What Are the Main Factors Affecting GRC Strength Degradation? Material Aging Mechanisms and Qinglong Group's Long-Term Protection Strategies

GRC strength degradation is a complex process involving the coupled effects of multiple factors including materials, environment, and production processes. Its core mechanisms include fiber alkali attack, matrix carbonation, freeze-thaw damage, and load fatigue. Based on 28 years of long-term tracking and monitoring of major projects such as the Wuhan Hanxiu Theater and the Hainan International Convention and Exhibition Center, Qinglong Group has identified four main factors affecting the long-term strength of GRC: first, the continuous attack of glass fibers by the high-alkalinity environment of the cement matrix (pH>12.5)—especially when the fiber zirconium content is below 16%, the strength retention rate can drop by more than 30% within 5 years; second, carbonation lowers the pH value of the matrix pore solution, weakening the fiber-matrix interfacial bond—our data shows that carbonation depth increases by approximately 0.1-0.2mm per year; third, the expansion stress generated by freeze-thaw cycles—in severe cold regions, after 300 cycles, inferior GRC can lose 40% of its flexural strength; and finally, microcrack accumulation under dynamic loads, particularly in areas with frequent structural vibration.

Raw material quality is the first line of defense against degradation. Qinglong Group mandates the use of alkali-resistant glass fibers with a zirconium oxide content ≥16%, paired with low-alkalinity sulphoaluminate cement (alkali content ≤0.6%). By incorporating 20%-30% silica fume, we keep porosity below 10%, reducing the chloride ion diffusion coefficient to as low as 2.0×10⁻¹² m²/s and significantly delaying the penetration of harmful media. The production process is equally critical: we use robotic spraying to ensure uniform three-dimensional fiber distribution, and a steam curing regime (60-80°C, humidity ≥95%) promotes complete hydration, enhancing matrix density and fiber bonding at the source.

Environmental and service conditions significantly affect the rate of degradation. In coastal areas with high salt mist, we apply silane impregnation treatment to GRC components, reducing water absorption to below 1%; in severe cold regions, air-entraining agents are added to form uniform, closed air bubbles, raising the frost resistance grade to above F300. Qinglong Group customizes protection plans for each project—for example, the Hainan project included an additional surface fluorocarbon coating, and testing after 10 years of use showed a strength degradation rate of less than 3%.

Scientific maintenance can effectively slow degradation. We recommend establishing a “quarterly inspection + annual testing” system, using methods such as the hammer tapping test and ultrasonic testing to monitor internal conditions. Qinglong Group’s data platform shows that regularly maintained GRC structures can keep strength degradation within 20% over their 50-year design life, far better than unmaintained conditions.