High Water Retention Agent Construction Grade HPMC Used in Drymix MortarJune 7th 2023
The importance function of HPMC in wet mix mortar mainly has the following 3 aspects:
1. HPMC has excellent water retention capacity.
2. The effect of HPMC on the consistency and thixotropy of wet-mixed mortar.
3. Interaction of HPMC with cement.
Water retention is an important property of HPMC, and it is also a property that many wet-mix mortar manufacturers are concerned about.
The water retention effect of HPMC depends on the water absorption of the base layer, the composition of the mortar, the layer thickness of the mortar, the water demand of the mortar, and the setting time of the coagulating material.
HPMC – water retention
The higher the gel temperature of HPMC, the better the water retention.
Factors that affect the water retention of wet-mix mortar include HPMC viscosity, addition amount, particle fineness and service temperature.
Viscosity is an important parameter for HPMC performance. For the same product, the viscosity results measured by different methods are very different, and some even double the difference. Therefore, when comparing viscosity, it is necessary to perform between the same test methods, including temperature, rotor, etc. Generally speaking, the higher the viscosity, the better the water retention effect.
However, the higher the viscosity and the higher the molecular weight of HPMC, the corresponding reduction in its solubility, which has a negative impact on the strength and construction properties of the mortar. The higher the viscosity, the more obvious the thickening effect of the mortar, but it is not proportional. The higher the viscosity, the more sticky the wet mortar will be, and it will show stickiness to the scraper and high adhesion to the substrate during construction. But, HPMC has little effect on the increase of the structural strength of the wet mortar itself, which shows that the anti-sagging performance is not obvious. On the contrary, some modified HPMC with low to medium viscosity have excellent performance in improving the structural strength of wet mortar.
The fineness of HPMC also has a certain influence on its water retention. Generally speaking, for HPMC with the same viscosity but different fineness, in the case of the same addition amount, the finer the water retention effect is better.