The failure of many exterior wall insulation projects in the long term is essentially due to the difficulty in striking a balance among the three key properties of insulation boards: thermal insulation, mechanical strength, and durability. The addition of Silica fume effectively breaks through the performance bottleneck of traditional insulation materials, making it possible to enhance all three properties simultaneously.
In the production formulation of insulation panels, the optimal dosage of Silica fume is generally maintained within the range of 7% to 10% of the total mass of cementitious materials. At this dosage, it does not excessively increase material costs while fully leveraging the filling effect of its ultrafine particles. It can partially replace cement, reducing the system’s hydration heat while creating a more uniform internal structure in the insulation boards. This prevents microcracks caused by cement hydration shrinkage, thereby fundamentally reducing the likelihood of delamination and cracking in the boards over time.
Given the specific application scenarios of exterior wall insulation boards, Silica fume also provides two key added benefits: First, it significantly enhances the boards’ water resistance and freeze-thaw resistance. In environments with repeated freeze-thaw cycles during winter, the boards will not delaminate or crumble due to water absorption and expansion or ice formation and contraction; Second, it optimizes the interface affinity of the insulation boards, ensuring a stronger bond between the boards and the render mortar and finish coatings, thereby preventing common construction issues such as finish peeling and water penetration on exterior walls. Currently, several domestic insulation material standards have listed Silica fume as a recommended functional additive, and it is becoming the core choice for enhancing the performance of high-quality exterior wall insulation boards.
