Advantages of Hydroxypropyl Methylcellulose As A Mortar Additive-HPMC

HPMC is an important product of Shijiazhuang Cellulose Co., Ltd.  This product serves as a thickening and water-retaining agent for cement in construction, ensuring excellent construction results. HPMC powder is highly popular worldwide.

When discussing mortar admixtures, it's essential to first understand the function and performance of ordinary mortar, as this serves as the basis for selecting mortar admixtures. Hydroxypropyl methylcellulose (HPMC)is a prime example of such an admixture.

The commercialization of mortar is primarily a market reform implemented by the government for environmental protection and quality control.  Traditional mortar mixing, often done with dry powder, generates significant dust pollution.  Another concern is ensuring consistent construction quality. Previously, ordinary mortar was mostly mixed mortar, containing cement, sand, and a significant amount of lime paste. Lime paste primarily served three functions: water retention, improved workability, and providing mortar strength while reducing shrinkage stress caused by cement hardening through expansion during setting. Therefore, many lime slaking pits were commonly seen on construction sites.  However, limestone production is energy-intensive and highly polluting, leading the government to gradually phase out the use of lime paste.

Consequently, modern commercial mortar admixtures aim to replace the functions of lime paste.  Therefore, water retention, improved workability, and reduced cement drying shrinkage stress have become the selection criteria for mortar additives. Hydroxypropyl methylcellulose has played a significant role in the building materials industry in recent years, leading to the development of many new types of mortar. Furthermore, hydroxypropyl methylcellulose is environmentally friendly and is considered an eco-friendly mortar admixture.

Currently, the main additives for mortar include the following:

1. Thickening Powder: Thickening powder was originally a mortar modifier developed by the Shanghai Institute of Building Science.  While its performance is generally good, the high transportation cost relative to its low unit price makes nationwide promotion difficult. Furthermore, the thickening powders currently available throughout the country are not true thickening powders in the strict sense.

2. Mortar King: Mortar King is actually a type of air-entraining agent with sodium dodecyl sulfate as its main component. It only provides air-entraining function in mortar. It is far from being a true substitute for lime paste, and it is detrimental to project quality. Air entrainment inevitably leads to a decrease in mortar strength, and the lack of water retention makes phenomena such as shrinkage cracking more common.

3. Bentonite: Regardless of the type of bentonite, its water retention and workability improvement are excellent. However, its fatal weakness is its large drying shrinkage, which is a deformation in the same direction as cement drying shrinkage, reinforcing each other and making cracking more likely.

4. Hydroxypropyl Methylcellulose (HPMC): Hydroxypropyl methylcellulose has absolute advantages in both water retention and workability improvement. It can effectively reduce mortar shrinkage and cracking, and improve mortar yield. Hydroxypropyl methylcellulose has air-entraining properties, so when adding it, the dosage, viscosity, and air-entraining properties should be considered.

Hydroxypropyl methylcellulose has many advantages and a large development potential in the building materials market.