Current Issue : January - March Volume : 2021 Issue Number : 1 Articles : 5 Articles
The following study is aimed at valorizing an important part of waste from\nbuilding demolition, particularly concrete as a source of aggregates for their\nusage in new hydraulic concrete formulation. The experimental study\nmainly consisted of physical characterization of natural and recycled aggregates\nrespectively and the impact of the latter on some properties of the\nnew formulated concrete, actually their respective consistencies for fresh\nconcrete and mechanical strength for the hardened one. The outcome of the\nstudy shows that the recycled aggregates are more heterogeneous and have a\nhigh capacity of water absorption, but which still respects the current standards\nof concrete....
Rwanda is undergoing rapid development in transportation through constructing\nnew roads and upgrading existing ones. During implementation of\nthese projects, many accidents for road workers, road users and environment\nissues are raised due to unsafe road construction management techniques.\nThis existing problem was carried out within the City of Kigali for three ongoing\nroad construction projects namely road Ruliba-Karama-Nyamirambo,\nKigali Urban Road Upgrading Projects of Agatare and the Sonatube-Gahanga-\nAkagera road, in order to investigate about the road construction safety management\ntechniques. From the findings, 64.28% results showed that the\nmaintaining of health and safety policy in the road construction sites is applied\nand there exist different means of maintaining safety, such as the provision\nof PPE (Personal Protective Equipment) to the workers at the level of\n57.14% as per the project managers; but from the field observations, it is\nalarming, and many workers do not wear as required....
Buildings collapse has now become a recurrent phenomenon in Cote dâ??Ivoire.\nTherefore, this study was conducted to find out the reasons for these disasters,\nand check in particular to the extent, and concrete steel bars produced in\nCote dâ??Ivoire and used in buildingsâ?? structures are involved. Samples having\n6, 8, 10 and 12 mm in diameter steel taken from the five (5) major manufacturers\nor suppliers of the Ivorian market were subjected to physical, chemical\nand mechanical tests to determine their performance. A comparison of these\nresults with the NF EN 10080 and NF A35 080-1 standards made it possible\nto calculate the probability to have out-of-standard products in a structure.\nPieces having 60 cm were cut from three bars of the same thickness and then\nsubjected to tests....
Environmental pollution and energy conservation in urban tunnels have become important issues that affect the scientific design\nand sustainable development of urban tunnels. The carbon monoxide (CO) concentration in urban road tunnels is regarded as a\ndirect reflection and a useful tracer of the intensity of anthropogenic transportation activities. Previous studies in recent years have\npaid more attention to pollutant emission factors, but less to the calculation parameters of ventilation design for tunnels. This\npaper aims to study a reasonable annual reduction rate of CO base emission factors. Therefore, a detailed field measurement was\ncarried out in the four typical urban road tunnels, Henglongshan Tunnel, Cejiexian Tunnel, Jiuweiling Tunnel, and Dameisha\nTunnel in Shenzhen, China, from March 29 to September 16, 2014. Measurement results showed that the traffic flow of the four\nurban tunnels had been approaching the design value, or even beyond the limit....
In this paper, the field monitoring method is used to study the variation of rock mass pressure during the construction of a tunnel\nin phyllite stratum, and three functions are used to fit and analyze the variation of rock mass pressure with deformation,\nexcavation time, and space. The results show the following (1) When the deformation increases significantly, the rock mass\npressure decreases firstly and then increases. This is caused by the insufficient bearing capacity of the rock mass in the arch foot of\nthe supporting structure after the excavation of the upper bench, which leads to a settlement of supporting structure and\nsurrounding rock. (2) Compared with other kinds of fitting functions, the logistic function can better characterize the variation of\nthe pressure of surrounding rock with deformation, excavation time, and distance from the face. This paper provides a reliable\nreference for the design and construction of the tunnel in phyllite stratum. The logistic function can be used to present and predict\nthe change of rock mass pressure with deformation, excavation time, and space in similar rock mass conditions....
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