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. During construction. It will stick to the scraper and have high adhesion to the substrate. But it does little to increase the structural strength of the wet mortar itself. That is, during construction, the performance of 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 water retention of HPMC is also related to the temperature used, and the water retention of HPMC decreases with the increase of temperature. However, in practical material applications, dry powder mortar is often applied to hot substrates at high temperatures (higher than 40 degrees) in many environments. Such as exterior wall putty plastering under the sun in summer, which often accelerates Curing of cement and hardening of dry mortar. The drop in water retention has led to a clear perception that both workability and crack resistance are affected. And it is particularly critical to reduce the effect of temperature factors under such conditions.
In this regard, HPMC additives are currently considered to be at the forefront of technological development. Although the amount of HPMC is increased (summer formula), the workability and crack resistance still cannot meet the needs of use. Through some special treatments, such as increasing the degree of etherification. MC can keep its water retention effect better at higher temperatures, so that it can provide better performance under harsh conditions.
The dosage of HPMC should not be too high. If it is too high, the water demand of the mortar will increase, the trowel will stick, and the setting time will be too long, which will affect the workability. Different mortar products use HPMC with different viscosity, do not use HPMC with high viscosity casually. Therefore, although the hydroxypropyl methylcellulose product is good, it is only applauded when it is used well. Choosing the right HPMC is the primary responsibility of the laboratory personnel of the enterprise. At present, there are many unscrupulous distributors compounding HPMC, and the quality is quite poor. When choosing a certain cellulose, the laboratory should conduct experiments to ensure the stability of the mortar product. And not to be cheap and cause unnecessary losses.
HPMC ltd—Hebei Landcel Cellulose Tech Co., Ltd.