Yishimei: Special Masonry & Plastering Mortar of Thin-Layer Ready-Mixed Dry Mortar Solves Wall Issues

Concrete blocks are a new type of wall material featuring energy conservation, land saving, and waste utilization. They offer advantages such as light weight, thermal insulation, sound absorption, earthquake resistance, fire resistance, ease of sawing, planing, and nailing, simple construction, and increased usable building area. Widely used in civil and public buildings, they also have drawbacks including low strength, high dry shrinkage value, and poor adhesion to mortar.

Hollowing and severe cracking on the surface of concrete walls have seriously hindered the promotion and application of aerated concrete. Consequently, many builders, owners, designers, and construction units are reluctant to use aerated concrete products. Hollowing and cracking of the paint layer have become a bottleneck restricting the further application of aerated concrete, and these issues must be addressed with due attention.

1.Analysis of Causes for Cracking in Concrete Wall Plastering

For concrete walls and brick walls, cement mortar is usually used to prepare the surface layer for painting. To ensure sufficient hydration of the cement in the plaster mortar on the wall, brick masonry must be thoroughly wetted to reduce water absorption before plastering. Concrete blocks and masonry also require wetting before plastering, but they have the characteristics of high water absorption and slow water absorption rate. Particularly for walls that have already been leveled, repeated wetting is inconvenient and results in little water absorption, leading to poor construction conditions (e.g., groundwater accumulation). Insufficient water supply causes inadequate hydration of cement in the mortar, resulting in poor adhesion, hollowing, and cracking of the plaster layer.

The more severe the hollowing and cracking, the greater the impact on the project. To solve this problem, a mortar mix of 1:1:3-6 (cement, slaked lime, and sand) is used under the premise of proper wetting. This mix is called lime mortar (or hydrated lime mortar) because it reduces cement content and increases slaked lime, which absorbs and neutralizes excess moisture. After years of application, this mix has demonstrated good performance with almost no cracking, provided that operators strictly follow the construction procedures. In recent years, with the development of construction technology and the stable supply of slaked lime, however, hollowing and cracking issues still persist.

2. Thin-Layer Premixed Dry Mortar: Masonry Mortar

Masonry mortar is used for bonding bricks, stones, blocks, and other masonry units.

Adopting the TLC method (Thin-Layer Construction), the mortar joint thickness is only 3-4mm, approximately 1/3 of that of conventional thick mortar joints. This not only saves material consumption but also significantly reduces cold bridges and thermal bridges due to the thin joints. It effectively enhances the thermal insulation performance of block walls, fully aligning with the national policy of improving building energy efficiency and constructing a resource-saving society while extending the service life of walls. Additionally, it allows wetting of both concrete and aerated concrete blocks before and after masonry, reducing construction steps, saving water, and avoiding later wall shrinkage caused by dehydration—addressing one of the root causes of masonry cracks.

3. Thin-Layer Premixed Dry Mortar: Plastering Mortar

Plastering mortar is suitable for internal and external walls, facades, and ceiling plastering in construction and decoration projects. It helps level and protect the base surface of buildings.

4. Shortened Construction Period (1-2 Days for Peak Efficiency)

No interface pretreatment (e.g., using interface agents, throwing cement paste, or roughening the surface) is required during plastering construction.

The cost per square meter of plastering is not higher than that of traditional cement mortar.

Due to its fast setting, strong adhesion, and excellent workability, thin-layer plastering reduces construction processes and shortens the construction period, facilitating schedule acceleration and improving economic benefits.

The plaster layer can be as thin as 3-5mm, reducing on-site waste and saving materials during construction.