Title: Development of Low Cost Housing Materials Based on Phosphogypsum and Calcium Sulfoaluminate Cement
Author(s): J. Ambroise, C. Angulski da Luz, and J. Pera
Publication: Symposium Paper
Appears on pages(s): 125-136
Keywords: building materials; calcium sulfoaluminate cement; ettringite; hydration; phosphogypsum; water-resistance
Gypsum is a cheap binder but its utilization remains limited due to its bad water resistance. The solutions usually proposed to improve this water resistance consist in adding water repelling agents like organo-polysiloxanes to the mixing water. This paper shows that another solution is to mix calcium sulfoaluminate clinker and gypsum. When hydrating, such mixture becomes water-resistant and gypsum is converted into hydraulic binder. Therefore, it is possible to develop low cost housing materials, mainly based on gypsum. The experimental results show that the quantity of calcium sulfoaluminate clinker necessary to stabilize gypsum is in the range of 20 to 30% of the total amount of binder (phosphogypsum + calcium sulfoaluminate cement). In such case, resistance to wetting-drying cycles is very good. Building materials like concrete blocks, renders, and screeds were developed and behaved very well under natural weathering for more than 18 months. This can be a solution to valorize large amounts of gypsum by-products and develop low cost housing materials.