Research on the Thermal Conductivity and Water Resistance of Foamed Phosphogypsum

Phosphogypsum is a kind of solid waste which pollutes the environment without reasonable treatment. The application of phosphogypsum in the field of building materials provides an ideal method to solve this problem. Meanwhile, the phosphogypsum mixed with foam can be used for the thermal insulation of wall materials. This paper aims to study the influence of foam volume and cement content on the thermal conductivity, water resistance coefficient and the mechanical strengths of foamed phosphogypsum. The volume of foam in this study ranged from 0% to 60%. Moreover, the influences of humidity and cement content on the mechanical strengths of phosphogypsum are investigated. Scanning electron microscope and the mercury intrusion porosimetry are used for the microscale research and analysis. Results indicate that the relationships between the parameters (thermal conductivity, water resistance coefficient and mechanical strengths) and foam volume fit well with a negatively correlated linear function. The addition of cement can improve the compactness of phosphogypsum and decrease the diameter and volume of pores. Therefore, the thermal conductivity, water resistance coefficient and mechanical strengths of phosphogypsum are increased by the addition of cement.