TITLE:
Prediction of Physic-Mechanical Properties of Geopolymers Based on Recycled Thermoplastic Materials for Stabilizing Buildings: Case of Mara and Toukra Sites of N’Djamena
AUTHORS:
Innocent Allahdoumbaye, Pagore Frédéric Djoda, Pagna Bertin Kagonbé, Gomdje Valery Hambaté, Raïdandi Danwé
KEYWORDS:
Stabilization, Earth Bricks, Thermoplastic, Microstructure, Physic-Mechanical Behavior
JOURNAL NAME:
Materials Sciences and Applications,
Vol.16 No.6,
June
11,
2025
ABSTRACT: Early settlement collapses led us to stabilize earth bricks in the Mara region and make predictions in Toukra. This work demonstrates the improvement in the mechanical properties of earth bricks combined with recycled polypropylene and polyethylene thermoplastics. This is due to the compatibility between the clay layers and the molecular chains derived from these polymers. Indeed, the investigations carried out on the materials of the two Mara sites first focused on geochemistry, which showed the presence of silica oxides SiO2 (59.11% - 63.28%), aluminum Al2O3 (12.62% - 12.78%) and iron Fe2O3 (6.12% - 6.97%) as major elements. Alkaline and alkaline earth elements such as potassium K2O (3.06% - 3.15%), titanium TiO2 (0.98% - 1.15%), sodium Na2O (1.02% - 1.13%), calcium CaO (1.01% - 2.13%), magnesium MgO (0.58% - 1.13%) then appear in small quantities. These oxides come from quartz, kaolinite, feldspar, illite and many other constituents of the ore confirmed by DRX, ATR FTIR and ATG/DTA. The vibrational movements observed with the presence of polypropylenes and polyethylene’s favored the physicochemical interactions with the mineral oxides. The rheological character of this polymer matrix made it possible to plug the micropores of the clay sheets by acting in a compatible manner with the oxides present. All these samples lose very little mass, 21.12% on average according to the TGA. They have an energy conservation capacity and degrade around 498˚C. All of these microstructural analyses allowed us to predict good water absorption behavior and good mechanical performance. Some formulations provided less than 2% water absorption in 10 days of immersion. Compressive strength ranges from 12.28 to 17.35 MPa at Mara and from 10.22 to 14.22 MPa at the Toukra site. This could be generalized to other areas sharing the risk of early collapse.