What are the methods of cellulose ether as dry mortar additive ?

One of the biggest differences between dry mortar and traditional mortar is that the dry mortar is modified with a small amount of chemical additives. Adding one kind of additive to dry mortar is called primary modification, adding two or more additives is secondary modification. The quality of dry mortar depends on the correct selection of components and the coordination and matching of various components. The chemical additives are expensive and have great influence on the properties of dry mortar. Therefore, in the selection of additives, the amount of additives should be in the first place. The following is a brief introduction to the selection of chemical additives cellulose ether.

Cellulose ether also known as rheological modifier a kind of admixture used to adjust the rheological properties of new mixed mortar, almost used in every kind of mortar. The following properties should be taken into account when selecting the variety and the amount added:

(1) Water retention at different temperatures;

(2) thickening, viscosity;

(3) The relationship between consistency and temperature, and the influence on consistency in the presence of electrolyte;

(4) the form and degree of etherification;

(5) the improvement of the thixotropy and positioning ability of mortar (which is necessary for mortar coated on vertical surface);

(6) Dissolution rate, condition and dissolution completeness.

In addition to adding cellulose ether in dry mortar (such as methyl cellulose ether), can also add vinyl polyvinyl acid ester, that is, secondary modification. The inorganic binder in mortar (cement, gypsum) can guarantee high compressive strength, but has little effect on tensile strength and bending strength. Vinyl polyvinyl ester builds elastic film in cement stone hole, make mortar can bear high deformation load, improve wear resistance. It has been proved by practice that by adding different amounts of methyl cellulose ether and vinyl polyvinyl ester into dry mortar, thin layer coating plate bonding mortar, plastering mortar, decorative plastering mortar, aerated concrete block masonry mortar and self-leveling mortar of pouring floor can be prepared. Mixing the two can not only improve the quality of mortar, but also greatly improve the construction efficiency.

In practical application, in order to improve the comprehensive performance, it is necessary to use multiple admixtures. The best match between the additive proportion, the right dosage range, proportion, can from different aspects have certain effect to improve the performance of mortar, but its modification effects of the mortar when used alone is limited, sometimes even have a negative effect, such as single doped fiber, in increase the adhesiveness of mortar, reduce the degree of stratification at the same time, However, the water consumption of mortar is greatly increased and stored in the slurry, which leads to the decrease of compressive strength. When the air entraining agent is added, the mortar delamination degree and water consumption can be greatly reduced, but the compressive strength of mortar will decrease due to more bubbles. Improve masonry mortar for maximum performance, while avoiding harm to the other property, the strength of masonry mortar consistency, degree of stratification and meet the engineering requirements and the regulations on technical specification, at the same time, do not use lime putty, saving cement, environmental protection, etc., from the water reduction, viscosity, water thickening and air-entraining plasticizing perspective, It is necessary to take comprehensive measures to develop and use compound admixtures.

Post time: Apr-29-2022