Influence of re-dispersible powder on the properties of mortars

This paper presents an experimental study on the effect of a re-dispersible powder on the properties of cement mortars in both fresh and hardened state. The effects of varying contents of re-dispersible powder on the adhesive properties and rheological behavior of mortar in fresh state and on the flexural strength of mortar in hardened state have been investigated. To determine the adhesive properties the probe tack test was used. The tack test results have been exploited to identify the adhesion strength, the cohesion strength and the support’ adherence force. The rheological behavior of the mortars was also considered. It is found that the influence of re-dispersible powder on the properties of fresh mortar is quite small. Re-dispersible powder seems to have only indirect and minor effects on the fresh properties through increase of air content. The flexural strength of mortar is determined by three-point bending test at the age of 2, 7, 14 and 28 days. The results indicate that re-dispersible powder decreases the flexural strength of mortar at early-age. However, it improves the flexural strength of hardened mortar, at which the polymer film has fully formed and spans all the materials.