Experimental study on dynamic and static structure establishment and recovery rate of fresh cement paste by composite thickening agents

Abstract

The rheological and thixotropic properties, as well as the establishment of dynamic and static structures effectively reflect the workability of the cement paste. In order to investigate the effects of organic and inorganic composite thickening agents on fresh cement paste, the rheological curves, structural recovery rate, storage modulus G′ and loss modulus G″ of cement pastes mixed with limestone powder (LP), re-dispersible polymer powder (RPP) and hydroxypropyl methyl cellulose ether (HPMC) were tested by Anton Paar MCR 102 rotary rheometer. The results showed that LP and RPP reduced the yield stress and enhanced workability, and LP also improved the establishment of static structures. The incorporation of HPMC facilitated the recovery rate of static structure, and obviously improved the deformation resistance of the cement paste by reducing the difference between the G′ and the G″. However, a single thickening agent was hard to balance the rheological parameters of the pastes. While the combination of LP, RPP and HPMC could improve the rate of structure establishment and recovery, and increase the deformation resistance as well as the stability of the paste. The dense filling effect of LP, the film-forming and bridging effect of RPP, and the winding and water retention effects of HPMC together made up the synergistic effect to further improve the stability of the pastes.