Structural efficiency of burnt clay bricks containing waste crushed glass and polypropylene granules

The need for alternative building materials and the call for a cleaner environment has led to the recycling of waste materials in the construction industry. This study investigated the use of crushed glass and polypropylene (plastic) granules in two sets of fired clay bricks. These wastes were added to bricks at 1, 2, 3, 4, and 5% proportions, the bricks were fired to 800 °C in an electric operated kiln for about four hours. The glass infused bricks were designated as T1, T2, T3, T4, and T5, while that of plastics were designated as P1, P2, P3, P4 and P5 respectively. The control burnt brick is without any waste. Water Absorption, Shrinkage, mechanical strength tests were carried out on each brick. Scanning Electron Microscopy (SEM) was used to investigate the microstructural characteristics of each brick. The mechanical test result showed that the control has a value of 6.15 N/mm2, which is above the 3.5 N/mm2 recommended for clay bricks by standards. The highest value for bricks containing glass was from sample T5 at 11.02 N/mm2, while that of the sample containing plastic was P1 at 4.02 N/mm2. All the bricks have a water absorption rate less than the recommended 18 %. The SEM result revealed micro-cracks and voids that aided the structural efficiency of each brick types. The study concluded that glass can be added to burnt bricks at 5% replacement, while plastic waste should not exceed 3% in burnt bricks.