Self-leveling cement/mortar (Self-Leveling Cement/Screed) is a highly fluid cement-based building material that can form a smooth surface by self-flowing and self-leveling during the construction process. Due to its excellent leveling performance and ease of construction, self-leveling cement/mortar is widely used in ground repair and decoration projects. It is widely used in various ground constructions, such as floors of residential, commercial and industrial buildings. The complexity and technical requirements of its formula are high. The following is a detailed analysis of the self-leveling cement/mortar formula.

1. Composition of self-leveling cement/mortar
The basic composition of self-leveling cement/mortar includes: cement, fine aggregate (such as quartz sand), admixtures, water and chemically modified materials. The key lies in the use and proportion adjustment of admixtures. The following will be a detailed analysis of each component:

Cement
Cement is the main bonding material of self-leveling cement/mortar. The commonly used type of cement is ordinary Portland cement, which provides strength for the mortar. However, in order to achieve good fluidity and self-leveling properties, the selection of cement will be adjusted according to actual needs. In some formulations, special cements such as white cement or ultrafine cement are also used to obtain better fluidity and surface smoothness.

Fine aggregate (quartz sand)
The particle size and distribution of fine aggregate have an important influence on the construction performance of self-leveling cement. Quartz sand is usually the main aggregate of self-leveling mortar, and its particle size is generally between 0.1mm and 0.3mm. Fine aggregate not only provides the stability of self-leveling cement, but also determines its surface finish. The finer the aggregate particles, the better the fluidity, but its strength may decrease. Therefore, the relationship between fluidity and strength needs to be balanced during the proportioning process.

Admixtures (modified materials)
Admixtures are one of the key components of self-leveling cement/mortar. They are mainly used to improve fluidity, extend construction time, improve crack resistance and enhance adhesion. Common admixtures include water reducers, plasticizers, tougheners, antifreeze agents, etc.

Water reducer: It can effectively reduce the water-cement ratio, improve fluidity, and make cement paste easier to flow and spread.
Plasticizer: Improve the adhesion and crack resistance of mortar, and improve its ductility during construction.
Leveling agent: Adding a small amount of leveling agent helps to adjust the surface flatness of the mortar, so that it can self-level.
Water
The amount of water added is the key to determining the construction performance of self-leveling cement/mortar. The hydration reaction of cement requires an appropriate amount of water, but too much water will affect the strength and durability of the mortar. The ratio of water to cement is usually controlled between 0.3 and 0.45, which can ensure that the mortar has both appropriate fluidity and its final strength.

2. Ratio and preparation of self-leveling cement/mortar
The ratio of self-leveling cement/mortar needs to be adjusted according to the use environment, functional requirements and construction conditions. Common proportioning methods include weight ratio, volume ratio and cement: aggregate ratio. During the preparation process, accurate proportioning is the basis for ensuring that the mortar performance meets expectations.

Cement: Sand Ratio
In traditional mortar, the ratio of cement to sand is about 1:3 or 1:4, but the ratio of self-leveling cement/mortar often needs to be optimized. A higher cement content helps to enhance strength and fluidity, while too much sand will lead to reduced fluidity. Therefore, a moderate cement: sand ratio is usually selected to ensure that the mortar can meet the requirements of fluidity and thickness during construction.

Ratio of admixtures
The amount of admixture added is crucial to the final performance of the mortar. Water reducers are usually added at 0.5% to 1.5% (based on cement mass), while plasticizers and leveling agents are added according to specific circumstances, with a common addition of 0.3% to 1%. Too much admixture may lead to instability of the mortar composition, so its use should be strictly controlled.

Ratio of water
The ratio of water is crucial to the workability of self-leveling mortar. Proper moisture helps to improve the fluidity and construction performance of the mortar. Usually, the ratio of water to cement is controlled between 0.35 and 0.45. Too much water may cause the mortar to be too fluid and lose its self-leveling properties. Too little water may affect the hydration reaction of cement, resulting in insufficient strength.

3. Construction characteristics and applications of self-leveling cement/mortar
Self-leveling cement/mortar has excellent self-leveling properties, strength and durability, and is widely used in construction. Its construction characteristics enable it to obtain a flat surface in a short time, especially suitable for projects such as ground and floors.

Easy construction
Since self-leveling cement/mortar has strong fluidity, the construction process can be completed by simple mechanical mixing and splashing operations without complicated processes. After the construction is completed, the cement self-leveling mortar can level itself in a short time, reducing manual intervention and improving work efficiency.

Strong durability
Self-leveling cement/mortar has high compressive strength and crack resistance, and can maintain stability during long-term use. In addition, its low hydration heat characteristics also make it suitable for large-area paving, avoiding the generation of cracks.

Widely used
Self-leveling cement/mortar is often used in ground repair, industrial plant floor, commercial building and home decoration, etc. It is especially suitable for those environments that require flat ground, no joints and strong load-bearing capacity.

The formula and mixing process of self-leveling cement/mortar is very complicated, involving the precise proportion control of cement, aggregate, admixture and water. The correct proportion and high-quality raw materials can effectively ensure its construction performance and final surface quality. With the improvement of the construction industry’s requirements for ground quality, the market demand for self-leveling cement/mortar as a high-performance building material will continue to grow, and its development prospects are broad. In practical applications, adjusting the formula according to different construction needs can better play its advantages and provide high-quality solutions for ground construction.