Self-leveling mortar has become one of the most widely used materials in modern flooring systems due to its excellent flow ability and automatic leveling performance. It is commonly applied in industrial plants, commercial spaces, parking areas, and residential floor leveling. However, in real-world projects, even high-quality materials often fail to deliver expected results, leading to issues such as cracking, dusting, and delamination. The root cause is rarely the material itself, but rather improper control of the construction process. Self-leveling is not a simple “pour and go” solution—it is a highly sensitive system that depends on substrate conditions, environmental control, accurate mixing, and precise application.
From a material perspective, self-leveling mortar is composed of cement or gypsum binders, fine aggregates, fillers, and various functional additives. It can be categorized into cement-based and gypsum-based systems. Cement-based products comply with JC/T 985-2017 and are suitable for a wide range of environments, while gypsum-based systems are typically used in dry indoor conditions. Regardless of the type, performance is highly dependent on proper execution during application.
The standard construction process includes site sealing, substrate inspection, surface preparation, primer application, mixing, pouring, deaeration, curing, and protection. The job site must be sealed to prevent airflow and cross-interference. The substrate must be thoroughly inspected for strength, flatness, moisture content, and surface integrity. A qualified substrate should have a compressive strength of at least C20, moisture content below 6%, flatness within 4 mm over 2 meters, and be free from dust, oil, and loose particles.
Substrate preparation is the most critical step in the entire process. Mechanical methods such as grinding, shot blasting, or milling must be used to remove contaminants and weak layers. Cracks and hollow areas must be properly repaired before proceeding. Many failures originate at this stage due to insufficient preparation. After treatment, a primer must be applied evenly to enhance bonding strength and reduce substrate absorption. Typically, one to two coats are required, ensuring full coverage without pooling, and the next step can only proceed after complete film formation.
During mixing, water ratio control is essential. Self-leveling mortar is extremely sensitive to water content, and the mixing ratio must strictly follow the manufacturer’s instructions, for example, a typical ratio of powder to water is 1:0.22. Excess water leads to bleeding, reduced strength, and dusting, while insufficient water results in poor flowability. Mechanical mixing is recommended, typically for 3 to 5 minutes until a homogeneous, lump-free mixture is achieved, followed by a resting period for defoaming and a brief remix before application.
Pouring must be continuous, with the material spread evenly using a notched rake, followed by spike roller treatment within the specified time to remove air bubbles and enhance flow. The application thickness is generally not less than 10 mm, while gypsum-based systems require layered application. Any interruption during pouring can result in joints or poor leveling performance.
After application, proper curing is essential. The floor should be maintained in a stable environment for at least 24 hours, avoiding airflow, direct sunlight, and temperature fluctuations. Under normal conditions (around 20°C), the surface can be walked on after 2 to 4 hours, and further finishing can proceed after 48 hours. Finally, proper protection must be implemented to prevent contamination, mechanical damage, or premature loading, ensuring long-term durability and performance.
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