Study on rheological properties of Mg(OH)₂ modified fire prevention paste

In order to explore the influence of flame retardant magnesium hydroxide (Mg(OH)₂) on the rheological properties of the fire-fighting agent of modified fly ash paste, the rheological parameters such as apparent viscosity, yield stress, slump, expansion and bleeding rate of modified fly ash paste of various proportions were measured by viscosity meter and collapse barrel. The results show that with the increase of Mg(OH)₂ mass fraction (from 1% to 5%), the particle mass fraction in the paste system increase, and the apparent viscosity and yield stress of the paste increase significantly; Mg(OH)₂ can absorb more free water, resulting in the slump, expansion and bleeding rate of the paste are correspondingly reduce, the paste does not easily lose moisture and precipitates, cracks, etc.; when the mass fraction of fly ash is from 60% to 65% and the mass fraction of Mg(OH)₂ is less than 3%, the rheological properties of fire-fighting paste can be guaranteed, enhancing the water retention property and reducing agglomeration and flocculation of particles, and make it difficult to isolate and precipitate; when the mass fraction of Mg(OH)₂ is greater than 4%, the paste bleeding rate is less than the specified value of 1.5%, which makes it lose the paste characteristics.