The Effect of VAE Redispersible Polymer Powder Dosage on Putty Adhesive Strength and Waterproofing

The Effect of  VAE Redispersible Polymer Powder dosage on Putty Adhesive Strength and Waterproofing Resistance

VAEP, as a main adhesive of putty, its dosage has significant influence on adhesive. Picture 1 showing the relationships between VAEP and Adhesive Strength. 

From the P1, it shows adhesive strength increasing with the VAEP dosage added more. 

When less dosage of redispersble polymer powder, adhesive strength increase obviously , with the VAEP dosage added more. When the dosage is 2%, the adhesive strength will reach to 0182MPa, meeting the 0160MPa of country standard requirement. 

When the dosage is 4%, the adhesive strength increasing trend gets slowly. Of course, the effect facts on adhesive, not only VAEP，but also the cement, coarse whiting and other inorganic material. So the adhesive strength change shows a linear rule with the dosage increasing. 

The water resistance and alkaline resistance are important test index to as a interior and exterior wall putty. See the Picture 2 , it shows the effect of VAEP Powder contect on the water resistance of the putty

From the Picture 2 , we can see , when the dosage is lowder than 4%, water absorption of the putty declined obviously with the VAEP dosage increasing. When more than 4%, the water absorption of the putty declined slowly. The reason is cement, as the substance, when no VAEP powders added, there are much gap in the system; when add some VAEP Powders, the powder re-disperse to form a vae emulation , then form film in the putty gaps, filling the gaps in the putty system. And then making compacter films after coating and shaving putty. As a result , prevent the water from penetrating , reducing the water absorption, increasing the water resistance. When the dosage is to 4% , VAEP re-disperse to form emulation, fully fill the gaps in putty system, forming full and compact film, to make the water absorption decline slowly with the VAEP dosage increasing. 

Picture 2 , the SEM graph of the putty. 

Compared the two SMP pictures, in P3a , the inorganic material is bonded incompletely, with many big or small gaps, so the adhesive strength is not good.  In the system , it’s easy to bring the water into the gaps, increasing the water absorption. In P3b , the vae emulation fills into the gaps, forming full flim. In the putty system , the inorganic material is bonded well, and less gap, then reduce the water absorption of the putty. 

Making a conclusion , the VAEP dosage is about 3%-4% , it’s good for the effect of VAEP powder on the adhesive strength and water resistance.