The effect of cellulose (hpmc) on the water retention capacity of cement and gypsum

HPMC is one of our best-selling products, offering high quality at a low price. It can be used as a thickener and water-retaining agent in building mortar and putty. Shijiazhuang Cellulose Co., Ltd., a cellulose manufacturer from China, can provide you with ample supply.

The selection of cementitious materials, aggregates, aggregates, water-retaining agents, binders, and workability modifiers is crucial. For example, gypsum-based mortar exhibits better bonding performance than cement-based mortar in a dry state, but its binder performance rapidly declines under moisture-absorbing conditions. The target bond strength of plastering mortar should decrease layer by layer, i.e., the bond strength between the base layer and the interface treatment agent ≥ the bond strength between the base mortar and the interface treatment agent ≥ the bond strength between the base mortar and the top layer mortar ≥ the bond strength between the top layer mortar and the putty material.

The ideal hydration target for cement mortar on the base layer is that the cement hydration products, along with the base layer's absorption of water, penetrate into the base layer, forming an effective "key bond" with it, thereby achieving the required bond strength. Directly pouring water onto the base layer surface will result in significant variations in water absorption due to differences in temperature, watering time, and watering uniformity. If the substrate has low water absorption, it will continue to absorb water from the mortar. Before cement hydration can proceed, this water is absorbed, affecting cement hydration and the penetration of hydration products into the substrate. Conversely, if the substrate has high water absorption, the migration of water from the mortar to the substrate is slow, and a water-rich layer may even form between the mortar and the substrate, similarly affecting bond strength. Therefore, common methods of watering the substrate not only fail to effectively solve the problem of high water absorption in the wall substrate but also negatively impact the bond strength between the mortar and the substrate, causing hollow areas and cracking.

The effect of cellulose ether on the compressive and shear strength of cement mortar.

With the addition of cellulose ether, compressive and shear strength decrease because cellulose ether absorbs water, increasing porosity.

Bond performance: The level of bond strength depends on whether the interface between the mortar and the substrate can achieve a stable and effective "key bond" over a long period.

Factors affecting bond strength include:

1. The water absorption characteristics and roughness of the substrate interface.

2. The water retention capacity, permeability, and structural strength of the mortar.

3. Construction tools, methods, and environment. Because the substrate for mortar application has a certain degree of water absorption, the substrate absorbs moisture from the mortar, which worsens the mortar's workability. In severe cases, it can prevent the cementitious materials in the mortar from fully hydrating, leading to reduced strength, especially at the interface between the hardened mortar and the substrate, causing cracking and spalling. The traditional solution to these problems is to pour water onto the substrate, but this cannot guarantee that the substrate will be evenly and appropriately moistened.