Influence of the processing temperature on the compressive strength of Na activated lateritic soil for building applications

• Alkali activation of lateritic soils can give rise to eco-friendly building materials.
• Specimens processed at 60–105 °C for 7 days and 250 °C for 3 h gave similar strengths.
• Rising processing temperature from 250 to 450 °C led to strength improvement of 45–65%.
• Iron in the soil is likely not to affect strength development during alkali activation.

The present study investigates the suitability of alkali activation of a lateritic soil for building applications. Lateritic soil was found to contain kaolinite, associated with quartz and hematite minerals. Both the processing temperatures and the amount of NaOH used were found to influence the development of compressive strength which was in the range of 12–51 MPa and 2–23 MPa respectively for dry and wet specimens. The synthesized products were thermally more stable, containing crystalline and amorphous phases mainly resulting from the dissolution of kaolinite. The XRD, FTIR, SEM and TG/DTA analyses showed an incomplete dissolution of the starting minerals.