which, on the other hand, are increasingly high. In addition, polluting emissions inherent in road construction, significantly contribute to global warming, the harmful effects of which are a global concern. Designers and decision makers are thus faced with a real challenge when choosing a pavement option to be built between asphalt concrete pavement (AC) and continuous reinforced concrete pavement (CRCP). The aim of this thesis is therefore to propose a new approach for the selection of pavement surfacing between AC and CRCP, particularly for heavily trafficked roads, in sub-Saharan Africa. The proposed concept is based on the overall lifecycle costs of the pavement instead of the initial costs generally used as a criterion for the award of construction contracts. The pavement to be constructed should require little maintenance, perform better at high temperatures of up to 50 ° C and withstand heavy traffic. This approach, insofar as it takes into account economic, environmental and social aspects, leads to the construction of sustainable roads.
The validation of this innovative and original design optimization approach and the selection of a pavement option between AC and CRCP is carried out on a section of the Autoroute du Nord in Côte d'Ivoire, using the Alizé-lcpc, Ecorce 2.0 and HDM-4 v2.0 tools, and considering the growth in heavy goods vehicle traffic. The analysis is made according to the three pillars of sustainable development on the phases of production and manufacturing of materials, of construction and of operation of the pavement.
Economically, following the evaluation made on three homogeneous sections with a total length of 50 km, the results indicate that the initial cost of construction of the CRCP option is more expensive by 10 to 20 % than that of the AC option. Over the 20-year life cycle, administration costs and user costs fall on average by 15 % and 30 % in favor of the BAC option. Ultimately, at the end of the life cycle, the overall costs of the AC option are 21 to 28 % more expensive than those of the CRCP option. According to the overall life cycle cost approach, the continuous reinforced concrete pavement should be carried out.
From an environmental standpoint, the results indicate, for the materials extraction and production phases, a reduction in greenhouse gas emissions of around 15 % for the CRCP option for high heavy traffic (70,000 vehicles per day, including 21 % heavy goods vehicles) compared to the AC option. Conversely, for light heavy traffic (43,750 vehicles per day including 1 % heavy goods vehicles), the CRCP option consumes up to 27 % more than the AC option. For the construction and operation phases of the pavement, the CRCP option pollutes 55 % and 25 % less than the AC option, respectively, regardless of the traffic. Over the 20-year life cycle, the overall greenhouse gas emissions rate of the CRCP option is 17 to 20 % lower than that of the AC option; overall energy consumption is also 15 to 16 % lower. These rates increase with the increase in heavy vehicle traffic. The CRCP option is more advantageous than the AC option over the life cycle, especially for pavements with heavy truck traffic.
At the social level, the results obtained in the material extraction and production phase, on the indicators of eutrophication (EI), acidification (AP) and ecotoxicity (EP) give an advantage to the CRCP option for roads with a high volume of heavy traffic. For tropospheric ozone (POCP) and toxicity (TP) indicators, it is more advantageous whatever the volume of heavy traffic. Therefore, when the heavy traffic is low, the AC option is more advantageous according to the EI, AP and EP indicators. In the construction and operation phases, the CRCP option is more advantageous whatever the level of heavy traffic. The monetization of these life cycle externalities indicates that the total cost of damage of the AC option is about 15 to 19 % higher for high heavy traffic (21 % of heavy goods vehicles). Conversely, the total damage cost of the CRCP option is approximately 7 to 8 % higher for light heavy traffic (1 % of heavy goods vehicles). The CRCP option is more advantageous than the AC option, especially for heavily trafficked roads.
Finally, this thesis concludes that the CRCP pavement is more durable than the AC pavement, particularly for heavily trafficked roads. A sensitivity analysis on the one hand and the comparison of the results on the other hand with those of the available scientific literature made it possible to verify the robustness of the study projects.
| Date | 18 Dec 2020 |
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| Original language | French |
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| Awarding Institution | - École de technologie supérieure
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| Supervisor | Gabriel J. Assaf (Supervisor) |
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