Stabilization of Compressed Earth Blocks (CEB) by Pozzolana Based Phosphate Geopolymer: Physico-Mechanical, Structural and Microstructural Investigations

This work proposes the poly(phospho-ferro-siloxo) binder resulting from the phosphoric acid activation of pozzolana (PZ) as a friendly stabilizing agent for compressed earth bricks (CEBs). Different proportions of pozzolana were incorporated into the clay soil (5, 10, 15 and 20 wt%). The CEBs were cured at room temperature and at 70 °C. Powder X-ray diffraction (PXRD), Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) spectroscopy, water absorption as well as mechanical strength tests were used to characterize the 28 days aged CEBs. The compressive strength of CEBs varies from 9.2 to 20.6 MPa and 10.2 to 42.8 MPa at room temperature and 70 °C, respectively. Water absorption ranges from 6 to 11% at 25 °C and 8 to 12% at 70 °C. This work showed that ground pozzolana can be used similarly as calcined laterites and clays for efficient geopolymerization stabilization of compressed earth bricks.