In building and industrial insulation engineering, humidity is a significant factor affecting insulation materials, especially for insulation systems exposed to humid environments for extended periods. The material's moisture resistance directly impacts its long-term stability and performance. Rock wool, a commonly used inorganic insulation material, has received considerable attention for its performance and moisture resistance in humid environments. This article analyzes the structural characteristics, moisture resistance, and impact on engineering applications of rock wool.

I. Structural Characteristics of Rock Wool

Rock wool is an inorganic insulation material made primarily from natural rocks (such as basalt and dolomite), melted at high temperatures and then fiberized. Its internal structure consists of fine fibers and pores. While providing good insulation performance, this structure also determines its performance in humid environments.

Because rock wool is made from inorganic materials, it is non-combustible and heat-resistant. However, its porous structure makes it prone to moisture absorption. If this moisture absorption is not effectively controlled, it may affect the insulation effect and long-term performance of the rock wool, especially in humid environments where its insulation capacity may decrease.

II. Moisture Resistance of Rock Wool

1. Water Absorption

The porous structure of rock wool determines its water absorption capacity. In humid environments or direct contact with water sources, rock wool may absorb moisture. This moisture absorption fills the pores inside the rock wool, reducing its insulation effect and increasing the rate of heat conduction. Therefore, in humid environments, the insulation performance of rock wool may decrease, especially under prolonged damp conditions. Moisture accumulation can also lead to condensation and frost formation, thus affecting the building's energy efficiency.

2. Moisture Resistance

Although rock wool has some water absorption, its moisture resistance is relatively strong. Most rock wool products undergo special treatments, such as applying a waterproof coating or incorporating a moisture-proof layer design, which effectively reduces moisture penetration. This moisture-proof design not only helps reduce moisture absorption but also improves the durability of rock wool in humid environments to a certain extent. Therefore, choosing suitable rock wool products in humid environments, combined with moisture-proof measures, can ensure its long-term stability to a certain extent.

3. Performance Changes After Moisture Absorption

When rock wool absorbs water in a humid environment, its thermal conductivity changes. Moisture entry leads to the filling of pores within the rock wool, resulting in increased thermal conductivity and decreased insulation performance. Furthermore, structural changes that may occur after moisture absorption, such as fiber expansion or collapse, will further reduce its insulation effect. Therefore, the performance changes of rock wool in humid environments require thorough consideration of moisture-proofing and waterproofing measures during construction and design.

III. Application Recommendations for Rock Wool under Different Humidity Conditions

1. High Humidity Environments

In high humidity environments, rock wool should be used in conjunction with waterproof and moisture-proof layers. For example, in basements, exterior walls, roofs, and other areas constantly exposed to moisture, rock wool installation must ensure adequate moisture-proofing to prevent moisture penetration and performance degradation. Using rock wool products with waterproof coatings or in conjunction with moisture-proof membranes can effectively improve the overall moisture resistance of the system.

2. Application to Interior and Exterior Walls and Roofs

For building components that need to remain dry for extended periods, such as interior and exterior walls and roofs, rock wool exhibits relatively good moisture resistance. Especially in dry environments, rock wool can maintain its excellent thermal insulation performance for extended periods. However, in applications exposed to extreme climatic conditions, special attention should be paid to the waterproof design of the rock wool to prevent moisture from affecting the insulation layer.

3. Selection of Waterproof Rock Wool

In high-humidity environments, selecting waterproof rock wool or rock wool treated with moisture-proofing is particularly important. Waterproof rock wool products can effectively prevent moisture penetration, ensure the stability of the insulation layer's performance, and extend its service life. This type of rock wool is commonly used in projects with high insulation requirements, such as cold storage, refrigerated equipment, and underground engineering.

As a high-quality insulation material, rock wool has excellent thermal insulation and high-temperature resistance, but its hygroscopicity in humid environments needs attention. Through reasonable moisture-proof design and selection of suitable rock wool products, the durability and performance stability of rock wool in high-humidity environments can be greatly improved. In construction projects, appropriate rock wool products should be selected based on actual humidity conditions and system requirements, along with necessary moisture-proof measures, to ensure the stability and effectiveness of the rock wool material during long-term operation.