Use of Plastic Waste and Lateritic Gravel in Bitumen Macadam Mix Design

The performance study of the bitumen macadam mix design with lateritic gravel made it possible to propose their use as a substitute for basalt aggregate in infrastructure projects in the interior of the country. Adding plastic waste to the bitumen made it possible to produce a modified binder of class 20-30 [1]. The Marshall tests, the Duriez test and the diametral compression allowed us to characterize the mechanical performances of three types of formulations F1, F2, and F3. The best performances are obtained with the addition of 15 % of plastic waste in the bitumen 50/70 (L3 binder) and at optimal binder contents between 6.0 and 6.5 %. The binder L3 used has the following results: the penetration is equal to 27mm (class 20-30), the softening point 50oC (standard value between 46-56◦C) and a very good adhesivity rating of Riedel and Weber 5-10 [1]. Formula F1 with a granular composition of 0/20 lateritic gravel has good Marshall stability 1320kg at the optimal content of L3 binder of 6.0 %, a minimum of 9000MPa for the modulus is obtained at the same content. The percentage of voids equal to 8.5 % is well within the 7-9 % range. This product meets the specifications of the bitumen macadam BM4. The F2 formula which uses crushed basalt sand and 5/20 lateritic gravel has better performance than F1. The module goes from 9000MPa to 9300MPa, the percentage of voids decreases to the median value of the envelope 7-9 and the stability increases to 1450kg. These characteristics correspond to those of the bitumen macadam BM2. The F3 formula is very similar to the bitumen macadam of class BM3. The r / R ratio is greater than 0.7, the grading is 0/14. It is much denser and has strong resistance to rutting. The minimum thickness becomes thinner and thinner, decreasing from 14cm to 8cm.