Effect of phosphogypsum and water-retaining in the stabilization and durability of stabilized mortars

Abstract

This work corresponds to a study on using a cellulose-based water-retaining agent, hydroxypropyl methylcellulose (HPMC), in phosphogypsum (PG)-stabilized mortars. The results in cementitious pastes showed that when PG replaced cement, there was a reduction in the fluidity of the mixture (by 64.32%) and a drastic increase in the flow stress (from 1.8 to 614.0 Pa) due to its greater need for water, proving to be porous. However, when PG was combined with the hydration stabilizing admixture (HSA) and HPMC, greater fluidity, lower yield stress, and lower viscosity were obtained. In addition, PG contributed to the delay in setting times. In the stabilized mortars, the use of HPMC ceased the phenomenon of water exudation, and the additions of 0.15 and 0.20% provided the highest compressive strengths to the 48 h mortars (±5.28 and 5.28 MPa, respectively). On the other hand, the increase in HSA content to 1.2% at 72 h stabilization caused losses in mechanical performance and modulus of elasticity. Still, when comparing the compressive strength of the 48 h mortar with PG vs mortar with cement, there is a 71.13% increase in strength.