Response surface methodology application in the optimization of the effect of argan nut shell waste on lightweight brick properties

The production of lightweight materials based on the addition of organic waste has gained attention of several researchers in order to produce bricks with superior properties. Despite the different advantages of incorporating this type of waste in brick's matrix, optimizing the material's performance remains crucial to achieve brick's with excellent characteristics. The present study focused on optimizing brick properties incorporating 5 wt.% of argan nut shell in their matrix, in order to produce eco-friendly lightweight bricks. A response surface methodology was employed to investigate the effects of three independent variables: firing temperature (800-1000 degrees C), heating rate (2-4 degrees C/min), and firing duration (2-8 h). Seventeen specimens were prepared and tested in terms of loss on ignition, linear shrinkage, water absorption, apparent porosity, bulk density, flexural and compressive strength. Statistical analysis confirmed the significance of the models, and a desirability function identified the optimal firing conditions as a temperature of 801.98 degrees C, a heating rate of 2.02 degrees C/min and a firing duration of 2 h 15 min. Under these conditions, a reduction in bulk density of approximately 38.40 kg/m3 was achieved, contributing to the production of improved lightweight bricks with good properties.