What Alkalinity Issues Should Be Noted When Using Sulphoaluminate Cement in GRC?

The application of sulphoaluminate cement in GRC requires strict control of its alkalinity level. Although its alkali content (Na₂O equivalent 0.3%-0.8%) is significantly lower than that of Portland cement, attention must still be paid to the long-term erosion risk posed to glass fibers by the alkalinity of hydration products. The optimal alkalinity range is pH 11.5-12.0, which both ensures normal cement hydration and guarantees fiber durability.

Extensive accelerated aging tests have shown that when the system pH exceeds 12.5, the annual strength decay rate of alkali-resistant glass fibers can reach 15%; when controlled within the 11.5-12.0 range, the 50-year strength retention rate can exceed 80%. Qinglong GRC effectively reduces the alkalinity of pore solution by adding active admixtures such as silica fume (8%-10%) and mineral powder (5%-8%), stabilizing the pH at 11.8±0.2, while generating more low-alkalinity C-S-H gel through pozzolanic reactions, significantly improving long-term fiber durability.

Alkalinity Control Technical Measures

Adding silica fume (8%-10%) to reduce the OH⁻ concentration in pore solution; using mineral powder (5%-8%) to consume Ca(OH)₂; controlling the water-binder ratio at 0.30-0.35 to reduce soluble alkali content. These measures effectively control alkalinity.

Fiber Protection Interface Optimization

Using zirconia-type alkali-resistant glass fibers (ZrO₂≥16.5%); applying coupling agent treatment to fiber surfaces; optimizing matrix density to reduce alkaline solution penetration. These measures protect the fibers.

Long-term Durability Assurance

90-day strength retention rate ≥75% in accelerated aging tests (80℃ alkaline solution); performance decay ≤15% after 300 wet-dry cycles; annual carbonation depth growth ≤0.1mm. These data verify durability.

On-site Application Control Points

Curing humidity ≥90% to prevent drying shrinkage cracks; avoiding early drying that causes alkali concentration in capillary pores; surface coatings to block CO₂ and moisture. These controls ensure long-term performance.

Alkalinity control is the key to GRC durability. Through systematic control, Qinglong GRC ensures the long-term safe use of its products in harsh environments.