International Journal of Engineering Research in Africa Vol. 41

Abstract: The weakening of the behavior of reactive powder concrete (RPC) under high temperature is a major drawback; therefore, it is necessary to find an ingredient that improves their resistance under rising temperatures. The present work involves the use of metakaolin as a substitute for sand in a reactive powder concrete (RPC) in order to assess its effect on the mechanical strength at high temperatures. The test specimens are preheated up to 100°, 300°, 500°, 700° and 900°C, respectively following a well-defined cycle, thereafter subjected to a three-point bending followed by compression tests. Samples of the tested specimens were used for thermal, mineralogical and microstructural analyses using the thermogravimetric and differential thermal analysis (TG / DTA), the X-ray diffraction (XRD) and the scanning electron microscopic Analysis (SEM).The heating tests revealed that all the specimens exploded before reaching 500°C. However, they can withstand 300°C before exploding for different exposure durations depending on the metakaolin substitution ratio. Therefore, the mechanical tests were applied only on unheated specimens and those heated up to 100°C. The results showed that the use of metakaolin improves the mechanical strength of the RPC, both at room temperature (25°C±1°C) and at 100°C. This result is confirmed by the microstructure analysis, which revealed the absence of portlandite. The latter did react with the metakaolin silica to form new calcium silicate hydrates (CSH) enhancing the mechanical strength.

Abstract: This work aimed to study anaerobic digestion of a new substrate made from the waste of Algerian date palm (Phoenix dactylifera L.) in order to evaluate its biogas production capacity. The lignocellulosic component biodegradability and the process stability were also tested. Two reactors were launched with the same concentration of 20g total solid (TS)/L. A physical pre-treatment (grinding) of dried leaves lowered the substrate size below 2 mm. The theoretical methane yield (499 - 538 mL CH₄/g of Volatile Solids (VS)) indicated a high substrate methanogen potential. The tested methane and biogas yield reached 130±6 mL CH₄/gVS and 197±6 mL/g VS respectively. The biodegradability through the volatiles solid reduction was 29%. The total alkalinity (TA) value increased from the beginning to the end, due to the substrate nature which gave a high buffering capacity of the medium. During the stable process, a higher Chemical Oxygen Demand (COD) removal was reached with a value of 77.58%. The majority of the biogas yield was generated during the same period, which confirmed that the anaerobic digestion process stability is indispensable. Finally, this study was an opportunity to better exploit local by-products for the bioenergy production.

Abstract: All over the world, even in developing countries, plastics have quickly become one of the most common things found around. Unsurprisingly, this has caused a major waste management problem, particularly because synthetic polymers do not break down and degrade like organic waste. As a result, an alternative is being sought out in biopolymers. This study explores the suitability of a biopolymer blend; Ipomoea batatas mixed with low density polyethylene (LDPE) at various compositions. Biodegradation of this biopolymer blend was observed periodically when produced samples of Ipomoea batatas/LDPE were buried in loamy sand over a period of 28 days. Results show that produced biopolymers are environmentally compatible and bio-degradable. It was also observed that the sample blend with equal portions by weight of Ipomoea batatas (50%) and LDPE (50%) showed the most optimum pattern of degradation. There was steady degradation over the study period and the rate of degradation observed showed sustainability.

Abstract: The importance of transportation in the socio-economic development of nations cannot be downplayed. Intermodal transport has become vital concept for ensuring sustainable freight transport in developed economies but less focused on among African scientific community as it attracts fewer researches and developments. This paper aims to review and promote the development of sustainable intermodal freight transport systems in African developing countries with insights from Ghana.The researchers adopted literature review approach for the global intermodal developments and that of developing economies with emphasis on Africa and Ghana.Transport experts and experienced practitioners’ opinions were sought to complement the limited literature on the means to improve intermodal transport and logistics management systems. Authors discovered that some African countries like Ghana potentially posses some relevant multimodal resources such as seaport, waterway, railway and road infrastructures. However, they are not well interconnected to acquire intermodal benefits. Besides, the existing transportation systems were mostly road dominated and frauded with cost-inefficiencies; greenhouse gas emissions, traffic congestion, accidents, high maintenance and service deficiencies.The constraints are lack of skilled labor, limited infrastructure, safety and security problems, limited institutional capacity, poor intermodal transport network and connectivity issues. Some practical measures to improve the lapses in the transport system were highlighted. It was suggested that management of African developing countries must remodify their transport policies to attract investors and transport players. This would strengthen Public Private Partnerships (PPP) collaborations in developing intermodal freight transport and logistics systems.

Abstract: In this paper, we propose an indicator to systems-of-systems (SoS) structural analysis through dependencies evaluation which is based on interoperability and exchange inefficiency assessments, with dependencies representing links between component systems within the SoS. Interoperability is a quality that can be viewed from various perspectives. Therefore, we propose an illustrative classification for interoperability that embraces: barriers, scopes and levels. Our study involves a set of metrics to assess each interdependency’s interoperability barriers within the SoS through interoperability levels. Two different case studies, from the Moroccan economic infrastructure, are presented to apply the proposed approach. Results are cross-compared and evaluated.