Comparing the performances of bricks made with natural clay and clay activated by calcination and addition of sodium silicate

The mix between 4M to 12M NaOH solution and aluminosilicate material forms a thick paste that can be compacted in a mold in order to manufacture bricks at relatively low temperatures (<100°C). Starting materials available in Senegal consist of soils that primarily contain kaolin. In this study, we compare the performance of clay from the Niemenike deposit and clay pre-treated at 700°C. The performance of the two clays depends on the temperature of curing and on the time of curing. In long-term tests (1week to 3months), for bricks kept at 40°C/60% RH, strength did not increase with time for both clays (natural and calcined) activated with sodium hydroxide but this depends on the NaOH concentration. The maximum strength is obtained after 14days for all concentrations. For all concentrations and periods, strength obtained with natural clay is greater.