Contribution à l'étude des caractéristiques physico-mécanique des mortiers de sable de dune avec ajouts

Abstract

This thesis focuses on the valorization and recycling of three materials entirely abandoned in Algeria for the production of new ecological mortars (dune sand, recycled sand and PET plastic fiber). Today, economic and environmental considerations havebecome imperative in construction projects. In this regard, the use of substitute materials for natural aggregates or cementcontributes to thepreservationof natural resources and the reduction ofcarbon dioxide emissions. The strategy involves the gradual substitutionofdunesandwith another sourced from demolitionwasteatdifferentproportions: 0,25,50,75, and100%, combined with a gradual rate of PET fiber (20-and-30mm) of length varying from 0-to-2%, with an interval-of-0.5%. The impact of these new compositesonthephysico-mechanical performanceof thedesignedmortars was examined through various tests, including spread, fresh-density, occluded air at the freshstate (Ac), porosity, capillaryand immersionabsorption, shrinkage (Sh), ultrasonic pulse velocity (UPV), compression strength, flexural strength, and flexural displacement (Yf). Additionally, a predictive approach using the ResponseSurfaceMethodology (RSM) was applied to optimize the parameters influencing the propertiesof thenewcementitiouscomposites.

The obtained results demonstrate significant interest in the composite mixture consisting of 50% dune sand (DS), 50% recycled sand (RS), and 0.5% PET fibers with a length of 30 mm. This mixture resulted in measured performances of 2.231% occluded air (Ac), 21.426% porosity, -22.76 µm/m linear shrinkage (Sh), 3.372 mm flexural displacement (Yf), 3606.74 m/s ultrasonicpulsevelocity (UPV), and 12.046% waterabsorption (WA), as well as 43.398 MPa compression strength (Rc) and 7.723 MPa flexural strength (Rf). Furthermore, the Response Surface Model (RSM) shows a satisfactory correlation with experimental data, indicating a notable improvement in the physico-mechanical propertiesof the studied eco-mortar. Itis noteworthy thatthe proposed model appears relevant, withahighdesirabilitycoefficientof 0,90.