To be more specific, It is better to see the purpose of material for building. In case of low cost building material, I would recommend you, clay brick material with appropriate stabilization.Some stabilization may not need fired in clay brick, therefore very important in energy conservation.
Cement stabilized clay brick is a good topic for research. I have produced in a real project cement stabilized marine clay bricks (brand name: marine mud made material, MMMM) for paving and non-structural wall constructions. You may need to add some superplasticizer to disperse the clay particles during mixing.