Influence of the Partial Substitution of Bitumen by a Mixture of Sulphur and Tyre and Plastic Bottle Powders on the Behaviour of Bituminous Concrete

This article deals with the influence of the partial substitution of bitumen by a mixture of sulphur and tyre and plastic bottle powders on the characterization of asphalt concrete. The approach adopted was to subject a control asphalt concrete to level 2 formulation tests as well as those modified at 10%, 20%, 30% and 40% by substituting bitumen with a mixture of tyre powder, plastic bottle powder and sulphur at 40%, 28% and 32% respectively. The results of the PCG, Duriez and rutting tests carried out on the control and modified bituminous concretes (manufactured using the wet process) revealed three (03) major findings, in particular with regard to workability, resistance to simple compression and rutting. The experimental results show an increasing trend in the essential parameters. At 40% substitution, there was a 22.73% increase in compactness, reflecting a significant improvement in the material’s workability. With regard to simple compressive strength, the increase is 34.02% at 40% substitution, highlighting the limitation of crack formation and propagation under heavy precipitation. With regard to rutting, the 16% drop in susceptibility at 40% substitution reflects a significant improvement in the behaviour of the material under dynamic mechanical stresses in heavy precipitation. The improvement in these behaviours results from the insertion of the plastic bottle powder into the interstices of the granular skeleton, thus reducing its cellular structure, and also from the interactions between the sulphur with the tyre powder and the sulphur with the plastic bottle powder, i.e. cross-linking or vulcanisation.

Influence of soft rock-fill material as dam embankment with central bituminous concrete membrane

This paper demonstrates the difficulties in determining the relevant material parameters for a valuation of the deformation behavior of the up-and downstream dam shell by means of an embankment dam of medium height.Laboratory as well as field tests on solid rock-fill material were performed before the beginning of construction.During the construction the properties of the available rock-fill changed from solid to soft materials.This gave rise to the necessity of adjusting the dam design of the downstream dam shoulder.Several times higher dam settlements as well as significant differential settlements between the up-and downstream dam shell were observed during construction and operation.Apart from this situation,the dam has been operated for nearly 20 years and the behavior of the water barrier has been very good.

Performance Evaluation of Asphalt Concrete Based on Basalt Aggregates of Diack and Quartzite of Bakel

In Senegal, basalt aggregates are the aggregates used for the production of asphalt. They are also in some condition in base layer. However, the only licensed and operated basalt quarry in the west-central part of the country is finished and has reached very important depths thus constituting an environmental threat. This is how quartzite present in the east of the country precisely in the department of Bakel would constitute an alternative to basalt. For this purpose, the performance of two bituminous concretes based on quartzite and basalt was compared. One is made from Diack basalt aggregates, considered as the reference aggregate for asphalt in Senegal and the other is based on Bakel quartzite aggregates, they are both class 0/14. The mechanical performance of two bituminous concretes is evaluated using the Marshall method. The results obtained from the marshall tests give compactness values between 94% and 97% representing the limits laid down in the technical specifications, the creep values for quartzite-based asphalt concrete, while respecting the limit values, are higher than those obtained with basalt aggregates. Thus showing that the former is less resistant to deformation than the former. For both bituminous mixtures, the stability values remain above the minimum value of 1000 kgf set by the specifications. The water resistance test carried out on the two bituminous concretes based on basalt aggregate and quartzite aggregate gives values of immersion/compression ratio (R’c/Rc) equal to 0.72 and 0.82 respectively. These values are above the minimum required value (0.70) in the technical specifications in Senegal.

Experimental Study of the Evolution of Temperatures in Pavement Structures and Influence of Traffic on the RN1 in Burkina Faso in a Hot and Dry Climate

Asphalt concrete pavements in hot and dry climates deteriorate prematurely some time after their construction. This degradation is accelerated under the effect of heavy vehicle traffic pressure and high temperatures after the bitumen has softened. A study was conducted on the RN1 in Burkina Faso in order to analyze the evolution of temperature and traffic in the process of degradation of asphalt concrete pavements. It consisted on the one hand in recording the temperatures at different points inside the layers of asphalt concrete pavements and the layer of laterite. These results were compared with the values of the softening temperatures of the bitumen obtained in the laboratory. On the other hand, this study is supplemented by the daily counting of heavy goods vehicles passing through the RN1 during the month of April in order to study the influence of the evolution of heavy goods vehicle traffic on the degradation of pavements in hot and dry climatic conditions. The results obtained for temperatures and the frequency of heavy goods vehicle traffic favor pavement deterioration under certain conditions.